SY T 0305-96 Tech.spec. of Pl Sys. Beach Shallow Sea

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China National Petroleum and Natural Gas Industry Standard

SY/T 0305-96

Technical Specification of Pipeline System forBeach-Shallow Sea

Issued at Dec.03,1996 Implemented from July 01,1997

Issued by China National Petroleum Corporation



China National Petroleum and Natural Gas Industry Standard

Technical Specification of Pipeline System for

Beach-Shallow Sea

SY/T 0305-96

Edited by: Survey and Design Institute, Shengli Petroleum Administration

No. 1 Oil Construction Company, Shengli Petroleum Administration

Approved by: China National Petroleum Corporation

Petroleum Industry Press

1996 Beijing



China National Petroleum Corporation Documentation

(96)CNPC Technical Supervision document No. 642

Re: the Notice of Approved publication of 14 Oil and Gas Industry Standardsincluding Gas Field Gas Gathering Project Design Specifications, and etc.

To all relevant units:

14 oil and gas industry standards (draft) including Gas Field Gas Gathering Project

Design Specifications, and etc. have been examined and approved to be publicized as

the oil and gas industry standards with their document numbers and names as follows:

No. Document Number Document Name

1 SY/T 0010-96 Gas Field Gas Gathering Project Design Specifications

(Replace SYJ 10-86)

2 SY/T0011-96 Gas Field Natural Gas Purification Plant Design

Specifications (Replace SYJ 11-85)

3 SY0043-96 Oil &Gas Field Ground Pipeline and Equipment

Coloring Standards (Replace SYJ 43-89)

4 SY/T 0091-96 Oil & Gas Field and Pipeline Computer Controlling

System Design Specifications

5 SY/T 0306-96 Petroleum Project Thermal Heating Technical

Specifications for Beach-Shallow Sea

6 SY/T 0307-96 Vertical Cylindrical Welded Steel Fixed Roof Storage

Tank Technical Specifications for

Beach-Shallow SeaPetroleum Project

7 SY/T 0308-96 Water Injection Technical Specifications of for Beach-

Shallow Sea Petroleum Project

8 SY/T 0309-96 Produced Water Treatment Technical Specifications for

Beach-Shallow Sea Petroleum Project

9 SY/T 0310-96 Instrumentation and Automation Technical Specification

for Beach-Shallow Sea Petroleum Project

10 SY/T 0311-96 ICT Standards for Beach-Shallow Sea Petroleum Project

11 SY/T 0312-96 Outfitting Technical Specification for Beach-Shallow

Sea Petroleum Project

12 SY/T 0313-96 Terminal Design and Construction TechnicalSpecifications for Beach-Shallow Sea Petroleum Project

13 SY/T 0314-96 Technical Specifications of Concrete Platform Structure

Design and Construction for beach-shallow sea

14 SY/T 0305-96 Technical Specifications of Pipeline System for beach-

shallow sea

The above standards will be implemented from July 1, 1997.

China National Petroleum Corporation

December 3, 1996



Table of Contents

1 General Principles...................................................................................................6

2 Technical Terms......................................................................................................7

3 Pipeline Routing Planning ......................................................................................8 3.1 General Rules...................................................................................................8

3.2 Routing Selection.............................................................................................8

3.3 Route Survey....................................................................................................9

4 Environment and Loads ........................................................................................10

4.1 General Rules.................................................................................................10

4.2 Natural Environmental Conditions ................................................................10

4.3 The pipeline Internal Conditions ...................................................................10

4.4 Loads..............................................................................................................11

5 Design ...................................................................................................................16

5.1 General Rules...............................................................................................16

5.2 The Piping system in the Mode of On-location.............................................17

5.3 The Piping System in the State of Installation...............................................22

5.4 Pipeline Fittings .............................................................................................24

5.5 Insulation Pipeline .........................................................................................24

6 Accessory Materials for Pipe and Pipeline ...........................................................25

6.1 General Terms and Conditions ......................................................................25

6.2 Steel Pipe for Pipeline and Riser ..................................................................25

6.3 Pipe Fittings ..................................................................................................27

6.4 Bolts ..............................................................................................................27

6.4 Supporting Member .......................................................................................28

6.5 Support Fittings..............................................................................................28

7 Pipeline Anti-Corrosion & Weight Coating .........................................................29

7.1 Pipeline anti-corrosion ...................................................................................29

7.2 Weight coating ...............................................................................................29

8 Pipe Section Onshore Prefabrication and Assembling .........................................30

8.1 General Requirements....................................................................................30

8.2 Quality Requirement for Pipes Delivered to the Workshop..........................32

8.3 Prefabrication and assembling .......................................................................35

9 Pipeline Installation on Beach-shallow Sea..........................................................38

9.1 General Requirements....................................................................................38

9.2 Pipeline Route Control...................................................................................40

9.3 Connection .....................................................................................................40 9.4 Trenching and pipeline burying.....................................................................43

10 Final inspection and completion test..............................................................44

10.1 Final inspection............................................................................................44

10.2 Work handover and acceptance ...................................................................45

Appendix A Wind Load ...............................................................................................49

Appendix B Set value of fluid dynamic factor CD, CM and CL value.......................51

Appendix C Set value of Group pile interference factor Kg and sun blind factor Kz.53

Appendix D Vortex shedding phenomenon caused by ocean current .........................54

Appendix E Wave impact load ....................................................................................57

Appendix F Buckle calculation....................................................................................59

Appendix G Sample collecting method .......................................................................62 Appendix H Identification of Welders.........................................................................68



Appendix J Pressure test report...................................................................................71

Additional Notes ..........................................................................................................73

Attachment Technical Specification for Pipeline System in Beach-shallow Sea........74



1 General Principles

In order to enable the standardization of the design and construction of the beach-

shallow sea pipeline system, to ensure the safety, reliability, the use of advanced

technology, to be economic and practical, and to realize environmental protection, thisSpecification is formulated.

This Specification is applicable to the design and construction of the steel pipeline

system for the transportation of oil, gas or water in the area of beach-shallow sea, but

not applicable to that of the pipeline system for the transportation of LPG and LNG.

Reference Standards:

GB 8163-87 Seamless steel pipe for fluids transportation

GB/T 8923-88 Rust grades and derusting grades of the Steel Surface prior to

Painting

GB 9711-88 Spiral submerged arc welded steel pipe for the transportation of

oil and gas

JB 755-85 Pressure Vessel Forgings Technical ConditionsSYJ4050-91 Seismic Design Specification of the underground oil (gas)

transportation steel pipe

SY 4052-92 Evaluation Methods for the oil/gas pipe welding technology

SY 4056-93 Butt weld radiography and quality classification of the oil/gas

steel pipe

SY 4060-93 Butt weld ultrasonic inspection and quality classification of the

oil/gas steel pipe

SY/T 4084-95 The beach-shallow sea environmental conditions and load

technical specifications

SY/T 4091-95 The anti-corrosion technical specifications of the beach-

shallow sea petroleum projectSY/T 4092-95 The heat preservation technical specification of the beach-

shallow sea petroleum project

SY/T 4100-95 The measurement technical specifications of the beach-shallow

sea project

SY/T 4101-95 Rock and Soil Engineering Survey specification of the beach-

shallow sea

SY 5297-91 Longitudinal resistance welded steel pipe for the transportation

of oil/gas

The design and construction of the pipeline part of the beach-shallow sea which

will go up with the tide shall comply with the relevant existing nationalstandards(specifications) for onshore pipeline system.

In addition to this specification, the design and construction of the pipeline system

for the beach-shallow sea shall comply with any other relevant existing national

standards(specifications).



2 Technical Terms

2.0.1 Pipeline System for beach-shallow sea:

Refers to all the facilities and components of the steel pipe engineering

project located at the beach-shallow sea for the transportation of oil, gas or water,including the pipelines for beach-shallow sea, risers, supporting structures, pipe

accessories, anti-corrosion system, leakage monitoring system, alarming system and

emergency shutdown system, and etc..

2.0.2 Pipeline for beach-shallow sea:

Refers to the pipelines located at the beach-shallow sea area, including the

pipelines connecting different platforms, or connecting platform with other facilities

within the beach-shallow sea area, and the pipelines within the tide supralittoral zone,

eulittoral zone and the very shallow sea adjacent with the shore (exclude the riser).

These pipelines may be partly or whole suspended across the seabed, or placed on the

seabed or buried under the seabed.

2.0.3 Riser:Refers to the pipes connecting the pipelines for beach-shallow sea with the

platforms or the production equipments of other beach-shallow sea facilities, with the

expansion bend connector at the bottom as part of it.



3 Pipeline Routing Planning

3.1 General Rules

3.1.1 In the routing planning of the pipeline system for beach-shallow sea (herein

refer as pipeline system), relevant route positions shall be selected based on the local

natural environmental conditions and the regional planning of the system and etc..

3.1.2 The physical environmental conditions of the location of the system mainly

include wind, wave, current, tide, ice, earthquake and tsunami, environment

temperatures(seabed, seawater, atmosphere), marine growths, beach-shallow sea

water quality and bottom material, beach-shallow seabed topography and soil

characteristics(include corrosiveness and conductivity), seabed deposition and its

activities, and etc..

3.1.3 The regional planning of the location of the pipeline system mainly refers to

comprehensive utilization plan, the engineering facility plan and the overalldevelopment plan of the oil(gas) of the beach-shallow sea, and different facilities and

installations plans within the oil(gas) field in the pipeline location and its adjacent sea

area.

3.2 Routing Selection

3.2.1 The route of the pipeline for beach-shallow sea(herein referred as the pipeline)

shall locate in the area with plain and stable topography, and shall be as smooth and

straight as possible. Appropriate marks shall be set up on the selected routing

locations, meanwhile, survey shall be carried out on the selected routes according to

3.3 of this specifications.3.2.2 The route shall avoid to be in the anchoring area of any ship or boat, the area

where there exist underwater objects( such as sinking ships, piles, and rocks, etc.), the

moving fault, the weakness soil sliding zone and the heavy cut-and-fill area of the

sedimentary layer. If it is not possible to avoid such areas, carry out protective

measures, meanwhile, choose a suitable location and shorten the passing distance.

And take into consideration of the impact on the pipeline system of the ship sailing,

fishing activities, mariculture, military restriction, environmental protection, pipeline

landing, the existing pipelines, cables and other facilities, and etc..

3.2.3 The distance between the new designed pipeline system and the existing

pipeline and other offshore engineering structures or offshore facilities and

installations shall comply with the following requirements:3.2.3.1 The trunk pipeline in the open sea area shall be far away from the

seabed barriers and dangerous objects with a distance of no less than 250m, and shall

be away from original pipelines or cables with a horizontal distance of no less than

30m.

3.2.3.2 The pipeline located within the oil(gas)field of the beach-shallow sea

shall keep a proper horizontal distance away from the original existing pipelines and

other offshore structures or petroleum project installations, so to ensure the safety of

the original offshore structures or the petroleum project installations during the

pipeline laying and installation, and also to ensure the normal work of well drilling

and workover operation in predetermined locations not be disturbed with an

appropriate safe distance.



3.2.4 The new designed pipeline shall not cross the original pipelines or cables. If not

possible to avoid, ensure a vertical distance of no less than 0.3m for the crossing

position.

3.3 Route Survey

3.3.1 Upon the determination of the pipeline route, detailed survey shall be carried out

on the selected route. The route survey will generally cover the hydrological and

meteorological conditions, the topography and shallow geological profile, the seabed

soil characteristics, seabed obstructions and potential hazards along the pipeline route.

3.3.2 The survey on the hydrological and meteorological conditions along the pipeline

route shall at least include: wind and storm, wave, current, tide, ice, environmental

corrosiveness and the environmental temperature change and etc., along the long

distance of the pipeline route.

3.3.3 The survey on the topography along the route shall comply with the following

requirements:

3.3.3.1 The methods and requirements of the survey on the topography shall be in compliance with the relevant regulations of the measurement technical

specifications of the beach-shallow sea project.

3.3.3.2 The width and accuracy of the route survey corridor on both sides of

the axis shall meet the safety requirements of the normal construction and operation

of the pipeline. Meanwhile, shall also consider the possible room for the adjustment in

the pipeline axis. Normally, the width on both sides of the axis shall be 250m, and

accuracy 1:5000 -1:2000. For the areas which need detailed investigation such as the

area near the platform or other offshore facilities, the obstruction area, and the area

where the seabed terrain changes obviously, 1:500 -1:200 bathymetric shall be

adopted.

3.3.3.3 Identify the seabed obstructions along the pipeline route combinedwith the topography survey. Specially pay attention to the investigation of the rock

outcrop, massive floating stones, unstable slopes, tidal creeks and river mouth,

erosion and sedimentation and other seabed topography changes, and the sinking

ships, seabed devices, seabed cables and potential hazards, and etc..

3.3.3.4 The measurement depth of the pipeline sediment shall excess the

maximum depth during the pipeline installation, digging, burying and operation

period.

3.3.4 The seabed soil characteristics along the pipeline route shall be obtained through

seismic survey, core drilling, site testing ,drilling and sampling and lab testing andetc.. Meanwhile, through geological investigation, seabed topography measurement,

diving touch, biological survey and chemical analysis and etc, necessary

supplementary materials and data can be also obtained. The site and lab testing

technology shall comply with relevant stipulations in Rock and Soil Engineering

Survey specification of the beach-shallow sea.

3.3.5 When asked to make evaluation on such specific matters as the difficulty of the

evacuation and (or) the laying operation, the possibility of soil sliding or liquefaction,

and the possibility of erosion and sediment, specific survey shall be carried out on the

seabed sediment.



4 Environment and Loads

4.1 General Rules

4.1.1 During the design and construction of the pipeline system, the impact of various

natural environmental conditions and the pipeline internal conditions on the pipeline

system shall be taken into consideration.

4.1.2 The loads imposed on the pipeline can be categorized as: environmental load,

work load (including the installation period and the operation period) and Incidental

load.

4.2 Natural Environmental Conditions

4.2.1 The choose of physical environmental conditions such as wind, wave, current,tide, ice, temperature and seism and etc. shall comply with the relevant regulations in

The Beach-Shallow sea environmental conditions and Loads Technical Specifications.

4.2.2 Shall take into consider the impacts on the pipeline anti-corrosionling and

protection system of such specialties as related to the seawater seasonal changes and

the seabed soil along the pipeline route, including the temperatures (the air

temperature, water temperature and the seabed soil temperature), the salinity, the

oxygen content, the PH value, the resistivity, current and the marine organism

activities, and etc..

4.2.3 Shall consider the effects of all the marine life within the pipeline area to the

pipeline system, as well as the loads changes and influences caused due to the marine

life clinging onto the pipelines and risers.

4.3 The pipeline Internal Conditions

4.3.1 Installation conditions

Shall compile a pipeline internal status explanation statement during the period of

pipeline storage, installation and pressure testing until being put into use. Determine if

temporary anti-corrosion methods to be carried out based on the duration of the

pipeline and its accessories exposing to the seawater and the moist atmosphere.

4.3.2 Operational conditions

4.3.2.1 Clarify in detail the physical characteristics and the chemical composition of

the transportation media , as well as the temperature, the pressures and their changesalongside the pipeline route.

4.3.2.2 Clarify in detail the limits of the temperatures and pressures, as well as the

allowable concentrations of the corrosive elements in the transportation media, the

following elements and their concentrations shall be specially paid attention to:

1) Hydrogen sulfide and other sulfides;

2) Carbon Dioxide;

3)Oxygen;

4)Water;

5)Chloride



4.4 Loads

4.4.1 Load conditions and design states

4.4.1.1 The design of the pipeline system shall be carried out based on thefollowing load conditions and the most unfavorable loads combinations:

1) Work loads;

2) The Physical environmental loads and the simultaneous work loads.

4.4.1.2 The following two major designing states shall be taken into

consideration for the pipeline system design:

1) After the completion of the pipeline installation and the designed

working states including the states of operation and maintenance have

been achieved;

2) The various installation working states prior to the fully completion of

pipeline installation, including transportation, towing, laying, lifting,

connecting and burying, and etc., and the overhaul states after thetermination of operation.

4.4.2 Loads combination principle

4.4.2.1 For the pipeline load conditions under the selected design states, shall

consider the most unfavorable loads combination which may imposed

upon it. However, the seismic loads shall not be combined with other

natural environmental loads.

4.4.2.2 For different components or pipe sections (pipeline, riser) of the same

pipeline, and when under different status (transportation, towing, laying,

lifting, connecting, burying, pressure testing and inspection), shall

consider the actual most unfavorable load combination. During the

combination, if the water depth has a sensitive impact, shall consider thechanges in the water level.

4.4.3 Work load

4.4.3.1 The work load refers to the load which the pipeline is bearing without

any natural environment loads such as wind, wave, ice, earthquake, and

etc..

4.4.3.2 The work load under normal operation status will generally come from

the following factors:

1. Weight, including:

1) The pipe section weight including that of coatings, weight coatings and

all pipe fittings.2) The weight of the transportation media,

3) Buoyancy.

2. Pressure, including:

1) Internal fluid pressure,

2) External hydrostatic pressure,

3) Soil pressure of pipeline burying,

4) Ice pressure

3. The expansion or contraction caused by the change of temperatures,

including the influence of the temperature of the transportation media to that

of the pipeline material, and the temperature changes of the pipe wall caused

by other reasons. The temperature differences between that of the



transportation media during operation and that of the pipe wall during

installation shall take into consider.

If the temperature fluctuation may cause material fatigue, shall take it

consideration during the inspection of the fatigue strength of the material.

4. The friction between the pipeline surface and the soil.

5. Under installation state, if the prestressing force caused by the permanent bending or elongation deformation shall affect other loads capabilities to a

certain degree, it shall be taken into consideration.

4.4.3.3 The work loads under installation state include:

1) Gravity

2) Buoyancy

3) Pressure

4) Installation force

4.4.4 Natural Environment loads

4.4.4.1 General requirements

1) The natural environmental loads imposed on the pipeline system shall

include various loads caused by natural phenomena such as wind load,wave load, current load, ice load and earthquake load, and etc.

2) The calculation of natural environmental loads shall be based on the

methods of probability and statistics. For various natural phenomena that

may occur simultaneously, the probability of their simultaneity shall be

considered, and various independent effects shall be summed up in a

proper manner.

3) When there’s not enough cumulative probability data for the wind, wave

and current in different directions, can assume there’s a same cumulative

probability for the wind, wave and current in all directions.

4) For the natural load under normal operation state, shall consider that therecurrence shall not less than the maximum load in 50 years.

5) For the installation state, the design cycle shall be 3 times of the scheduled

duration of the operation, and not less than 3 months. However, for the

short operation duration of 5 days or less than 5 days, if 48 hours of

weather forecast can be obtained, and meanwhile such operation may be

suspended in between, the environment loads can be determined according

to the reliable weather forecast.

4.4.4.2 Wind load

1) Based on the obtained wind data, determine the wind load in

accordance with the general regulations or the Appendix A of this

Specification. Can also use the data obtained through testing.2) When determining the wind load, the wind data shall be identified

based on the statistics. When the wind load combine with the

maximum wave load, shall take the continuing wind speed in 1 minute

as the basis. If gust is more unfavorable than the continuing wind, 3s

gust speed shall be taken as the basis.

3) In addition to determine the maximum static(or quasi-static) wind load,

the possibility of riser vibrating caused by the cyclic loads induced by

the wind shall be taken into consideration.

4.4.4.3 Wave load

1) The wave load imposed on the pipeline shall be determined through

recognized methods and proper wave theory calculation based on the data of wave



height, cycle, water depth, pipeline size, and etc. It can also be determined through

mode testing.

2) For round risers, the wave force (f) of the unit length which perpendicular

to the pipe axis can be obtained through Morison formula:

21

2 4 D l M l f C D u u C D u

π ρ ρ = + &………………………. (4.4.4-1)

f —the wave force on the unit length which perpendicular to the axis, N/m;

ρ —water density, kg/m3

CD—Drag coefficient perpendicular to the axis,

CM—Inertia coefficient;

Dl— the effective diameter of the pipe (including the increased thickness of anti-

corrosion coating, concrete weight layer and marine life attachment)

u—The velocity distribution of the water particles perpendicular to the pipe axis,

relative to the pipe components, m/s, u represents the absolute value. When

considering the combined effects of the current and wave, u will be the composition

vector of the sum of the speed vectors of water particle and the current, which is perpendicular to the pipe components.

u&—The acceleration distribution of the water particles perpendicular to the pipe axis,

relative to the components, m/s2

3) The wave force on the pipe lying on the seabed shall be calculated through the

following methods:

(1) The same formula as that of the unit length horizontal wave force, (f x)

(4.4.4.-1)

(2) The unit length lift force ( f L) can be calculated through formula 4.4.4.-2.

21

2 L L l

f C D u ρ = ................................................... (4.4.4-2)

f L—The lift force of unit length , N/m

CL– The lift force coefficient.

4) The horizontal wave particle velocity distribution (u) and the acceleration

distribution ( ) shall be identified through appropriate wave theory based on the

designed wave characteristics and the water depth, with. The angle between the

movement direction of the wave particle and the pipe shall be based on the actual

situation, but shall no less than 35

u&

o

5) The selection of CD, CM, and CL shall be based on the mode testing. When there’s

no testing data or the data is not sufficient, can refer to the recommended value inAppendix B based on the Reynolds Re, Kc (Keulegan-Carpenter)numbers, the pipe

roughness and the distance between the pipe and the fixed boundary, and etc..

6) When the ratio of the effective diameter (Dl ) and the space (hr ) between risers or

between risers and platform jacket center is less than 4.0, it can be considered as a

risers group. Upon calculating the wave load, the interference factor (Kg) and the

screen coefficient (Kg) of the risers group shall be multiplied with. The choosing of

the Kg and Kg can refer to the recommended value in Appendix C.

7) For the exposed riser and pipeline suspending section, shall consider the vibration

caused by vortex separation and the instability induced by waves.

8) For the pipeline and risers impacted by waves, shall consider the influence

of the wave impact to the pipeline and risers in accordance with Appendix E.4.4.4.4 Current load



1) When only considering the current on the pipeline or the risers, the unit

length current load f DC can be calculated through formula (4.4.4-3):

21

2 DC D C f C Au ρ = ………………………………….. (4.4.4-3)

f DC— the unit length current load, N/m.

uc—design current speed, m/s

A—the projection area of the pipe unit length perpendicular to the current direction,

m2

2) When only considering the current effect on the pipe, the current lift of unit

length f LC can be caculated through formular 4.4.4-4,

21

2 LC L C

f C Au ρ = ………………………………………….. (4.4.4-4)

3) For the pipe or the risers’ suspending section with current effect, the

possibility of vibration caused by Von. Karman vortex shall be considered, with the

calculation method complying with Appendix D.

4.4.4.5 Ice load

1) For the area with ice or floating ice, shall consider the possibility of various

ice loads on the pipeline system. The effects of the ice to the pipeline system shall

include the compression and gravity of the ice formation, and the abrasion, impact

and pipeup of the floating ice.

2) When the water surface of the pipeline system is under freezing status (may

caused by the wave splash, and etc.), the following forces shall be taken into

consideration:

(1) Ice weight,

(2) The impact force induced by the ice moving upon ice melting.

(3) The force induced by ice expansion

(4)The increased wind load or wave load due to the expansion of the exposing

area or volume.

3) Under the force of the wind and current, the identification of ice load

induced by the squeezing of large scale of ice field shall comply with the relevant

regulation in the Beach-shallow Sea Environmental Conditions and Load Technical

Specifications.

4.4.4.6 Earthquake Load

1) When laying of pipeline system in seismic active area, shall consider the

impact and effect of the inertia force and the fluid pressure caused by earthquake. For the pipes buried under the seabed, shall consider the impact and effect of the soil

deformation and earth pressure caused by earthquake.

2) The identification of the basic seismic intensity of the sea area shall comply

with the regulations of the state seismological department.

4.4.5 Incidental Load

4.4.5.1 The Incidental loads generally will include:

1) Ship collision, anchor bumping and catching,

2) Impact of the trawl gear,

3) Bumping of the falling objects.



4.4.5.2 For the pipe sections and components which are vulnerable to the

incidental loads, effective protective measures shall be carried out to prevent any

damage to the pipeline system caused by such incidental loads.



5 Design

5.1 General Rules

5.1.1 In the piping system design, the designed internal pressure should not be lessthan the maximum allowable internal pressure value of the internal medium in the

said pipe section under normal transmission condition.

5.1.2 Any component and pipe section of the piping system should be able to stand

the pressure difference between design internal pressure and the minimum allowable

external pressure, and be able to endure the maximum allowable external pressure.

5.1.3 The maximum and the minimum design temperatures of the piping system are

determined by the operating temperature and environmental temperature. Different

segments or pipe sections of the piping system should have different design

temperatures when there is obvious change in the operating and environmental

temperatures along the route of pipeline.

5.1.4 The normal design temperature of the pipeline should be -20 to 120℃. Thedesign should consider its cold brittleness when pipeline metal temperature is below -

20℃, but when pipeline metal temperature is higher than 120℃, correction factors for

high temperature shall be introduced in the relevant safety guidelines.

5.1.5 In designing, it is required to ensure the piping system functions under design

conditions, and prevent the occurrence of the following damages:

5.1.5.1 yielding

5.1.5.2 buckling and destabilization

5.1.5.3 fatigue damage

5.1.5.4 brittle fracture

5.1.5.5 ductile fracture propagation

5.1.5.6 excessive damage or falling off of pipeline weight-coating

5.1.5.7 loss of on-location stability

5.1.6 The strength standard should use allowable stress or allowable strain methods.

5.1.7 The structure analysis model of piping system should accurately simulate the

major characteristics of actual structure system including load, support condition and

structural feature. For risers, apart from taking into account of various working loads,

environmental and accidental loads, other factors such as platform displacement,

action and influence by submarine horizontal pipe sections and surrounding medium

shall be considered also. The binding features of riser support clamping shall also be

simulated correctly.

5.1.8 The mechanical calculation of the piping system, that is: force, moment of force,stress, strain, fatigue, and buckle should follow generally accepted methods such as

statics, dynamics, strength of material and fracture mechanics and damage mechanics

and others; it should also comply with the relevant regulations of the specification.

5.1.9 When the dynamic response of the structure imposes big impact, it is necessary

to conduct verification of dynamic strength and fatigue. Conventional methods such

as time domain or frequency domain shall be applicable to dynamic analysis. On the

condition of conservative method, quasi-static analysis method can also used.

5.1.10 Model test can be used to assist or replace theoretical analysis under special

conditions. When theoretical analysis is not applicable, it is necessary to obtain design

data by model testing or field full-scale test.



5.2 The Piping system in the Mode of On-location

5.2 The Piping system in the Mode of On-location

5.2.1 General requirements

5.2.1.1 The pipeline and risers should meet the minimum safety standards to prevent structural failure or damages listed in 5.1.5 of the specifications.

5.2.1.2 The risers and the platform supports should be connected reliably by

clamping apparatus (fixture). The layout of fixture should be helpful to reduce

environmental load, prevent or reduce accidental load; if necessary, riser collision

avoidance system (CAS) or other protection measures should be set above the

designed low water level in order to protect risers.

5.2.1.3 The route of pipeline should not be too close to other offshore facilities,

and should comply with requirements of 3.2.3 of this Code.

5.2.1.4 The piping system should be equipped with the following protection

device and provide the protection in case of damage.

a. external coating in concrete or other materials b. buried under seafloor

c. backfilling or covering with gravels, etc.

d. other forms of mechanical or structure protection

5.2.1.5 During the piping system design, it is necessary to avoid free spanning

and riser bottom hanging. If inevitable, its supporting part should provide reliable

support for the pipeline. Any spanning or hanging section should have sufficient

strength, stability and sufficient fatigue life; It is required to adopt all kinds of

technical methods prevent against non-design spanning or hanging resulted from

scouring of seabed, and so on.

5.2.2 Strength5.2.2.1 At any position of the piping system, the pipe wall circumferential

stress (hoop positive stress) caused by the pressure difference between design

internal pressure and minimum external pressure, should not surpass the allowable

circumferential stress value ypσ given in formula 5.2.2-1.

yp s s t K σ η σ = ...................................................... (5.2.2-1)

of which, ypσ --------- allowable circumferential stress, N/mm2

ηs --------- strength utilization coefficient in on-location mode

σs --------- minimum Yield strengthof steel pipe, N/mm2

K t --------- temperature reduction coefficient; when pipe wall metal

temperature gets below 120℃, it is necessary to consider the reduction of K t

according to the nature of metal material.

Strength utilization coefficient under on-location condition Table 5.2.2

Condition of load

Position

Operating load Environmental load and

simultaneous operating load

Pipeline 0.72 0.96



Riser 0.50 0.67

* Seismic load may be taken as 0.80.

5.2.2.2 If more accurate calculation is not available, circumferential stress σy

stated in 5.2.2.1 can be calculated by formula 5.2.2-2.

( )2

y i c

D p pσ

δ = − ...................................... (5.2.2-2)

of which, σy --------- pipe wall circumferential stress, N/mm2

pi --------- internal design pressure, MPa

pc --------- minimum design external pressure, should not be

higher than the external hydrostatic pressure the

calculation point of pipeline at design low water

level, MPa

D --------- nominal pipe outer diameter, mm

δ --------- pipe wall nominal thickness, mm

5.2.2.3 The total cross-section out-of-roundness due to pipeline bending and

manufacturing tolerance should be no more than 2%.

5.2.2.4 When calculating longitudinal stress of riser and pipe wall, it is

required to consider all factors (that may cause longitudinal force) such as

temperature, internal pressure change, residual pulling force during the course of

pipe laying, soil friction force of buried pipeline, etc.

5.2.2.5 When circumferential stress, longitudinal stress and tangential stress

are present simultaneously, equivalent stress should be used as one of the strength

standards. Pipe wall equivalent stress σc is calculated by formula 5.2.2-3.2 2 23

c x y x y xyσ σ σ σ σ τ = + − + ................................... (5.2.2-3)

c ypσ σ ≤ .................................................... (5.2.2-4)

of which,

σc ------ equivalent stress, N/mm2

σc p ------ pipe wall allowable equivalent stress, N/mm2

σx ------ longitudinal stress, N/mm2

σy ------ circumferential stress, N/mm2

xyτ ------ tangential stress, N/mm2

5.2.2.6 The seismic impact on piping system should comply with

specifications of 4.4.4.6 of this Code. Buried pipeline may use allowable strain

method and carry out Aseismatic checking computations by referring to the

Specification for Aseismatic Design of Buried Steel Pipeline for Transmission of

Oil and Gas.

5.2.3 Buckle

5.2.3.1 Three types of possible buckle instability should be examined for

piping system.

a. Pipeline partial buckle acted by external pressure, axial force and bending

moment



b. Pipeline partial buckle propagation acted by external pressure

c. Overall pressure bar instability of pipeline and riser acted by axial load

5.2.3.2 In the most unfavorable situation of combined load acted by external

pressure, axial load and bending moment, pipeline and riser should have adequate

capacity to prevent against partial buckle instability. When testing partial stabilitytesting, external pressure is calculated according to the hydrostatic head at design

high water level. As for buried pipelines, soil pressure forces should be counted.

Internal pressure is calculated in empty pipe status, that is: ZERO internal

pressure.

The combined stress caused by combined load should be no more than the critical

buckle value of compound stress; the buckle value can be determined by the result

of corresponding experiment or applicable formula, but it should introduce the

coefficient of utilization listed in Table F1.1 of Appendix F into its calculation, or

adopt the buckle control formula given in Appendix F.

5.2.3.3 Attention should be given to pipeline buckle propagation. Buckle

arrestor should be used when external pressure is larger than buckle propagation

pressure and that accidental load is likely to bring pipeline to initial buckle. The

buckle propagation pressure can be calculated according to generally accepted

theories and empirical formula, or on the basis of recommended formula in

Appendix F.

5.2.3.4 Pipeline and riser should undergo overall pressure bar stability test;

such calculation should include axial force and axial effect caused by difference

between internal and external pressures. Such overall instability is allowable if

displacement (deformation) caused by overall instability will not cause pipe wall

stress or strain to get beyond the limits of 5.2.2.3 to 5.2.2.5, and will not affect

other structures in vicinity.

5.2.4 Fatigue

5.2.4.1 Fatigue test should apply to components having notable fatigue effect

as a result of alternate stress; Fatigue test time interval should equal to the design

life of the system. The cumulative effect of alternate stress should cover all

experiences of the tested points, that is: the total sum of both installation and

operation stages.

5.2.4.2 The major factors creating alternate stress in the piping system are:a. impact effect by waves;

b. vibration of piping system;

c. platform displacement;

d. operating pressure and temperature changes;

5.2.4.3 Fatigue analysis may use cumulative damage method, which is based

on the empirical S-N curve, criterion of cumulative fatigue damage should meet

requirements of formula 5.2.4.

( ) s

ir

i t i

n

N η

=

≤∑ ..................................................... (5.2.4)

of which,



s -------- number of stress classification

ni -------- actual cycle index of stress class i

Ni -------- circle index of the stress that cause structural fatigue

damage when stress remains at class i value

ηr -------- fatigue damage coefficient of utilization, depending on

conditions of detection and repairs at the point; refer toTable 5.2.4 for use

Fatigue damage coefficient of utilization (ηr ) Table 5.2.4

Coefficient of

utilization

Detectable and

repairable position

Undetectable and

abandoned position

ηr 0.3 0.1

5.2.4.4 Fatigue analysis may also adopt fracture mechanics method; its special

parameters and safety standards should meet with the actual situations of objectsof analysis.

5.2.4.5 As to the practical structure alternate stress cycle index in its entire

design life, that is the ni value of formula 5.2.4, it should be determined by the

long-term distribution of structural dynamic response acted on by periodic load or

random load.

5.2.4.6 It’s important to accurately simulate and test the piping system’s

resilience and inertia features and boundary support feature so as to work out

accurately the dynamic force of system. During calculation, damping coefficient

should use its conservative value.

5.2.4.7 The experimental conditions for empirical curve S-N of formula

5.2.4.3 should match the reviewed structure’s formation, material, and state of

stress.

5.2.4.8 When a pipeline and riser has a free spanning, it is required to control

its spanning distance in order to make its natural frequency of vibration avoid the

vibration frequency caused by either individual or combined action of wind, wave,

ocean current and sea ice. Fatigue analysis should be given to such pipe sections.

5.2.5 On-location stability

5.2.5.1 Make sure pipelines remain in their initial mounted position during the

entire installation and operation period. Except for displacement caused by

allowable deformation, thermal expansion and limited post-installation settlement,

no other notable displacement is allowed either in axial, vertical or horizontaldirection. The maximum allowable displacement is subject to the following

restrictions:

a. Pipe wall stress is no larger than allowable strength, buckle and fatigue

damage;

b. Should not cause severe rupture or drop-out of the concrete weight

coating;

c. Should not damage corrosion preventive coating or sacrificial anode;

d. Should not affect the normal use of adjacent offshore facilities.

5.2.5.2 It is important to pay attention to the fact that pipeline will generate

axial expansion or contraction under the influence of temperature difference and pressure; the calculation should consider the maximum range of temperature



variation and any unfavorable combination of temperature and pressure.

5.2.5.3 Buried pipeline should go through testing and verification for anti-

sedimentation and anti-fluctuation purpose; bare pipes should go through anti-

sedimentation testing. Pipeline per unit volume quality pγ should meet the

requirement of formula below:

sc V p sc V R Rγ γ γ − < < + (5.2.5-1)

of which,

scγ ------ equivalent volume of soil in kg/m3 , worked out from formula

5.2.5-2

pγ ------ pipeline per unit volume quality in kg/m3

R v ------ soil impedance in kg/m3, worked out from formula 5.2.5-3

(1 )1

W sc

r

G W GW

r γ γ +

= +...................................... (5.2.5-2)

of which,

G ------ density of soil particles

W γ ----- seawater capacity in kg/m3

Wr ------ water content in soil, %

2V

t

C R

D

= ............................................... (5.2.5-3)

of which,

C ------ shear strength of soil remolding in kg/m3

5.2.5.4 The pipeline per unit volume quality at pipeline anti-sedimentation

testing is based on water-filled pipeline condition; and calculation of pγ is based

on gas-filled pipeline condition when anti-fluctuation testing is conducted.

5.2.5.5 When submarine soil has the likelihood for liquefaction, pipelines

should undergo anti-sedimentation testing according to the soil’s state of

liquefaction and adsorbability, as well as the depth of soil liquefaction. For safety purpose, pipelines should be buried below the possible liquefaction depth of soil.

5.2.5.6 Pipelines in laying stage or laid bare on the seafloor should go through

horizontal stability testing upon possible environmental load. The formula below

will work out the minimum required submarine quality for pipelines to retain

horizontal stability upon action by waves and ocean currents.

( ) DC sub L LC

f f W K f f

µ

+= + + ..............................(5.2.5-4)

of which,

Wsub ------ minimum required submarine quality for pipelines to retain

horizontal stability, N/mK ------ coefficient of horizontal stability, may take 1.1;



µ ------ coefficient of friction between pipeline external surface and

submarine soil

5.2.5.7 When conducting the test and examination of the pipeline horizontal

stability, it is required to consider the least favorable load combination and phase

according to different engineering conditions and design conditions. For instance,

seafloor has transverse pitch, its adverse effect should be considered.5.2.5.8 It’s essential to consider how pipeline settlement on the sea floor might

affect pipeline horizontal stability. Pre-trenched pipelines should undergo

evaluation on pre trenching.

5.2.5.9 Selection of both horizontal and vertical frictional coefficients between

pipeline external surface and submarine soil should comply with the actual

situation of the sea floor of the specific sea area, and determined by on-site testing

if necessary.

5.2.5.10 If bare pipeline fails to meet requirements for on-location stability,

measures should be taken to increase stability, i.e., increasing pipeline submerged

weight, burying them in part or in whole, increasing pressing blocks or anchor

points.

5.2.5.11 When pipelines require backfilling and cover, the materials used

should ensure stability on the sea floor ( no washout, scouring, or displacement),

and should not cause any damage to pipeline and pipeline coating.

5.3 The Piping System in the State of Installation

5.3 The Piping System in the State of Installation


5.3.1.1 Riser and pipeline should undergo stress analysis in all their

installation operations to ensure their pipe wall stress is within allowable

requirements for strength, partial buckle and fatigue damage; There should be no

severe damage or fall-off of weight coating and no excessive damage to erosion

resistant coating.

5.3.1.2 The installation operations should cover the key test items listed below:

a. launching pipe sections into water, towing, steering down, and

positioning for towing method

b. bottom pull, off-bed pull

c. initial pipelaying vessel operations

d. normal pipelaying operations

e. pipe abandon and retrieve

f. riser liftingg. connection between pipe sections and between pipeline and risers

h. Pipeline crossing

i. pipeline crossing waterway and sea floor sags

j. burying pipes

k. backfill and covering (mulching)

l. any other operations that might cause pipeline deformation

5.3.1.3 The installation operations should ensure availability of effective

testing methods for deformation or stress, or provide effective control parameters

and testing methods for designed operations. If any damage of pipeline or risers is

identified, it is necessary to repair or replace.



5.3.2 Strength

5.3.2.1 In the installation of riser and pipeline, pipe wall maximum

longitudinal stress should not be more than 0.004, and no more than 0,02 if the

strain increase effect at the discontinuity points of concrete weight coating is

considered.

5.3.2.2 The strain control aforementioned in 5.3.2.1 can be substituted by theequivalent stress rule of formula 5.3.2.

2 2

2

0 0

0.85 0.85 y

N M N M

A W A W y c sσ σ η σ

⎛ ⎞ ⎛ ⎞+ + − + ≤⎜ ⎟ ⎜ ⎟

⎝ ⎠ ⎝ ⎠ ..........(5.3.2)

of which,

N ------ axial force, N

M ------ bending moment, N mm⋅

A0 ------ pipe net sectional area, mm2

W ------ pipe sectional anti - bending modulus, mm3

ηc ------ coefficient of strength utilization in the installation

mode, should take values according to specifications of 5.3.2.3

5.3.2.3 Take 0.72 as utilization coefficient ηc for load condition 4.4.1.1 (1),

take 0.96 for load condition 4.4.1.1 (2), and may broaden to 0.96 at points where

the buckle and deformation of pipeline and risers are under complete control, such

as pipe sections positioned either on bracket with fixed curvature or other fixed

pipe supports.

5.3.2.4 Pipeline pipe sections that are forced to have permanent bending

should limit their gross sectional out-of-roundness within 2%; total permanent

bending within 0.02. If on such basis the pipeline continues to bend or level off deformation, then permanent bending strain should be within 0.01.

5.3.2.5 The stress and strain calculations should count in non-linear effects

caused by major displacement, and use the least favorable load combination that

might happen in the installation. The recurrence period of parameters for wind,

waves and ocean currents should comply with the relevant specifications of

4.4.4.1 of this Code.

5.3.3 Buckle

The pipeline and risers in the installation condition should undergo testing on their

partial buckle stability and overall pressure bar stability under the combined action byaxial force, external pressure and bending moment.

5.3.4 Fatigue

5.3.4.1 Pipelines laid by towing will undergo remarkable alternating load in

the towing process, their fatigue effects should be evaluated through computing or

testing.

5.3.4.2 The identical parts or pipe sections should add up their fatigue damages

in both the installation and on-location modes as their total accumulative damage

assessment.



5.4 Pipeline Fittings

5.4 Pipeline Fittings

5.4.1 It is required to ensure that under the action of operating load and environmental

load, all pipeline fittings’ strength index, buckle index and fatigue index are not lower than the standards for pipeline and risers set up by this Code.

5.4.2 Any pipeline fittings that are not given detailed design and standards by this

Code should be subject to the strength test by at least one of the following methods:

a. examples showing the identical or similar parts operating safely under

similar operating conditions and environment

b. material object full-scale test

c. model test

d. example of engineering computations

5.4.3 Pipeline and risers should not be installed with any fittings that use pipeline and

risers as the support of any other external force. The connecting type for pipeline or risers support should be well-calculated design in order to prevent pipeline or riser

from being damaged and concentration of stress.

5.5 Insulation Pipeline

5.5 Insulation Pipeline

5.5.1 The insulation of pipeline should ensure temperature of delivered medium meet

with design and standards in the entire transmission process. In general, double pipe

structure consisting of a steel inner pipe, thermal insulation layer and a steel outer

pipe is used; in some other cases single layer structure without steel outer pipe can

also be adopted.5.5.2 The heat insulating material should have low coefficient of heat conductivity

and low water absorption, good heat endurance, durability and chemical stability, and

no corrosive action upon pipeline; they should have sufficient strength to ensure no

damage to the pipeline insulation layer, no matter the pipeline is in installation or on-

location mode. It’s also important to ensure their compatibility with other materials

used at the same time.

5.5.3 In both installation and on-location modes, the total length of pipeline should

ensure good concentricity degree of inner and outer pipes and homogeneous depth of

heat insulating layer. Lateral depth reduction of heat insulating layer due to

misalignment (concentricity tolerance) should be no more than 1/5 of design thickness,

if necessary, Supporting Member should be placed between the inner and outer

pipes to limit radial displacement at a certain interval.

5.5.4 The double pipe structure calculations of the strength and stability should

consider all kinds of loads that both pipes will endure respectively in installation and

on-location modes, moreover count in the interaction of heat expansion between inner

and outer pipes. Take zero for external pressure in inner pipe calculation; take zero for

internal pressure in outer pipe calculation.

5.5.5 Test-proved rigidity constraint components should be available between inner

and outer pipes of double pipe structure to prevent against axial displacement.

5.5.6 The outer pipe should have adequate strength and toughness to remain water

tight in both installation and operation periods. If necessary, water-tight partition boards should be available in the annular space between inner and outer pipes at a



regular interval to create water-tight spaces.

5.5.7 Test should be given to pipe ends of both heat insulating pipeline and pipe

sections to verify axial displacement caused by temperature difference, such test

should consider the maximum possible temperature difference upon heat insulating

pipeline and pipe sections.

5.5.8 The joint coating materials used in site operation should be easy to operate,have sufficient strength and adequate waterproof capability; they should also be

inflaming retarding and anti thermal deformation if welding is needed in its vicinity.

6 Accessory Materials for Pipe and Pipeline

6.1 General Terms and Conditions

6.1.1 This chapter specifies the technical requirements for pipeline, riser and

accessory materials, these requirements apply to carbon steel, carbon

manganese steel, fine-crystalline grain processed steel, low-alloy steel andwelding materials with minimum yield strength less than or equal to 500Mpa.

6.1.2 Choice of materials are subject to factors such as nature of the delivered

medium, pipeline environmental conditions, loads, temperature, corrosive

environment, and outcome of possible damage as a result of pipeline or pipe

sections transportation, layout, installation, operations and maintenance. Based

on both technical and financial comparisons, selected steel pipe and steel

products should have good toughness and weldability.

6.1.3 The materials should have no defects that might affect the designed usage, i.e.,

crack, gap, gouge, tearing, interlayer, air cap and so on; welding beading, burr

fin, mill scale, if any, should be removed by grinding.

6.1.4 The authorities should certify the materials; new materials and products shouldgo through certification and obtain certificate issued by the authorities. Each

batch production of materials should present outgoing quality certificate on

which information such as manufacturer, grade, heat number, size and usage

are provided and the labeling and marking should be easy to locate and

identify.

6.2 Steel Pipe for Pipeline and Riser

6.2.1 Steel pipe material should be killed steel, semikilled steel can be used if the

pipeline is for transmission of fluids and the steel product to be used has the minimum

yield strength less than or equal to 300Mpa. The steel pipe material to be used shouldhave typical stress-strain curve attached.

6.2.2The selected steel pipe should comply with the requirements set forth in the

Seamless Steel Pipe for Transmission of Fluids, The Longitudinally Weld Seam

Electric Resistance Welding Steel Pipe for Petroleum and Natural Gas Pipelines, and

the Helical Weld Seam - Buried Arc Welding Steel Pipe for Petroleum and Natural

Gas Pipelines.

6.2.3 Selecting steel pipes other than those specified in 6.2.2 should meet the

following requirements:

6.2.3.1 The proportion of yield strength to tensile strength should not be more than

0.85.

6.2.3.2 For finished product testing carbon content is less than 0.25%, carbon



equivalent less than 0.45%.

6.2.3.3 For finished product testing phosphorus content is less than 0.04%,

sulphur content less than 0.035%.

Note: Carbon equivalent is calculated by6 5 15

n Cr Mo V Cu NiC

+ + ++ + +

A v e r a g e C h a r p y V - n

o t c h i m p a c t ( J )

Specified minimum Yield strength (Mpa)

Graphic 6.2.4 Average Charpy V-notch toughness

6.2.4 The requirements for toughness are based on factors such as strength level,

pipe diameter, wall thickness, welding method and temperature of operating

environment, and should comply with the following specifications on steel pipes:

6.2.4.1 The temperature for steel pipe and welding seam materials to change from

plasticity to brittleness should be lower than the minimum design temperature,

steel pipe material should have Charpy V-notch impact toughness transition curve

attached.

6.2.4.2 The average Charpy V-notch impact should meet requirements of graphic

6.2.4, conversion between standard test piece and under-sized test piece should

follow Table 6.2.4-1.

Standard and under-sized test piece conversion factors Table 6.2.4-1

Section of test piece (mm2) Conversion relation

10 X 10 1

10 X 7.5 5/6

10 X 5 2/3

6.2.4.3The temperature for impact test is selected according to Table 6.2.4-2 and

should not be higher than +20 ℃.

Temperature for impact test Table 6.2.4-2



Temperature for impact test (℃)

Riser Pipeline

Nominal Wall

thickness

δ

(mm)Gas and liquid Gas Liquid

δ< 20 t = td - 10 t = td - 10 t = td

20< δ <30 t = td - 20 t = td - 10 t = td

δ>30 t = determined by actual situations

○1 In the table, t – test temperature, td– design temperature, ℃

○2 Corrosion allowance can be ignored.

○3 Mixture of gas and liquid is treated as gas.

6.2.5 The hardness at any point of steel pipe material and welded joints should not

exceed 523HV5, piping system requiring anti-corrosion by sulphide stress

should not exceed 260HV5 in hardness.

6.3 Pipe Fittings

6.3.1 Bend pipe, three-way pipe and other pipe fitting materials should meet the

technical requirements set for pipeline and risers of the identical grade and wall

thickness.

6.3.2 Elbow, valve, flange and other fittings should use forged steel parts, their quality

should comply with the Technical Specifications for Forged Pieces for Pressure

Vessels.

6.3.3 When welding connection is required between pipe fittings and pipeline or risers,

materials used by both of them should be identical or close. Special requirements, if

any, should be remarked in the design.

6.3.4 The pipe fittings should meet with China’s currently applicable standards

(specifications).

6.4 Bolts

6.4.1 The bolts and nuts should meet the relevant national and international standards

in terms of the chemical composition, mechanical property and processing

requirements.

6.4.2 Impact test shall be required for bolts and nuts materials used for cryogenic

applications or of large diameter.

5.5.9 If they are the integral part of a component that requires stress resistance and

corrosion resistance, the bolts and nuts should then use materials having equivalent

performance of stress and corrosion resistance as the aforementioned component, and

adopt the same manufacture and quality inspection standards as the component.

6.4.3 Bolts, nuts and other fasteners should have corrosion protection in compliance

with the Technical Specifications for Corrosion Protection of Petroleum Engineering

in Beach Shallow Sea.



6.4 Supporting Member

6.4.1 Supporting member should use the same material as being used for pipeline and

risers when they are welded directly onto pipeline or risers.

6.4.2 Supporting member that are not directly welded onto pipeline or risers shoulduse the same materials as being generally used for marine steel structures.

6.4.3 If they are the integral part of a component that requires endurance to stress

corrosion, the bolts and nuts should then use materials having equivalent endurance to

stress corrosion as the aforementioned component, and adopt the same manufacture

and quality inspection standards as the component.

6.4.4 Bolts, nuts and other fasteners should have corrosion protection in compliance

with the Standards for Corrosion Protection of Offshore Oil Engineering .

6.5 Support Fittings

6.5.1 Support fittings should use the same material as being used for pipeline and

risers when they are welded directly onto pipeline or risers.

6.5.2 Support fittings that are not directly welded onto pipeline or risers should use

the same materials as being generally used for marine steel structures.



7 Pipeline Anti-Corrosion & Weight Coating

7.1 Pipeline anti-corrosion

7.1.1 Apart from the Technical Specifications of Anti-corrosion for Petroleum Engineering on Beach-shallow Sea, the design and construction of

pipeline anti-corrosion system should also comply with the regulations stated in

section 7.1.2.

7.1.2 Pipeline anti-corrosion system should meet the following

requirements:

7.1.2.1 The external corrosion prevention in continuous immersion zone

should be a combined protection of cathode protection and coating.

7.1.2.2 The design of external corrosion prevention system for risers in the

splash zone should take full considerations of the abrasion and impact effect from

ice, sea waves and so on. It should be protected by means of coating, cladding or

spraying coated mental layer and whenever necessary, use special anti-corrosionmeasures, such as coated organic compound layer, resin slurry, corrosion resisting

metal spraying, etc. External corrosion prevention should be carried out by

referring to the corrosion allowance of pipe wall thickness described in Form 7.1.2.

7.1.2.3 The external corrosion prevention for pipeline system in the

atmospheric zone should adopt the protection of coating or metal spraying.

7.1.2.4 The internal corrosion prevention of pipeline system transmitting

corrosiveness medium, should be a combination of corrosion inhibitor injected into

the medium in accordance with the specific corrosion allowance of pipe wall

thickness.

7.1.2.5 When selecting pipeline external coating materials, the suitability of

the materials for beach-shallow sea should be taken into considerations.Furthermore, the compatibility of coating with the insulating layer, concrete weight

coating should also be matched properly. When selecting the corrosion prevention

materials for worksite coupler, the application of worksite coupler or joint coating

should be considered too.

7.1.2.6 The protection of cathode protection should be based on the sacrifice

protection. Under special consideration and being approved by certification and

supervision department, the protection of cathode protection can also adopt the

method of adding impressed current to certain parts of pipe section.

7.1.2.7 Electrical isolation (insulation) must be conducted when carrying out

the outer parts of external systems joint connection with the pipeline system.

Form 7.1.2 Riser Corrosion Allowance for Function as Working TemperatureWorking Temperature (oC) Corrosion Allowance (mm)

< 20 2

20~40 4

40~60 6

60~80 8

80~100 10

7.2 Weight coating

7.2.1 This section is applicable to concrete weight coating. The concreteweight coating should provide sufficient minus buoyancy force to beach-shallow



pipeline during its designed life; maintain its in-position stability; avoid or decrease

any mechanic damage to its external coating during the periods of pipeline laying,

installation and operations.

7.2.2 The concrete weight coating should be able to stand any friction and

possible mechanical damage caused by the contact between the pipeline and the sea

bed during the period of pipeline system laying and installation, and prevent it fromfalling off from pipe. On the other hand, measures should be taken to prevent the

concrete weight coating from falling off due to the serious irregular crack created

by the bending stress in pipeline laying.

7.2.3 As for the concrete weight coating for each pipe or pipe section,

according to onsite joint coating and process requirements, adequate length of

blank pipe shall be reserved for welding at the both ends of corrosion protection

coating,.

7.2.4 The density and the thickness of the weight coatingconcrete should

be determined properly in accordance with the pipeline designed minus buoyancy

force and the construction technique and pipe laying availability. Heavy quality

concrete should be adopted for this construction.7.2.5 The weight coating concrete should have sufficient strength and

compactness, freezing resistance, impermeability, anti corrosion, and prevent steel

bar or steel net from being rusty, and prevent frazil ice collision, etc. The strength

shall be determined by the design. Normal strength class of concrete is C30.

7.2.6 The reinforcing steel in the concrete weight coating should be plain

bar or deformed bar which has been welded into a framework or using wire mesh.

Type of the stiffener, configuration, connections, etc should be determined by the

expected pipeline load and the working conditions to take control of the damage

type of concrete weight coating.

7.2.7 The construction, designed proportioning and maintenance of the

concrete weight coating should ensure that the concrete weighting fulfill every

designed function requirements (Especially the density and thickness of the

weighting). The testing, inspection and repairing of the concrete weight coating

should follow the applicable national standards and regulations.

8 Pipe Section Onshore Prefabrication and Assembling

8.1 General Requirements

8.1.1 The onshore prefabrication and assembling should be performed in

accordance with engineering scale, schedule and the methods of construction. The

prefabrication and assembling workshop should be equipped with associated

equipment and facilities, which match the project requirement in quality and

progress.

8.1.2 The pipe manufacturer should provide qualified pipe and pipe

fittings and the construction company should be qualified and have the ability to

handle onshore pipe fittings prefabrication and assembling; the related certificate

must be submitted for verification.

8.1.3 Incoming pipes should be subject to visual inspection; the tolerance

of the size and the outside dimension should meet with the requirements of section

8.2 of this specifications.



8.1.4 Pipe section to be prefabricated and assembled onshore, should be

butt welding after the completion of corrosion protective coating. Weld should pass

the nondestructive examination prior to joint coating for corrosion prevention.

8.1.5 The external corrosion prevention coating should be satisfied with

the following requirements:

8.1.5.1 External corrosion prevention coating for various parts of the pipeline system, such as coatings for pipes, worksite joints, supporting members

and so on, should be carried out as per coating process requirements and

techniques, generally including:

(1) Treatment and process of coating compound.

(2) Steel pipe surface preparation.

(3) The repairing techniques for fittings, such as cables for the cathode

protection, the perforated bedplate, etc.

(4) Quality control and inspection.

(5) Methods of record and labels.

8.1.5.2 The pipe external surface preparation (treatment) should be

conducted according to the requirements of corrosion prevention coating, better usegrit blasting or sandblasting. The de-rusting quality should satisfy with related

levels as stated in the Levels of Steel Surface Corrosion before Coating and Levels

of De-rusting.

8.1.5.3 Generally the quality control records should include followings:

(1) The technical requirements and acceptance standards of corrosion

preventing coating.

(2) Data of surface treatment.

(3) Measurement values of temperature and moisture.

(4) Total coating layers and the dry film thickness.

(5) Data of the agglutinating power.

(6) Insulating property.

(7) Inspection data of electric spark.

(8) Data of the reinforced materials position in the coating.

8.1.5.4 The worksite joint coating should be carried out strictly in according

with the worksite joint corrosion preventing techniques. The worksite joint coating

should be matched with the pipe coating. Before a pipeline section is launched into

water, documentations of the acceptance, repairing or disposal should be available.

Repairing methods for the damaged joint coating found in the worksite, should be

clearly described in the technique specifications.

8.1.6 The construction and quality of pipeline external insulating layer

should be complied with relative requirements of the Technical Specifications of Heat Insulation for Petroleum Engineering in Beach-shallow Sea.

8.1.7 The installation of the anode should meet the following

requirements:

8.1.7.1 The layout of anode should meet the design requirements. The

installation method of anode should avoid any mechanical damage due to pipe

section handling and during the course of installation. The thickness of the anode

should be less than that of the weight coating. For pipeline without weight coating,

its anode hoop (or block) and the connecting fittings should be protected properly

during installation.

8.1.7.2 The anode hoop should be fixed firmly on the steel pipe external

surface. There should be at least 2 electric connecting positions between everycathode hoops and the pipe.



8.1.7.3 Usually the connection between the anode and the pipe is welded by

means of manual or thermite welding. The solder bead should be at least 150mm

away from other welds on the pipe.

8.2 Quality Requirement for Pipes Delivered to the Workshop

8.2.1 Steel pipe outer diameter

8.2.1.1 The ultimate deviation of steel pipe body outer diameter should be

complied with following specifications in Form 8.2.1 – 1:

Form 8.2.1-1 Pipe Body Outer Diameter Ultimate Deviation Nominal Outer Diameter D (mm) Ultimate Deviation (mm)

< 508 ± 0.75% D

> 508 ± 1.00% D

8.2.1.2 The outer diameter ultimate deviation of steel pipe within 100mm

away from the pipe end should be complied with following specifications in Form

8.2.1-2: Form 8.2.1-2 Pipe End Outer Diameter Ultimate Deviation Nominal Outer Diameter D (mm) Ultimate Deviation (mm)

< 323.9+ 1.6

- 0.4

> 323.9+ 2.4

- 0.8

For steel pipe with an outer diameter less than 508 mm, the upper deviation

should be measured through gauge ring method while the lower deviation uses

perimeter method.

For steel pipe with an outer diameter more than 508 mm, the pipe end outer

diameter ultimate deviation should be measured by means of perimeter.8.2.2 Steel pipe wall thickness

8.2.2.1 wall thickness of each steel pipe should be measured. Except for

welding reinforcement, the ultimate deviation of the wall thickness in every

location of the pipe should conform to the following specifications in Form 8.2.2:

Form 8.2.2 Steel Pipe Wall Thickness Ultimate Deviation

Nominal Outer Diameter D

(mm)

Type of Steel Level Ultimate Deviation

(mm)

< 508 - ± 10.0% D

S205~S240 ± 10.0% D > 508

S290~S480 ± 8.0% D 8.2.2.2 Pipe wall thickness can be measured by micrometer or other non-

destructive inspection facilities with the same accuracy.

8.2.3 Ovality

For steel pipe with an outer diameter more than 508 mm, within the range of

100 mm at the pipe end , the permissible variation of the steel pipe outer diameter

could be ± 4 mm (excluding ± 4 mm). Caliper, standard divider or other

measurement tools should be used to measure the largest and the smallest size of

outer diameter.

8.2.4 Pipe end bevel

8.2.4.1 The steel pipe end should be processed with bevel. The bevel angle

is (300+5)o. The root face size is 1.6mm ± 0.8mm. The bevel angle is measured based on steel central line verticality. According to client requirement, pipe end



could be flat ended when being delivered, or other types of bevel angles could be

used subject to negotiations and agreement by both parities.

8.2.4.2 No burr is allowed on pipe end bevel and the root face. Any inner

bevel edge formed due to the cleaning of pipe end bevel internal deburr should not

be bigger than 7o. The measurement of internal bevel angle is based on steel pipe

central line.8.2.4.3 The overlength of the welds within 100mm length from the steel

pipe end should be removed.

8.2.4.4 The surface of a steel pipe end should be vertical to its central line,

the ultimate variation should not be more than 1.5mm.

8.2.5 Steel pipe quality

Steel pipe could be delivered as per actual quality or, as per its theoretical

quality. Steel pipe theoretical quality per meter could be calculated (8.2.5) by using

the following formula (Steel density is 7.85kg/dm3):

W=0.024665δ ( D -δ )........................................... (8.2.5)

In the formula,

W – steel pipe theory quality, kg/m;

D – steel pipe nominal outer diameter, mm;

δ - steel pipe nominal wall thickness, mm.

8.2.6 Bending

Bending of a steel pipe must not excess 0.2% of the total pipe length, which

can be tested by using a twine or thin metal wire from one end to the other end of

the steel pipe parallel to its central line. Maximum distance can be obtained from

measurement of the length from the tensed metal wire to pipe surface.

8.2.7 Steel pipe surface defect

8.2.7.1 Steel pipe surface should be free from any of the defects, such ascrack, scar, fold and others dents exceeding wall thickness deviation. For defect

with uncertain depth, it should be removed using grinding method before test.

8.2.7.2 Separate layer or lamination which propagates to pipe end or bevel

surface by transverse distance more than 6mm, are not allowed on steel pipe. Any

pipe end with more than 6mm transverse lamination should be cut till to qualified

pipe section.

8.2.7.3 Any indent more than 5mm is not allowed on pipe wall. The indent

depth refers to the distance between the lowest points of indent to the extension of

pipe’s original profile. An indent defect must not exceed 0.5 D in any direction.

Depth of indent with sharp scratch should not exceed 3 mm. Sharp scratches should

be removed. The depth and length after grinding should meet the aboverequirements.

8.2.7.4 Displacement: For steel pipe with δ value less than or equal to

12.7mm, the displacement (the radial displacement of the opposite side with weld

lines along the central steel pipe) should not exceed 1.6mm. For steel pipe with δ

value large than 12.7mm, the transposition should not be more than 0.125 δ ,

maximum transposition should not exceed 3.0mm.

8.2.7.5 The overlength of weld lines should conform to the regulations

stated in Form 8.2.7, but the overlength within 100mm to the pipe end should be

leveled off properly.

Form 8.2.7 Allowable Deviation of Weld Line Overlength Nominal Allowable weld line Overlength (mm)



Internal pipe wall External pipe wallWall Thickness

δ (mm) Maximum Minimum Maximum Minimum

δ < 12.5

δ > 12.5

2

3

0

0

3

4

0

0

Remarks: The weld line overlength refers only to helical weld steel pipes.

8.2.8 Inspection of pipes delivered to the workshop

8.2.8.1 The pipe manufacturer must ensure that the ex workshop pipes

quality is complied with requirements of the Seamless Steel Pipe for Fluid

Transmission; the SAW Helical Steel Pipe for Oil & Gas Transmission and the

ERW Longitudinally Welded Steel Pipe for Oil & Gas Transmission. Associated

manufacture paper and certificates should be submitted to the clients accordingly.

8.2.8.2 After check and acceptance of incoming steel pipes as per section

8.2 requirements, if there is any doubt about the pipe quality, it is necessary to

conduct chemical composition analysis or steel material mechanical performance

test. If steel pipe material is selected for non proven welding process, it is required

to conduct evaluation and experiment for such welding process.8.2.8.3 As for the pipe for first trial welding, before the construction, every

onsite welder should first have a test. The experiment quantity and type of

mechanical performance should be carried out as per the requirements stated in

Table 8.2.8.

Table 8.2.8 Quantity and Type of Mechanical performancePipe Materials Test Welding Test

Tensile testPipe size, outer

diameter D (mm) Longitud

inalTransvers

e

Charpy VNotch Test

Weld linetransverse

Tensile test

Guidebend test

Charpy VNotch Test

Macro-crosssection

hardness

Seamless steel

pipeD<300D>300

1 1

1testingsample

- - - -

Welded steel

pipeD<300D>300 1 1

1testing

sample1

12

2testingsample 1

8.2.8.4 If any of the selected samples fails in the testing, the said pipe

should be abandoned. In order to make use the remaining pipes of the same lot

(maximum 50 pipes or weight of 50t pipes), it is necessary to randomly select

different pipes for the same experiment twice. Only when all the testing samples

pass the repeated testing, can the lot be accepted.8.2.8.5 If the non conformance of the testing sample is caused only by its

own process defect, further test should be allowed for replacement samples. The

sampling procedures should comply with the requirement stated in Appendix G.

8.2.9 Pipe fittings manufacturing and inspection

8.2.9.1 Ex work pipe fittings should be presented together with

manufacturing quality certificate (including associated testing results), which

should satisfy the requirements of section 6.3 of this specification.

8.2.9.2 The technique specifications can be confirmed by testing the first lot

of produced fittings, such as elbow pieces, T-joint pieces, etc. Pipe fittings can be

first grouped into different categories by means of material class, wall thickness,

bending radius and methods of manufacturing, then start the acceptance test bysampling from each groups.



8.3 Prefabrication and assembling

8.3.1 Welding materials

8.3.1.1 The welding materials should meet the following requirements:

(1) The welding materials should be applicable to the specific welding purpose. The welds should satisfy the requirements in mechanical

property, firmness and corrosion protection.

(2) When welding high strength steel, it is necessary to use low

hydrogen type of filler rod; if special welding technique of anti-

hydrogen brittleness is adopted, cellulose type filler rod should

be selected.

(3) It is required to ensure that in low hydrogen type of welding

materials, the content of diffusion hydrogen in each 100g

welding metal is less than 5ml (tested by glycerin method) and

be confirmed by random inspection.

(4) The chemical composition of deposition metal should be similar to that of the base metal.

(5) The mechanical properties of the deposition metal and the

welding joint should be superior to the base metal; avoid higher

weld yield strength and tension strength than that of the base

metal.

(6) Heat treatment should not reduce welding joint intensity and

tenacity.

(7) Welding filler rod and materials should be stored in dry place,

and prevent them from pollution, damping and rusting.

(8) Low hydrogen type filler rod should be stored at a place with

relative dampness below 40%. Under all circumstances, thestorage temperature for welding materials should meet the

requirements stated in Form 8.3.1. The drying of unsealed filler

rod and the re-drying of remaining welding rods shall be

performed strictly according to the manufacturer’s instructions.

Form 8.3.1 Storage Temperature for Welding MaterialsStorage temperature for welding materials (oC)Categories of the welding

materials Sealed storage Unsealed storage Storage when in use

Low hydrogen type filler rod

Cellulose type filler rod

20~30 150

20~30

70

Remarks: 1) The storage temperature should be above the ambient temperature by +5 oC.

2) When a filler rod is removed, a low hydrogen type filler rod should be stored in temperature preservation container and be used within 4 hours.

8.3.2 Evaluation of the welding process

8.3.2.1 The evaluation content for welding processes should include the

followings:

(1) Specifications of the pipe materials, chemical composition

and the mechanical performance.

(2) Matching interspaces and bevel requirements.

(3) Serial numbers of welding filler rod, welding wire

specifications, strength and the weld filler rod double check.

(4) Welding parameters: current, voltage, type of the current,

polarity and the welding speed, etc.(5) Welding location and directions.



(6) Time interval between weld pass.

(7) Preheating and the lamination temperature.

(8) Post weld heat treatment.

8.3.2.2 The evaluation test of the welding processes should comply with the

regulations of the Evaluating Methods of Oil & Gas Pipeline Welding

Process.8.3.3 The assembling of double-layer pipes

8.3.3.1 The total length of every double-layer pipe section should be

determined by factors such as the prefabricating ground, equipment, the

field assembling capacity in beach-shallow sea and the environmental

conditions, etc.

8.3.3.2 The assembling should be carried out as per the following steps:

(1) Aligning and lining up internal and external pipes.

(2) Measuring the actual length of internal and external pipes.

(3) Removing any soil and dirt from the internal and external

pipes.

(4) Checking the internal pipe heating proof and the foot block support, etc.

(5) Internal pipe should be inserted into the casing.

(6) Butt welding the duplex-wall pipes.

(7) Welding the anode block and the fittings for pulling head.

(8) Inspect and repair the external anti corrosion coating.

(9) Measuring the total length of double-layer pipe section.

8.3.3.3 When welding double-layer pipe structure and casing weld joint, it is

not allowed to damage the heat insulation layer of the internal pipe.

Weld seams of the internal and external pipes should be dislocated by at

least 100 mm.

8.3.4 Welding and inspection

8.3.4.1 Field welding must follow welding process procedures strictly.

8.3.4.2 The bevel end pipe should be cleaned and free of moisture, grease,

oxide skin, etc.

8.3.4.3 The line up gripping device should not be removed before the first

layer weld pass is completed. When tack welding is carried out for

alignment purpose, the requirements of welding process procedures

should be observed and be carried out only within the weld seam bevel.

Disqualified tack weld should be completely removed.

8.3.4.4 The welding process should be completed by one time continuously

without moving the pipe.8.3.4.5 The weld joint of weld pass must be checked with non-destructive

test. If the pipe is double-layer structure, all weld joints on the internal

pipe should be subject to 100% full-length radiograph flaw detection.

While on the other hand, the weld joint on the external pipe should be

tested by 100% entire length ultrasonic flaw detection.

8.3.4.6 The welding repairing should be subject to radiograph flaw

detection. The range of inspection should include the repaired zones and

the extended 50 mm length of each end of the repairing weld lines.

8.3.4.7 The quality of weld lines inspected by radiograph, should meet the

acceptance standards of the Radiograph Detection and Quality Level of

Steel Pipe Weld Lines for Oil & Gas Industry. Grade II is the qualifiedlevel.



8.3.4.8 The quality of weld lines inspected by ultrasonic wave flaw

detection, should meet the acceptance standards of the Ultrasonic Wave

Defect Detection and Quality Level of Steel Pipe Weld Lines for Oil &

Gas Industry. Grade II is qualified level.

8.3.4.9 The external surface defect of the pipe should be removed by

grinding wheel and inspected by magnetic particle examination.8.3.4.10 The evaluation of the welders should be carried out in accordance

with the requirements in Appendix H.

8.3.5 In-place weld joint repairing

8.3.5.1 The surface defect of any weld lines could be removed by grinding

wheel. After defect is removed, the weld surface should not be lower

than the pipe external surface. The abrasion should smoothly pass to the

pipe surface.

8.3.5.2 The following welding repairing should be subject to process

evaluation:

(1) Full thickness repairing.

(2) External repairing to sidewall undercut by string bead.(3) Interior repairing by one pass weld from the root.

(4) Repeat weld lines repairing at the same zone

8.3.5.3 Accordance to the requirements of weld process evaluation, the

testing weld lines for full thickness repairing should be checked by

visual inspection, by non-destructive testing and mechanical

performance testing.

8.3.5.4 The weld process procedures should be established for the removal

of internal defect of weld and weld repairing. The following contents

should be included:

(1) Methods to remove defects.

(2) Welding zone pre treatment.

(3) Allowable maximum and minimum weld repair dimension.

(4) Non-destructive testing (to prove the defects are removed)

and requirements.

8.3.5.5 Preheating is required before weld is repaired. The defined minimum

preheating temperature and the interlayer temperature should at least

maintain to the completion of the weld repairing.

8.3.5.6 Long weld defect should be repaired by section. Maximum length of

section repair should be determined by the stress caused by weld

repairing. If the defect is short, the repairing length should be at leastmore than 100mm.

8.3.5.7 When using arc air gouging clear the defects, the welding should be

processed on the grinded carburet layer.

8.3.5.8 Two remedial welding are allowed on the same point of weld. After

two remedial welding, if the weld joint still has defect, this entire weld

joint should be cut, except for special weld repairing process that is

identical to the actual repairing times and has been approved.

8.3.5.9 A pipe with defect should be repaired or cut. If the mechanic

property of fusedon metal is not qualified, the said fusedon metal should

be removed completely before re-welding.

8.3.5.10 The pipe internal defect and those within 100mm of the pipe endcould only be removed by grinding wheel. The remaining wall thickness



after abrasion should not be less than required minimum wall thickness.

Otherwise the section of pipe length should be cut off. If the depth of a

defect in other parts is less than one third of the wall thickness, only one

time weld repairing is permitted.

8.3.5.11 The preheated pipe after weld repairing should be subject to heat

treatment again.8.3.6 General ball purging and hydraulic pressure test

The pulling pipe sections finished in prefabrication workshop should be

tested by general ball purging and hydraulic pressure test in accordance

with the design requirements or relevant specifications.

8.3.7 Labeling

8.3.7.1 Before assembling and welding operation, the external surface of the

pipe should be marked with serial number by paint to enable

identification and measurement keeping. A cut off pipe should be re-

measured and labeled again.

8.3.7.2 When the weighting material is different from the specifications, an

obvious mark should be labeled on the pipe surface accordingly toensure that the pipe would be installed accurately to the designed

position.

9 Pipeline Installation on Beach-shallow Sea

9.1 General Requirements

9.1.1 The installation of pipeline system should be performed according to the

approval from the certification and inspection institute and in



accordance with client’s approved technical conditions, specifications

and drawings.

9.1.2 The welding process specifications should be compiled in accordance

with the technical requirements stated in section 8.3.2 of this

specification.

9.1.3 The technique specifications of in-place coupler coating should bedefined in accordance with the related requirements stated in section

8.1.5 of this specification.

9.1.4 Strict quality assurance system must be defined for all installation

operations. Among the technical requirements for installation

operations, the restricted technical parameters and data should be clearly

described and listed out to take correct protecting measures for he

possible affected pipe length and to maintain the pipeline in a permitted

stress level.

9.1.5 Workers participating in the beach-shallow sea engineering construction

must be a holder of qualified certificate.

9.1.6 No matter what methods the construction will use, the pipeline layingmust first establish its techniques construction standards and being

reviewed and approved by the certification institute and accepted by the

client, then put into implementation.

9.1.7 The technical requirements for the installation of beach-shallow sea

engineering should include beach-shallow sea pipeline equipment, such

as pipeline lay barge, beach-shallow operating equipment, beach-

shallow sea ditching and pipe laying and risers’s installation technical

conditions.

9.1.7.1 The installation technical conditions for beach-shallow sea operation

vessel should include the following items:

(1) General layout of various operating vessels.

(2) Brief descriptions of various constructing equipment and tools

(3) Descriptions of associated apparatus and equipment for the

operations.

(4) Descriptions and control of working characters of various

operating vessels.

9.1.7.2 The technical requirements of risers installation should include the

following:

(1) Location descriptions of riser supporting component parts,

bending, expansion bend, flange and others, and the general

installation chart and the descriptions of every part.(2) Major equipment and descriptions required for the installation.

(3) Risers corrosion prevention system chart and the descriptions.

(4) The installation chart of riser protecting structural component

parts and the descriptions.



9.2 Pipeline Route Control

9.2.1 After the pipeline route design is selected and prior to the installation, it

is required to conduct study on all materials and data of the previous

survey route and the investigation of hydroclimate along the route inorder to meet the requirement of beach-shallow sea installation. When

necessary, it is necessary to conduct an investigation or partial

investigation again.

9.2.2 During the installation period, proper marks or directory system

indicating the pipeline route location should be made to ensure the

pipeline laying follow the designed route and the pipeline location is

marked on marine chart in proper scale.

9.3 Connection

9.3.1 Pipe laying methods for submarine pipelines include: pipe laying vessel, push in construction or other proper method; the installation method for

risers include: lifting method, pre installation method or other proper

method. No matter which method is used, the pipeline system after

installation shall meet the requirements of design and relevant

specifications.

9.3.2 Connection between pipes or between pipe and riser pipe can use the

following methods:

9.3.2.1 Mechanical coupler;

9.3.2.2 Welding on the pipe laying vessel before laying the pipes;

9.3.2.3 Welding on other beach-shallow sea equipment before laying the pipes.

9.3.3 Connection operation shall include the following technical

requirements:

9.3.3.1 Descriptions and technical requirements for the pipe fittings that will

be served as the permanent parts of the pipeline system.

9.3.3.2 Stress calculation during installation and operation.

9.3.3.3 Whole procedure and technical requirements for the connection

operation.

9.3.3.4 Basic equipment required for installations, instrument instruction and

technical requirements.

9.3.3.5 Instructions and technical specifications for the methods of

inspections and testing.

9.3.4 Loading/unloading, transportation and storage for the pipes and pipe

sections shall meet following requirements:

9.3.4.1 When lifting the pipes or pipe sections or pipe fittings (especially the

riser pipes), necessary measures shall be taken to prevent the damage or

fall off of the pipes’ weight coating and anticorrosion coating caused by

equipment failure or wrong operation, etc. Pipe ends shall be protected

before lifting.



9.3.4.2 All lifting equipment shall be safe and reliable. The lift fittings shall

be designed in the shapes that they will not damage the pipes or pipe

sections (especially the bevels on the pipe ends), and also will not let

them slip away or fall down during lifting.

9.3.4.3 Pipes, pipe sections, riser pipes and pipe fittings shall be transported

safely to prevent damages caused by improper supporting or protectionmethods during transportation.

9.3.4.4 Pipes, pipe sections, riser pipes and pipe fittings shall be stored

properly without permanent deformation caused by their own weight or

loaded weight; storage of the pipes with weight coating or anticorrosion

coating or the pipes or pipe sections having been equipped with

sacrificial anode shall be specially careful. The maximum piling layers

for various pipes and pipe sections shall be properly calculated.

5.3.4.5 Carefully survey the towing route and establish proper technical

methods before the towing of long pipe sections, carry out pipe stress

analysis and control during towing (conduct simulation experiment if

necessary), and submit them to certification and inspection organizationfor approval.

9.3.5 Pipeline crossing shall meet the following requirements:

9.3.5.1 If the pipeline crosses over the other pipeline or cables, the

installation shall be carried out by strictly following the relevant

technical requirements.

9.3.5.2 The technical requirements for the installation at crossover positions

shall at least include the following items:

1) Detailed positions and illustration for such crossing (plane drawing and

sectional drawing);

2) The installation drawing for the fittings and spare parts including the

insulating layer (isolation layer);

3) The adopted installation methods and equipment;

4) Inspection methods, etc;

9.3.6 Buckle inspection shall meet the following requirements:

9.3.6.1 During submarine pipe laying in beach shallow sea, if the pipe laying

method may cause buckle on submarine pipeline, it is necessary to

check the pipeline buckle section by section. The testing method and the

instrument for checking the buckle shall be approved prior to pipe

laying operation.9.3.6.2 Generally the method to check the buckle is to put a steel disc into the

pipeline (the detector’s diameter shall be selected according to pipe’s

internal diameter, wall thickness, allowable ovality, misalignment

degree and the height of internal weld seams), the calculation formula

for its diameter is as below:

ф = D – 2δ- S (9.3.6)

In which:ф ——— the diameter of the disc (detector), mm;

D ——— nominal outer diameter of the pipeline, mm;

δ——— nominal wall thickness of the pipeline, mm;



S = (0.01 D ÷ 0.4δ + 5 I )mm: I is 20% of δ, its maximum is 5 mm.

9.3.7 Anchoring of pipeline system shall meet following requirements:

9.3.7.1 During the installation or upon the completion of the installation, the

pipeline system shall have relevant minimum safety capacity to prevent

all kinds of damage.9.3.7.2 Pipeline system shall be anchored or protected properly to ensure

the safety under following situations:

1) The movement vertical to axial direction;

2) impact;

3) corrosion.

9.3.7.3 Anchoring or protection of pipeline system shall be carried out

according to the following technical requirements:

1) Regulated completion conditions;

2) The methods, measures and equipment for anchoring or protection;

3) The methods and equipment for control and inspection.

9.3.7.4 For the pipeline covered with concrete weight coating, if it is laid on

the seabed and its displacement acted by waves or currents or sea ice is

too big, it is necessary to take additional protection methods. Special

care shall be taken for the installation of riser pipes. For relevant

methods and detailed calculation shall be specially considered.

9.3.8 Welding connection on the pipe laying vessel (equipment for beach-

shallow sea operation) shall meet the following requirements:

9.3.8.1 During pipeline connection and installation, the pipelin’s stress caused

by lifting and sinking shall be limited within the allowable value, and

the lifting up and lowering analysis or simulation experiment arerequired.

9.3.8.2 Use proper method to check pipeline’s relative position and

deformation.

9.3.8.3 The joint seams on beach-shallow sea pipeline shall be subject to

100% nondestructive inspection testing, which shall be up to the

standards of radial Class Ⅱ or ultrasonic Class Ⅰ.

9.3.9 Offshore pipeline joints shall meet the following requirements:

9.3.9.1 When conducting the joints connecting for the equipment in beach

shallow sea, stress analysis shall be performed for the jin pole, gangway

lifting and lifting positions.9.3.9.2 Check the integral strength and stability of the construction equipment

which shall be operated only under allowable environmental conditions.

9.3.9.3 Analyze the strained force on the pipes when installing the pipe joints,

properly select the positions of lifting points, lifting height and laying

speed to ensure that the all pipes will not have the occurrence of buckle

and deformation. The safety inspection during construction and

installation shall include the following items:

1) Pipeline buckling;

2) Local buckle and instability;

3) Pipeline fatigue damage;

4) Excess damage of concrete weight coating and anticorrosion coating;



9.3.9.4 The connection of riser pipes with horizontal pipes shall meet the

following requirements:

1) Perform the analysis for the lifting up and lowering of the riser pipes;

2) Reasonably arrange the lifting equipment and lifting tools according to

result of analysis, make sure that the connection of riser pipes with

horizontal pipes can meet relevant strength requirements and can be puton their preset locations accurately;

3) The joints of riser pipes with pipeline shall use dependable positioning

and ranging method to ensure a riser can accurately set on the

supporting fitting (riser spider).

9.3.9.5 Around the joints of pipe section to pipe section, pipe section to

riser pipe, insulation tile can be used inside the pipeline, and wrap the

fireproof asbestos board onto the insulation tile; heat shrink sleeve can

be used onto the outer anticorrosion coating.

9.4 Trenching and pipeline burying

9.4.1 Trenching and pipeline burying can use pre-trenching method or post-

trenching method. If use pre-trenching method, shall conform ditching

speed and gradient according to the soil’s characteristics, and for the

area of instable foundation, shall lay the pipes in the course of trenching

to avoid silting or sliding; if use post-trenching method, shall analyze

the stress and confirm the total layers of digging and the depth of each

layer; if use filling material for backfill, the filling material shall be

selected according to the requirement of design.

9.4.2 If the pipeline needs to be backfilled and covered, the stability of thematerial for subsea backfill shall be ensured, and it would not cause any

damage over the pipeline’s anticorrosion coating.



10 Final inspection and completion test

10.1 Final inspection


10.1.1.1 The installed pipeline system shall go through final inspection

according to the design requirements.

10.1.1.2 If the pipeline uses trenching method or other methods to maintain

its stability, the pipeline’s stability shall be inspected.

10.1.1.3 The final inspection report to be submitted shall include following

items:

1) The detailed pipeline layout, and all facilities or obstacles nearby the

pipeline route shall be clearly marked;

2) Describe the thickness of covering layer or the depth of pipelinetrench, as well as the status along the route after the pipeline has

been laid;

3) Description for all locations and status of the damaged parts on

pipeline or its anticorrosion coating or in its cathode protection

system;

4) Check the riser pipe units on landing point and on platform point to

see whether they have met relevant technical requirements.

10.1.2 Buckle inspection

10.1.2.1 Buckle inspection shall be conducted by launching the detector into

the pipeline after the pipeline has been laid. For the buried pipeline, the

final buckle inspection shall be performed after the pipeline is fully

stable.

10.1.2.2 Any defect caused by local buckle shall be repaired or cut off, the

length of pipeline to be cut off shall be at least 3 m.

10.1.3 Anticorrosion inspection

10.1.3.1 Check the pipeline’s external anticorrosion coating especially the

riser pipes in splash zone.

10.1.3.2 For any pipeline section whose external anticorrosion coating is

damaged, its polarization degree can be spot-checked along such pipeline section. Especially for the section in which is far from



sacrificial anode and the section in which the stress is concentrated, the

anticorrosion effect shall be carefully watched and tested.

10.1.3.3 For any pipeline section, if its basic anticorrosion parameters can not

meet the requirement of cathode protection, it is necessary to take

relevant additional anticorrosion measures, such as to add sacrificial

anode module and to add external weight coating, etc.10.1.3.4 Take additional protection methods for some pipeline sections where

original protection may be not enough (such as the riser pipes at landing

point and the platform).

10.1.3.5 Confirm the presence of stray current and its disposal method

through measuring and visual inspection.

10.1.4 Safety system

10.1.4.1 Carry out professional inspections for the safety facilities including

alarm system, pressure safety device, leakage detection device, pipeline

block valve and one-way valve (non-return valve), etc.

10.1.4.2 Inspect the transmission emergency stop system (including reversetransmission if necessary) before the operation of the system according

to the design.

10.2 Work handover and acceptance


10.2.1.1 After completion, the pipeline system shall go through pressure

test.

10.2.1.2 The test shall be performed according to the test outline, or

perform the test section by section if necessary. If the pipeline needs to

be buried or covered, the pressure test can be performed after the

pipeline has been covered up.10.2.1.3 For the liquid transmission pipeline system, the medium for

pressure test shall use clean fresh water. If use seawater as the medium,

except filtering the seawater, it also needs to add some bactericide, anti-

corrosive agent and oxygen scavenger into the seawater.

10.2.1.4 For the gas transmission pipeline system, the test medium shall

use dry gas and clean gas, and shall meet the following requirements:

1) The purging mouth shall be set at a higher elevation position, the

exhausting outlet shall have dependable earthing device to prevent

static electricity.

2) If use natural gas for the test and purging, the vent outlet can not beset at the places nearby the offshore oil production plant, onshore

forests, highways, residential areas or buildings, the minimum

distance must not be less than 300 m, and relevant safety measures

shall be taken according to local conditions. The measures shall be

approved by local safety supervision organization. The

representative of safety supervision organization shall attend and

inspect the on site testing.

. 3) In testing, mark the whole pipeline route to prevent other unrelated

ships or boats to enter into the test area.

10.2.2 Test preparation



10.2.2.1 Use cleaning pig to clean the residual wastes and dirt in the

pipeline before test, and use detector to go through the whole

tested pipeline section.

10.2.2.2 After purging and testing, inject the test medium into the tested

pipeline section according to the requirement of the test outline.

10.2.2.3 The designed strength factor for the pressure test bulkhead shall be at least 2.

10.2.3 Test equipment and test configuration.

The instruments and equipment for testing the pressure, volume and

temperature shall have proper measuring range and shall have been

inspected and calibrated by the test organization to achieve required

precision.

10.2.4 Test pressure

10.2.4.1 Carry out strength and tightness test for the pipeline section

according to the requirements of design.10.2.4.2 If there is no relevant design requirement, the minimal test

pressure shall be 1.25 times of design internal pressure. During

pressure test, the circumferential stress shall not exceed 90% of

minimal yield strength, and under any circumstance the higher stress

shall be considered.

10.2.4.3 During hydraulic pressurizing, the relation curve of test liquid

volume and pressure value shall be recorded, so as to evaluate the

residual air volume in the tested pipeline section, such residual air

volume shall not exceed 0.2% of actual capacity.

10.2.5 Test duration

10.2.5.1 After pressurizing, sufficient time shall be given in order to let the

pressure in the tested pipeline section to be stable. In tightness test, the

pressure shall be holding stabilized not less than 24 hours.

10.2.5.2 Generally short pipelines or riser pipes do not need tightness test,

the pressure stabilization time for their strength test shall be 8 hours;

for the pipeline sections which can be 100% visual inspected, the

pressure stabilization time for their strength test shall be at least 2

hours.

10.2.6.1 Test outline10.2.6.1 The test outline shall be submitted to the certification and

inspection organization prior to hydraulic (gas) test. Only with

the approval, the outline can serve as a guidance for the test.

10.2.6.2 The test outline shall include following items:

1) Description for the tested pipeline section, such as total length,

elevation, valves and joints on the pipeline, branch lines, joints for

connecting the test equipment, test flow chart and equipment

allocation chart, etc;

2) Test medium (including additives);

3) Test pressure;

4) Pressure test duration;



5) The equipment and instruments for the pressure test and their

operation directions;

6) Pressurization sequence;

7) The monitoring system and record for the pressure test;

8) The method to clean the air from the tested pipeline section;

9) Depressurizing and venting out of the testing medium;10) Installation and inspection of the test bulkhead;

11) Safety measures, etc.

10.2.7 Acceptance and repair

10.2.7.1 The representative of the certification and inspection organization

and the representative of the owner shall attend the pressure test.

10.2.7.2 If all pressure parts and components in the tested pipeline section

can maintain their complete status without any leaking during the

course of testing, it means that the test is acceptable. By considering

the fluctuation of temperature, the pressure might have ±0.2%

variation during the pressure stabilization time. If the pressure drops

greatly, it means that the test is not acceptable, now the stabilization

time can be extended until the pressure variance during 24 hours is

up to the design requirement.

10.2.7.3 If the tested pipeline section has any rupture or leakage, the

damaged part shall be repaired or replaced, then such repaired or

replaced pipeline section shall be subject to hydraulic pressure test

again.

10.2.8 Hydraulic pressure test report

10.2.8.1 The hydraulic (gas) pressure test report for each tested pipelinesection shall be presented to the certification and inspection

organization.

10.2.8.2 The hydraulic pressure test report shall include following items:

1) Fill in the hydraulic pressure test report according to the specified

table and format, see Attachment J;

2) The relation curve chart of pressure and time;

3) Comparison between actual pressure-volume chart and theoretical

pressure-volume chart;

4) If necessary, the relation curve chart of whole temperature and time

variance shall be included;

5) The conformity certificate for the pressure test system.

10.2.9 Pressure test report

10.2.9.1 Fill in the gas pressure test report according to the specified table

and format, see Attachment J;

10.2.9.2 The relation curve chart of pressure and time;

10.2.9.3 Comparison between actual pressure-volume chart and theoretical

pressure-volume chart;

10.2.9.4 The conformity certificate for the pressure test system.

10.2.9.5 The depressurizing and exhausting method for the test medium.

10.2.10 When handing over the work, the construction unit shall submit thefollowing technical documents:



10.2.10.1 The factory conformity certificate and reexamination document for

the pipes and pipe fittings;

10.2.10.2 The conformity certificate and reexamination document for the

anticorrosion coating materials;

10.2.10 3 The conformity certificate for anode materials;

10.2.10.4 The conformity certificate and reexamination document for thewelding materials;

10.2.10.5 Operating test record (visual inspection, nondestructive testing and

dimension inspection);

10.2.10.6 Anticorrosion coating inspection record;

10.2.10.7 Route location chart and data during pipelaying period;

10.2.10.8 Pressure test report;

10.2.10.9 various operation records (records of foam insulation joint coating,

pipeline purging, welding, etc);

10.2.10.10 Final inspection report;

10.2.10.11 Trenching/protection project report;

10.2.10.12 Buckle inspection report.





Chart A.0.2 cylinderical form factor K 1

A.0.3The basic wind pressure P 0 can be calculated by the below formula:

p0 = α • V12…………………………………….. (A.0.3)

In the formula, p0 — basic wind pressure, Pa;

α — wind pressure factor, considered as 0.613;V1 — design wind velocity m/s under time gap t .

A.0.4The design wind velocity is the value of maximum average wind velocity over

1min time gap in the area of 10m above sea surface with 50 years of recurrent period.

A.0.5 T is the basic self-vibration circle of the riser. When T ≥0.5s, all the wind

pressures should be β time of the wind pressure p0. β is the wind vibration factor, its

value should be taken from Table A.0.5.

Wind vibration factor β Table A.0.5

Basic self-vibration circle of the

riser

0.5 1.0 1.5 2.0 3.5 5.6

β 1.45 1.55 1.62 1.65 1.70 1.75



Appendix B Set value of fluid dynamic factor CD, CM and CL value

B.0.1Drag force factor CD, can be checked from Chart B.0.1 based on Keulegan-

Carpenter number Sc ( m

ct

U T K

D

⋅= ). In the formula, U m represents the highest

trajectory particle velocity of fluid movement; Dt represents the effective outer

diameter of pipe; T represents the wave period.

B.0.2The formula CM = Cm +1 shows the relation between the inertial force factor

CM and the additional mass factor Cm, in which the value of Cmcan be checked from

Chart B.0.2 according to different ratio of h to Dt; h represents the fixed boundary

distance of pipe bottom; Dt represents the effective pipe diameter.

B.0.3The lifting force factor GLO at the fixed boundary can be defined based on the

K c number in Chart B.0.3 – 1.

The ratio of lifting factor C L to C LO apart from the fixed boundary can be calculated

by the ratio of h to Dtin Chart B.0.3 – 1.

Chart B.0.1 cylinder drag force C D in the vibration flow

Chart B.0.2 additional mass factor Cm



Chart B.0.3 – 1 lifting factor GLO at the fixed boundary in the vibration flow

Chart B.0.3 – 2 cylinder lifting factor C L at a certain distance to the fixed boundary



Appendix C Set value of Group pile interference factor Kg and sun blind factor Kz

C.0.1The hydrodynamic characteristics of the riser groups or the riser clusters are

considered to be similar to the group piles and share the related data with it. Value

of the group pile interference factor K g and sun blind factor K z can be checked out

from Chart C.0.1. In the Chart, l represents the distance between pipe center lines, Dl represents the effective diameter of pipe.

Chart C.0.1 Group pile interference factor K g and sun blind factor K z



Appendix D Vortex shedding phenomenon caused by ocean current

D.1 General requirement

D.1.1Vortex shedding frequency f can be obtained from the formula below:t

t

S V f

D= …………………………………………………… (D.1.1)

In the formula, f — vortex shedding frequency, Hz;

S t — Strouhal number as shown in Chart D.1.1;

V — flow speed m/s to the vertical direction of the pipe axis;

Dt — effective pipe diameter m.

Chart D.1.1 Function relation of cylinder S t number and Reynolds number

D.1.2 In order to determine the velocity range of the possible vortex shedding

causing vibration, a parameter named converted velocity V r which can be calculated

by the below formula:

r

p t

V V

f D=

⋅……………………………………………… (D.1.2)

In this formula, V r — parameter of the converted velocity;

V — flow speed m/s to the vertical direction of the pipe axis;

f p — self-vibration frequency Hz of the pipe;

Dt — effective pipe diameter m.

D.1.3 Other parameter is the stability factor K s which controls the oscillation. It can

be set by the below formula:

2

2 s

t

me K

D

λ

ρ

⋅= ……………………………………………… (D.1.3 – 1)

In this formula, K s — stability factor;

λ — logarithmic attenuation rate of the structural damping;

ρ — desity of water around the pipe; kg / m3,.

Dt — effective pipe diameter m,

mc — effective mass of unit length of the pipe, can be set by the formular

below (see D.1.3 – 2).



( )

( )

2

0

2

0

L

c d

m y x dxm

y x dx

⎡ ⎤⎣ ⎦=

⎡ ⎤⎣ ⎦

∫

∫……………………………… (D.1.3 – 2)

In this formula, m — effective mass of unit length of the pipe, which includes the

mass of the structure, the additional mass and the mass of thefluid in the pipe, kg / m;

y( x) — actual vibration form of the spanning section of the pipe;

L — length of the pipe, m;

d — submerged depth of the pipe, m.

D.2 Same direction vibrationD.2.1When 1.0＜V r ＜3.5 and K s＜1.8, it is possible to generate resonance

vibration causing

by the same direction vortex shedding.

D.2.2According to flow velocity, the vortex will be separated from both sides of

the pipesymmetrically or alternatively. When 1.0＜V r ＜2.2, the vortex shedding is

symmetric. The start up current velocity can be found out from Chart D.2.2.

When V r ＜2.2, the vortex shedding will be asymmetric.

D.2.3The maximum amplitude caused by the same direction vortex shedding can

be defined according to Chart D.2.3.

Chart D.2.2 start up current velocity of the same direction vibration

Chart D.2.3 amplitude of the same direction vibration



D.3 Lateral vibrationD.3.1When K s＜16 and V r value is defined according to Chart D.3.1, it is possible

to generate lateral vibration.

Chart D.3.1 start up current velocity of the lateral vibration

D.3.2 The maximum amplitude of the lateral vibration can be defined based on

Chart D.3.2.. The parameter of vibration form used in the chart can be calculated

from the below formula:1

22

0max

4

0

( )

( )

L

L

m y x dx y

m y x dxγ

⎧ ⎫⎡ ⎤⎪ ⎪⎣ ⎦= ⎨

⎡ ⎤⎪ ⎪⎣ ⎦⎩ ⎭

∫

∫⎬ ………………………………… (D.3.2)

In this formula, γ — parameter of the vibration form;

y( x) — vibration form; ymax — maximum value of the vibration form.

For the first type of vibration form, the tube supporting beam γ is 1.16. For the first

and the second type of vibration form, the cantilever beam γ are 1.31 and 1.50

respectively.

Chart D.3.2 amplitude of the lateral vibration



Appendix E Wave impact load

E.1 Wave impact loadE.1.1As the pipe located in the wave impact section is bearing the force caused by

wave impact, the dynamic effect of the pipe should be calculated.E.1.2The force of wave impact on the unit length of pipe can be calculated by the

below formula:

21

2 s s s t

F C V D ρ = …………………………………………… (E.1.2)

In this formula, F s — wave impact force on the unit length of pipe at the velocity

direction,

N / m;

ρ — density of water around the pipe; kg / m3,.

C s — impact factor;

Dt — effective diameter of component part, m;

V s — velocity component of water particle to the vertical surface of thesteel pipe at the impact point, m/s.

E.1.3 Impact factor C s can be set by theory or / and test method. The value of the

smooth cylinder, C s, is not lower than 3.0.

E.1.4Power amplification factor should be taken into account when calculating the

impact force. The dynamic factors of butt ends moment and middle cross moment

are better to be set as 1.5 and 2..0 respectively.

E.2 Fatigue caused by wave impactE.2.1Fatigue failure caused by wave impact can be obtained through the below

process:E.2.1.1To define the minimum wave height that may cause impact, H min;

E.2.1.2To divide the long distributed wave height that exceeds the H min into

certain sections;

E.2.1.3The stress range value of every section can be obtained from the below

formula:

( )( )2 j slam b waσ σ σ σ ⎡ ⎤∆ = − +⎣ ⎦ …………………..(E.2.1 – 1)

In this formula, ∆σ j — stress range value of each section, Pa;

σslam — stress in a calculation unit caused by the impact load listed in

E.1.2, Pa;

σ b — stress acts on the calculation unit caused by net buoyant, Pa;

σw — stress acts on the calculation unit caused by vertical wave force,

Pa;

α — consider the power amplification factor, value to be obtained

from E.1.4.

E.2.1.4The impact can involve up to 20 approximate linear attenuate stress

areas every time.

E.2.1.5The influence to fatigue of each wave section can be calculated by the

below formula:

20

20 20i

k i j

j n j

n iY R

N

=

= −

⎛ ⎞= ⎜ ⎟

⎝ ⎠∑ ……………………………………(E.2.1 – 2)

In this formula, Y — influence to fatigue of each wave section;

n j — wave number in j section;



N j — critical number of stress circle in the corresponding range of ∆σ

(can be found out from S — N curve);

n j — stress area number over the specified range at the corresponding

boundary point of S — N curve;

R — reduction coefficient of wave number. For the calculation unit

given, only the wave in the sectorial area within 10° at both sides to the vertical direction of the component

parts, need to be considered. For those wave distributed

without direction, R is 0.11.

k — slope of S — N curve (marked on the double logarithmic

coordinate).

E.2.2When calculating the fatigue influence to the other loads, the fatigue

influence caused by wave impact should be added in.



Appendix F Buckle calculation

F.1 Local BuckleF.1.1 If no further more precise method, formula or experimental data, below

critical conditions of combined stress should be adopted to control the buckle under longitudinal stress and circumferential stress:

2

1.0 y x

xp xcr yp ycr

σ σ

η σ η σ

⎛ ⎞ ⎛ ⎞+⎜ ⎟ ⎜ ⎟⎜ ⎟ ⎜ ⎟

⎝ ⎠ ⎝ ⎠≤ …………………………..(F.1.1 – 1)

3001

y

ycr D

σ α

δ σ = + ⋅

In this formula, σx — longitudinal stress, N / mm2,

σy — circumferential stress, N / mm2,

σxcr — critical longitudinal stress, N / mm2,

σycr — critical circumferential stress, N / mm2

,ηxp (ηyp) — Buckle utilization factor, listed in Chart F.1.1;

D — nominal outer diameter of pipe, mm;

δ — nominal thickness of pipe, mm. N M

x x xσ σ σ = + …………………………..(F.1.1 – 2)

(If σx＜0, σx= 0 is to be set)

σ N x = N / A………………………(F.1.1 – 3)

σ M x = N / M ……………………….(F.1.1 – 4)

A = π(D – δ) δ………………………(F.1.1 – 5)

( )2

4

W Dπ

δ δ = − ………………………(F.1.1 – 6)

In this formula, σ N x — longitudinal stress under axial force, pressure stress should

be positive and tension stress should be negative, N / mm2,

σ M x — longitudinal stress under bent moment, pressure stress should be

positive and tension stress should be negative, N / mm2,

N — axial force, N;

M — bent moment, N • mm;

A — net section space of pipe, mm2;

W — elastic modulus of section, mm3.

σy = ( pc – pi) D / 2δ ………………….. (F.1.1 –7)

p = pc – pi ……………………….(F.1.1 – 8)

In the formula, pc — external pressure, N / mm2; pi — internal pressure, N / mm2;

p — external over pressure, N / mm2. N M

N x x xcr xcr xcr

x x

σ σ M σ σ σ σ

= + σ …………………………(F.1.1 – 9)

N

xcr sσ σ = ……………………………………….(F.1.1 – 10)

(when D / δ ＜20)

σ N x = σs［1– 0.001 ( D / δ – 20) ］…………(F.1.1 – 11)

(when 20＜ D / δ＜ 100)

σ

M

x = σs (1.35 – 0.0045 D / δ) …………..(F.1.1 – 12)



In the formula, σ N x — critical longitudinal stress with only effect of N ( M = 0, p =

0), N / mm2;

σ M x — critical longitudinal stress of pipe under with only effect of bent

moment M ( N = 0, p = 0), N / mm2.

σs — relevent yield stress for 0.2% of the remained strain, N / mm 2.

2

ycr yE E

D

δ σ σ

δ ⎛ = = ⎜ −⎝ ⎠

⎞⎟ …………………………. (F.1.1 – 13)

(whenσyE＜2 / 3σs)2

211

3 3

s ycr s

yE

σ σ σ

σ

⎡ ⎤⎛ ⎞⎢= − ⎜ ⎟⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

⎥ …………………………….(F.1.1 – 14)

(whenσyE＞2 / 3σs)

In the formula, σycr — critical circumferential stress with only effect of p, N = 0 and

M = 0, N / mm2;

σyE — elastic critical circumferential stress, N / mm

2

; E — elastic modulus, N / mm2.

Table of Buckle utilization factor Table F.1.1

Design state Installation state In position state

Position Pipe and riser Pipe Riser

Utilization

factor

load condition

ηxp

ηyp

ηxp

ηyp

ηxp

ηyp

4.4.1.1 (1) in this

specification

0.86 0.75 0.72 0.62 0.50 0.43

4.4.1.1 (2) in thisspecification

1.00 0.98 0.96 0.82 0.67 0.56

F.2 Buckle propagationF.2.1 It is necessary to study the possibility of pipeline buckle propagation.

F.2.2 If no further more precise formula, critical pressure of buckle propagation P pr

can be calculated by through the below formula:2

1.15 pr s

p D

δ πσ

δ

⎛ ≅ ⎜

−⎝ ⎠

⎞⎟ ………………………………… (F.2.2.)

In the formula, P pr — critical pressure of buckle propagation, N / mm2.

F.2.3 Generally, buckle arrestor should be an option for the pipeline sectionswhere the external over pressure is higher than P pr . But if the buckle arrestor is

used for the section under condition P ＞ P in (initial buckle external pressure of the

pipeline), it can be dispensed in section under condition P pr ＜ P ＜ P in.

F.3 General ‘pressure bar’ buckling of the pipelineF.3.1 The pipeline should be regarded as a straight bar under equivalent axial

pressure, and its overall calibration for stability should be proceeded. Equivalent

axial pressure S can be calculated by the below formula:

( )2 2

0

4 4i

S N D p D pπ π

δ = + − − …………………….. (F.3.1)

In the formula, S — equivalent axial pressure, N.



When the axle is under pressure, N should be a positive value. The axle force

should enclose the internal axle force caused by axle restraint generated during the

pipeline deforming process.

If S is in negative, it means that overall pipeline calibration for stability is not

necessary. Underground pipelines are normally not to be considered.

F.3.2 If overall ‘pressure bar’ buckling is acting on the pipeline, the buckling dueto loss of stability should be calculated and its additional stress should also be

added into the stability calibration.



Appendix G Sample collecting method

G.0.1Sample collecting method should follow the specification described in Chart

G.0.1 – 1 to G.0.1 – 8.

Chart G.0.1 – 1 Welding end sample collecting for on-site welding procedure

identification and test

Notes: The positions listed above for sample collecting should be used for welding

position 2G, 5G and 6G. The position of collecting sample of 1G for identification

can be any position.



Chart G.0.1 -2 Sample collected for on-site welding performance of the welders

and the welding operators

Notes: The positions above can be 45° reversed to the clockwise sense or evenly

distributed on the periphery, but vertical welding seam should not be included into

the samples.



Chart G.0.1 -3 Samples for tensile test



Chart G.0.1 – 4 Sample for bending test



Chart G.0.1 -5 Sample of Notch fracture test

Chart G.0.1 – 6 Charpy-V notch impact test



Chart G.0.1 – 7 Hardness test for welding joints

Chart G.0.1 – 8 Sample collecting for the welding procedure identification of the pipe

and the pipe parts



Appendix H Identification of Welders

H.1 Identification of welders

H.1.1The specified welding position for welders should fulfill the descriptions in

Chart H.1.1.Specified welding positions for welders Table H.1.1

Main testing positions Specified welding positions

1G 1G

2G 1G, 2G

5G 1G, 3G

2G+5G All

6G All

H.1.2The welder’s judgment is valid within the range specified below on the main

variable elements. If any one of the main elements below changes, the identification

test should be taken again.(1) Change of welding process;

(2) Change of welding direction;

(3) alkaline flux changed to cellulosic flux, vice versa;

(4) diameter of the pipe changed from one group below to the other, D＜100mm,

100mm＜ D＜300mm and D＞300mm;

(5) Thickness of pipe wall changed from less than 5mm to more than 5mm;

(6) Changes to the main welding positions specified in Chart H.1.1;

(7) Obvious change of the welding seam bevel, for example changed from V shape

bevel to Y shape bevel.

H.1.3The main tasks of the welder includes to make plan, to adjust, to start, to guideand to stop the welding operation, and to have identification check if their operation

may affect the welding quality. For those welders, who have already had sufficient

training on practical welding equipment and have been handling jobs that have no

effect to the welding quality, the identification check can be exempted.

H.1.4The welder should have identification check at the main position by seam

matching welding at one side of the pipe. Under special circumstance, the checking

can be done on the steel board.

The repair welder may identify the position by mending the welding with a local

thickness as a typical checking.

H.1.5The Identification test should be performed with equipment used in operation or

equivalent, and be carried on in actual situations, such as in the workshop, at prefabricated field and on the operation vessel.

H.1.6Visual and radiograph examination should be applied for the identification test.

Mechanic function should also be tested when gas metal arc welding technique is

used. Usually, the lateral bend and notch break sample will be applied.

H.1.7 If a welder or a welding operator has not been working with the welding

techniques in the identified area over 6 months, their certification will be void.

H.1.8 If a welder or a welding operator has finished all and applicable welding

procedure tests, their identification test will be passed.

H.1.9 If the welding personnel can not pass the identification welding in 6 months,

they should start the identification test again from the beginning.

H.2 Testing weld



H.2.1Before the testing weld, a certain period of time for equipment adjustment is

allowed.

H.2.2 If the welding procedure involves one or more than one operation steps or

welding equipment, the testing welding should include all operation steps and

equipment for completing the welding. In function testing, different weldingequipment and welding factor should be applied.

H.2.3 In the test, two pipe joints, which are enough and can meet the actual restrain

condition, should be connected according to the welding procedure identified. The

pipe diameter, thickness of wall and the main welding positions should all be chosen

within the range specified.

For the delivery pipe installed at the field, actual dry pipe should be used for

identification test.

For the welding on steel pipe, in which the thickness of pipe wall is below 5mm or the

outer diameter is less than 100mm, size of such testing pipe should be defined

separately.

H.2.4For the pipe with diameter less than 300mm, welding should be done for thewhole junction. For the test welding on the wider pipe in diameter, the welding length

should be half of the periphery of the steal pipe at least. The typical flat weld, stand

weld and upward weld should be performed continuously.

H.2.5When performing the welding on bottom or topping course, one stop and start

welding step should be applied at least.

All the welding rods prepared should be used. In order to remove the welding peel,

residue and those unimportant local faults, mild mechanic process is allowed. But the

mechanic process should not used to make up the welding seam faults caused by bad

welding operation. The welding should be performed under the normal operation

speed.

H.3 Inspection and testing for the verification of testing weld

H.3.1Every testing weld pass should be subject to visual inspection. If visual

examination passed, the welding seam should be further examined by X ray flaw

detection procedure identified to perform the radiograph examination.

H.3.2 If the welding seam being tested is welded by using gas metal arc welding

technique or other welding procedure with techniques that may probably cause

incomplete welding defects, destructive test for the welding seam should be

performed according to Chart H.3.2.

Type and quantity of destructive test for welding seam Table H.3.2

Pipe diameter

D(mm)

Thickness

of wall

δ(mm)

Notch

fracture test

Surface

bend test

Root bend

test

Lateral

bend test

D＜100

10＜ D＜300

D＜300

δ＜12.5

2

4

8

0

0

2

2

2

2

0

0

0

D＜100

10＜ D＜300

D＜300

δ＜12.5

2

4

8

0

0

0

0

0

0

2

2

4



If test failure is caused by the situation out of control of the welder or welding

operator, the failure should not be counted. At the same time, new identification

opportunity should be given. Test sample collecting method should be applied

according to the specification in Appendix G.

H.3.3 If testing weld is not satisfied, the welder or welding operator may be requested

to repeat the testing weld immediately with doubled weld quantity. Meanwhile, thetwo new welding seams should both be satisfied. The welder or welding operator is

not allowed to perform further testing weld until they pass all the additional training.



Appendix J Pressure test report

Name of the project:

_______________________________________________________

Design requirement for testing:_______________________________________________

Testing section: from________________to_____________________________

Testing factor quantity, type, position:_________________________________

Type, location, height, quantity of the pressure manometer:________________

Type, length, volume of pipe of the testing section:_______________________

Type and source of the testing medium:________________________________

Actual pressure test figure:

Strength test pressure__________ Mpa, At the beginning of the test______________

Mpa

At the end of the test____________________ Mpa

Pressure stabilized Date of the strength test_____________. Time_______________ h

Tightness test pressure__________ Mpa, At the beginning of the test______________

Mpa

At the end of the test______________ Mpa

Pressure stabilized Date of the tightness test____________ time

from_______to________

Notes and conclusion:

_____________________________________________________________________

___

_____________________________________________________________________ ___

_____________________________________________________________________

___

_____________________________________________________________________

___

Representative of property owner______________________

Date________________

Representative of construction company_________________

Date________________

Representative of supervisory department________________ Date________________



Appendix K Description for the wording in this specification

K.0.1 Following wordings in this specification shall have different degrees of

strictness:K.0.1.1 The word to express very strict, no other selections but to do so:

Positive word is “must”;

Negative word is “must not”.

K.0.1.2 The word to express strict, have to do so under normal situations:

Positive word is “shall” or “can”;

Negative word is “shall not” or “can not”.

K.0.1.3 The word to express a slight degree of optional, to do like this first of all if

condition allows:

Positive word is “should” or “could”;

Negative word is “should not” or “could not”.



Additional Notes

Name list of the main drafters of this specification and the main bodies of editing and

the participating bodies

Main bodies of editing :

Participating bodies: The engineering and technology research institute of China

National Petroleum Corp.

Main drafters: Liu Jinkun Zhang Keming Wang Lichun



Attachment Technical Specification for Pipeline System in Beach-shallow Sea

Technical Specification for Pipeline System

in Beach-shallow Sea

Clause explanation



Compilation explanation

According to the requirement of the document- (95)Zhong You Ji Jian Zi Di No. 35,

the document SY/T 0305- 96 “Technical Specification for Pipeline System in Beach-shallow Sea” compiled by the Survey and Design Institute of Sheng Li Petroleum

Management Bureau and the First Oil Facilities Construction Company of Sheng Li

Petroleum Management Bureau has been approved and issued by the China Oil and

Natural Gas Corporation with the approval document -(96) Zhong You Ji Jiang Zi Di

No. 642.

During the course of compiling, the compilers abided by the state’s relevant principles

and regulations, had carried out lots of research and investigation, concluded the

works and experience on design and construction of pipeline system in beach-shallow

sea, widely asked for other units opinions and suggestions, and repeatedly discussed

and corrected for the document, finally the document had been examined and

accepted by the Fundamental Construction Engineering Bureau of China Oil and

Natural Gas Corporation together with other relevant authorities.

This specification has totally 10 chapters and 10 attachments, mainly include: general

rules, technical terms, pipeline planning, environment and loading, design, pipeline

and pipeline accessories, pipeline anticorrosion protection and weight coating,

onshore pipeline prefabrication and assembly, pipeline installation in beach-shallow

sea, final inspection and completion tests.

For the purpose of that this specification would be correctly understood and carried

out by the units and personnel which are in relations with foundation building, design,

construction, scientific research, and universities and institutes, this “Clause

explanation” is compiled according to state’s consolidated requirements on the

compiling standards and specifications of this field, and following the sequence of

original context, provided for the reference of the personnel in this trade.

Whereas this specification is firstly compiled, we hope that all units and personnel

concerned shall learn and sum up their experiences during work, and record relevant

data; for any corrective suggestions and supplementary opinions, please send your

materials to: Survey and Design Institute of Sheng Li Petroleum Management Bureau,Dong Ying City, Shan Dong Province (Post code: 257026), and the Standard Office

of the Petroleum Engineering Technology Institute, No. 40 Jin Tang Highway, Tang

Gu District, Tian Jin City (Post code: 300451), for the reference of further revision.

Survey and Design Institute of Sheng Li Petroleum Management Bureau

Aug. 1996



Index

1. General rules

3.Route planning

3.1 General rules3.2 Route selection

3.3 Route survey

4. Environment and load

4.2 Natural environmental condition

4.3 Internal conditions of pipeline

4.4 Loading

5. Designing

5.1 General rules

5.2 On-position pipeline system

5.3 Pipeline system during installation 5.4 Pipeline accessories

5.5 Insulated pipeline

6. Pipeline and the Materials of Pipeline Accessories

6.1 General rules

6.2 Steel pipes used in pipeline or riser pipes

6.3 Pipe fittings

6.4 Bolts

6.5 Supporting components

7. Pipeline anticorrosion and weight coating

7.1 Pipeline anticorrosion

7.2 Weight coating8. Onshore pipeline prefabrication and assembly

8.1 General rules

8.2 Quality requirement for the pipes delivered to the workshop

8.3 Prefabrication and assembly

9. Pipeline installation in beach-shallow sea

9.1 General rules

9.2 Pipeline route control

9.3 Connection

9.4 Ditch digging and pipeline burying

10. Final inspection and completion test

10.1 Final inspection10.2 Work handover and acceptance



1. General rules

1.0.1 This clause describes the purpose of this specification. Due to that the beach-

shallow sea has its special characters, the design and construction of the pipeline in beach-shallow sea can neither completely follow the standards of common subsea

pipeline design and construction, nor completely follow the standards of onshore

pipeline design and construction. This specification is specially established for the

purpose to standardize the engineering construction of pipeline in beach-shallow sea.

When designing and constructing the pipeline in beach-shallow sea, it is necessary to

learn from domestic and abroad the advanced technology and the latest achievements

in this field continuously, and integrate them with local practice and conditions.

1.0.2 This clause describes the application scope of this specification. This

specification is practicable for the design and construction of steel pipeline system in

beach-shallow sea petroleum engineering, including whole and part of the pipelines or

riser pipes spanning over, laying on or buried into the seabed. But the design and

material selection of the beach-shallow sea pipeline system for transmitting LPG and

LNG has special requirements, so it is not included in this specification.

1.0.4 According to the “Beach-shallow Sea Environmental Conditions and Loading

Technical Specifications”, the definition for “beach-shallow sea” is denoting the

zones of “supratidal zone”, “intertidal zone” and “very shallow sea”. The “supratidal

zone” denotes the marsh zone above the high tide level, so the affection of sea

environment to the pipelines in the supratidal zone are very limited. Current state

specifications for onshore pipeline system design and construction have relativeregulations for the pipeline system crossing over the marsh zone. For the purpose of

unitive description, this clause has given the regulations on the design and

construction of the pipeline system in supratidal zone.

1.0.5 This clause has described the relations of this specification with other

specifications, laws and regulations.

3 Route planning

3.1 General rules

3.1.1 This clause describes the elements needed to be considered comprehensively for

planning the pipeline routes.

3.1.2 This clause is the detailed description for “natural environmental conditions” in

Clause 3.1.1 of this specification.

3.1.3 This clause is the detailed description for “regional planning for the location” in

Clause 3.1.1 of this specification.



3.2 Route selection

3.2.1 This clause is the general rule for route selection. Under the prerequisite of

safety, for economical purpose, it is necessary to select a most optimal route for the

pipeline from its starting point to its end point, i.e. that the route shall be straight andlevel as possible, and such is also good for construction.

3.2.2 Due to that the ship anchoring area, moving fault area and soft soil sliding area

have great affection to the pipeline’s safety, so route selecting shall keep away from

these areas as far as possible. If for the limitation of conditions or after design study,

pipeline passing through these areas would be more reasonable, then after taking

necessary preventive measures to ensure the safety, select a most proper and shortest

route to pass through these areas, so as to minimize the project investment and to

eliminate the threat to the pipeline’s safety.

3.2.3 For the purpose to ensure the safe installing and positioning of the pipeline in beach-shallow sea and without endangering the original facilities, this clause has

regulated the distance between the new pipeline and original pipeline or other

offshore facilities.

3.2.3.1 The distance between the trunk pipeline and subsea obstacles and dangerous

objects in open sea area shall not be less than 250 m, this is by referring to the

SY/T 4804-92 “Specification for Subsea Pipeline System” and considering the

actual situation of the beach-shallow sea. The distance to original pipeline or cables

shall not be less than 30 m is regulated according to the general requirements for

the pipeline’s laying and backfill.

3.2.3.2 If platform building and pipeline laying is before well drilling, the pipeline in

the oil (gas) filed shall keep away from the well repairing position, and sometimesalso shall keep away from well drilling position, to avoid the affection of well

repairing and well drilling.

3.2.4 By considering the difficulty of offshore construction and safety reasons, this

specification has regulated that in principal the newly designed pipeline shall not

cross over the original pipeline or cables. But actually, especially in oil fields,

sometimes pipelines are needed to cross with each other. So for to prevent the

interactive affection of stray current produced from cathode protection, and for

considering the maintenance and exterior tests after the pipeline has been laid,

keeping certain distance between them is important. This specification has regulatedthat the minimum net distance between pipelines shall be bigger than 0.3 m by

referring to the SY/T 4804-92 “Specification for Subsea Pipeline System”.

3.3 Route survey

3.3.1 This clause describes the contents of route survey.

3.3.2 This clause describes the contents of hydrological and meteorological survey

along the pipeline area.

3.3.3 This clause describes the requirement for landform survey along the pipelineroute, including the width, measuring precision and method of the passageway, etc.



The width of passageway shall consider the transversal moving scope after the

pipeline has been laid, and also shall consider the reasonable adjustment of pipeline’s

axial line position during designing. In this specification the width and precision of

passageway survey is specified according to the “Subsea Oil/Gas Pipeline

Engineering” compiled by Professor Ma Liang of Da Lian Science and Engineering

University and the “Technical Requirements for Sheng Li Beach-Shallow SeaPipeline Route Investigation”.

3.3.4 This clause describes the method to obtain the data of soil characters along the

pipeline routes and the technical requirements for the soil data tests, by referring to

the SY/T 4804-92 “Specification for Subsea Pipeline System”.

3.3.5 According to the subsea bottom soil investigation and ditch digging experiment

for the Sheng Li Cheng Dao Oil Filed, the bottom soil of Cheng Dao Oil Field is very

unstable. Because the current speed in the bottom is high, the flushing and silting

phenomenon is serious, the backfill speed after ditch digging is quick, these will cause

big affection to the design and construction of subsea pipeline (especially if the soil of the top layer is the sandy soil which may cause liquefaction, it shall attract the great

attention of relevant design and construction persons). The beach-shallow sea areas in

Da Gang and Liao He also have these problems. Under the action of external force,

the pipeline may have displacement, up floating, sinking, vibrating, and even being

damaged. So it is regulated that when in route surveying, the soil along the route shall

be investigated so as to evaluate above problems beforehand. Generally the soil

symptoms include: seabed gradient, seabed soil characters, unstable scope and

landform, soil displacement frequency and speed, etc.

4. Environment and load4.2 Natural environmental condition

4.2.1 Selection of the natural environmental conditions such as wind, wave, current,

tide, ice condition and temperature has been clearly regulated in “Beach-Shallow Sea

Environmental Conditions and Loading Technical Specification”, so this speculation

will not give another description.

4.2.2 The seawater and soil characters relating to seawater’s seasonal variations and

seabed soil along the pipeline route, such as PH value, saltness, oxygen level, and unit

resistance, will affect the design of pipeline’s anticorrosive system, so the data of this

concern shall be collected.

4.2.3 Marine growth on the pipeline may increase the pipeline’s effective diameter

and the roughness on the surface, thus correspondingly increase the liquid flow load,

and also it will have corrosive affection on the pipeline. The data about the marine

growth shall be collected for the design to consider the affection of marine growth to

the pipeline.

4.3 Internal conditions of pipeline

4.3.1 The internal conditions of pipeline during the period from storage, installation,

pressure test to production will have relations to pipeline’s strained status and

anticorrosive design.



4.3.2 Medium’s temperature and pressure and their variance in the pipeline under

operating status will decide the design values of temperature and internal pressure.

According to the corrosive elements and content in the transmitted medium, whether

the internal anticorrosive method is needed and what anticorrosive method is to apply

can be decided.

4.4 Loading

4.4.1 This clause is referring to the relevant clauses in SY/T 4804-92 “Specification

for Subsea Pipeline System”, and has regulated 2 loading conditions and 2 design

status. Different design status and different load conditions are using different

strength utilization coefficient, see the Clause 5.2.2 and Clause 5.3.2 of this

specification.

4.4.2 This clause describes the load combination principal for beach-shallow sea

pipeline system. For a selected design status, shall analyse the various loads acting onthe pipeline at a same time, consider their reasonable and possible load combination

of most adverse situation, and check the pipeline’s strength. Load combination shall

consider not only the value of load, but also its acting point and direction. For the

loads caused by wind, wave or current, if no definitive data at hand, it shall be

considered that the probabilities of loads from all directions are the same. Variance of

water level will affect the value selection of wave data, the acting position of sea ice,

buoyancy variance, water pressure variance and the working water depth during

construction, etc. So it is necessary to consider the affection of water level variance.

4.4.3 Work load denotes all loads acting on the pipeline except the natural

environmental loads such as wind, wave, tide, sea ice, earthquake, etc. and other casual loads. So when the pipeline has been properly installed on its position, the

work load is generally including the weight of pipeline itself and its accessories, the

medium weight in the pipeline, buoyancy, internal/external pressure, thermostress,

soil friction, and the pipeline’s residual stress after installation. When in installing

status, the work load is generally including structure’s own weight, buoyancy,

external pressure, and all forces acting on the pipeline during constructing such as the

stretching force, pipeline pulling force and ditch excavator’s force during pipelaying.

4.4.4 This clause is for the calculation of natural environmental loads and the

principal of consideration.4.4.4.1 This clause is for the general requirements on natural environmental loads.

The value of reoccurrence period for environmental loads after the pipeline has

been installed at its position shall be taken by the same standard as the platform

itself. By referring to “Beach-Shallow Sea Environmental Conditions and Loading

Technical Specification”, this value is selected as 50 years per occurrence.

4.4.4.2 This clause is for the calculation of wind load, which is introduced from the

SY/T 4804-92 “Specification for Subsea Pipeline System”. For the vibration caused

by wind, especially the vibration on the fine and long riser pipes, the chapter of

“Marine Pipeline” in “Technical Standards for Port Facilities – Description” (Japan)

has given following regulations: for to prevent the affection of vibration, relation

between the external diameter of riser pipe and the supporting space of riser pipe



shall meet following formula, but if a special anti-vibration method has been taken,

and blasting test has also proved its stability, this formula might not have been used.

L 0.8 Lr D ≥ —— √ ——, and D ≥ —— (1)

30 δ 40

(注：√ 表示根号)

In which D — the external diameter of riser pipe, cm;

Lr — the supporting space of riser pipe, cm;

δ — the thickness of riser pipe, cm;

4.4.4.3 This clause describes the confirmation method for the wave load acting on

the riser pipe and the pipelines in laying or not yet laid. The ratio of pipelineexternal diameter to wave length in beach-shallow sea is generally smaller than 0.2,

such passing of waves will not change the waves’ original status, and generally the

Morison formula is used for calculating the wave load. The wave load acting on the

pipeline and riser pipe includes the forces of dragging and lifting which are in

consistent with the absolute velocity or relative velocity of the water mass point,

and the inertia force which is in consistent with the absolute acceleration or relative

acceleration of the water mass point.

About the hydrodynamic force parameters of C D , C M , C L, the elements of affection

are many, they are relevant to the components’ shape, surface roughness, Reynolds

numbers Re, Kc, and the distance to the boundary, etc., and it is better that they

should be confirmed by model test or by updated study results. The value selection

for C D , C M , C L in this specification are introduced from SY/T 4804-92

“Specification for Subsea Pipeline System”.

When calculating the wave load by Morison formula, the movement velocity and

acceleration of waves’ water mass point shall be calculated by proper wave theory

according to the design wave characters and water depth, etc. The selected wave

theory shall be consistent with actual situation. When considering the waves’ action

on the pipeline, according to the water depth, landform and other elements, beach-

shallow sea can be divided into following zones:

1) Shallow water zone: 0.5 L＞d ＞ d b (d is water depth, d b is the critical water depth

when the wave is breaking, L is the wave length), the wave movement in this zoneis affected by subsea landform, but it will not break. The wave theory generally

used for this zone is as following:

If d/L＞ 0.2, H/ d ＜0.2, use linear wave theory;

If 0.1＜d/L＜0.2, H/ d＞ 0.2, use “Stokes 5-step wave” theory;

If 0.04～0.05＜d/L＜0.1, use elliptical cosine wave theory.

In which, H – design wave height, m;

L – design wave length, m;

d – water depth, m.



2) Wave breaking zone: d ＜ d b , waves are pushing to the bank, H/ d is to the extreme

value, waves are breaking. According to “Technical Standards for Port Facilities –

Description” (Japan), here except the required dragging, inertial and lifting forces,

it also has an impact wave force which is similar to the impact breaking pressure

acting on the vertical wall. The wave force shall be confirmed according to the

velocity field of breaking waves and Morison formula.3) Bank upwelling zone: waves are finally breaking on the bank slope and forming a

strong impacting current upwelling along the bank slope. Here it shall be

considered by the beating wave velocity after the waves are breaking.

The velocity component and acceleration component of waves’ water mass point

movement are variable along with the time and location. For calculation, according

to these variances, it is necessary to consider the most adverse wave force, water

mass point, velocity and acceleration acting on the pipeline, and the included angles

of their directions with the pipeline. But by considering the reasons that the waves

and currents nearby the bank are complicated and disordered, it is recommended

that under general situation the included angle shall not be less than 35°. 4.4.4.4 This clause describes the calculation method for the sea current load acting

on the pipeline system. Generally the sea current can be considered as a stable

current, so it only needs to consider the resistance in horizontal direction.

Designing of sea current velocity shall take the maximal possible sum of tidal

current and remaining current.

When sea currents are acting together with waves, the sea current force and wave

force can be calculated separately, then be added together in vector, or also can add

the sea current velocity and wave’s water mass point velocity together in vector, to

be integrated as the resistance in wave force for calculation.

Equally, for the spanning sections of pipeline and riser pipe, shall consider the

possibility of vibration caused by sea currents. The Von Karman vibrationcalculation method in this specification is introduced from the SY/T 4804-92

“Specification for Subsea Pipeline System”. Following is the method adopted by

the chapter “Marine Pipeline” in “Technical Standards for Port Facilities –

Description” (Japan) for reference:

The affection of vibration caused by sea current shall be calculated by the Formula

(2).

f ＞2 f p or f ＜0.5 f p (2)

In which, f –Von Karman vibration frequency caused by sea current, to be confirmed

by the Attachment F in this specification. f p – the natural frequency of pipeline.

If the Formula (2) can not meet the requirement, it can be considered that the

affection of vibration is great, it is necessary to analysis the characters of the

vibration, and may use the proper vibration absorption methods such as to increase

the pipeline’s toughness or to set more supports at the middle of the pipeline.

4.4.4.5 This clause describes the affection of sea ice to the pipeline system and the

calculation method for ice load. For pipelaying, sea ice may damage the riser pipe

mainly by pressing and extruding, and the strength of such pressing and extruding

is relevant to the sea ice’s shape, the facility’s structure and the ocean environment.

The calculation formulas for the ice load are many, in which the representative onesinclude the formula in API RP2N “The Recommended Methods of Plan, Design



and Construction for the Fixed Structures in the Ice Sea” (1988), ZC (1992)

formula, Schwarz Hrragama formula, and Zuobo formula (Japan). Different

formulas may have different results. Comparing with the legs of platform, the riser

pipe generally has smaller external diameter, the ice load will be the biggest if

using the Schwarz Hrragama formula. About the acting force of sea ice onto the

riser pipe, both the SY/T 4804-92 and the CCS “Specification for Subsea PipelineSystem” have not given any definite formula, this specification adopts the formula

recommended in the “Beach-shallow Sea Environmental Conditions and Loading

Technical Specifications”, and this formula is consistent with ZC (1992) formula,

but relevant parameters are referring to API RP2N “The Recommended Methods of

Plan, Design and Construction for the Fixed Structures in the Ice Sea” (1988).

4.4.4.6 This clause describes the affection and action of earthquake to the pipeline

system. For the pipeline not buried, shall consider the inertial force and flow

pressure. The inertial force can be worked out by the deadweights of pipeline,

pipeline medium and soil multiplied by the seismic coefficient; take the centre of

gravity of the deadweight as the acting point of inertial force, take two horizontal

directions and vertical direction as the acting directions. Flow pressure caused byearthquake can be worked out generally by the inertial force of the water volume

displaced by the pipeline, the acting direction is the same as the inertial force

direction. For the buried pipeline when in earthquake, shall also consider the

affection of additional earthquake soil pressure and soil deformation. The additional

soil pressure can be worked out by the soil pressure acting on the pipeline

multiplied by the vertical seismic coefficient. For the affection of soil deformation

to the pipeline see the relevant clause in this specification.

4.4.5 This clause describes the types of casual load that the pipeline system might

encounter. Since the casual load is harmful to the pipeline, and for the purpose to

ensure the pipeline’s safety, it is regulated that necessary measures shall be taken to

prevent the hazard of casual load that may be brought to the pipeline, and also it shall

be noticed that pipeline route designing shall keep away from the positions of well

repairing and well drilling works, see the Clause 3.2.3 of this specification.

5. Designing5.1 General rules

5.1.1～5.1.4 These clauses are for general consideration of design internal pressure,

design external pressure, design temperature and design operational mode. Designinternal pressure is the maximal possible internal pressure value under normal

transmission status, if the counter-transmission flow has been designed technically,

the design pressure shall not be less than the higher one of positive/negative direction

transmission under stable high pressure operation status; during the normal

construction or normal operation of the pipeline in beach-shallow sea, it may have the

instance that the pipeline’s external pressure is higher than the internal pressure, such

as the piling up of ice, so the selected pipe thickness shall be thick enough to

withstand the pressure to avoid flatting; when calculating the stress caused by

pipeline’s wall temperature variation, for insulative pipeline, normally take the

difference of highest transmission medium temperature in operating and the

environmental temperature when laying the pipeline; for double layer pipeline, take



the difference of environmental temperature when laying the pipeline and the

highest/lowest environmental temperature.

5.1.5～5.1.6 These clauses describe the possible damage types of pipeline and

strength design principle, which is introduced from CCS “Specification for Subsea

Pipeline System”, basically similar to SY/T 4804-92 “Specification for SubseaPipeline System”. For the design standard of subsea pipeline, it is generally using the

“permissible stress” method, which is consistent with the strength standard used by

steel platform, and it is a stable and reserved design method. But it also can use

“permissible strain” method. For this method, the SY/T 4804-92 “Specification for

Subsea Pipeline System” has given following regulation: for buried pipeline or the

pipeline has continuous contacts with seabed, or the pipeline although has not

continuous contacts but its yielding may cause the contacts with seabed, under the

condition that if the possible strain will not exceed the permissible strain, it is not

necessary to use the stress as the safety judgement for preventing over-yielding. But

how to select the permissible strain value, SY/T 4804-92 “Specification for Subsea

Pipeline System” has only given a guideline “the permissible strain is decided by the

material’s plasticity and the previously suffered plastic strain”, and required that after

the material has been deformed, the material must have certain fracture toughness.

Such regulation will have certain difficulty in practice. In this specification the

strength calculation is basically using permissible stress method, but not excluding the

permissible strain method. For pipeline’s anti-earthquake calculation, using

permissible strain method is allowed.

5.1.7～5.1.10 These clauses give general regulations for the setting of pipeline system

structure analysis model and mechanical analysis method, etc., by referring to the

SY/T 4804-92 and the CCS “Specification for Subsea Pipeline System”.

5.2 On-position pipeline system

5.2.1 This clause gives the general requirement to prevent the on-position pipeline

system from damaging, by referring to SY/T 4804-92 “Specification for Subsea

Pipeline System”. Generally the pipeline in beach-shallow sea is adopting burying

method to protect the pipeline especially the straight pipeline section, thus on one side

it can prevent the adverse affection of current flushing onto the pipeline, on the other

side can avoid the direct action of wave and current loads onto the pipeline. The

chapter of “Marine Pipeline” in “Technical Standards for Port Facilities –

Description” (Japan) has given a definite explanation: in principle the subsea pipelinemust be buried, if necessary, the buried pipeline must be backfilled and covered.

5.2.2 This clause is referring to SY/T 4804-92 and CCS “Specification for Subsea

Pipeline System”. The allowable values of pipe wall circumferential stress and

equivalent stress are taking the product of utilization coefficient multiplied by the

minimal yield strength of steel pipe; using of temperature reduction factor is for

considering the affection of temperature to the material, in common formulas it needs

to be multiplied by welding seam coefficient; for the steel pipe standard used by this

specification, the welding seam coefficient is 1.0, so the Formula 5.2.2-1 and Formula

5.2.2-5 have not mentioned this coefficient. By considering the Bauschinger effect,

the δ s in Formula 5.2.2-1 and Formula 5.2.2-5 shall use the minimal yield strength of pipeline instead the minimal yield strength of pipeline material.



About the strength factor, different countries have different regulations, such as

America takes the strength factor at 0.6～0.72 generally, riser pipe at 0.5; Japan is 0.5

generally, and regulates the additional factor for additional load, see Table 1. The

strength factor in this specification is introduced from SY/T 4804-92 “Specification

for Subsea Pipeline System”, it is equal to the factor in DnV “Specification for Subsea

Pipeline System” (1981), and it refers to CCS “Specification for Subsea PipelineSystem”, has added the strength factor for earthquake load. According to the degree

of affection and the possibility of accident if the pipeline has been damaged, DnV

“Specification for Subsea Pipeline System” has regulated that the pipeline section

within 500 m from the platform is Class 2 area, the other pipeline sections are Class 1

area, and this two areas have different allowable stress factors, so the wall thickness

for the selected pipelines in design will be different, thus will be inconvenient for the

material purchase and construction. In beach-shallow sea, such classification has not

much significance.

5.2.3 This clause describes the yielding damage types and yielding detection method

for the pipeline system by referring to SY/T 4804-92 “Specification for Subsea

Pipeline System”.

5.2.4 This clause describes the fatigue analysis method for the pipeline system by

referring to SY/T 4804-92 and CCS “Specification for Subsea Pipeline System”.

5.2.5 On-position stability shall include transversal stability and vertical stability.

5.2.5.1 This clause describes principal requirements for the stability design when the

pipeline is maintained at its original position and is acted on by various external

elements, by referring to SY/T 4804-92 and CCS “Specification for Subsea

Pipeline System”.5.2.5.2 In designing, the pipeline (especially on the ends) shall have the capacity to

absorb the axial deformation caused by temperature variance. If necessary,

expansion bend or flexible hose can be set on the ends.

5..2.5.3～5.2.5.5 The pipeline on the seabed may have the phenomenon of floating

or sinking under the action of stormy waves or earthquake or other dynamic forces,

and its stability on the seabed will lose. So it is necessary to check the pipeline’s

capacity of anti-sinking and anti-floating. The check method is introduced from the

OTC 2272 “Stability Research for the Pipeline in Soft Clay Soil”. Under periodical

loading, the top soil layer may have periodical straining and may cause big pore

water pressure, so the soil strength after cyclic loading will be lower than the

undrained shear strength of static force. Here when checking the anti-sinking andanti-floating capacity, the soil remolding (turbulent) shear strength i.e. the value C

in Clause 5.2.5–3 of this specification shall be used. When the seabed soil has the

possibility of liquefaction, must pay proper attention in designing and constructing.

5..2.5.6～5.2.5.7 The pipeline during laying or the pipeline laid uncovered on the

seabed may suffer the actions of currents and waves, so it is necessary to check its

transversal stability. This check formula is introduced from the “Subsea Oil/Gas

Pipeline Engineering” compiled by Professor Ma Liang of Da Lian Science and

Engineering University, and it is consistent with the formula in the chapter “Marine

Pipeline” in “Technical Standards for Port Facilities – Description” (Japan). The

chance of that the sea ice may directly acting on the subsea horizontal pipeline is

small, so the check formula does not include the force of sea ice. If sea ice isdirectly and transversally acting on the horizontal pipeline, only to improve the



friction between pipeline and seabed soil is not enough, it needs to take other

effective methods such as burying to prevent.

5.2.5.8 Relevant research achievements published in the country have shown that the

sinking of pipeline on seabed has the coverage effect, which is reflected on the

selection of various hydrodynamic force parameters. The hydrodynamic force

parameters C D C M C L are roughly related to the exposed area (volume) of the pipeline. Also after sinking, the side pressure of soil will prevent the pipeline from

transversal movement.

When digging the ditch, the ditch bottom is lower than seabed, local flow filed in the

ditch is increasing, and the current will separate on the ditch borders, so it will

provide coverage effect to the pipeline’s hydrodynamic force. In recent years

relevant researches from domestic and abroad have shown that the coverage effect

has correlation with ditch’s bottom width, side slopes and depth.

5.2.5.9 The friction factor between pipeline and soil is related to the soil’s characters

and the roughness of pipeline’s surface, and also is related to the depth of the

pipeline sinking into the soil. Generally the friction factor shall be worked out by

experiment.5.2.5.10 The commonly used methods to maintain the stability of the pipeline on

seabed.

5.2.5.11 If the pipeline needs to be backfilled, proper material shall be selected for

the backfill without only using the original soil, because under the action of storm,

waves may produce tremendous horizontal and vertical flow velocities nearby the

seabed, the original soil cover may be rushed away and the pipeline may be pushed

out of the ditch.

5.3 Pipeline system during installation

5.3.1 For the purpose to ensure that the pipeline system will not be damaged duringinstalling, it is necessary to analyse the pipeline’s strained status during every period

of installation. The strained analysis shall be carried out by proper method according

to the pipeline’s specification, pipelaying method and the possible natural conditions

may be encountered.

5.3.2 This clause describes the analysis method for strength control under installing

status by referring to the SY/T 4804-92 and CCS “Specification for Subsea Pipeline

System”.

5.3.3 This clause is for considering the inflexion of pipeline and riser pipe under installing status.

5.3.4 This clause is for considering the fatigue of pipeline and riser pipe under

installing status.

5.4 Pipeline accessories

5.4.1 This clause is the general requirements for the design of pipeline accessories.

5.4.2 This clause is the check method for the strength of pipeline accessories.



5.4.3 This clause is the design principle for the pipeline’s supporting components.

Designing for the supports of pipeline and riser pipe shall ensure the pipeline in a

favorable strained condition without creating any concentrated stress or affecting the

free expanding and contracting of the pipeline.

5.5 Insulated pipeline5.5.1 The structure of an insulated pipeline includes the steel internal pipe, insulating

layer and external pipe. The external pipe is mainly for to protect the insulating layer,

to ensure the watertight property of the insulating layer during installing and operating,

and ensure the insulating layer without being damaged and invalid. According to the

types of such external pipe, the structure of the insulated pipeline has two types: one

is the double layer type which is using steel external pipe and one is the single layer

type which is using non-steel external pipe. At present in our country, most of the

subsea insulated pipelines are using double layer type, not yet having any application

instance of single layer type. But in abroad the research for such single layer type was

carried out very early, and there were some successful instances for such application

early in 1970’s. The single layer pipeline is easy for installation and needs less capitalinvestment, it is a trend of development for subsea insulated pipeline. The designers

shall pay attention to collect such kind of data and conclude such kind of experience.

5.5.2 This clause describes the principle and requirements for the insulating materials.

The selected insulating materials shall have enough strength to meet the flexible

laying requirement, and shall not produce any chemical reaction with other materials

such as pipeline coating materials when contacting. Because the “Insulation Technical

Specification for Petroleum Engineering in Beach-shallow Sea” has given detailed

regulations for general insulating materials, so this specification does not give another

description on it.

5.5.4 This clause is the considering guideline for the calculation of structure strength

and stability of steel double layer pipeline.

5.5.5 When using steel double layer pipeline, set inflexible constrain components

between the internal and external layers in certain interval, to let both external and

internal layers to withstand the axial force, and also to make the space between the

two layers to be watertight in several separated sections. As such for safety

consideration, if the pipeline is suffering any accident, one damaged part on the

pipeline would not affect the completeness of other parts.

5.5.6 The external protective pipe is mainly to protect the insulating layer without

being damaged and invalid during installing and operating. So when designing the

external pipe, the external pipe shall have enough strength and toughness to avoid

being damaged during installing and operating, and to keep the space between internal

layer and external layer watertight.

5.5.7 For insulated pipeline, calculate the axial displacement of pipe ends according to

the possible maximal temperature difference. The bottoms of riser pipes or the

direction changing points of pipeline shall have full space for the expansion of

pipeline.



5.5.8 Due to the difficulty of construction in beach-shallow sea, the selected on-site

joint coating insulation material shall be feasible for the construction in beach-shallow

sea, and shall have certain waterproof and heatproof properties, so as to be feasible for

joint welding. If necessary, cover a layer of anti-high temperature material on the

insulating material.

6. Pipeline and the Materials of Pipeline Accessories6.1 General rules

6.1.1 This clause describes the materials’ technical requirement and application scope.

6.1.2 Material selection for the pipeline system in beach-shallow sea is an important

part for designing. There are many elements needed to be considered for material

selection, including not only natural conditions and transmitted medium conditions,

but also welding or installing conditions, etc. So after universal and comprehensive

comparing and having met all application conditions, select the safest and mosteconomical materials. The selected steel materials shall have good anti-brittle fracture

capacity and good welding performance to prevent the happening of breaking.

6.1.3 The cracks, gaps and notches on the steel pipe can be the stress concentration

points, which can be the originating places of pipeline breaking and the main cause of

pipeline damaging. So the defects on the pipeline’s surface shall be prevented,

eliminated or fixed up; the internal defects shall be detected by ultrasonic wave, if

necessary replace the defect parts.

6.1.4 This clause describes the approval and acceptance for the materials of pipeline

system used in beach and shallow sea. All new products and new materials used in pipeline system shall be proved and authenticated be relevant authorities.

6.2 Steel pipes used in pipeline or riser pipes

6.2.1 Because when casting the ingots of rimming steel, oxygen and nitrogen can not

emit properly, the liquating of sulphur and phosphor and other harmful wastes is big,

and the steel’s structure and the size of grains are not even, the steel’s plasticity,

toughness and weldability are poor, easy to be age-hardening and brittle. So this

clause requires that the pipeline for transmitting the gas or the compound of gas/liquid

shall use degasified steel. By referring to the SY/T 4804-92 and CCS “Specification

for Subsea Pipeline System”, for the pipeline of transmitting the liquid, when its

yielding strength is ＜300 MPa, it is allowed to use semi-degasified steel.

6.2.2 This clause regulates that the steel pipes used for the pipeline and riser pipes can

select the steel pipes made according to the standards regulated by the “Straight Seam

Electric Resistance Welding Steel Pipeline for Oil/Natural Gas Transmission”,

“Seamless Steel Pipeline for Liquid Transmission” and “Spiral Seam Submerged Arc

Welding Pipeline for Oil/Natural Gas Transmission”.

About the selection of subsea steel pipeline, according to the regulation of

“Recommended Practical Rules for the Design, Construction, Operation and

Maintenance of Offshore Hydrocarbon Medium Pipeline”, the steel pipelines meet thestandard specified by the API Spec 5 L “Transmission Pipeline Specification” can be



used. The regulation of the chapter “Marine Pipeline” in “Technical Standards for

Port Facilities – Description” (Japan) has specified that the steel pipelines meet the

Japan Industrial Standard (JIS) can be used. In the “Straight Seam Electric Resistance

Welding Steel Pipeline for Oil/Natural Gas Transmission”, “Seamless Steel Pipeline

for Liquid Transmission” and “Spiral Seam Submerged Arc Welding Pipeline for

Oil/Natural Gas Transmission”, the technical requirements on mechanical property,chemical composition, steel pipe’s geometrical measures, welding seam requirement,

hydraulic pressure test and non-destructive flaw detection for the steel pipe materials

are consistent with or similar to the standards described in “Transmission Pipeline

Specification”. At present in our country, most of the pipelines for offshore

application are of the standard of “Transmission Pipeline Specification”, and the built

offshore pipelines in Sheng Li Oil Field are all using the steel pipelines in the

standard specified by “Seamless Steel Pipeline for Liquid Transmission”.

6.2.3 This clause is the basic requirements for the steel pipeline to have good anti-

brittle property and good weldability.

6.2.3.1 Flexibility/hardness ratio shows the brittleness of metals, when theflexibility/hardness ratio is 1, it means that the steel may break without having any

bending. So too high flexibility/hardness ratio is dangerous. This specification is

referring to the SY/T 4804-92 “Specification for Subsea Pipeline System”, GB

50521—94 “Engineering Design Specification for Gas Transmission Pipeline”, and

GB 50523—94 “Engineering Design Specification for Oil Transmission Pipeline”,

if the flexibility/hardness ratio is bigger than 0.85, this steel may not be used.

6.2.3.2 If carbon content is higher, steel’s yield strength and tension strength will be

higher too, but its plasticity and tenacity especially the low temperature impact

tenacity will be lower, also the steel’s weldability, fatigue strength and antirust

property will decrease greatly. Carbon content shall not exceed 0.25% and carbon

equivalent content shall not exceed 0.45% are the standards commonly regulated in

relevant domestic and foreign specifications.

6.2.3.3 Sulphur and phosphor are the harmful elements in steel. Sulphur and ferrum

can compound into ferric sulfide (FeS) which can cause heat crack in welding or

hot working, i.e. “hot short”; Phosphor and ferrum may compound into unstable

solid-liquid, which will serious reduce the steel’s plasticity, impact tenacity and

weldability, especially it makes the steel more brittle when the temperature is lower,

i.e. “cold short”.

For the subsea steel pipeline in abroad, America API 5L X52 regulates that the

carbon content is 0.20%～0.30%, API 5L X56 regulates that the carbon content is

less or equal to 0.26%, their phosphor content is less or equal to 0.40%, and sulphur content is less or equal to 0.25%. Japan JIS standard JIS STK41 regulates that

carbon content is less or equal to 0.25%, phosphor content and sulphur content are

all less or equal to 0.04%. However the SY/T 4804-92 “Specification for Subsea

Pipeline System” i.e. the DnV standard regulates that carbon content is less or

equal to 0.2%, phosphor content is less or equal to 0.03%, and sulphur content is

less or equal to 0.025%, which are all higher than the relevant regulations and

limitations in “Transmission Pipeline Specification” and the three Japan industrial

standards: “Seamless Steel Pipeline for Liquid Transmission”, “Straight Seam

Electric Resistance Welding Steel Pipeline for Oil/Natural Gas Transmission” and

“Spiral Seam Submerged Arc Welding Pipeline for Oil/Natural Gas Transmission”,

similar to the “Transmission Pipeline Specification” and the Japan industrialstandards, so this specification is referring to the “Transmission Pipeline



Specification”, the Japan industrial standards and the “Engineering Design

Specification for Gas Transmission Pipeline”, and integrating with our country’s

actual situations, regulates that the sulphur content and phosphor content will not

be bigger than 0.035% and 0.04% respectively.

6.2.4 Steel’s tenacity has close relation with steel’s brittle rupture property. Theimpact tenacity denotes the capacity of material’s plastic deformation and energy

absorption in breaking, it is a comprehensive reflection of material’s strength and

plasticity. So relevant design shall consider the pipe’s strength, diameter, wall

thickness and environmental temperature to decide the required tenacity, so as to

prevent the pipeline from brittle damage.

The impact tenacity of steel pipe is relative to temperature. Under low temperature

conditions, metal’s tenacity will decrease greatly, and the brittleness increase

correspondingly. So the design shall consider the pipelines exposing at the places of

very low ground, air or water temperatures. The selected materials used at these

places shall have corresponding low temperature mechanical property. At present

some countries have regulated that the boundary of low temperature is 0～-30℃,

while our onshore steel structure standard regulated that the boundary of low

temperature is -20℃. For the material’s tenacity requirement, this specification is

referring to the SY/T 4804-92 and the CCS “Specification for Subsea Pipeline

System”.

6.2.5 This clause is the hardness requirement for the steel pipe materials and welding

seams to prevent hydrogen brittleness and sulfide stress cracking.

6.3 Pipe fittings

6.3.1 This clause is the principal technical regulation for pipe fitting steel. The pipe

fitting steel shall at least meet the same requirement for the pipeline and riser pipe of

same grade and same wall thickness.

6.3.2 Because the cast pieces contain more sulphur and phosphor, their texture is not

compact and even enough, and their quality is poor. Especially the cast iron has

bigger brittleness, the texture is loose. So generally the pipe fittings in beach-shallow

shall use the cast steel materials very limitedly, and never use the cast iron materials.

6.3.3 Pipelines and riser pipes are connected by welding, the weldability of metals is a

primary condition to ensure the welding quality. Same or similar chemicalcomposition and mechanical property for the pipes and pipe fittings is the basis to

ensure the satisfying welding quality.

6.4 Bolts

6.4.1～6.4.4 These clauses are the technical requirements for the materials of bots,

including the anticorrosive treatment for the bolts and nuts.

6.5 Supporting components



6.5.1～6.5.2 These clauses are the principal regulations for the supporting

components. The material of supporting components directly welded to the pipeline or

riser pipe shall be the same as the material of such pipeline or riser pipe.

7. Pipeline anticorrosion and weight coating7.1 Pipeline anticorrosion

7.1.1 About the design and construction for pipeline external anticorrosion and

cathode protection, the “Anticorrosive Technical Specification for the Oil Engineering

in Beach-Shallow Sea” has given detailed regulations, so this specification only gives

general requirements on the pipeline anticorrosive system in beach-shallow sea”.

7.1.2 This clause is the general requirements for the pipeline anticorrosive system in

beach- shallow sea.

7.1.2.4 For the internal coating at each welding seam especially at each on-site joint,

because the difficulty of its construction and its construction quality can not beensured, this specification does not give regulation for pipeline’s internal coating

protection, only after such construction technics and quality has been recognized

and approved by relevant authorities, can this internal layer protection regulation be

adopted.

7.1.2.6 Because the value of impressed current density can not be confirmed easily

(especially in water level changing area), so generally for beach-shallow sea

pipeline, the impressed current method is only provided as an assisting method for

the sacrifice anode method.

7.1.2.7 For the purpose to ensure the normal work of pipeline’s cathode protection

system, any connecting point between pipeline system and external system shall be

electrically insulated, such as riser pipe to the platform and to the equipment on the platform, beach-shallow sea pipeline to onshore pipeline, etc.

7.2 Weight coating

7.2.1 The pipeline in beach-shallow sea is generally using concrete weight coating.

The purpose of weight coating is to increase the pipeline’s negative buoyancy to meet

the stability requirement of the pipeline during operating period and installing period.

For riser pipe, the concrete weight coating will have anticorrosive and antiwear

function in splashing zone. So the concrete weight coating shall have certain strength

to ensure that it will not occur serious cracking or falling during each period of

construction, so as to realize the purpose of weight coating.

7.2.4 If the weight coating is thicker, the pipeline’s underwater negative buoyancy is

bigger, also the hydrodynamic force load acting on the pipeline and the buoyancy of

pipeline are bigger too. Besides, due to the condition limitation for construction and

pipelaying, the thickness of weight coating may not be too big. So in engineering,

generally heavy concrete is used to increase the density of the concrete, so as to

reduce the thickness of the weight coating. The aggregates for the heavy concrete are

generally containing ores (brown iron ore, magnetite) and barite, etc.

7.2.5 This clause is the requirement for to increase the strength and durability of weight coating concrete. For to increase its durability, the general method is to



increase the content of cement and the grade of cement, and reduce the water/cement

ratio, etc. For the concrete needs to be frostproof, airbleeding agent can be added to

bleed the air. The JTJ 221—87 “Specification for Port Engineering Reinforced

Concrete Construction” has regulated that if the concrete has frostproof requirement,

its air contain shall be controlled within 3%～5%.

7.2.7 The weight coating construction method must ensure the thickness, strength and

other indexes of the weight coating to meet the design requirements. Generally the

construction methods include injection, pouring, press covering, etc.

8. Onshore pipeline prefabrication and assembly8.1 General rules

8.1.1 This clause describes the pipeline prefabrication and assembly methods.

Generally it is to use an onshore prefabrication ground to prefabricate and assemble

the pipes. By considering the construction capacity and construction conditions alsocan take other methods such as pipe laying ship method to prefabricate and assemble

the pipes, without needing to set a prefabrication and assembly ground.

8.1.2 This clause is the requirements for the qualification of steel pipe manufacturer

and its production capacity.

8.1.3 Construction unit inspects the exteriors of the pipes delivered to the workshop

before acceptance, and the inspection standards must be clear.

8.1.4 This clause describes the general procedure of pipeline prefabrication: pipeline

butt welding—nondestructive inspection—anticorrosion.

8.1.5 This clause gives the requirement for external anticorrosive coating technics,

quality control and record.

8.1.5. 4 This clause gives the requirement for on-site joint coating. For to improve

the working efficiency, the design is generally using the method of on-site heat

shrink tape joint coating, its construction method and acceptance standard are

according to the design.

8.1.6 The construction requirement and acceptance standard for pipeline external

insulation layer are in accordance with the standard series of beach-shallow sea, sothis clause does not give detailed description.

8.1.7 This clause gives the requirements for anode protection, installation and welding.

8.1.8 This clause describes the construction, maintenance and acceptance of the

weight coating. At present the weight coating technics has not yet been used in beach-

shallow sea pipeline system, referring to CCS “Specification for Subsea Pipeline

System” for its detailed construction methods and technical requirements.

8.2 Quality requirement for the pipes delivered to the workshop



8.2.1 This clause gives the requirement for the deviation of external diameter of the

steel pipe.

8.2.2 This clause gives the requirement for the deviation of wall thickness of the steel

pipe.

8.2.3 This clause gives the requirement for the deviation of ellipticity of the steel pipe.

8.2.4～8.2.6 This clause gives the requirement for the acceptance of quality, end

bevel and curvature degree of the steel pipe.

8.2.7 This clause describes the allowable deviations and disposal methods for various

defects of the steel pipe.

8.2.8 Clauses 8.2.4～8.2.6 are referring to the standards in “Seamless Steel Pipeline

for Liquid Transmission”, “Spiral Seam Submerged Arc Welding Pipeline for

Oil/Natural Gas Transmission” and “Straight Seam Electric Resistance Welding Steel

Pipeline for Oil/Natural Gas Transmission”, etc.

8.3 Prefabrication and assembly

8.3.1 This clause gives the requirements for the selection, storage and drying of

welding materials, by referring to the Section 5, Chapter 5 in CCS “Specification for

Subsea Pipeline System” .

8.3.2 This clause describes the evaluation for welding technics.

8.3.3 This clause gives the principal requirements for the length of onshore

prefabrication and assembly for the subsea cased pipes. Generally the length is 300～

1500m. Including the brief description of assembling procedure for the cased pipes.

8.3.4 This clause gives the requirements for the on-site welding and welding technics,

and specifies that other relevant standards have not yet given clear regulations for the

nondestructive test of double layer pipelines. Clause 8.3.4.5 of this specification

defines that double layer pipeline shall carry out 100% full length radial flaw test for

its internal pipe welding seams, and 100% full length ultrasonic flaw test for all its

external pipe welding seams.

8.3.5 This clause gives the detailed requirement for on-site welding seam repair.

Especially for the defects on welding seams, the “Specification for Subsea Pipeline

System” has specified that the defect repair length for the welding seams is about 100

mm, while this specification specifies that the defect repair length for the welding

seams is above 100 mm.

9. Pipeline installation in beach-shallow sea9.1 General rules



9.1.1 This clause gives the requirements for the installation in beach-shallow sea. Any

technical conditions, regulations and drawings, etc., without having been approved by

the certificate inspection organization, the construction unit must not adopt or perform.

9.1.2 This clause gives the requirements for the compilation of the regulation of

welding technics.

9.1.3 This clause gives the requirements for the implementation of the regulation of

on-site joint coating technics.

9.1.4 This clause specifies the general rules for the quality control and pipeline

protection during installation and construction.

9.1.5 All working personnel shall have relevant certificates for their works, generally

including the training certificate of beach-shallow sea safety operation for

construction workers, the qualification certificate for welders and nondestructive

inspectors.

9.1.6 This clause is the requirements for the compilation of construction technics.

Such compilation shall match the actual situations. Especially after such construction

methods and construction procedures have been checked and proved, they shall be

carried out strictly.

9.1.7 This clause gives the detailed description of the technical conditions and

technical requirements for the installation of pipelines and riser pipes in beach-

shallow sea by the workboat.

9.2 Pipeline route control

9.2.1 Before installing in beach-shallow sea, relevant hydrology and meteorology data

along the route shall be collected, especially the conditions of the seabed along the

towing line including seabed obstacles. If the collected data is not enough, the

construction unit shall perform the investigation again, or can perform an experiment

by simulating the towing conditions.

9.2.2 Marks for the towing are necessary, this clause gives detailed method for such

marking.

9.3 Connection

9.3.1 This clause describes the general methods for pipelaying and riser pipe

installation in beach-shallow sea.

9.3.2 This clause describes the general methods for pipeline connection.

9.3.3 This clause describes the technical requirements for the pipeline connection,

including the requirement to strictly check the pipeline stress during operation, ensure

the pipeline without being damaged during construction.



9.3.4 This clause gives the requirements for the loading, unloading, transporting and

storage of the pipes and pipes sections, including the towing methods for long pipe

section, such as bottom pull method and near-surface pull method, etc. The

construction unit shall consider all conditions before making any towing plans.

9.3.5 This clause describes the technical requirement for the installation at crossing positions. The interval of crossing positions or minimal distance between two lines is

0.3 m. Especially when the subsea pipeline crossing with previous pipeline or cables

is unavoidable, and if their minimal distance can not meet the requirement of 0.3 m,

then such crossing position shall be properly protected, after being proved by

certificate inspection organization and the owner, the construction can be started, and

the detailed crossing position must be marked on the chart.

9.3.6 This clause gives the requirements for inflexion inspection and inspection

method during the course of pipeline installing in beach-shallow sea. If the owner or

the representative of the certificate inspection organization considers that the

construction method of subsea pipeline is dependable, and there is another dependablemethod to check the positions on the joints and riser pipes where are easy to occur

inflexion, such inflexion inspection may not have to be carried out.

9.3.7 This clause gives requirements for the anchoring and protection of pipeline

system, including making a dependable method to protect the weight coating pipeline

during construction.

9.3.8 This clause describes the general requirements for welding and connecting on

the pipe laying ship (equipment for beach-shallow sea work). When performing

welding and connecting above the water, stress analysis is necessary for pulling up

and laying down the pipeline, and the stress calculation report shall be presented

before construction and it has to be strictly carried out.

9.3.9 For offshore pipeline joining, inspect the equipment’s working capacity firstly,

and select proper lifting tools, and check them according to the requirement of Clause

9.3.8. The range measuring method for positioning the connection of riser and

pipeline is usually using underwater measuring method, assisted by amplifying

method, etc.

9.4 Ditch digging and pipeline burying

9.4.1 This clause describes the construction methods and technical requirements for

ditch digging and pipeline burying. The allowable depth for each digging layer and

the total number of digging layers shall be strictly in accordance with the design. The

digging devices shall have dependable protection method to protect the anticorrosive

coating and weight coating.

10. Final inspection and completion test10.1 Final inspection

10.1.1 This clause specifies the content and requirements for final inspection.



10.1.1.1 This clause is for general technical requirements. Generally the design will

give the requirements for final inspection, which shall be strictly followed by the

construction unit.

10.1.1.2 There are many methods to ensure the stability of pipeline after being laid

in the seabed. Flushing is serious in the beach-shallow sea, the general method for

pipeline’s stability is ditch digging, its inspection method is generally by coursemonitor, and the construction unit shall provide relevant documents. If use other

construction method, the construction unit shall follow the regulated technical

procedure strictly. Underwater works shall have dependable quality insurance

measures, and relevant documents shall be presented.

10.1.1.3 This clause gives the requirements for final inspection report. The pipeline

location map shall include accurate pipelaying positioning routes, pipeline burying

depth, route side structure or obstacle positions, and the cross positions with other

pipeline or cables.

10.1.2 This clause gives requirements for inflexion inspection and defect treatment.

The purpose of inspection is to inspect whether the pipeline’s anticorrosive coatinghas been damaged and whether the pipeline has any deformation during the course of

offshore pipeline towing, joining and riser pipe installing. Because the water in beach-

shallow sea is not deep, if the owner, designing unit and construction unit all consider

that the applied pipelaying method, pipeline anticorrosive coating protection and

offshore pipeline connection method are all dependable, and after being approved by

these three parties, the whole-line inflexion inspection may not be needed.

10.1.3 This clause gives the requirements for the inspection of anticorrosive system,

especially for the inspection of riser pipes.

10.1.4 This clause describes the inspection for the safety system. Generally the safety

system is checked by utility test.

10.2 Work handover and acceptance

10.2.1 This clause describes the method of hydraulic pressure test and its technical

requirements after the pipeline construction is complete, and supplements the test

methods and technical requirements for the gas transmission pipeline which are

absent in the “Specification for Subsea Pipeline System”.

10.2.2 This clause gives the requirements for the preparation work before test.

10.2.3 This clause gives the requirements for the test equipment and test configuration.

10.2.4 This clause gives detailed requirements for test pressure and test record.

Generally the design has specified the detailed pressure test requirements, if no such

requirements, this clause has regulated the general regulations for the pressure test.

10.2.5 Generally integral pressure test includes the pipeline and riser pipes; if pipeline

and riser pipes are tested separately, this clause has given detailed regulations for

them; if design has detailed regulations, such regulations shall be followed.



10.2.6 Test outline shall be presented before test, and the content of this test outline

shall be described in detail.

10.2.7 Final acceptance requires the representatives of 3 parties to inspect the water

(air) test report, examine the displayed values of pressure meter, propose the solution

for all faults, and supervise the implementation.

10.2.8 This clause describes the content of hydraulic pressure test report.

10.2.9 This clause describes the content of air pressure test report.

10.2.10 After work handover and acceptance, relevant technical documents shall be

presented to the certificate inspection organization and the owner. This clause

describes the contents of the technical documents.

SY T 0305-96 Tech.spec. of Pl Sys. Beach Shallow Sea

Documents