Federal Electricity & Water Authority Water Directorate STANDARD … · 2017. 2. 22. · 5.3 Radiographic Examination 5.3.1 Reporting 5.4 ... 5.9.6 Additional Acceptance Criteria

WAM

client: FEDERAL ELECTRICITY AND WATER AUTHORITY (FEWA) project: STANDARD SPECIFICATIONS FOR WATER WORKS

Engineer WATER DIRECTORATE - ASSET MANAGEMENT DEPARTMENT

title: Technical Terms / Chapter 4/ Engineering Specifications / Pipeline Works Specifications.

PS14- WELDING WORKS

office: DUBAI order: Document: MWA_PRO_07/WAM-04-PS14 rev: DEC/2014 sheet:

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Federal Electricity & Water Authority

Water Directorate

Asset Management Department

STANDARD SPECIFICATIONS

FOR WATER WORKS

TECHNICAL TERMS

Chapter – 4

Engineering Specifications

E – Pipeline works Specifications

PS 14

WELDING WORKS

WAM




PS14- WELDING WORKS

office: DUBAI order: document: MWA_PRO_07/WAM-04-PS14 rev: DEC/2014 sheet:

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SPECIFICATIONS FOR PIPELINE WELDING WORKS

TABLE OF CONTENT

1. SCOPE

2. APPLICABLE STANDARDS AND CODES

3. DESIGN CONSIDERATION

4. WELDING REQUIREMENTS

4.1 Approved Welding Processes

4.2 Welding Procedure Qualification

4.2.1 Welding Procedure Specifications (WPS)

4.2.2 Procedure Qualification Records (PQR)

4.3 Welders Qualification

4.3.1 Welder’s Qualification Tests

4.4 Essential Variables

4.4.1 Base Material

4.4.2 Welding Process

4.4.3 Joint Design

4.4.4 Base Material Thickness

4.4.5 Welding Consumable

4.4.6 Welding Position

4.4.7 Welding Parameters

4.5 Qualification Tests

4.5.1 Non-Destructive Examination

4.5.2 Destructive Tests

4.6 Production Welding Requirements

4.6.1 Welding Equipment

4.6.2 Welding Processes

4.6.3 Weather Protection

4.6.4 Welding Consumables

4.6.5 Electrode Size

4.6.6 Shielding Gases

4.7 Cutting and Weld Joint Preparation

4.8 Cleaning Requirements

4.9 Edge Preparation and Joint Alignment

4.10 Tack Welds

4.11 Joint Backing Requirements

4.12 Heat Treatment of Welding Works

4.12.1 Preheat Requirements

4.12.2 Preheat Temperatures

4.12.3 Application of Preheat

4.13 Interpass Temperature

4.14 Interruption Of Welding

4.15 Weld Bead Sequence

4.16 Interpass Cleaning

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4.17 Peening

4.18 Seal and Socket Welding

4.19 Attachment Welds

4.20 Weld Spacing

4.21 Workmanship and Weld Finish

4.22 Welding Technique

4.23 Post Weld Heat Treatment

4.24 Weld Identification

5. INSPECTION AND TESTING

5.1 General

5.1.1 Reduced Percentage Examination

5.2 Visual Examination

5.3 Radiographic Examination

5.3.1 Reporting

5.4 Ultrasonic Examination

5.5 Magnetic Particle/Dye-Penetrant Examination

5.6 Ultrasonic Thickness Measurement

5.7 Extent of Non-Destructive Examination

5.8 NDE Personnel Qualifications

5.9 Repair of Defects

5.9.1 General

5.9.2 Minor Surface Repairs

5.9.3 Repairs Involving Welding

5.9.4 NDE of Repair Welds

5.9.5 Limitations on Repairs

5.9.6 Additional Acceptance Criteria

6. WELDING OF D.I. PIPES ON SITE

7. VENDOR DOCUMENTATION

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SPECIFICATIONS FOR PIPELINE WELDING WORKS

1. SCOPE

This specification prescribes the minimum requirements for welding, welding inspection and

Non-Destructive Examination of shop fabricated and field fabricated steel piping (carbon steel

and stainless steel and ductile Iron pipes). The requirements apply to pipework associated

with vendor supplied equipment packages, longitudinal seam welds of bulk purchased piping

components such as pipes, tees and elbows, pipework fabricated as part of a contractual

fabrication and field erected piping.

This specification shall apply to the main Contractor and to all his sub-contractors.

2. APPLICABLE STANDARDS AND CODES

All materials and work manship shall comply with the latest edition of applicable standards

and codes which shall include but not be limited to the following.

API 5L Specification for Line Pipe

API 1104 Welding Pipelines and related facilities.

BS 4504 Sect 3.1 Circular Flanges for Pipes, Valves and Fittings (PN

designated) Specification for steel flanges.

ASME B31.3 Process Piping

ASME Section II Part C Welding Rods, Electrodes and Filler Metals

ASME Section V non-destructive Examination

ASME Section VIII Div. 1 Pressure Vessels

ASME Section IX Welding and Brazing Qualifications

ASTM A 312 Seamless and welded austenitic stainless steel pipe

ASTM A 106 Seamless carbon steel pipe for high temperature service.

ASTM E110 Indentation Hardness of Metallic Materials by Portable

Hardness Testers

ASTM E92 Vickers Hardness of Metallic Materials

ASTM E94 Standard Recommended Practice for Radiographic Testing

ASTM A 370 Mechanical Testing of Steel Products

3. DESIGN CONSIDERATION

The welding type selection, welding preparation, welding procedure, welders qualification,

welding machine type and welding inspection and tests, all shall be in accordance with the

ASTM, ANSI, ASME IX or equivalent British Standards. Filler metal shall comply with the

requirements of the AWS or equivalent.

The design, fabrication and inspection of pipework shall comply with the requirements of

ASME B31.3 except as modified herein.

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4. WELDING REQUIREMENTS

All welding and quality control of welding fabrication shall be done by the Contractor in

accordance with the requirements of this Specification. Weld metal composition shall

becompatible with the parent metal.The Contractor shall comply with FEWA/Engineer Safety

Regulations.All welding shall be as specified by the Contractor on the drawings and the

isometric drawings showing all welds, each marked with a unique identification number.

4.1 Approved Welding Processes

Welding of pipe work joints shall be by fusion welding or argon welding as required, using

manual or semi-automatic welding process. The process shall be such that the arc and the

deposited metal are protected from atmospheric conditions.

The following processes are approved for use on pipework :

a) Shielded Metal Arc Welding (SMAW)

b) Gas Tungsten Arc Welding (GTAW, or TIG)

c) Gas Metal Arc Welding (GMAW or MIG/MAG)

d) Submerged Arc Welding (SAW)

e) Electric Resistance Welding - high frequency process (for longitudinal seams only)

The selection of the welding process, electrodes, shielding gas etc. depend on the materials

properties of the pipes to be welded in accordance with the welding code's

requirement.Manual GTAW (TIG) welding must be done with the addition of filler metal and

high frequency starting unit. It is limited to a thickness range of 3 mm to 6 mm for carbon

steel.

Short circuiting arc (MIG, MAG or GMAW) welding, Gas Shielded Flux-Cored Arc or Plasma

Arc Welding may be used only upon specific approval by FEWA/Engineer.

Self shielded flux-cored arc welding shall not be permitted.

The root pass welding of pipework of all materials for pipes of nominal diameter less than or

equal to DN 50 mm (2" NB) shall be done by GTAW process.

Full welding of pipework of all materials for pipes of nominal diameter less than or equal to

DN 50 mm (2" NB) and wall thickness less than 6 mm shall be done by GTAW process.

4.2 Welding Procedure Qualification

4.2.1 Welding Procedure Specifications (WPS)

Fabrication welds executed at factory/works, which are liable to be highly stressed, such as

may be the case in pressure parts of those subjected to rotational stresses or reversal of

stresses in operation, the Contractor shall provide, if requested, with details of welding,

fabrication procedure adopted and relevant test certificates

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Copies of all welding records including welding procedure, protecting and post heating, stress

relieving, analysis report, physical preparation of material and copies of the tests of welds

shall be submitted to FEWA/Engineer.Certified copies of the essential welds shall be included

in the operational and maintenance manuals. Where required by FEWA/Engineer the

selected welds shall be subjected to penetrate tests as per relevant standards

Unless otherwise agreed a qualified third party inspection agency shall be appointed by the

Contractor for the qualification welders and evaluation of welding works at the fabrication

shop and at site.Welding procedure specifications and repair weld procedures are required to

cover all circumferential butt welds, any longitudinal butt welds and attachment welds

including branch, weldolet, sockolet and pipe support welds.

All welding procedures should be submitted for approval on Form QW-482 of ASME Sec. IX.

The proposed WPS shall include but not be limited to the following :

a) Contractor's name

b) WPS number, revision and date

c) Welding process and type (manual, automatic, etc)

d) Joint design and sketch and sequence of passes

e) Base material P number and group number

f) Material type and grade

g) Pipe diameter and thickness range

h) Welding consumables - AWS classification, manufacturer, brand name, F number, A

number, size, etc.

i) Welding positions

j) Welding progression

k) Preheat temperature, minimum

l) Interpass temperature, minimum and maximum

m) Method of preheat application and measurement

n) Post weld heat treatment, holding temperature and time, heating rate, cooling rate and

method of application.

o) Type of current and polarity

p) Method of edge preparation

g) Method of back grinding

r) Gas shielding - flow rate and composition

s) Gas backing - initial duration of purging, flow rate, composition and duration

t) Current, voltage and welding speed for each layer.

Written approval by FEWA/Engineer is required prior to the use of any pre-qualified WPS.

4.2.2 Procedure Qualification Records (PQR)

Welding procedure qualification tests shall be conducted in accordance with ASME Section

IX and shall be carried out under the surveillance of FEWA/Engineer.

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The results of the qualification tests along with the test reports shall be submitted in the

approved format, as recommended by ASME Sect. IX Code by the Contractor.

The procedure Qualification Record (PQR) shall include the following:

a) Contractor's name

b) PQR number and date

c) WPS number, revision and date

d) Welding process

e) Type (manual, automatic, semi-automatic)

f) Joint design and sequence of passes

g) Base material specification, grade, carbon equivalent, thickness and pipe diameter.

h) Filler metal AWS classification, size, manufacturer, brand name, A. No. and F. No.

i) Welding position and progression

j) Preheat temperature, method of application and measurement.

k) Interpass temperature

l) Post weld heat treatment, holding temperature, holding time, heating and cooling rates

m) Shielding gas, composition and flow rate

n) Backing gas composition and flow rate

o) Current type and polarity

p) Tungsten electrode type and size (for GTAW )

q) Orifice or gas cup size (for GTAW & GMAW)

r) Method of cleaning

s) Method of back grinding

t) Welding current, arc voltage, welding speed and heat input as per sect 6.3.7 for each

pass.

The Contractor shall submit the following back up certificates/reports for approval prior to the

commencement of production welding :

a) Welding procedure specifications (WPS), and Procedure Qualification Records (PQR)

revised if necessary.

b) Mill certificates of the test piece sample metal used.

c) Batch test certificates of the welding consumables.

d) Heat treatment charts, where applicable.

e) Non-destructive examination reports.

f) Mechanical test reports including photo micrographs.

g) Welding consumable control/electrode redrying procedure.

The sample welds shall be carried out on specimens of similar shape, thickness and chemical

analysis as of the material to be welded, and in a position, which shall represent as far as

possible the worst conditions under which actual welding would take place.NDE and

mechanical testing shall be conducted after post weld heat treatment where applicable. NDE

shall be conducted by American Society of Non Destructive Testing (ASNT) Level II or

equivalent certified personnel.Mechanical testing shall be carried out in accordance with

ASME Sec. IX in an approved testing laboratory using calibrated instruments.

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4.3 Welders Qualification

Only approved qualified welders shall do all welding works at manufacturer/ fabricator works

or at site. Such welders shall be certified by a qualified independent testing authority. If not

otherwise agreed upon, the tests and certificates shall not be older than six months prior to

the time of execution of the welding works. The certificates shall be first submitted to FEWA/

Engineer for approval then be filed with the Contractor on site.

Welders engaged on welding at Site shall be under the supervision of a competent welding

engineer. The welding engineer shall exclusively employed for this work with due approval of

FEWA/Engineer.

4.3.1 Welder’s Qualification Tests

Welders and welding operators shall be qualified in accordance with ASME Section IX. And

the requirements stated hereunder.Automatic MIG/MAG/GMAW welding operators shall be

qualified by radiography and guided bend tests.

All welders and welding operators shall be qualified for all welding positions in which they will

carry out production welding. All welds executed by unqualified welders shall be rejected.No

welder shall be qualified on production welds.

A welder or welding operator who fails the performance qualification test of this

specification,may be granted an immediate retest in accordance with ASME Sec. IX (QW-321

solely at FEWA/Engineer discretion. If the welder or welding operator fails in the retest, he

may be given only one further test in accordance with QW-321.3 but only after he has

received adequate training to the satisfaction of FEWA/Engineer.

Welder’s valid qualificatrion shows that the welder or welding operator has been continuously

engaged on work of a similar nature with the specific welding process since successful

qualification. A break in continuity of more than 3 months (90 days) shall require

requalification.

All qualified welders for production welding shall be assigned a unique identification number

with welder's photograph on identification badges singed by FEWA/Engineer and to be worn

by the welders during welding.

4.4 Essential Variables

Where notch toughness is required as part of the mechanical tests for procedure qualification,

a change in any supplementary essential variable shall call for requalification of the welding

procedure. The following variables shall be treated as essential variables in addition to those

listed in ASME Sec. IX.

4.4.1 Base Material

Each base metal within a given P number or Group number having nominally different

chemical or mechanical properties (as Table QW-422 of ASME Sec. IX) require:

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a) Separate welding procedure specification (WPS)

b) Separate procedure qualification whenever a welding operation satisfactory for one base

material is, in the opinion of FEWA/Engineer, unsatisfactory for another base material

within the same P or Group number.

4.4.2 Welding Process

Any change in welding process, addition, deletion or combination of welding processes.

4.4.3 Joint Design

a) A change from double sided weld to a single sided weld but not vice versa.

b) An increase of more than 20° or a decrease of more than 10° in the included angle.

4.4.4 Base Material Thickness

The maximum thickness qualified shall be limited to twice the thickness of the test pipe.

4.4.5 Welding Consumable

The following will require procedure requalification :

a) Change in wire chemistry.

b) A change in filler metal.

c) A change in submerged arc welding flux. manufacturer's grade.

d) Changes in the chemical composition of the weld deposit A number.

4.4.6 Welding Position

Any change in welding position except that qualification in the 6G position or 2G plus 5G

positions will qualify for all positions.

4.4.7 Welding Parameters

Any change in the parameters affecting heat input (current, voltage and welding speed)

outside ± 15% of those qualified for root, fill and capping passes.

Heat Input = (current in amps x volts x 60)

(KJ/cm) (welding speed (cm/min) x 1000)

4.5 Qualification Tests

4.5.1 Non-Destructive Examination

The test weld shall be 100% visually examined.

After satisfactory visual examination, butt welds shall be subjected to 100% radiographic

examination.

Fillet welds shall be examined by magnetic particle inspection (MPI) for magnetic materials

and dye penetrant (DP) examination for non-magnetic materials.

The acceptance criteria shall be ASME B31.3, Table 341.3.2 except as modified by this

specification.

The Contractor shall supply a welding schedule indicating also the extent and kind of non-

destructive tests of the welds which are subject to approval by FEWA/ Engineer.

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Unless otherwise agreed or specified 10% of normal weld works and 100% of all critical

welds are subjected to weld tests such as Ultrasonic tests (BS 3923) BS EN ISO 17640:2010

Non-destructive testing of welds. Ultrasonic testing. Techniques, testing levels, and

assessment or radiographic tests (BS 2600) BS EN ISO 17636-2:2013 Non-destructive

testing of welds. Radiographic testing. X- and gamma-ray techniques with digital detectors or

magnetic particle test (BS 4397) BS ISO 4397:2011.

If any defect is noticed in the welds the Contractor shall rectify the defect by cutting, replacing

and re-welding as if the process is being carried out freshly

4.5.2 Destructive Tests

The type, number and location of specimens to be removed from the test weld, test specimen

dimensions, testing procedure and evaluation of tests shall be in accordance with ASME Sec.

IX.All mechanical tests shall be conducted after post weld treatment wherever applicable.

4.6 Production Welding Requirements

4.6.1 Welding Equipment

All welding equipment shall be of sufficient capacity for the work to be performed and shall be

capable of producing welds of acceptable quality.

All equipment shall be maintained in good working condition by the Contractor.

Any equipment which does not meet these requirements shall be replaced.

All welding equipment and accessories shall meet the safety regulations of the relevant

international specifications (such as NEMA) and shall be safe to operate.

When using the GTAW process, a high frequency (HF) arc initiation unit, a controlled current

delay device (to eliminate crater) and suitable pre-end post-gas flow device (to eliminate

porosity and air entrapment) shall be used.

4.6.2 Welding Processes

Only approved welding processes shall be used for production welding.

4.6.3 Weather Protection

The Contractor shall provide approved adequate shelter to protect the welding environment

from inclement weather and drafts.No welding shall be carried out when the weld surfaces

are wet or dirty and if inadequate provision has been made for weather protection .

All surfaces to be welded and the adjoining area of the material shall be warm and dry.Where

the surfaces to be welded are covered by moisture and where there is no requirement of

preheat by the applicable WPS, the surfaces should be completely dried and warmed up by a

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hydrocarbon torch using a soft flame before starting to weld. The use of oxy-acetylene

torches shall not be permitted.

4.6.4 Welding Consumables

Electrodes, filler wires and fluxes shall conform to the requirements of ASME Boiler and

Pressure Vessel Code Section II Part C. Gases, both combustible and inert, shall meet the

requirements of American Welding Society or any other standard acceptable to

FEWA/Engineer.

The Contractor shall prepare and submit to FEWA/Engineer a list of welding consumables to

be used on the project showing type, manufacturer, brand and the manufacturer's

recommended storage and drying procedure for each.

Storage and control of welding consumables shall be in accordance with the following :

- All electrodes shall be stored in fully sealed packages and stored in dry storage rooms.

- All electrodes which are damaged, wet, rusty or contaminated with oil, grease, dirt etc.

shall be scrapped. Electrodes partly used shall not be used.

- The Contractor shall provide separate ovens for baking and storing of low hydrogen

welding consumables.

- SMAW electrodes of different weld metal compositions or having different flux type

covering shall not be stored or baked together in the same oven.

- Low hydrogen electrodes shall be baked at 300°C for at least one hour or as per

manufacturer's recommendations.

- Cellulose coated SMAW electrodes shall be kept in a dry and dust free enclosure after

opening of the factory container.

Filler wires, Fluxes and bare electrodes shall be stored in sealed, dirt and moisture proof

containers within a dry, dust-free enclosure.

Only fused type fluxes shall be used and they should be dried according to manufacturer's

recommendation. If agglomerated fluxes are used, they shall be baked at a temperature of

250°C - 300°C for a minimum of two hours and kept in drying ovens at all times.For carbon

steel materials, the SAW process shall not utilise an active (Mn-Si) flux nor EHXX (high

manganese) wires.

Only low hydrogen electrodes shall be used for the following cases with SMAW :

(a) Welding and/or installing hot-tap connections on pipes containing flammable liquids, gas

or combustible materials.

(b) For the repair of all welds in carbon steel plates.

(c) Full penetration double-groove joints.

(d) Fill and cap passes of all other applications for all carbon steels for all thicknesses.

With the exception of low hydrogen electrodes, (a) through (c), cellulose coated electrodes

may be used only for the root passes of carbon steels with prior written permission of

FEWA/Engineer.

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Welding electrodes kept in the drying oven shall be consumed on "first in - first out" basis.

4.6.5 Electrode Size

(a) The maximum electrode diameter for all single sided welding using the SMAW process

shall be 3.2mm for the root pass and 5mm for the fill and cap passes.

b) The maximum electrode diameter for double sided welds using SMAW shall be 4mm for

the root pass and 5mm for the fill and cap passes.

4.6.6 Shielding Gases

The shielding gases are used for the protection of the electrode and the weld pool from the

surrounding air. Depending on the welding process adopted, parent material, weld

configuration and shielding gas shall be selected.

4.7 Cutting and Weld Joint Preparation

Preparation and cutting of carbon steels may be done by machining, grinding, machine

guided gas torch or plasma arc cuttings. Gas torch and plasma arc cutting shall only be used

where it is not practicable to use mechanical methods.

Thermal cutting is acceptable for carbon and low alloy steels. For plates less than 25 mm

thick, cold shearing may be used. For plates between 11 mm to 25 mm thick the cut edges

shall be dressed back atleast 2 mm by machining or grinding. The edges shall be inspected

by MP or DP method. For stainless steel material, flame cutting is not allowed but plasma

cutting may be applied.

End profiles of pipes and fittings which are to be butt welded shall be in accordance with

ASME B 16.25. Pipes for socket weld joints shall be cut square. All cut surfaces shall be

finally prepared by grinding or machining to clean, bright metal. After the edges have been

prepared for welding, they shall be visually examined to confirm that the preparations are

smooth and uniform and free from tears, cracks, gouges and other discontinuities which

might affect the weld quality.

Further the prepared welding ends shall be examined by ultrasonics for a distance of 50mm

back from the bevelled edge to ensure freedom from laminations, and magnetic particle

inspection on bevels. The use of arc air gouging shall not be permitted.Branch connection cut

outs shall be carefully bevelled and accurately matched to form a suitable groove for welding

and to permit complete penetration of the welds at all points.

4.8 Cleaning Requirements

All surfaces to be welded and the surrounding areas shall be clean and free of paint, oil

dirt,rust , oxides or any other foreign matter which could interfere with welding, prior to the

application of preheat or welding. The deemed surface shall extend at least 25 mm beyond

the substrate actually touched by the arc.

4.9 Edge Preparation and Joint Alignment

The edge preparation for butt joints shall be as indicated below:

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a) For piping with thickness upto 26 mm the preparation shall be 'V' type, with 370 30' + 20

30' bevelling.

b) For piping with thickness over 26 mm, the preparation shall conform to ASME B31-3, or

shall be of another type approved by FEWA/Engineer.

For butt welding of all piping components, pipe ends, fittings and welding neck flanges, a

uniform root opening its required as shown:

<DN 50 mm 1.5 mm

DN 50 to DN 250 mm 1.5 to 2.5 mm

>DN 250 mm 2.5 to 3.5 mm

Butt weld alignment shall satisfy the requirement of ASME B31.3 and the conditions stated

below.Internal misalignment of pipework shall not exceed 1.0mm in order to facilitate welding

of the root pass. When a GTAW root pass is to be used the maximum misalignment shall not

exceed 0.8mm Misalignment may be reduced by the use of hydraulic or screw type of

clamps.

Hammering heating and buttering of weld shall not be permitted.In case of pipes/components

with different thickness misalignment upto 3.2 mm may be improved by internal machining

provided the taper does not exceed 1 in 4 max. However the minimum required wall

thickness shall be maintained. Grinding shall not be used.Correction of misalignment by use

of cold working shall not be permitted.

Where internal pipe aligners are used, they shall not be removed until the root pass has been

completed. Where external lineup clamps are used, the clamp may be removed when the

root bead is at least 50% completed. The root bead should be spaced evenly around the

circumference.The longitudinal welds of adjacent pipes shall be staggered by at least

100mm.

4.10 Tack Welds

All tack welds shall be made by qualified welders using approved electrodes and pre-heat, as

specified by the approved welding procedures.Tack welds to assist alignment shall have a

minimum length of 25mm and shall be of sufficient size to maintain joint alignment until

production welding begins.All tacks welds which will be part of the main welds shall be

cleaned, ground to a feather edge at both ends and visually inspected prior to welding of the

root pass.

Any defective tack shall be completely removed by grinding prior to welding of the root pass.

When tack welds are removed, the Contractor shall ensure that the root preparation is

correctly maintained for the subsequent pass.Tack welds not incorporated in the final weld

shall be removed by grinding or other mechanical means to achieve smooth surface without

reduction in wall thickness, followed by Non destructive test inspection.

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4.11 Joint Backing Requirements

Permanent backing rings or backing plates shall not be used.The use of consumable inserts

for root passes shall not be permitted.

4.12 Heat Treatment of Welding Works

Heat treatment prior to and after welding in order to achieve stress relieving shall be applied

as specified in the following table:

Welding after stress relieving is basically prohibited. Should welding on a piece of equipment

which has previously undergone a stress relieving heat treatment become necessary, the

relevant piece shall undergo a new stress relieving process.

Welding Heat treatment

Material

Pre-heating

After-heating

Temperature

Wall thickness

Temperature

Wall thickness

St 35

St 35.8

St 45.8

15 Mo3

13CrMo44

10CrMo910

X20CrMoV121

-

-

-

150C

200-300C

200-300C

400-450C

-

-

-

Above 10 mm

Above 10 mm

Above 6 mm

All

650-700C

650-700C

650-700C

660-700C

680-720C

730-780C

720-780C

Above 20 mm

Above 20 mm

Above 10 mm

Above 15 mm

Usual (*)

Usual (*)

All

(*) Not necessary for fusion butt-welded pipes with DN <51mm and Wall thickness

8 mm

Above table of heat treatment shall be completed by a supplementary table including all heat

treatment recommended for any other material included in the Contract subject to welding

either at workshop or at Site. This supplementary table shall be supplied to FEWA/ Engineer

for approval not more than 3 months after Award of Contract.

4.12.1 Preheat Requirements

Preheating of the parent metal prior to any welding, tack welding and thermal cutting can be

necessary to minimise the detrimental effects of high temperature and severe thermal

gradients inherent in welding.

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4.12.2 Preheat Temperatures

The minimum pre-heat temperature for welding, flame cutting and arc cutting shall be as

specified below. Where welding procedure specification (WPS) indicates that a higher

preheat temperature is necessary, this shall be used for production welding.

Materials Minimum Temperature

Carbon steels upto 25mm thick 10 Deg C (50 Deg F)

Carbon steels above 25mm thick 79 Deg C (175 Deg F)

Austenitic stainless steel (all thickness) 10 Deg C (50Deg F)

The determination of pre-heat temperature for carbon steel production welds should be based

upon ASME Section 1X Code after consideration of specific heat input, joint thickness metal

composition, welding process and welding consumables.

Unless notified otherwise by FEWA/Engineer the following criteria should be used to

determine preheat levels :

(1) The relevant carbon equivalent (CE) should be calculated from the maximum CE allowed

by the material specification.

(2) Consideration should be given to joint restraint as in case of branch connections

(weldolets, sockolets and nippolets).

When the base metal temperature is below 21 deg.C for carbon steels, the material shall

bepreheated to 50 deg.C prior to welding.Whenever material is wet or contains surface

moisture or condensate, it shall be dried by heating. The fusion faces and 100 mm on each

side of the welds shall be preheated up to 50 deg.C.

4.12.3 Application of Preheat

Preheat shall be applied by electrical resistance methods. Preheating methods with

hydrocarbon gases shall only be used with prior written approval of FEWA/Engineer.The use

of oxy-acetylene torch for preheating is prohibited.Preheat shall be applied in a gradual and

uniform manner and shall be maintained throughout the welding operation.

The minimum preheat temperature shall be established on both sides of the joint

preparationfor a minimum distance of 75 mm or 3 times the material thickness whichever is

greater. If possible, the preheat temperature shall be measured on the opposite face to that

being heated. Where access to only one face is possible, the heat source shall be turned off

to allow for temperature equalization (one minute for each 25mm of wall thickness) before

measuring the preheat temperature.

The preheat temperature shall be held for at least 5 minutes before welding is

commencedand shall be checked before and during welding by thermo-couples, contact

pyrometer or bytemperature indicating crayons. (colour charging crayons shall not be used)

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4.13 Interpass Temperature

Interposes temperature is the temperature at which the weld area must be before the

nextpass is started.The maximum interpass temperature shall not exceed the following limits

unless stated in the approved welding procedure specifications (WPS):

(a) Carbon Steels : 250 0C

(b) Austenitic Stainless Steel : 175 0C

The interpass temperature shall be measured at a distance of about 12.5mm from the bevel

ends and shall be measured by contact pryrometer, thermo-couples or temperature indicating

crayons. (colour changing crayons shall not be used)

4.14 Interruption of Welding

Welding of each joint should be a continuous operation. No weld shall be allowed to cool

unless at least 3 runs have been deposited and 50% of wall thickness is deposited. If for any

reason welding is discontinued, the following criteria shall apply:

a) If 3 runs, and 50% wall thickness has not been deposited, then the weld should be cut

out and recommenced from a new preparation.

b) If 3 runs, and 50% wall thickness have been deposited then the welding operation may

commence provided the following conditions (c) and (d) are met:

c) The weld on interruption shall be allowed to cool slowly from welding temperature to

room temperature (this may be done by wrapping the weld with insulation and allowing

the joint to cool in still air.)

d) Before welding is resumed the weld shall be preheated to the specified temp, after a

close visual or MPI as required by FEWA/Engineer.

Root runs and second passes (hot passes) shall be made without interruption other than

forchanging electrodes or filler wires or to allow welders to reposition themselves.The second

pass (hot pass) of carbon steel pipe welds shall be deposited immediately after the root pass

in order to prevent "cold cracking' in the root area due to shrinkage stresses and joint

restraint.

4.15 Weld Bead Sequence

Weld bead deposition shall be established during welding procedure qualification and shall be

indicated on the joint design of the Procedure Qualification Record (PQR). The specified

welding sequence shall be adhered to during production welding.Adjacent weld beads shall

be staggered and not started from the same location.Welding shall be carried out in a

sequence which will minimize distortion.All welds shall be full penetration welds apart from

the following:

a) Socket welds which may be used on pipe of nominal size DN 40 mm and less, as defined

in the contract drawings.

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b) Pipe support attachment welds.

c) Fillet welds, as specified, which shall be continuous.

Where access permits, pipework with nominal size over DN 600 mm shall be welded from

both sides. Double sided welds shall be back-gouged to sound metal and ground smooth

prior to welding from the second side. However the Contractor shall ensure safe working

atmosphere like ventilation/fume extraction/respirators etc. is provided in order for the welder

to perform the welding.

All pressure containing welds shall have a minimum of three passes with overlaps of starts

and stops. This shall include seal welds of threaded connections and socket

welds.Longitudinal butt-welded pipe fittings are not allowed without written approval of

FEWA/Engineer.

4.16 Interpass Cleaning

After each welding pass, the weld shall be cleaned of all flux, slag and spatter by power

wirebrush, grinding or hand chipping tools. In case of root pass the weld shall be

ground.Every welding pass shall be visually examined by the welder to ensure that the weld

is free from slag, porosity and uneven contour before the start of the next pass.Any defects

found shall be removed or repaired prior to the start of the next pass.Any cracks found shall

be brought to FEWA/Engineer's notice before removal and restart of work.Upon completion of

the weld, the adjacent surfaces shall be cleaned of all spatter, slag, flux,soot and other

foreign materials.

4.17 Peening

No weld peening of any sort shall be permitted.

4.18 Seal and Socket Welding

Sealing compound or Teflon tape shall not be used on joints which are to be seal

welded.Seal welding of threaded connections shall cover all exposed threads. Seal welds

shall contain a minimum of two passes and shall extend from the outer diameter of the fitting

smoothly to the nipple surface without any undercut.Seal welding shall be carried out using a

low heat-input welding process such as GTAW or SMAW. When SMAW process is used, the

electrode size shall not exceed 3.2 mm in diameter.

During socket welding, the inserted end of the pipe nipple shall not come in contact with the

bottom of the socket. A minimum clearance of 1.6mm shall be given prior to welding. Use of

contraction rings to achieve minimum clearance are not allowed without written approval of

FEWA/Engineer.

4.19 Attachment Welds

Fillet welds used for attachments shall be carried out by qualified welders using approved

electrodes and preheat as specified by FEWA/Engineer approved welding procedure.Fillet

welds shall have proper fusion and penetration at the root of the joint. Fillet welds shall fuse

gradually into the pipe and be free from marked irregularities, convexity/concavity and

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undercut.Temporary attachments welded to pipework to facilitate fabrication shall be

permitted with the prior approval of FEWA/Engineer.All temporary attachments shall be

completely and carefully removed checked by DP/MPI test prior to any post weld heat

treatment. Removal of temporary attachments by hammering or bending is not permitted.

4.20 Weld Spacing

Distances between welds shall be measured between the adjacent edges of the cap

passes.Weld joints shall not be arranged so close to each other. Sufficient weld clearance

shall be maintained to prevent thermal stresses near the joint. Circumferential butt welds on

the pipeline shall be separated by maximum possible distance. Longitudinal butt welds of

adjacent pipes shall be separated by at least 100 mm or 5 times the thickness of the thicker

pipes whichever is greater.

Should the site conditions warrant, short pipe lengths between fittings can be used and its

butt welds shall not be closer than 75 mm or 5 times the thickness of the thicker pipes

whichever is greater.Branch/nozzle and other pressure attachment welds shall not be closer

than 75mm to adjacent pressure welds.

Cases which fail to meet this criteria shall be referred to FEWA/Engineer for approval prior to

the commencement of fabrication.Non-pressure containing attachment welds, such as pipe

support welds shall be at a minimum distance of 50mm from any pressure containing

welds.Where pup sections are to be inserted, the length of such insert pup sections for both

new and existing fabrication shall not be less than three pipe diameters, or 150mm whichever

is greater.

4.21 Workmanship and Weld Finish

The welding arc shall be struck inside the joint groove or where the weld is to be made. Arc

strikes, gouges and other indications of careless workmanship outside the weld arc shall be

carefully removed by grinding and the ground area shall be examined by MPI or Dye

penetrant test, and ultrasonics to ensure min. wall thickness is maintained.

Arc strikes, gouges etc. outside the fusion face shall be limited to one per pipe and one per

joint.Repair of Arc strikes shall be at the discretion of FEWA/Engineer.If resultant wall

thickness after grinding is less than the minimum design thickness, the position of pipe

containing arc burn shall be removed as a cylinder.Insert patching and rewelding to increase

the wall thickness shall not be permitted.

Coated surfaces shall be protected from the welding arc and the associated weld

spatter.Weld reinforcement and internal weld protrusion shall be as required by ASME B31.3

but in no case shall the height exceed the weld crown.Excessive internal weld protrusions on

accessible joints shall be removed by grinding. Welds having excessive protrusions on

inaccessible joints shall be cut and re-welded.

Welds which are to be examined by non-destructive testing shall be appropriately surface

finished to facilitate easy interpretation of results.External weld undercutting shall not be

permitted.The acceptability of fillet welds shall be established by suitable gauges or

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templates. The minimum required size of each fillet weld shall be as specified in the

applicable drawing.

Where leg length is specified, the throat thickness for a 1 x 1 fillet weld shall be from 0.7 to 1

times the required leg length. The throat thickness for a 1 x 2 fillet weld shall be 0.7 to 1.2

times the size of the shorter leg.

4.22 Welding Technique

Wherever possible, welding should be carried out with minimum weaving.The width of weave

during production welding shall be within acceptable limits of FEWA/Engineer approved and

qualified welding procedure. In no case shall the width of weaving exceed three times the

core wire diameter or 12 mm whichever is less for SMAW.

For SAW process, welding shall be done without any weaving (oscillation.)All pressure

containing welds shall have at least two passes with overlapping starts and stops.Only single

electrode processes shall be used. Use of multiple electrodes shall require prior

FEWA/Engineer approval.Welding of all pressure containing welds shall be done with direct

current unless otherwise previously approved by FEWA/Engineer.All vertical welding shall be

done uphill. Downhill ('stove-pipe') welding of pressure containing welds shall not be

permitted.

4.23 Post Weld Heat Treatment

Post Weld Heat Treatment shall be required under the following conditions:

a) All carbon steel pipework when the material thickness through a butt weld joint exceeds

19mm.

b) Carbon steel pipework subject to vibration, such as compressor piping, when the

material thickness through the butt weld joint exceeds 12.7mm.

c) Carbon Steel branch connections when the thickness in any plane through the branch

weld exceeds thickness requirements as indicated in ASME B31.3 para 331.1.3.

d) Wherever required for the fabrication of fittings as applicable.

Post weld heat treatment shall be carried out as soon as possible after completion of welding

and shall be conducted in accordance with ASME B31.3 except as modified by this

specification.The temperature controls during heating and cooling shall meet the

requirements of ASME Sec. VIII Division 1.

A post weld heat treatment (PWHT) procedure shall be submitted for FEWA/Engineer

approval prior to any PWHT being conducted.Wherever possible PWHT shall be conducted in

an enclosed furnace. For site or field welds,local PWHT by electrical resistance method shall

be conducted.

The use of manually operated gas torches or gas rings or proprietary exothermic kits shall not

be permitted.Where Local PWHT is done, the weld being post-weld heat treated shall be in

the centre of the heated band. The heated band shall be sufficiently wide such that a band at

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least 25mm on each side of the weld edges reaches the specified temperature range. There

shall be sufficient insulation to avoid an undesirable temperature gradient.

During furnace or local post-weld heat treatment, there shall be a minimum of 4

thermocouples (or as otherwise approved by FEWA/Engineer) used to ensure that thermal

gradients outside the requirements of this specification do not occur during the heat treatment

cycle. Thermocouples shall be positioned at a distance of 25mm from the weld edges on

each side of the weld. The minimum number of thermocouples required may be decreased

only with prior FEWA/Engineer approval.

A time temperature chart recording the thermal history of the part heat treated shall be

provided by the Contractor. The chart shall be clearly identified with the drawing/ISO number,

part and weld number an signed by the CONTRACTOR and certifying authority where

applicable. The chart shall be included in the project record work/"As-built"

documentation.Thermocouples shall, if possible, be placed on the inside for objects being

heated from the outside, and vice-versa, if internally heated.

Thermocouples and temperature recording equipment shall be calibrated prior to use and

shall have a valid certification by a reputed certifying authority.Welding shall be avoided on

any post-weld heat treated material. If any welding is to be carried out on any post weld heat

treated material, this shall be referred to FEWA/Engineer.

Failure to do so will call for repeating heat treatment.All machined surfaces such as pipe

ends, flange faces and threads shall be suitably protected during the PWHT cycle.NDT of

welds, where applicable, shall be conducted after PWHT for final acceptance.

4.24 Weld Identification

Each weld shall be uniquely identified with a weld number and ISO/drawing number and the

same must be represented on the weld identification/NDT drawings. After the completion of

each weld and prior to its visual examination, the weld and welder identifications shall be

marked adjacent to the weld at a distance of about 50mm from the weld using paint or

indelible crayons. This identification shall remain on the pipe till the completion of all NDT for

any verification by FEWA/Engineer.

5. INSPECTION AND TESTING

5.1 General

Contractor to include the provision of service by FEWA/Engineer approved third party

inspection (TPI) subcontractor to cover inspection activities in addition to Contractor ‘s own

inspection.Contractor shall submit to FEWA/Engineer his proposed QA/QC/Inspection

organisation.The Contractor shall submit detailed non-destructive examination (NDE)

procedures for FEWA/Engineer approval.

All NDE shall be carried out in accordance with the procedures approved by

FEWA/Engineer.The radiographic inspection procedures shall include film-processing

procedures to be usedfor non-destructive examination (NDE).The Contractor shall

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demonstrate, to the satisfaction of FEWA/Engineer nondestructive testing production

technique of exposure, film screen combination, use of lead screens, and film processing and

handling are satisfactory and meet this specification.

The Standard Test Radiograph shall be repeated at the option of FEWA/Engineer whenever

any change has been made in the operation procedure or whenever production films vary

appreciably in details, contract or density, from the Standard Test Radiograph.Radiographic

inspection shall be conducted by the use X-rays. Gamma ray examination may only be used

with the approval of FEWA/Engineer.

The Contractor shall submit detailed radiation safety procedures which comply with FEWA

safety regulations.Radiographic inspection shall comply with the relevant safety codes and

radiation control procedures. Special attention is drawn to the necessity for audible and visual

warning devices and for regular monitoring of radiation levels.Radiographic procedures shall

be qualified using both source and film side penetrameter.

Each radiographic film shall contain the following identification information:

Project identification

Weld number

Welder number

Pipe diameter and wall thickness

Date

Film location markers related to the area of weld that the radiographic covers

NDE Contractor's symbol

Weld thickness

Image Quality Indicator

The zero datum shall be top dead centre of the pipe. Defect location shall be in metric units

system. Each radiograph shall have reference markers at 10 cm intervals.The letter "R" shall

appear on all radiographs of weld repairs in addition to the above information.The RT films

shall be stored and kept by the Contractor until final handing over, and shall be available at

anytime for FEWA/Engineer review.

Prior to the commencement of work, the Contractor shall establish an identification system

such that each assembly, each component and each weld can be uniquely and fully identified

with welder/welding operator, welding procedure specification (WPS), NDE

procedure/technique, extent of NDE and NDE results.Procedures for radiography, ultrasonic,

magnetic particle and dye-penetrant examination shall all be conducted in accordance with

ASME Section V.

All personnel performing NDE shall have ASNT Level II or equivalent certification as

approved by FEWA/Engineer prior to the commencement of work.The Contractor must

submit weld map showing NDE system for written FEWA/Engineer approval prior to the

commencement of fabrication.

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5.1.1 Reduced Percentage Examination

For any examination frequency less than 100%, say 'X' percent examination (X may be 5, 10

or 25%), the following rules shall apply:

(a) At least 'X' percent of the total number of welds within the specified line class shall be

examined for 100% of their length (circumference).

(b) At least 'X' percent of the total number of welds on each isometric shall be examined and

shall not be less then one weld per isometric.

(c) At least 'X' percent of the total number of welds made by each welder shall be examined

for 100% of their length. At least one complete weld shall be examined for each welder.

(d) Examinations shall be representative of the entire range of pipe sizes and joints that

have been welded.

(e) Where reduced percentage examination is required and the resulting test shows defects,

then additional examinations as required by ASME B 31.3 para 341.3.4 shall apply

regardless of the examination process used.

(f) Defect acceptance criteria for all reduced percentage examinations shall be the same as

for 100% examination.

(g) 'X' percent shall be determined by FEWA/Engineer and shall be specified for each piping

class.

5.2 Visual Examination

Prior to visual examination, welds and the adjoining areas shall be thoroughly cleaned free of

all slag, mill scale, dirt, weld spatter, paint, oil, flux, stub ends and other foreign matter.The

Contractor shall provide easy access to the pipework for inspection. This will include the

provisions of ladders and scaffolding when required.

The workmanship and weld finish shall be as per this specification.Weld acceptance criteria

for visual examination shall be as per ASME B31.3, Table 341.3.2 except as modified by this

specification.

5.3 Radiographic Examination

Radiographic procedures shall be in accordance with the methods described in ASME

Section V Article 2 except as modified by this section.Radiographs should be evaluated in

accordance with ASME B31.3, Table 341.3.2, except as modified by this specification.Only

fine grain, high contrast film or ultra fine grain high contrast film shall be used. Type 1film

(AGFA, structurix D4 or equivalent) of ASTM E94 shall be used for gamma ray radiography of

pipes with wall thicknesses below 10mm.

Gamma radiography shall only be used if it can be proven that the required sensitivity can be

achieved.Wherever possible, DIN penetrameters (wire type Image Quality Indicators) shall be

used.Radiographic sensitivity shall be 1.8% or better.Where film side IQI's are used,

correlation of sensitivity with source side IQI'S shall be established before proceeding with

inspection.Only lead intensifying screens shall be used.

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The radiographic density in the diagnostic area shall be between 2.0 and 3.5All burn-through

shall not be permitted.Radiography shall be conducted after any required PWHT for final

acceptance.

5.3.1 Reporting

The radiography report shall include the following information:

- Contract number

- Project title

- Name of the component

- Source type (X-ray/Ir-192)

- Source strength (mA/curies)

- Focal spot size

- Technique (SWSI/DWDI/DWSI/PANAROMIC)

- Film type and size

- Penetrameter type and number

- Exposure time

- Developing time and temperature

- Density

- Sensitivity

- Lead screens (front and back)

- Specification (ASME B31.3)

- Weld identifications

- Pipe diameter and wall thickness

- Welder identification

- Interpretation

- Remarks (Accept/Reject)

- Radiographer's name and signature

- Date of exposure

5.4 Ultrasonic Examination

The Contractor shall submit an ultrasonic examination procedure for all full penetration butt

and branch welds for FEWA/Engineer approval prior to the commencement of examination of

production welds.Ultrasonic examination shall be carried out in accordance with ASME

Section V Article 5, except as modified by this section and the results shall be evaluated in

accordance with ASME B31.3 Table 341.3.2.

The ultrasonic equipment shall be checked for linearity, db attenuation etc. and a valid

calibration certificate shall be submitted for FEWA/Engineer review, prior to use.As a

minimum requirement, ultrasonic examination shall be conducted using a minimum of three

transducers, one 0° compression and two angle beam transducers with a frequency of 1 to 5

MHZ. Where access permits, ultrasonic examination shall be conducted from both sides of

the joint.

Prior to conducting ultrasonic examination, the Contractor shall ensure that the weld and the

surrounding area are sufficiently smooth to avoid false or misleading indications. Transfer

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correction should be applied to accommodate surface curvature and roughness.Branch

connections that include a reinforcing pad plate shall be examined after welding the branch to

the header and again after welding on the reinforcing plate.

The test report should outline the technique employed, type and size and frequency of probes

used, and defects discovered and shall contain the following information as a minimum:

(a) Weld identification and welder number

(b) Weld procedure used

(c) Size of reportable defect

(d) Depth of reportable defect

(e) Location and orientation of reportable defect (with a sketch)

(f) Weld acceptable/not acceptable.

(g) Specification

(h) Inspector's name and signature

(i) Date of Examination

(j) Scanning Diagram.

Ultrasonic examination of welds shall be conducted after PWHT that may be required for final

acceptance.

5.5 Magnetic Particle/Dye-Penetrant Examination

Magnetic particle examination shall be carried out on magnetic materials.Dye-penetrant

examination shall be carried out on non-magnetic materials (stainless steels and non-ferrous

materials).Weld areas to be examined by magnetic particle/dye-penetrant examination shall

be sufficiently smooth to avoid spurious indications that may result from irregular weld

surfaces.All magnetic particle examination shall be carried out by alternating current yoke

method with a white background and black magnetic ink.

Magnetic particle examination shall be carried out in accordance with ASME Section V Article

7. Dye-penetrant examination shall be carried out in accordance with ASME Section V

Article6. The acceptance criteria shall be as per ASME B31.3 and Table 341.3.2.Where

PWHT is required, magnetic particle/dye-penetrant examination shall be conductedafter

PWHT for final acceptance. Examination shall be conducted before PWHT for any

repair/rectification that may be required before PWHT.

5.6 Ultrasonic Thickness Measurement

Ultrasonic thickness measurements, where required by the ASME B31.3 code, and/or by

FEWA/Engineer, it shall be done with Ultrasonic Flaw Detectors. The use of D-Meters is not

permitted for thickness measurements.Where specified by FEWA/Engineer, ultrasonic

thickness measurements shall be made on both sides of welds at a distance of 25mm from

the weld edges.

The thickness readings shall be recorded on NDE spool drawings.

5.7 Extent of Non-Destructive Examination

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The minimum requirements of non-destructive examination of welds shall be as per

ASMEB31.3 code. More stringent NDE may be specified based upon materials of

construction,service severity and/or testing limitations.

5.8 NDE Personnel Qualifications

Welding inspectors shall be certified to AWS or equivalent.All personnel carrying out non-

destructive examination (radiography, ultrasonic, magnetic particle and dye-penetrant

examination) shall be ASNT Level II certified or equivalent.

Where the NDE technician is certified by the Contractor himself, the qualification shall be in

accordance with Contractor's written procedures which shall use ASNT'S recommended

practice No. SNT-TC-1A, as a guide. This written procedure shall be subject to

FEWA/Engineer approval.

New qualification tests may be required if a technician's performance indicates

deficiencies.The Contractor shall bear all costs for qualifying technicians and FEWA/Engineer

Inspector will have the option to witness any qualification tests.The Contractor shall have

records of qualifications and certificates for each technician available for review by

FEWA/Engineer prior to the commencement of work by the technician.Any technician may be

disqualified by FEWA/Engineer upon proof of unethical practices, negligence, non-

compliance with procedures or poor performance.

5.9 Repair of Defects

5.9.1 General

Prior to carrying out any repairs involving welding, the Contractor shall submit a written repair

welding procedure to FEWA/Engineer for approval.This shall include details of the type and

extent of defects, method of removal, preparation of area to be welded, method of application

of preheat, reference welding procedure specification and NDE procedures.Acceptance of all

repair work shall be subject to FEWA/Engineer approval.

5.9.2 Minor Surface Repairs

Minor surface imperfections may be removed by grinding provided that the wall thickness

isnot reduced locally by more than 12.5% of the nominal value specified or the minimum

design thickness whichever is greater and the minimum wall thickness is maintained, which

will be verified by ultrasonic thickness survey.The ground area shall be dressed to a uniform

and smooth profile with no sharp corners ornotches.The ground area shall be examined by

MPI or dye-penetrant examination to ensure that the defects have been completely removed.

5.9.3 Repairs Involving Welding

Any defect that cannot be removed by surface grinding shall be repaired by welding.Any

defect exceeding acceptance criteria of this specification shall be carefully removed by

grinding.The excavation shall extend at least 25mm beyond both extremities of the defect

without substantial removal of the base metal and shall be done in such a manner that the

remaining weld or base metal is not nicked or undercut.

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The grooves shall be free from scale, have a smooth contour to facilitate welding. Surface

should be ground to a smooth, bright metal surface.The ground area shall be carefully

examined visually and then by MPI or dye-penetrant examination prior to commencement of

re-welding to ensure that the defect has been completely removed.

The area to be repaired shall be pre-heated to at least 50 deg.C above the temperature

specified in the corresponding initial welding procedure but shall not exceed the maximum

interpass temperature. Repair welding shall be carried out using the approved repair welding

procedure. The Contractor shall take appropriate care such as proper weld sequencing,

control of interpass temperature etc. to minimize residual stresses.

All repair welding shall be carried out by qualified welders.If any repairs are carried out after

PWHT or hydrostatic test, the PWHT and hydrostatic test shall be repeated.Planar defects

such as cracks etc. shall not be permitted. Such joints containing cracks shall be cut out.

5.9.4 NDE of Repair Welds

All areas repaired by welding shall be thoroughly cleaned free of slag, spatter etc. and ground

to a smooth contour with the parent material and existing weld taking care that over-grinding

does not occur.The repaired weld shall be subject to 100% visual examination and then NDE

by the same techniques used for the original examination. The acceptance criteria shall be

the same as for the original welds.A weld with defects may be only repaired twice.

If the repair is not acceptable after the second repair, the complete weld shall be removed,

rebevelled, re-welded and re-examined.

5.9.5 Limitations on Repairs

Repairs shall be limited to 30% of the weld length. For internal repairs or external repairs

which open the root, only 20% of the weld length shall be repaired. Repairs opening the root

shall only be carried out in the presence of FEWA/Engineer. The minimum length of a repair

area shall be 25 mm.If the repairs cannot be carried out without exceeding these limitations,

or not carried out successfully, the weld shall be cut out.

5.9.6 Additional Acceptance Criteria

Defect Acceptance levels shall be as per ASME B31.3. Hollow bead porosity and concave

root shall not be permitted.Visual Acceptance standard for undercutting length shall be as per

API 1104, Section 6.7.

The Contractor shall have the various inspection stages witnessed and reports reviewed by

FEWA/Engineer."Acceptance" by FEWA/Engineer does not relieve the Contractor of his

responsibility to fulfill his contractual obligations.

6. WELDING OF D.I. PIPES ON SITE

On-site welding of D.I. pipes, fittings, flanges and the like shall be by electric arc in

accordance with approved international standards and procedures. Welding shall only be

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carried out by welders well qualified and experienced in this work. The welders shall be

subject to FEWA approval.

Prior to any welding, the parts to be joined must be thoroughly cleaned by grinding or filing in

order to obtain a bright metallic surface. Any coatings which might stick to the tools shall be

scraped off or must be removed by chemical means (e.g. turpentine). All surfaces shall be

free of zinc.All parts to be welded shall be kept dry and shelters shall be erected over the

working area in the event of inclement weather.

Welding shall be carried out using sheathed nickel-iron electrodes containing approximately

50% nickel. Welding shall be either by alternating current or direct current on the negative

pole. The current shall be 110 - 120 amps. Preheating or post -heating shall be applied as

and when required. All parts to be welded shall be held firmly in jigs or clamps. Restraining

beads on spigot ends shall follow a copper gauge held tightly around the pipe in accordance

with pipe manufacturer recommendations. No undercutting shall be permitted.

All welds shall be allowed to cool naturally without forced ventilation. They shall be cleaned of

slag and as a minimum requirement painted with one coat of Zinc rich paint and one coat of

bituminous paint giving a minimum dry film thickness of 150 microns. Where specific coatings

are required then the same coating specification shall be applied to the welded item.

All internal cement mortar linings shall be made good in accordance with the specifications.

Any damaged or rejected pipe work shall be replaced by the CONTRACTOR at his own

expense. No on-site welding of D.I. pipes shall be allowed prior to having written approval

from FEWA.

7. VENDOR DOCUMENTATION

The as-built QC dossier shall include the following:

(a) Material identification/traceability reports for each item in the contract drawings.

(b) Mill certificates of all materials giving the chemical composition and mechanical

properties.

(c) FEWA/Engineer approved procedure specifications (WPS)

(d) FEWA/Engineer approved Procedure Qualification Records (PQR) along with backup

NDE and mechanical test reports.

(e) List of Qualified Welders and Welder Performance of Notification Certificates.

(f) NDT reports.

(g) As-built drawings.

(h) Weld identification drawings.

(i) NDT summary control sheets, which show weld numbers, type and extent of NDT for

each weld, report numbers for each weld identification drawing and welding date.

(j) Heat treatment reports and charts.

(k) Dimensional inspection reports.

(l) Hydrotest reports.

(m) Blasting and painting reports.

Federal Electricity & Water Authority Water Directorate STANDARD … · 2017. 2. 22. · 5.3 Radiographic Examination 5.3.1 Reporting 5.4 ... 5.9.6 Additional Acceptance Criteria

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