8/3/2019 Calculation of Negative Buoancy for Pipelines http://slidepdf.com/reader/full/calculation-of-negative-buoancy-for-pipelines 1/18 .. CALCULATION OF BUOYANCY PREVENTION BY CONCRETE SADDLE WEIGHTS WITHIN SABKHA AREAS MOG DOCUMENT NO. SOC DOCUMENT NO. CLIENT: PROJECT NO.: 520 01 20880 30" GAS & 12" CONDENSATE TRUNK LINES EROMATTAHADDYTO KM 91,5 PROJECT TITLE: I~' i 2 1 'ev. ISSUED FOR CONSTRUCTION-! ISSUED FOR CONSTRUCTION - ISSUED FOR SOC APPROVAL- Description of Revision BUOYA104
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8/3/2019 Calculation of Negative Buoancy for Pipelines
The line pipes to be coated are a portion (about 9200 Meters) of the 36" pipes, API 5L X-eO, 0.344"w.thk. The exact amount to be established during the detail design of the line. Pipes intended for
concrete coating will be provided of a FBE external anti-corrosion coating, 700 micron thick.
2.2 Coating Method
The concrete coating will be applied By Contractor with the impingement method, in his shop area.Contractor shall submit a detailed written description of the coating equipment, procedures and
materials for Purchaser's review.
Bases of design
The purpose of the concrete coating is to provide the pipe with a negativj3 buoyancy adequate tc-
ensure stability to the pipeline in the swampy sections of the R.O.W.
The theoretical Negative Buoyancy of the empty pipe shall be calculated·as per following formula:
8N =Wc -8
We = Wp + TC· te(D + te)y e + W R ( 1 - ~ )- YR
B= ~ ( D + 2 . t e ) 2 Y LI 4
where:
BN =We =B =Wp =te =0 =WR =Ye =YL =
YR =
Negative Buoyancy per unit length of concrete coated pipe (kg/m).'- I
Weight (in air) per unit l e n g t ~ of concrete coated pipe (kg/m)
Buoyancy of the concrete coated pipe (kg/m)Weight (in air) per u n i l l e n g t ~ of steel pipe FBE coated (kg/m)
Thickness of the concrete ~ J a t i n g (m) ..
Outside diameter of the steel pipe, FBE coated (m)
Weight of reinforcement pJr! unit length of pipe (kg/m)
Specific weight of water s a : t ~ r a t e d concrete coating (kg/m3)
Specific weight of fluid (kg1m3)
Specific weight ofr e i n f o r c ~ m e n t
(kg/m
3)
I
8/3/2019 Calculation of Negative Buoancy for Pipelines
The specified Negative Buoyancy and specific weight of fluid are as follows:
BN =101 kg/m
yL = 1025 kg/m3
based upon the following parameters:
lc=0.125 m Yc=2410 kg/m3
Contractorshall design the concrete Iihing such as to attain the above specified Negative Buoyancy
BN with the specified specific weight of fluid YL' Contractor may establish design concrete thicknessand specific weight different from the !above reference ones, provided that they meet said Negative
Buoyancy BN· _ IJ.! . _
1.1 'I!
3. MATERIAL fil3.1 Concrete Mix Design
Contractor shall design the mix using approved aggregates and materials and shall determine the
material proportions to give the rsquired concrete density and strength. Required compressive
strength after 28 days curing shall bJ not less than 25 N/mm2
(tested on cubic specimen). .
The mix design specification shall be approved by Purchaser prior to commencement of the coating
operations. The specification shall be supported by.certificates of tests carried out by an approved
laboratory. Full details shall be provided by Contractor with regard to:
a) the Supplier's certificates of the cement
b) the chemical/physical analysis of the aggregates
c) the water analysis '
d) the grading of the various aggregates, with combined grading curves as necessary
e) the water/cement ratio and the proportions of the components
f) the types and specifications o,f admixtures, if any
All component of concrete shall oe resistant to slurry condition of "Sabka" (salty marsh) environment.
Cement
BS 4027 type 32.5R s u l p h a t ~ resisting Portland c ~ m e n t shall be used, or equivalent cement
according to ASTM C 150 a p p r ~ v e d by P u r c h ~ s e r .3.2.4 Cement that has hardened, become partially set or has become lumpy shall be rejected and removed
from the site by Contractor.
3.2.5 The cement shall be stored in a manner which will provide satisfactory weather protection
8/3/2019 Calculation of Negative Buoancy for Pipelines
SIR1TE OIL COMPANY ~ r B o n a t t i-' TP-1326AT ,"
..
-'- SPC NUMBER JOB 83301Sheet 6 of 15I
INDEX I PLANT SEQUENCEA 0 1 SPC. No.
Rev.LD1 31 C1-9004 31-C1-9004
Manufacturer's cement chemical analysis certificates shall be collected by Contractor and transmittedto Purchaser as follows: '
_Included in the "Concrete Mix Design" for the first shipment delivered to shop (copy)
-Included in the final documentati?n for first and any additional material delivered to shop (originals).
Fine aggregates
Fine aggregate shall consist of natural sand, manufactu'red sand or a combination thereof and shall
conform to the requirements ot:ASTM C33. Grains shall be clean, hard, strong, durable free from
other foreign and deleterious substance. ' "1 '
sand grading shall conform to ,standard ranges indicated in ASTM C33, with reasonable tolerances.
Deviations in the sieve analysis' will be allowed, provided they are supported by positive results oftests.
Sand shall be stored in a manner to avoid contamination from soil or other foreign matter.
3.4 Coarse a g g r e g a t ~ s
Coarse aggregates shall consist of gravel, crushed gravel or crushed stone and shall conform to
requirements of ASTM C33. The materials shall be clean and free of any injurious amount of
c ~ e m i c a l compounds, organic materials, or solids Which may impair the strength and durability of theconcrete.
Tl:1e maximum size of coarse aggregate shall be compatible with the size of the mesh reinforcement.
Aggregate grading shall con(orin to standard ranges indicated in ASTM C33, with reasonabletolerances. Deviations in the sieve analysis will be allowed, provided they are supported by positiveresults of tests. .,
3.4.4 Aggregate shall be stored sep,arately from sand and suitable provisions shall be made to prevent
contamination with soil and other foreign matter.
3.5 Mixing water
3.5.1 Mixing water shall be fresh water, clean and free from injurious oils, acids, alcohols and organicmaterials. Water containing more than 2,000 ppm of silt or suspended particles shall not be used.
3.5.2 The follOWing maximum contents of dissolved solids are a l l o ~ e d :
Sodium and Potassium carbonates and bicarbonates
Sodium chloride and sulphate
Calcium and Magnesium carbonates
Iron saltsSalts of Manganese, Tin, Zinc, Copper and Lead
Sodium sulphide
Sugar
pH
1,000
10,000400
40,000
500
100
0.02
~
ppm
ppm
ppmn
ppm
ppm
ppm%wt
8/3/2019 Calculation of Negative Buoancy for Pipelines
b) Data sheet and drawings, i f applicable, showing the established dimensions of the coating, in
particular the thickness consistent.'f. 'ith the aimed density, the calculation of the Negative
Buoyancy, the details of wire mesh application, if any, etc...
These documents may be incorporated in a revised issue of this specification. .
8.2 Pre-production documents
The following dQcuments shall be submitted by Contractor to Company review prior to starting the
production:
a) Description of the coating facilities, including a lay-out of the yard, the list of equipment and test
instruments, the drawings of the moulds for concrete casting, etc...
b) Certificates of lifting equipment
c) Certificates and/or calibration certificates of testing equipment and instruments
d) Pipe stacking procedure
e) Curing method statement
f) Quality plan, including the description of the tesVinspection procedures, the relevant forms and the
traceability procedure
8.3 Production data dossier
C ~ n t r a c t o r shall gather in an ordered file the data and information relevant to the production,
including but not limited to the following ones:
a) Daily production of coated pipes (With individual pipe numbers)
b) Daily report of repaired pipes ..c) Reports of all tests and inspeCtionsd) General remarks covering operation of eqUipment, weather conditions (including ambient
temperature), testing, pipe stacking, etc...
8/3/2019 Calculation of Negative Buoancy for Pipelines
SJRTE OIL COMPANY ~ r 8 0 n a t t i~ ~ - y,.,. _...\TP-132GAT- ' ~ " - 1 .!
..t .
.J -
Iheet 14 or 15 SPC NUMBER JOB 83301.; INDEX PLANT SeQUENCE
A 0 1SPC. No.
Rev. LD1 31 C1-9004 31-C1-9004
,"rrrI
F
The Negative Buoyancy BN must be found to be equal to the design one (i.e. 101 kg/m) within the
following tolerances:
a) On a single pipe length: :
b) On the average of the daily production:
-25 kg/m
-10 kg/m
+40 kg/m
+15 kg/m
G.7 Data recording
-Contractor shall establish suitable procedures for recording the results of all tests and inspections,
together with the most important data/information, and for having them f i l ~ d in a rational manner. Allinspection and test reports shall be traceable to the original pipe identification number assigned bythe pipe mill.
A written description of these procedures, including details of data to be recorded and samples of the
forms proposed for this purpose, shall be submitted to Purchaser prior to starting the coating activity.
7. HANDLING
7.1 The handling of pipe shall be performed in a manner preventing damages to the pipe and its coated
surfaces.
7.2 Pipe shall "not be dragged but shall be picked up bodily using fork lift with SUitably padded forks or bymeans of crane and non-metallic slings. Alternatively, i f end hooks are to be used, they shall be
suitably radiused and lined with plastic or similar material. A spreader bar shall be used between
lifting lines. During handling,Jhe pipe shall not be subject to impacts or jars. Any pipe SUffering impact
or jars shall be immediately marked for subsequent repair, when applicable.
7.3 After coating the pipes shall be SUbjected to minimal handling until concrete is set and SUfficiently
hardened. Concrete coated pipe shall not be placed on skids or racks until the coating has hardened
SUfficiently to prevent flattening.
As a general rule, concrete coated pipes shall not be handled or stacked until the concrete has
achieved.a compressive streQ9th of at least 16 N/mm2.
Pipe shall be stacked in such a manner so as to prevent damage to the pipe and coating. Contractor
shall submit proposed-stacking arrangement, including stacking heights.
8. DOCUMENTATION
8.1 Design documentsi
Contract;r shall submit the following documents to Company's approval, at latest one month prior to
the starting of production: I -
a) Concrete mix design specificatiorl, supported by the certificates of all tests carried out for proving
that the proposed material and the mechanical characteristics and density of the concrete are
suitable for the purpose and fulfil lhe requirements of this specification.The mix design specification shall include the data sheets and/or technical bulletins of the
products that Contractor i n t e n d s ~ to use for the fabrication.I!I i
8/3/2019 Calculation of Negative Buoancy for Pipelines
~ l *' PROJECTNUMBER S I R ~ ~ OIL COMPANY ~ r B o n a t t if lP-1326AT
Sheet 12 of 15 i SPC NUMBER JOB 83301
INDEX I i PLANT SEQUENCEA 0 1
SPC. No.
Rev. LD1 . 31 C1-9004 31-C1-9004
-,
6.2 Inspection of anti-cor;osion coating
Contractor shall carry out visual and Holiday tests on the FBE coating of each pipe length, prior to
proceeding with the concrete lining. Procedure for holiday test shall be as specified by the F8E
Manufacturer. In case holiday(s) are detected, the defective section of coating shall be identified and
repaired in accordance with procedure recommended by the FBE coating Supplier/Applicator and retested.
Concrete strength
The compressive strength of the corcrete coating shall be determined by testing concrete c u b ~ s (150mm size), prepared with fresh material taken before to enter in the mixer of impingement unit.Each cube will be marked with the date of sampling, the cube number and concrete batch No.Test samples of eight (8) cubes shall be taken during each shift production.
Two cubes will be--weighed after the specified period and the dry density will be calculated. The
acceptable tolerance on concrete dry density shall be + 5% - 2% to those measured during concrete
mix design. Two additional test will be carried out on two extra cubes in case of test failure bothcubes shall meet the requirement.
The first couple of cubes will be crushed after 28 days. The second couple of cubes shall be crushed
to determine the strength if the pipe are to be moved for shipment.
The minimum compressive required at 28 days test is 25 N/mm2 on cubic specimen..
Two extra cube will be prepared and tested in case of failure of any cube.
6.3.2 In the event that concrete cubes do not meet the minimum compressive strength requirements of this
specification, additional tests'of the suspect pipe coatings shall be made by schlerometer. (as perA.C.1. 318) in order to decide about the suitability of the pipe joints coated with the concrete from the
same batch. Schlerometer shall be calibrated prior to use.
6.4 Electrical insulation of reinforcement
6.4.1 Measurements shall be made on coated pipes, after curing, in order to make sure that there is no
electrical contact between the reinforcement and the steel pipe.
Tests shall normally be done on one pipe every len (10) coated pipes. Should any test fail, all pipes
of same day's production shall be tested.
6.4.2 The test shall be carried out when concrete coating is sufficiently dry. One measure shall be taken of
the electrical resistance between the steel pipe and the reinforcement prior to be cutted (para 4.2.4)
--
6.4.3 -The measurement is carried out using a megaohmmeter providing 500 Volts d.c. The electrical
resistance, measured between the reinforcement and the pipe, shall'not be less than 100 kW. When
the megaohmmeter gives values below 100 kW , the pipe section being t ~ s t e d must be put aside andthan inspected by C o i n p a n y ~ s Representative who, after furthertestsand checks, shall decide on the
corrective action to be taken.
8/3/2019 Calculation of Negative Buoancy for Pipelines
. ~ TP-1326AT SIRTE OIL COMp·ANY ~ r B o n a t t i
I
Sheel 10 of 15 SPC NUMBER JOB 83301
0 1INDEX PLANT SEQUENCE
ASPC. No.
Rev. LD1 31 C1-9004 31-C1-9004
5. REPAIRS
5.1 General
Repairs shall be made either using c o n c r ~ t e with the same proportion of constituents as the original
coating (a slight iRcrease in water content' is acceptable for hand repairs) and shall be performed assoon as possible after discovery of the damage.
The concrete-shall be placed by either jehing or trowelling. such that the surface is continuous with
the level of the undamaged coating a r o u n ~ the repair. All repairs shall be visually inspected to ensurethat the finished coating complies with thi,s specif icat ion.-
All rejected sections of pipe coating, to be subsequently re-coated. shall have the concrete carefullyremoved. After the removal of the defective concrete coating, the anti-corrosion FBE coating shall beexamined for damage and tested by Ho!iday Detector. All damaged anti-corrosion coating shall berepaired in accordance with procedure recommended by the FBE coating Supplier/Applicator and retested before subsequent re-coating with concrete.
5.2 Permissible repairs to Concrete Coating
The following repairs shall be permitted for concrete coating defects or damages during har.dling or
st,prage.
5.2.1 Spalling
Spalling due to compression or shearing caused by impact against other objects will be handled as
follows: :
a) Spalling which causes a loss of no more than 20% (25% after site transportation) of the total
thickness of the coating in an area of less than 300 cm 2, where the remaining concrete is soundwill be accepted without repairs.:
b) Spalling which causes a loss of more than 20% (25% after site transportation) of the coating
thickness or which affects an area larger than 300 cm 2, but having a dimension not exceeding 1/6
of the pipe circumference, shall be repaired.The damaged concrete shall be removed such as to expose the sound concrete. The resultingcavity will then be filled by the mix used for the repair. Before pouring, the cavity surface shall be
brushed and wetted with a mortar prepared with one part cement and two parts sand.
c) In case the dimension of damaged area is larger than 1/6 of the pipe circumference, the coating
shall be completely removed on an annular portion exceeding the dimension of the damaged
area. A new coating shall be applied on this portion, including the steel reinforcement. if al]y, using
a metallic sheet as a formwork. such as to obtain the requiredcoating thickness. Before casting.
the surface of the adjacent concrete shall be brushed and wetted with a mortar prepared as per
previous item b). '
8/3/2019 Calculation of Negative Buoancy for Pipelines
The uncoated portion of the pipe and the bevels shall be kept clean and free from concrete spatter,
oil, grease, etc. : :I : '
4.5 Stripping
Coated pipes shall be removed from impingement unit, and shall be laid on sand berms. Particular
care shall be taken in pipe picking up and handling in order to prevent any damage to the freshI
concrete.! - .I
Curing of Concrete
Concrete coatings may be cured by any of the two following methods (see next art!. 4.6.2 and 4.6.3)
but, whichever is used, the concrete shall not be allowed to dehydrate and the temperature of the
concrete coat shall not be allowed to fall below 2 °C during the initial 24 hours of curing.
.-
If water curing method is adopted, curing shall commence not later than two hours after stripping and
shall comprise keeping the coating continuously moist for a period of not less than seven days. This
maybe accomplished by water spray, application ofJutefgunny bags spreaded over the pipes. or any
other approved mean. Use of curing compound, that may be proposed by Contractor in his curing
procedure, can reduce the above specified watering period. Contractor shall submit details of the
rl)ethod to Company for approval.
Water spray curing shall not be allowed when ambient temperature falls below 5°C.
If any s h ~ e t or. film is used for concrete curing, i t shall comply with ASTM C17i. Samples 9f thematerialshall be taken and tested to ensure conformity with ASTM C171, unless Manufacturer's test
results are available.
4.6.4 Pipes shall not be removed from their first curing site nor handled for transportation until a time has
elapsed from casting equal to the time required by concrete to attain a compressive cube strength of
16 Nfmm2.
4.7 Marking
4.7.1 Care shall be taken by Contractor to preserve the original pipe marking by pipe mill and the marking
applied by tbe FBE coating Applicator.
4.7.2 The date of casting and the pipe number shall be stencilled using indelible paint on the external
surface of the co,,!cretecoating.-
8/3/2019 Calculation of Negative Buoancy for Pipelines
,.Contractor shall take all necessary measures to prevent any damage to FBE pipe coating and to pipe
bevels and to avoid any entrance of concrete into the pipe during coating operations.
4.2 Placement of steel wire mesh
Three concentric layers of galvanized steel wire mesh shall be applied. The Contractor shall propose
a positioning of the reinforcement l ~ y e r s for Purchaser approval..
The distance from anti-corrosion coating to the inside of the reinforcement shall be a minimum"ofi5
mm and 20 mm between the mesh and the outer surfaceof
the concrete. <1>
Overlap for reinforcing shall be not less than 25 mm.
4.2.4· The wire mesh at the end shall be cut in a such way that shall be covered by at least of 15 + 20 mm
of concrete. <1 >
Placement of Concrete Coating
The constituent parts of the concrete mix shall be weight-batched using a batching plant daily
c9librated.
A water gauge accurate to within 2 of the indicated values shall be used for adding water to themix. :1' -.
Ii
,!.The accuracy of the weight device fot:weight batcher shall be 2%, calibrated prior to production and acalibration chart issUed to Purchaser; ,The weight-batcher and water gauge shall be regularly checked
'. 'Ifor accuracy (at least once a month).;:
,II:The dry materials shall be batch mixed with the required quantity of water to make a homogeneous
mix using a mechanical mixer. The concrete shall then be transferred to impingement unit an than
impinged upon the pipe within amaximum of 30 minutes from the time of mixing water.! .
In case fresh concrete needs to be.applied after an interruption the surface of the previously placed
concrete shall be cleaned and wetted in order to obtain a good bond between the fresh and thepreviously placed material. i .
Each joint of pipe shall be coated in a continuous operation, the time allowed between the first coat
and the last coat shall not exceed one hour.. '
Concreting shall not take place if temperature of pipe, or of reinforcement or of concrete . ~ i x is lower
than5°C.'
4.4.1
4.4 Cut back
The concrete coating shall be applied to within 350 ±10 mm from the ends of each length of pipe. The
ends of the concrete coating s h ~ 1 I be square cut back and in accordance with paragraph 4.2.4. <1>