20-05 - Concrete Coating of Line Pipe

8/17/2019 20-05 - Concrete Coating of Line Pipe

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Chevron Nigeria Limi ted Specification 20.05

November 20; Revision A 11- 22- 91 CN- 2 516- 20. 05

20.05 - CONCRETE COATING OF LINE PIPE


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CONCRETE COATING OF LINE PIPE

November 20, 1991; Revision A Page 1 of 15 11- 22- 91 CN- 2 516- 20. 05

TABLE OF CONTENTS

1.0 SCOPE

2.0 COATING CONTROL DATA AND TOLERANCES

3.0 STANDARDS AND SPECIFICATIONS

4.0 MATERIALS

5.0 PROPORTIONING AND MIXING OF CONCRETE

6.0 EQUIPMENT AND APPLICATION

7.0 CURING

8.0 PERMISSIBLE REPAIRS TO CONCRETE COATING

9.0 CAUSES FOR REJECTION

10.0 CARE, HANDLING, AND STORAGE OF PIPE

11.0 SPECIAL WORK

12.0 IDENTIFICATION OF PIPE JOINTS AND REPORTS

APPENDIX

I Standards and Codes

ATTACHMENTS

1 Concrete Coating of Line Pipe Data Sheet (3 Sheets)


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1.0 SCOPE

1.1 General

This specification covers application of concrete coating to line pipe for useoffshore off the coast of West Africa. Contractor shall furnish all materials, labor,equipment, utilities, supervision, services, and all other items required to performthe work. Contractor shall make all arrangements and obtain permits required forhis performance of work at the coating application site, whether on propertyowned or arranged for by Contractor, by Company, or by Others.

1.2 Slippage Control for FBE Coated Pipe

Contractor shall provide adequate shear strength between the concrete and thefusion-bonded epoxy (FBE) corrosion coating to prevent slippage of the concrete

during installation.

The required minimum shear strength shall be calculated by Contractor andapproved by Company, and shall be as shown on the data sheet.

Shear strength enhancement shall be achieved by any of the followingtechniques:

• Application of an intermediate barrier coating between the FBE andconcrete.

• Forming of a continuous, raised spiral of epoxy between the FBE andconcrete.

• Forming of rough bands of epoxy with embedded flint chips on one end ofthe pipe prior to application of the concrete.

• Forming of a ring of cementitious epoxy on one end of the pipe prior toapplication of the concrete.

Contractor shall demonstrate the ability of the enhancement technique to meet therequired minimum shear strength by means of a full scale push-off test or otherexperimental method. The results of the test shall be submitted to Company forapproval of the proposed shear strength enhancement method.

1.3 Intermediate Barrier Coating

For coating application by the impingement method over FBE coated pipe,Contractor shall apply an intermediate barrier coating to protect the FBE fromdamage.


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Acceptable intermediate barrier coating are:

• FRC Composites Ltd. FRC 80• Active Protective Coatings Ltd. Forton 2000

Alternatively, Contractor may propose other methods of limiting damage to theFBE such as increasing the FBE thickness and using a fine sieved aggregate.Prior to Company approval of such methods, Contractor shall perform a field trialwhere the concrete shall be applied and then washed back off, and the FBEreinspected for damage both visually and for holidays according to NACERecommended Practice RP-0490-90. The concrete application shall have causedno significant visual damage to the FBE, in the opinion of Company, and shallresult in no more than five detected holidays.

1.4 Exceptions

Contractor shall obtain written approval of Company for any deviations from therequirements of this specification.

This document is not intended to be all inclusive, and the use of the guidelines setforth does not relieve Contractor of his responsibility to supply a finished productcapable of performing its intended service.

2.0 COATING CONTROL DATA AND TOLERANCES

2.1 Coating Control Data

Contractor shall weigh each concrete-coated pipe joint immediately after coating,and shall measure the outside diameter of the concrete either on the scale or assoon as the joint is placed on the curing rack. The outside diameter shall bemeasured at a minimum of five points evenly spaced along the length of the pipe

joint. The average of these measurements shall be reported and used incalculations for coating thickness and concrete density. Report entries andcalculations required by Sections 2.2 and 2.3 shall be made within 30 minutesafter the pipe joint is placed on the curing rack.

2.1.1 Weighing Devices

Weighing devices used to determine the weight of the concrete-coated joints shall

be certified in writing to an accuracy of 0.5%. When specified on the data sheet,the weighing device shall be calibrated just prior to start of coating by anindependent agency approved by Company. Checking of the weighing devicesshall be done at the beginning of each day's production, and Company shall retainthe option to request a check at any time. The check shall be performed using a

joint of pipe with a known weight, that weighs within plus or minus 25% of theweight of a concrete-coated pipe joint to be coated.


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2.2 Density

2.2.1 Density of concrete coating shall not vary from the design density by more thanplus 10% or minus 5%.

Density of coating as determined by methods given in Section 2.2.2 for"as-applied" concrete coating on the pipe, and Section 5.3.2 for 24-hour samplecylinders, shall be used for control of mix and application during the period ofconcrete coating.

If the density varies from the specified density by more than the stated tolerance,Contractor shall take corrective measures to obtain specified density, and shallimmediately inform Company of the deviation and corrective measures.

2.2.2 Density of "as-applied" concrete coating shall be determined using the weight anddimensions of a concrete-coated joint, by the following calculation:

Density in lb per cubic foot =

(Weight of joint, lb) - (L x Wp) x 1

L - 2h 0.00545Dc2 - Ap

where:

Wp = Nominal weight of corrosion protective-coated pipe, lb/ft (without

concrete coating)L = Length of joint, fth = Hold back length at each end of joint, ft

Dc = Average outside diameter of concrete-coated pipe, in.

Ap = Cross-section area of protective-coated pipe, ft2

The "as-applied" density shall be calculated immediately after weighing andmeasuring diameter for at least every fifth joint coated.

2.3 Weight of Concrete-Coated Pipe Joint

2.3.1 The calculated weight for the pipe joint, in pounds, shall be:

(Joint Weight)calc = (L x Wp) + [(L - 2h) x Wc]

where:

Wp, L, and h are as stated in Section 2.2.2, and Wc = concrete coating weight,

lb/ft.


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The total weight of any single pipe joint shall not vary from the total design jointweights by more than plus 7.5% and minus 5.0%.

The total weight of any 10 consecutive pipe joints shall not vary from the total ofdesign joint weights for those joints by more than plus 7.5% and minus 0.0%.

2.4 Concrete Coating for Mechanical Protection Only

2.4.1 Coating Control Data

The average outside diameter of each concrete-coated pipe joint shall bedetermined as described in Section 2.1 above. Weighing shall not be required.Calculations for "as-applied" density per Section 2.2 and joint weight tolerancesper Section 2.3 shall not be required.

2.4.2 Concrete Coating Thickness

Coating thickness shall not vary by more than minus 0 or plus 1/4 inch from thenominal thickness specified on the data sheet.

3.0 STANDARDS AND SPECIFICATIONS

Concrete weight-coating shall conform to the latest edition of the standards andspecifications listed in Appendix I.

4.0 MATERIALS

Materials shall be subject to Company approval. Sand and aggregate certificates

shall be available to Company. The grading and purity of sand and aggregateshall be checked at least once a week. Company reserves the right to reject anymaterial not deemed acceptable by virtue of either source or quality.

4.1 Cement

Cement shall be Portland cement conforming to ASTM C-150 Type II.

4.2 Sand

Sand shall be clean and graded. Clayey and schistose sands shall not beacceptable. Sand shall be free of injurious amounts of salt, alkali, deleterious

material or organic impurities. Suitability of the natural sand for use in concreteshall be determined in accordance with ASTM C-33.


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4.3 Aggregate

The aggregate shall be granite, iron ore, or any other aggregate approved byCompany. The aggregate shall be well graded from fine to coarse.

The aggregate shall be clean and free from salt, alkali, deleterious material ororganic impurities. It shall conform in all respects to ASTM C-33.

4.4 Water

Water shall be clean fresh water, free from oil, alkali, organic matter or otherdeleterious matter. Water shall not contain more than 250 ppm of chlorides.Source of water supply shall be identified, and an analysis of the water supplyshall be furnished when requested by Company.

4.5 Admixtures

Admixtures shall be limited by the requirements of ASTM C-494 and shall beadded only if approved by Company.

4.6 Reinforcement

4.6.1 Reinforcement shall be high quality 1 1/2 by 1 1/2 inch No. 17 American SteelWire Gage galvanized woven wire mesh, hexagon weave with reverse twist,conforming to ASTM A-390.

At the time concrete coating is applied, the wire fabric shall be free from rust,

scale dirt, oil or other coatings that may reduce the bond with the concrete.

4.6.2 Other reinforcement may be used if approved by Company in writing. Wire fabricshall conform to ASTM-185 with galvanizing per ASTM A-153.

4.7 Storage of Materials

All materials shall be stored and handled in accordance with the applicable ASTMSpecification and the ACI Manual of Concrete Practice.

5.0 PROPORTIONING AND MIXING OF CONCRETE

5.1 Proportioning

5.1.1 Contractor shall select the necessary proportioning of materials to produce therequired strength and density. The proportions of mix to be used shall besubmitted to Company for review. For concrete other than nominal 140 lb/ft3 density, Contractor shall determine the density of the proposed mix, and submittest method and test results to Company before start of coating.


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5.1.2 Concrete shall have minimum compressive strengths of 1000 psi at 24 hours,3000 psi at 7 days, and 4000 psi at 28 days.

5.1.3 Prior to commencement of production coating, Contractor shall have compressivestrength test specimens of the design mix prepared and tested in accordance with

ASTM Method C-39 or British Standards Institute Method BS 1881. Testspecimens shall be tested after a period of 24 hours and shall have a minimumcompressive strength of 1000 psi. If more than one design mix is to be usedbecause of the use of more than one source of any one material for the concrete,testing shall be done for all design mixes. Testing shall be by an independentagency approved by Company and test results shall be submitted to Company.No coating shall commence until Company has accepted all design mixes.

If the mix is changed for any reason after commencement of coating, the new mixshall be tested, and test results accepted by Company before the mix is used.

5.2 Batching and Mixing

5.2.1 Primary mixed concrete shall be placed within a time-temperature controlledperiod so that it will produce a homogenous cohesive grout.

The concrete materials shall be accurately proportioned and mixed in a machinethat will ensure a thorough intermingling of all materials in the concrete. Themetering and feed systems shall be initially calibrated by weight before the start ofthe concrete application. The amount of water and the method of its introductioninto the mix shall result in a mixture providing the physical properties stipulated inthis specification.

5.2.2 Should Contractor propose a method other than batching or using sacked andweighed materials, a description of such method, including the measures to betaken to assure a coating conforming to the specification, shall be presented toCompany for approval prior to beginning of coating.

5.2.3 For the impingement method of application, the use of reclaimed rebound materialshall be allowed if placed within 30 minutes. Both freshly mixed material andrebound material shall be placed so that there is no detrimental effect to the finalconcrete product.

5.2.4 Any mixed concrete which has not been placed within 30 minutes after the

introduction of the water into the mixture shall be unacceptable and shall bedisposed of by Contractor.


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5.3 Testing

5.3.1 Compressive Strength

Samples of the mixed concrete shall be taken to determine the compressivestrength of the concrete coating mix. Three samples shall be taken each morningand three samples each afternoon in accordance with ASTM Method C-31. Ofthe sets of three samples, one sample shall be tested after 24 hours, one after 7days, and one after 28 days. Testing shall be in accordance with ASTM MethodC-39 or British Standards BS 1881.

5.3.2 Density

Density shall be determined twice daily by weighing the samples for the 24-hourcompressive strength test before making the compressive strength test, and

calculating density based on the measured volume.

5.3.3 All testing shall be at Contractor's expense and as approved by Company. Testresults shall be submitted to Company daily.

6.0 EQUIPMENT AND APPLICATION

6.1 Equipment

Contractor shall provide suitable mechanical equipment in good operablecondition, necessary to apply a concrete coating to the corrosionprotective-coated pipe. Accessory equipment includes proper proportioning,

mixing, and handling equipment.

If required, Contractor shall demonstrate to Company by field test that hisapplication method, equipment and personnel will produce a concrete coatingconforming to this specification without damage to the underlying corrosionprotective coating. In the event of such damage, repairs shall be made to meetCompany requirements.

6.2 Any temporary protection for the corrosion protective coating shall be completelyremoved. Maximum bond must be achieved between the corrosion protectivecoating and the concrete coating.

6.3 Placement of Reinforcement

6.3.1 The reinforcement shall be spirally applied simultaneously with the concrete andshall have an overlap of not less than 3/4 inch.


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One wrap of reinforcing shall be used for concrete thickness up through 23/4 inches. An additional wrap of reinforcing shall be applied for concrete coatingthickness greater than 2 3/4 inches. The reinforcement shall be placed so as toprovide maximum reinforcing properties to the coating.

There shall be a minimum clearance of 1/2 inch between the protective-coatedpipe and the reinforcement, and a minimum cover of concrete of 1/4 inch over thereinforcement. The reinforcement shall not protrude at the concrete coatingholdback.

6.3.2 If cathodic protection anodes are to be installed, Contractor shall provide 2 inchminimum and 3 inch maximum clearance between anode and the reinforcement.Reinforcement may be applied over bonding cable where the concrete coatingcovers the cable.

6.4 Appl ication by the Impingement Method

Concrete shall be applied to the rotating pipe by the high velocity impact methodso as to form a continuous coating. The surface shall be trimmed to give auniform thickness of concrete coating concentric with the pipe.

6.5 Application by the Compression Coat Method

Concrete mix shall be extruded onto the rotating pipe, with the requiredreinforcement fabric, and shall be simultaneously covered with a plastic sheetouter wrap under suitable tension to give a smooth surface, with a uniformthickness concentric with the pipe.

6.6 Holdback and Cleanup

Concrete coating shall terminate to provide the holdback distance from the end ofthe pipe as specified on the data sheet, or 3 inches short of the end of thepreviously applied corrosion protective coating, whichever provides the greaterholdback. Coating edge shall be perpendicular to the axis of the pipe and thesteel reinforcement wire shall not protrude through the concrete coating edge.Pipe ends shall be cleaned and examined immediately after removal from thecoating station to ensure the proper holdback distance and to remove anyconcrete from the holdback area and the inside of the pipe. Where needed tokeep concrete out of the pipe, pipe ends shall be capped prior to concrete

application.


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6.7 Temperature

Concrete shall not be applied to the pipe when the ambient temperature is lessthan 40°F unless Contractor has made provisions acceptable to Company toproperly protect the newly applied concrete.

7.0 CURING

7.1 The concrete coating shall be cured for a minimum of 4 days at temperatures ofnot less than 40°F. During curing, the concrete coated pipe shall be placed onsand ridge windrows and shall not be stacked. Sand windrows shall be placed insufficient number and position to eliminate detrimental deflection in the pipe. Theconcrete shall not be allowed to dehydrate. The pipe shall not be transporteduntil after the minimum 4 days of curing except for the initial transfer of pipe fromthe coating machine to the curing area.

7.2 Curing for Impingement Method

7.2.1 Water curing, if used, shall commence as soon as possible but no later than2 hours after coating. Water spray shall keep the coating continuously moist forno less than 4 days providing temperatures are above 50°F, or no less than7 days if temperatures are below 50°F.

7.2.2 Membrane curing, if used, shall be with a liquid membrane-forming compoundconforming to ASTM C-309. It shall be applied by mechanical equipment to thecoated surface in sufficient quantity to provide complete coverage in accordancewith manufacturer's recommendations. The application of curing compound shall

take place immediately after concrete coating is completed and shall be precededby a fine water spray.

7.2.3 Other curing procedures shall be subject to Company approval.

7.3 Curing for Compression Coat Method

The plastic sheet outer wrap must be kept in place a minimum of 7 days, andpreferably longer.

8.0 PERMISSIBLE REPAIRS TO CONCRETE COATING

Concrete coating with defects or damage or which does not conform otherwise tothis specification shall be promptly repaired to the satisfaction of Company.

8.1 Repairs to defective or damaged concrete coating shall be as follows:


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An area of defect or damage of 1 ft2 or less in any 5-foot run of pipe, for which thedepth is 25 percent or less of the total thickness of the coating, may be acceptedwithout repair, provided the remaining concrete is sound and the reinforcement isnot exposed.

Defective or damaged areas exceeding 1 ft2 or 25 percent deep shall be repairedby removing the concrete to sound coating material and to expose reinforcement. Any damaged reinforcement shall be replaced. The edges of the removed areashall be undercut to provide a key lock for the repair material. Undercut for keylock is not required if original reinforcing mesh remains intact and is exposed or ifreplacement reinforcing can be securely attached.

A stiff mixture of grout or concrete shall be troweled into and through thereinforcement, and built up until the surface is even and smooth with the originalcoating around the repair. The coating resulting from the repair shall be equal in

strength to the coating originally applied.

The repaired joint shall be carefully laid in a safe position and moist cured or liquidmembrane cured for a minimum of 4 days before further handling.

8.2 Cracks

Hairline cracks less than 1/16 inch in width need not be repaired.

Circumferential cracks exceeding 1/16 inch in width at the surface and extendingmore than 180 degrees shall be repaired.

Longitudinal cracks exceeding 1/16 inch in width at the surface and in excess of12 inches in length shall be repaired.

Crack repairs shall be made by widening the crack to 1 inch for the necessarydepth and length and packing the prepared crack with the repair material specifiedabove until level with the existing coating. Pipe joints with repaired cracks shallremain undisturbed for a minimum of 36 hours.

9.0 CAUSES FOR REJECTION

Causes for rejection of the concrete coating shall include but not be limited to thefollowing:

• Concrete compressive strength less than the specified value.• Failure to initiate and maintain the concrete control data and testing

procedures.• Density of concrete coating does not meet the tolerance specified on the

data sheet.• Weight of a concrete-coated pipe joint, or total of 10 consecutive joints, is

not within the tolerances specified on the data sheet.


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• Coating in which the reinforcement is improperly placed.• Coating application on a joint interrupted for more than 30 minutes.• Coating that is defective or damaged to such an extent that Company

considers satisfactory repair is impossible.• Concrete coating does not fully adhere to the corrosion protective coating.• Any failure of the materials employed to conform to the specifications.• Any defective condition of equipment, materials or workmanship which in

the judgment of Company would render the coated pipe unsuitable for theconditions and purposes stipulated in this specification.

10.0 CARE, HANDLING, AND STORAGE OF PIPE

a. Reasonable care shall be exercised while handling pipe to preventdamage to coating, pipe, beveled ends, etc. Padded forks, canvasslings/belts, and/or relatively soft plastic or rubber-lined hook ends, etc.,

shall be used.

b. Pipe and protective coating damaged while in the possession of Contrac-tor shall be repaired to Company's satisfaction at Contractor's expense.

Any pipe which cannot be repaired shall be scrapped.

c. Contractor shall inspect the corrosion protective coating on inspectionracks prior to concrete coating, using a holiday detector approved byCompany. The holiday detector voltage shall be appropriate for theprotective coating, but no higher than 80% of the voltage used at the plantwhere the protective coating was applied. If pipe was wrapped with kraftpaper or similar wrapping, the paper shall be completely removed before

inspection and concrete coating.

Contractor shall repair all defects in protective coating using a methodapproved by the Company.

d. Protective-coated pipe shall be racked in rows and tiers in a manner thatwill prevent damage to pipe and protective coating.

e. Concrete-coated pipe shall be handled and stored by Contractor so as tominimize cracking or other injury to the concrete.

f. Concrete-coated pipe joints needing cleaning or repairs shall not be stock

piled until such time as cleaning and repairs have been completed.

g. The loading of pipe shall be approved by Company. Pipe lots of eachcoating thickness and weight shall remain segregated and shall beshipped separately.


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7. Weight of pipe after weight coating

8. Percent deviation in weight from calculated weight, plus or (minus)

9. Measured average outside diameter of concrete-coated pipe

10. Average weight-coating thickness

11. Number and nature of concrete coating defects/repairs

12. Date and time of shipment

13. Coating and/or pipe defects at shipment


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APPENDIX I

STANDARDS AND CODES

1. INDUSTRY STANDARDS

American Concrete Inst itute

Manual of Concrete Practice

American Society for Testing and Materials (ASTM)

A-153 Standard Specification for Zinc Coating (Hot-dip) on Iron and SteelHardware

A-185 Standard Specification for Welded Steel Wire Fabric for ConcreteReinforcement

A-390 Specification for Zinc-coated (Galvanized) Steel Poultry Netting(Hexagonal and Straight Line) and Woven Steel Poultry Fencing

C-31 Standard Method of Making and Curing Concrete Test Specimens inthe Field

C-33 Standard Specification for Concrete Aggregates

C-39 Standard Method of Test for Compressive Strength of CylindricalConcrete Specimens

C-150 Standard Specification for Portland Cement

C-309 Standard Specification for Liquid Membrane-Forming Compoundsfor Curing Concrete

C-494 Standard Specification for Chemical Admixtures for Concrete

British Standards Institute

BS 1881 Methods of Testing Concrete (British Standards Institute)


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20-05 - Concrete Coating of Line Pipe