CW9 PART2

CW9: PART 2

TECHNICAL SPECIFICATION FOR

CONCRETE COATING OF PIPESPART 2- SECURITY COATINGS

APRIL 1993

J016 ( Rev 08/98 )

.

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CONTENTS

Page

FOREWORD iii

BRIEF HISTORY iv

1. SCOPE 1

2. REFERENCES 1

3. DEFINITIONS 1

4. MATERIALS 1

4.1 Concrete coating 1

4.2 Reinforcement 2

4.3 Curing membrane 2

5. ANTI-CORROSION COATINGS 2

5.1 General 2

5.2 Painted pipework 2

5.3 Bare pipework 2

5.4 Existing anti-corrosion coatings 2

6. DESIGN REQUIREMENTS OF THE CONCRETE COATING 3

6.1 Reinforcement 3

6.2 Concrete mix 3

7. SITE SAFETY 4

8. COATING PROCEDURE AND OPERATOR PROOF TESTS 4

9. CONCRETE COATING EQUIPMENT 5

10. PREPARATION FOR CONCRETE COATING 5

10.1 Anti-corrosion coating 5

10.2 Control of concrete coating thickness 5

10.3 Placing of concrete mix 5

11. APPLICATION PROCEDURE 5

12. CONTROL OF REBOUND MATERIAL 6

13. CURING OF CONCRETE COATING 6

14. INSPECTION AND TESTING 7

14.1 General 7

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Page

14.2 Anti-corrosion coating 7

14.3 Concrete coating 7

14.4 Causes for rejection 9

15. VARIANTS 9

APPENDICES

A LIST OF REFERENCES 11

B CONCRETE COATING EQUIPMENT 13

C REPAIR REQUIREMENTS AND DEFECT LIMITS FOR CONCRETE COATINGS 15

D TESTS FOR POLYPROPYLENE FIBRE CONTENT IN CEMENT MIX 17

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FOREWORD

This specification has been adopted by Transco and is an editorial revision of the former British Gas TransCospecification GBE/CW9: Part 2. It reflects the identity and organizational structure of Transco - a part of BGplc.

This Transco specification has been approved for use throughout Transco.

Comments and queries regarding the technical content of this Transco specification should be directed to:

Lead EngineerTranscoNorgas HousePO Box 1GBKillingworthNewcastle upon TyneNE99 1GB

Further copies of this Transco specification can be obtained from Dataform Print Management using the printrequisition form G004 quoting the Form Number of this Transco engineering document (not the designation)and your cost code.

Transco engineering documents are revised, when necessary, by the issue of new editions. Users shouldensure that they are in possession of the latest edition by referring to the Transco Register of EngineeringDocuments available on the Transco Information Library.

Compliance with this engineering document does not confer immunity from prosecution for breach of statutoryor other legal obligations.

Contractors and other users external to Transco should direct their requests for further copies of Transcoengineering documents to the department or group responsible for the initial issue of their contractdocumentation.

DISCLAIMER

This engineering document is provided for use by Transco and such of its contractors as are obliged by the termsof their contracts to comply with this engineering document. Where this engineering document is used by anyother party, it is the responsibility of that party to ensure that the engineering document is correctly applied.

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BRIEF HISTORY

First published as BGC/PS/CW9: Part 2Amended issue published as GBE/CW9: Part 2

March 1984April 1993

© BG plc 1993

This Transco specification is copyright and must not be reproduced in whole or in part by any means withoutthe approval in writing of BG plc.

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TECHNICAL SPECIFICATION FOR

CONCRETE COATING OF PIPESPART 2- SECURITY COATINGS

1. SCOPEThis Part 2 of Transco Technical Specification* CW9 deals with the quality of materials, mix and finishedprofile for concrete security coatings applied by pneumatic means to steel pipework. The main function ofsuch concrete coatings is to protect the pipeline from impact or shock damage from external sources.

* Hereinafter referred to as 'this specification'

2. REFERENCESThis specification makes reference to the documents listed in Appendix A. Unless specified otherwise thelatest editions of the documents, including all addenda and revisions, shall apply.

3. DEFINITIONSFor the purposes of this specification the following definitions shall apply:

Transco: Transco - a part of BG plc.

Contractor: the person, firm or company with whom Transco enters into a contract to which thisspecification applies, including the Contractor's personal representatives, successors and permitted assigns.

Engineer: the Engineer appointed from time to time by Transco and notified in writing to the Contractor toact as Engineer for the purposes of the Contract.

4. MATERIALS

4.1 Concrete coating

4.1.1 GeneralAll concrete coating shall comply with BS 8110 unless superseded by this specification.

4.1.2 CementPortland cement used in the preparation of the concrete shall conform to BS 12 and BS 1370.

Sulphate-resisting cement shall conform to BS 4027.

4.1.3 AggregateIn general, aggregates used shall comply with BS 882.

The aggregate shall be washed and from a natural source. Tests on aggregate shall be in accordance withBS 812.

4.1.4 SandAll sand used shall comply with BS 882.

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4.1.5 WaterAll water used in the preparation of concrete shall be potable (see 14.3.2). Water from the intended source ofsupply shall initially be tested for purity in accordance with BS 3148. Water from any other source shall notbe used without a test for purity.

4.2 Reinforcement

4.2.1 Polypropylene filamentsThe reinforcing filaments to be used shall meet the following requirements:

a) mechanically fibrilated from 12 000 denier polypropylene;

b) breaking load of individual strands not less than 57 kg;

c) density not less than 0.92 g/cm 3 .

4.2.2 SteelThe reinforcement shall consist of 50 mm x 50 mm mesh formed from 2.5 mm diameter high tensile steel wireand shall comply with BS 4483 and be galvanized in accordance with the minimum requirement of BS 729.

4.2.3 Reinforcement spacersReinforcement spacers shall be non-metallic, non-hygroscopic, electrically insulating and have sufficient basearea to prevent damage to or penetration of the anti-corrosion coating.

4.3 Curing membraneThe curing membrane shall conform to either of the following:

a) Polyethylene wrap: thickness of material not less than 500 gauge and overlaps not less than50 mm.

b) Spray coating: this shall be applied in accordance with the manufacturer's instructions.

5. ANTI-CORROSION COATINGS

5.1 GeneralConcrete security coatings may be applied over the protective coatings used on Transco pipelines but shall notbe applied directly over painted or bare pipework.

5.2 Painted pipeworkPainted pipework shall be wrapped with a cold applied self adhesive tape, in accordance with the relevantsupplement to CW5, before the application of a concrete security coating.

5.3 Bare pipeworkBare pipework shall be wrapped with a cold applied laminate tape, in accordance with the relevantsupplement to CW5, before the application of a concrete security coating.

5.4 Existing anti-corrosion coatingsConcrete security coatings may be applied over:

a) Cold applied laminate tapes when applied in accordance with CW5 and the relevantsupplements to CW5.

b) Fusion bonded powder or multi-component liquids when applied in accordance with therelevant part of CW6.

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c) Brush/spray applied coating or compound when applied in accordance with CW5 and therelevant supplement to CW5.

In all cases of applying concrete coating over an existing anti-corrosion coating, care shall be taken to ensurethat the anti-corrosion coating is satisfactorily bonded. Any disbonded or damaged anti-corrosion coatingshall be removed and repaired in accordance with the relevant Transco specification.

6. DESIGN REQUIREMENTS OF THE CONCRETE COATING

6.1 Reinforcement

6.1.1 SteelReinforcement shall be to a design specified by Transco.

Reinforcement shall be formed and placed in accordance with BS 8110 and with this specification, whereapplicable. The reinforcement shall at all times be adequately supported and secured to prevent contact withthe pipework and at the correct location by the use of spacers.

Reinforcement shall be electrically isolated from the pipe.

The cut ends of reinforcement shall not penetrate or damage the pipework anti-corrosion coating or contact thesurface of the steel pipework.

Overlaps shall be not less than 50 mm and shall be securely fixed together using malleable mild steel tyingwire or purpose-made clips.

For concrete coating thicknesses equal to or less than 50 mm, one layer of reinforcement shall be applied andshall be positioned as near to the centre of the thickness of the final coating as practicable.

For concrete coating thicknesses greater than 50 mm, two layers of galvanized reinforcement mesh shall beapplied. The inner wrap shall be positioned 15 mm to 20 mm from the surface of the pipework and the outerwrap shall have 15 mm to 20 mm cover of concrete coating. The two wraps shall be positioned with thenecessary size of spacer standing independently off the pipework surface prior to the application of theconcrete.

6.1.2 PolypropylenePolypropylene fibre shall be used in the proportion of 0.2% by weight of the dry mix.

The correct proportions of chopped polypropylene fibre shall be dispensed into and uniformly distributedwithin the mix using specialized equipment.

6.2 Concrete mix

6.2.1 GeneralTransco shall specify the limiting parameters, i.e. density, strength and water to cement ratio.

The Contractor shall design a mix using appropriate materials as specified in clause 4 in order to obtain therequired densities and strengths.

Full details of the following shall be made available to Transco:

a) The properties and densities of the respective dry aggregates.

b) The weight and properties of the polypropylene.

c) The cement weight per cubic metre of concrete.

d) The volume of water per cubic metre of concrete.

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e) The density of the proposed mix.

The proposed composition shall meet the minimum mechanical strengths specified in 6.2.2 and shall ensureeasy and satisfactory application of the concrete coating. The strength of the concrete mix shall bedemonstrated, prior to production commencing, by tests on cubes from trial batches prepared and tested inaccordance with BS 1881: Parts 108 and 116 respectively.

All concrete work shall be in accordance with BS 8110, except where superseded by this specification.

6.2.2 Compressive strength of concreteThe concrete coating shall be tested to BS 1881: Parts 116 and 120 and have a compression strength of notless than:

a) 40 N/mm 2 after seven days;

b) 60 N/mm 2 after 28 days.

Tests shall be carried out in accordance with 14.3.5.

6.2.3 Concrete mix proof testThe strength of the concrete mix shall be demonstrated, prior to production commencing, by tests on cubesand cores from trial batches prepared by spraying on to test panels and tested in accordance withBS 1881: Parts 116 and 120 respectively.

Before and after compressive testing of cores, they shall visually be checked for uniform dispersion ofpolypropylene fibres.

6.2.4 Concrete thicknessThe thickness of the concrete coating shall be specified by Transco in the contractual drawings or documents.

In all cases the tolerance on the coating thickness shall be +5%, -0%.

7. SITE SAFETYThe Contractor shall ensure that all his personnel work strictly in accordance with current safety legislation.

Work, including holiday detection which is to take place on an operational site, shall be subject to a 'Permit toWork', issued by the Engineer responsible for the site. This will stipulate the plant or equipment which may beused in a specified area and the precautions which must be taken to protect plant, equipment and personnel.

8. COATING PROCEDURE AND OPERATOR PROOF TESTSBefore the commencement of any work, the Contractor shall demonstrate his ability to comply with therequirements of this specification by applying a coating to test pipework.

The test shall be carried out by the operatives who will be carrying out the work, so that their ability andexperience in applying concrete coating can be assessed.

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9. CONCRETE COATING EQUIPMENTThe concrete coating equipment is required to be of a special impingement type to ensure that the specifiedmix is applied in accordance with the requirements of this specification.

The type of equipment and method of application are broadly outlined in Appendix B.

10. PREPARATION FOR CONCRETE COATING

10.1 Anti-corrosion coatingHoliday detection shall be carried out in accordance with the relevant coating specification on clean dry anti-corrosion coated pipework immediately prior to the positioning of reinforcement. Detected holidays shall berepaired and retested. The anti-corrosion coating shall not be damaged as a result of a concrete coatingactivity. No area of the pipework shall have a coating thickness less than 625 µ m or greater than 750 µ m.

10.2 Control of concrete coating thickness10.2.1 The required thickness of concrete coating shall be achieved by the use of taut and true-to-linepiano wires spaced around the circumference such that the distance between any two wires is not greater than225 mm for pipes equal to or greater than 450 mm diameter. On pipes of lesser diameter, the wires shall bespaced at distances not greater than 150 mm. At no position are the piano wires to span greater than 5 mwithout being supported securely by collars or other means. Guide wires and their supports shall be removedafter the applied coating has been inspected and found to be satisfactory.

Uncoated areas arising from the removal of supports shall be made good with the same mix of coating asoriginally applied. Where guide wires cannot be used, the Contractor may propose an alternative method ofachieving and maintaining the required thickness as a variant to be considered by Transco.

10.2.2 Surfaces which are not to receive applied concrete shall be masked with 500 gauge polyethylenesheeting and adequately taped to avoid all contamination. Particular attention shall be paid to all electricalequipment and other services.

Vulnerable and delicate equipment shall be physically protected to avoid damage.

10.2.3 Where a run of applied concrete abuts an adjacent surface, due allowance shall be made forexpansion by the use of expansion joint material suitable for use on flat or curved surfaces as appropriate.This expansion joint material shall be securely fixed prior to work commencing.

10.3 Placing of concrete mixConcrete shall not be applied to a pipe or component if any required hydrostatic pressure testing of the pipe orcomponent has not been completed.

The concrete coating applied by a contractor shall be placed by a special purpose pneumatic technique. Othermethods may be proposed as a variant for consideration by Transco and subject to a demonstration that therequirements of this specification are satisfied.

11. APPLICATION PROCEDUREEach layer of pneumatically applied concrete shall be built up by making several passes of the nozzle over theworking area. The mix shall emerge from the nozzle in a steady uninterrupted flow. Should the flow becomeintermittent for any cause, the nozzle operator shall direct the flow of material away from the work area untilit again becomes constant. Particular care shall be taken to comply with clause 12.

Where more than one layer is to be applied, the first layer shall be allowed to take its initial set withoutconflicting with the requirements of clause 13.

If for any reason coating work ceases for longer than 30 min, the conditions of clause 13 shall apply.

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If coating is halted for longer than 24 h, all laitence, loose materials and rebound shall first be removed byblast cleaning and the surface cleaned with a water spray before coating operations are resumed.

Care should be taken, when applying the concrete, to ensure that a truly homogenous mix and the specifiedthickness are achieved. Particular care will be required to meet the specified thickness when the concretecoating is being applied to bends and irregular pipework, e.g. reducers.

The ends of the concrete shall be chamfered smoothly at an angle of approximately 65 ± 15 0 to the pipeworksurface.

The concrete shall be placed upon the pipework within 30 min of the water being added to the mix.Concreting shall not take place if the following conditions prevail:

a) the temperature of the pipework, anti-corrosion coating, reinforcement or concrete mix isoutside the range 3 0 C to 30 0 C ;

b) air temperature is outside the range -3 0 C to 30 0 C ;

c) adverse weather conditions which (unless the work face is suitably shielded) would prevent thefinal coating from meeting the requirements of this specification.

Should it become necessary to suspend work and form a day joint, the edge of the material shall be run out.When application is resumed, the new joint shall overlap the existing material to form a scarf joint.

12. CONTROL OF REBOUND MATERIALRebound material shall not be worked back into the construction by the nozzle operator. Rebound materialwhich has been removed shall not be included in later batches. Any build up of excess material shall beremoved and treated as rebound material.

Cleanliness is essential and no escape beyond the working area of rebound spray or particles of materialsfrom the workings shall be permitted. All rebound must be completely contained within the working area andremoved by skip, chute or similar method to a tip to be provided by the Contractor. The rebound shall notcause any contamination of adjacent structures or equipment.

The basic screening necessary to avoid contamination from the application process and the means of disposalof the rebound material from the working areas shall be provided by the Contractor.

The Contractor shall ensure that the build-up of rebound as waste material on any boarded areas of scaffold isnot greater than 40 mm in depth on any boards or tubes and that all rebound material is removed from theworking areas and the site.

Similarly, all materials employed at the mixer shall be completely contained within the working area of themixer and later removed without any contamination of adjacent works.

The delivery equipment including hoses, connections and valves shall at all times be maintained in first classcondition to ensure that there is no leakage whatsoever from the plant.

13. CURING OF CONCRETE COATING13.1 The Contractor shall demonstrate the efficiency of the method of curing, particularly under adverseclimatic conditions.

13.2 The curing process shall ensure that no moisture loss occurs for a period of seven days afterapplication. If a plastics membrane is wrapped around the concrete coating as part of the curing process, thismembrane shall be removed on completion of curing.

13.3 Precautions shall also be taken to protect the coating against sudden temperature changes.

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13.4 Checks shall be made to ensure that the first seven days of curing takes place in an air temperaturerange of 3 0 C to 35 0 C . After seven days of curing, the lower air temperature limit may be reduced to -3 0 C .Should the temperature fall below -3 0 C during the period seven days to 28 days, non-destructive strengthchecks using a Schmidt hammer shall be carried out to ensure compliance with 6.2.3.

13.5 Concrete coated pipework shall be left undisturbed until the concrete has achieved its 28 daysstrength.

14. INSPECTION AND TESTING

14.1 GeneralInspection and testing to be implemented by the Contractor shall be as specified in 14.2,14.3 and 14.4.

Records of all tests shall be maintained.

14.2 Anti-corrosion coatingHoliday detection and repair of faulty zones shall be carried out immediately prior to reinforcement cagesbeing fitted and only when the area is certified 'gas free'. The test voltage shall be in accordance with therelevant coating specification.

14.3 Concrete coating

14.3.1 CementThe cement being used shall be checked for satisfactory condition and method of storage. Cement that hasdeteriorated shall not be used. Relevant test certificates shall be retained by the Contractor and madeavailable for inspection by Transco.

14.3.2 Aggregate, sand and waterThe grading and purity of sand and aggregate shall be checked twice weekly in accordance with BS 882, andthe purity of the water used shall be checked in accordance with BS 3148. Test certificates for aggregate shallbe retained by the Contractor and be available for inspection by Transco.

The sand and aggregate shall be stored on rolled hard core or other paved areas.

14.3.3 Reinforcement

14.3.3.1 Steel meshThe steel reinforcement mesh shall be stored under cover and kept dry. Relevant test certificates shall beretained by the Contractor and made available to Transco on request.

The mesh shall be formed and placed as specified in 6.1.1 and checks made and recorded.

14.3.3.2 Polypropylene fibreThe polypropylene fibre shall be stored under cover and kept dry. Relevant test certificates shall be retainedby the Contractor and made available for inspection by Transco on request.

14.3.3.3 Electrical isolation testsElectrical isolation tests shall be undertaken to cover the requirements of 6.1.1.

A simple continuity tester shall be used, comprising a 6 V or 12 V battery in series with a compatibly ratedbulb. The condition of the battery shall be such that the bulb shall normally emit white light, but whenconnected between the pipework and the mesh reinforcement shall show no visible sign of current flow.

Access to the reinforcement mesh shall be obtained by removing concrete locally. Renovation shall be carriedout in accordance with Appendix C.

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14.3.4 Proportions of concrete constituentsThe Contractor shall demonstrate that the concrete batching and mixing arrangements produce a consistentlyhigh quality of concrete.

The mixing proportions shall be checked at least once per day to ensure that they are within the tolerancesallowed.

The weight of the mix shall be controlled for each operation. The accuracy of measurement shall be checkedat least once per day.

14.3.5 Strength and density of concreteInspection and testing during coating operations shall be carried out to demonstrate the strength and density ofthe concrete as follows:

a) Compressive strength and density tests shall be carried out on test cubes (minimum side of100 mm) prepared from samples taken from mixes throughout the day's production.

b) Two sets of three cubes shall be taken twice a day for each application machine.

c) Along with preparation of cubes, the Contractor shall apply concrete on to panels by the samemethod as the application to the pipework. The concrete shall be the same thickness as thepipework coating.

d) Testing of cubes shall be carried out seven days and 28 days after casting.

e) If low values are obtained from test cubes, cores shall be taken from the coated panelsassociated with such cubes. Three core samples shall be taken in accordance with BS 8110.Any remedial action shall be the full responsibility of the Contractor.

f) Cubes and cores shall be tested for strength and density in accordance with BS 1881: Parts116 and 120 respectively.

g) If any repairs are necessary, the previous procedures may be applied. Repairs shall meet therequirements of Appendix C.

14.3.6 Polypropylene fibres14.3.6.1 The polypropylene fibre content shall be tested in accordance with one of the methods inAppendix D.

14.3.6.2 The dispersion of polypropylene fibres shall be visually checked for uniformity in a fractured testspecimen (see 6.2.3).

14.3.7 Concrete coating profile and thicknessConcrete coating shall be applied uniformly over the pipework. The thickness of coating on all surfaces shallbe checked. A total of at least 10 check points at four different radial positions along the length of thepipework shall be selected. The chamfered ends of the concrete coating shall be checked for the correct angleand reinforcement ends shall terminate within 40 mm to 60 mm of the chamfered face.

14.3.8 Defects in concrete coating during applicationEach length of concrete coated pipework shall be visually checked immediately after the coating operation.The degree of damage accepted for repair is specified in clause C.2. The repair procedure is specified inclause C.1.

14.3.9 CuringCuring shall be in accordance with the conditions specified in clause 13. Air temperatures, humidity andgeneral weather conditions shall be recorded and made available for inspection by Transco. Additional checksshall be carried out after seven days for other defects in the concrete coating.

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14.3.10 Defects in cured concrete coatingAll pipework shall be examined for defects. Voids and bad compaction areas shall be detected by ringing*.Excessive spalling, voids and cracking shall be cause for rejection. Specific limits and repair procedure arespecified in Appendix C.

* Ringing shall be carried out by using a 1 kg hammer with a minimum striking face of 2000 mm2

14.4 Causes for rejectionCauses for rejection shall include, but not be limited to, the following:

a) Incorrect placement of the reinforcing steel (see 6.1.1 and 10.1).

b) Unacceptable dispersion and density of the polypropylene fibres in the concrete (see 6.1.2 and6.2.3).

c) Inadequate strength of concrete mix (see 6.2.2).

d) Unacceptable thickness measurements of the applied concrete (see 6.2.4 and 10.2).

e) Damage to the anti-corrosion coating or unsatisfactory repair of such damage (see 14.2).

f) Damage to concrete coating (see 14.3.8).

g) Excessive spalling, voids or cracking (see 14.3.10).

h) Electrical isolation failing to meet the specified requirements (see 14.3.3.3).

15. VARIANTSA contractor shall only propose variants to this specification where the text indicates that variants would beconsidered by Transco.

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APPENDIX A

LIST OF REFERENCESThis specification makes reference to the documents listed below (see clause 2).

British Standards

BS 12 - Specification for Portland cement

BS 729 - Specification for hot dip galvanized coatings on iron and steel articles

BS 812 - Testing aggregates

BS 882 - Specification for aggregates from natural sources for concrete

BS 1370 - Specification for low heat Portland cement

BS 1881 - Testing concrete:Part 108 - Method for making test cubes from fresh concretePart 116 - Method for determination of compressive strength ofconcrete cubesPart 120 - Method for determination of the compressive strength ofconcrete cores

BS 3148 - Methods of tests for water for making concrete (including notes on thesuitability of the water)

BS 4027 - Specification for sulphate-resisting Portland cement

BS 4483 - Specification for steel fabric for the reinforcement of concrete

BS 8110 - Structural use of concrete

Transco specifications

CW5 - Code of practice for the selection and application of field appliedexternal pipework coatings (other than resin coatings).

Supplement toCW5 - Application instructions for field applied external pipework coatings

CW6 - Technical specification for external protection of steel pipe and fittingsusing resin powder and associated coating systems:Part 2 - Factory applied coatings.

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APPENDIX B

CONCRETE COATING EQUIPMENT

B.1 BATCHING AND MIXING EQUIPMENTB.1.1 The correct proportions of sand and cement shall be established by weigh batching. The weighingequipment shall be suitably accurate for the process requirements and any equipment which is not satisfactoryshall be removed from site and replaced. Periodic testing of this weighing equipment shall be carried out atintervals during any contract to provide proof of its accuracy. Alternatively, cement may be batched by bag,and aggregate may be batched volumetrically, if periodic checks are made to ensure that the proportions aremaintained within the required tolerances.

B.1.2 The moisture content of the sand shall be such that the sand cement mixture will flow at a uniformrate (without slags) through the material hose. The optimum moisture content will depend upon the deliveryequipment being used, but it shall be within the range of 3% to 6%. The sand shall be dampened or dried asrequired to bring the moisture to a satisfactory level. Fluctuations in moisture content shall be minimized.

B.1.3 The mixing equipment shall be capable of thoroughly mixing the sand and cement so that the sandparticles are thoroughly coated and capable of producing the mix in sufficient quantity to maintain continuityof placing. The Contractor shall show that the mixing plant he proposes to use is capable of meeting theserequirements.

B.1.4 The mixer shall be self cleaning and capable of discharging all mixed material without any carry-over from one batch to the next. It shall be inspected and thoroughly cleaned at least once a day.

B.2 DELIVERY EQUIPMENTB.2.1 The delivery equipment shall be of the pneumatic feed type and shall be of a design and size whichhave given proven results. The equipment shall be capable of discharging the sand cement mixture into thehose under close control and it shall be capable of delivering a continuous smooth stream of uniformly mixedmaterial at the proper velocity from the discharge nozzle at all heights of the work.

B.2.2 The discharge nozzle shall be equipped with a manually operated water injection system (waterring) for directing an even distribution of water to the sand cement mixture. The water valve shall be capableof ready adjustment to vary the quantity of water and shall be convenient for the nozzle man.

B.2.3 The nozzle shall be capable of delivering a conical discharge stream of uniform appearancethroughout. Distortion of this stream or any non-uniform appearance shall be remedied by examination of thenozzle, and any malfunction rectified by replacement of defective parts before further work is carried out.

B.2.4 The delivery equipment shall be thoroughly cleaned out at least at the end of each shift. Equipmentparts, especially the nozzle liner and water ring, shall be regularly inspected and replaced as required.

B.3 AIR SUPPLYB.3.1 The Contractor shall ensure that the air compressor he intends to employ is of sufficient capacity tomaintain continuity of placing. The compressor shall maintain a supply of clean dry air adequate to maintainsufficient nozzle velocity for all parts of the work while simultaneously operating a blow pipe for clearingaway rebound. The compressor capacities given in Table B.1 are recommended but the Contractor shall befully responsible for proving the adequacy of his equipment.

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TABLE B.1 - Compressor capacities

B.3.2 The operating air pressure is the pressure driving the material from the delivery equipment into thehose and shall be measured by a gauge near the material outlet of the delivery equipment. The air pressureshall be uniformly steady and non-pulsating under operating conditions. The gauge shall cover the range ofpressures produced and shall be graduated in intervals not greater than 0.35 bar.

B.3.3 The information given in Table B.1 is based on a hose length of 46 m with the nozzle not greaterthan 8 m above the delivery equipment. Operating pressures should be increased by about 0.35 bar for each8 m the nozzle is raised above the delivery equipment.

B.3.4 The water pressure at the discharge nozzle shall be sufficiently greater than the operating airpressure to ensure that the water is intimately mixed with the other materials, forming a homogeneous mix.The water pressure shall be independent of mains water pressure, uniformly steady and non-pulsating underoperating conditions. Water storage tanks may be used provided adequate supplies for continuity of the workcan be achieved.

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APPENDIX C

REPAIR REQUIREMENTS AND DEFECT LIMITS FOR CONCRETE COATINGS

C.1 REPAIR REQUIREMENTSC.1.1 Concrete used for repairs shall contain the same proportions of constituents as the original coating,but a slight increase in water content will be permitted for hand repairs only. Alternative repair materials maybe proposed as a variant for consideration by Transco.

C.1.2 Prior to application, the defective areas shall be thoroughly cleaned of loose material and be cutaway to ensure a 25 mm minimum thickness of repair, at any point.

C.1.3 The concrete surfaces to receive the repair material shall be well soaked with water complying with 4.1.5.

C.1.4 All repairs shall be carried out within seven days of the application of the concrete coating.

C.1.5 All repairs shall be cured in accordance with clause 13 and must meet the full requirements of thisspecification.

C.1.6 Damage to the reinforcement, anti-corrosion coating or the pipework during repairs shall result inrejection of the security coating.

C.2 DEFECT LIMITS

C.2.1 SpallingAreas where the uncured concrete coating has not adhered or has been damaged during handling shall berepaired subject to the following conditions:

a) The area of repair(s) in any 3 m length is not greater than 5% of the concrete surface area ofthat 3 m length.

b) Total area of repairs is not greater than 2.5% of the total concrete surface area of the coatedpipework.

C.2.2 VoidsWhere voids are detected in the concrete coating and do not exceed the following tolerances, they shall bebroken out and repaired so that:

a) The total area of a void or voids in any 3 m length is not greater than 2.5% of the concretesurface area of that 3 m length, and

b) the total area of all voids in any concrete coated pipework is not greater than 0.5% of the totalconcrete surface area of the coated pipework.

C.2.3 CrackingC.2.3.1 Hairline cracks equal to or less than 1 mm width, indications of normal shrinkage, will be allowedprovided the frequency of cracks is not greater than one crack for each 250 mm length of concrete coating.

C.2.3.2 Cracks with widths greater than 1 mm but not greater than 3 mm width are tolerable provided thereis no association with any other form of defect, only one crack occurs in any 3 m length and such cracks arenot less than 2 m from one another.

CW9: PART 2

- 16 - J016 ( Rev 08/98 )

C.2.3.3 Where a crack having a width of between 3 mm and 9 mm is detected in a length of concretecoating, it may be considered for repair provided that no other crack of any size occurs within the same 10 mlength of concrete coating.

The crack shall be cut out and enlarged to a width of not less than 15 mm and to a depth of not greater than25 mm. It may then be repaired provided that the following conditions are satisfied:

a) For cracks deeper than 25 mm, the width of the crack exposed at the bottom of the cut-outshall be not greater than 3 mm.

b) No damage to the reinforcement has occurred during evacuation of the crack.C.2.3.4 Any crack having a width greater than 9 mm shall be cause for rejection of the security coating.

CW9: PART 2

J016 ( Rev 08/98 ) - 17 -

APPENDIX D

TESTS FOR POLYPROPYLENE FIBRE CONTENT IN CEMENT MIX

D.1 GENERALThe procedures specified in clauses D.2 and D.3 provide alternative test methods for determining thepolypropylene fibre content in the cement mix. The two methods are for measuring the amount ofpolypropylene reinforcement in the mix, but do not define its distribution.

D.2 WET METHODD.2.1 Take a sample of concrete mix (any convenient weight between say 500 g and 1000 g) from a testplate that is coated with the same mix and at the same time as the component. A sample representative of eachapplication is required. (Frequency of sampling is specified in 14.3.6).

D.2.2 Completely fill a suitable size container (the volume of which is known) with the sample mix. Avolume of approximately two litres is suggested.

D.2.3 Immerse the container and contents in clean water of sufficient quantity (five litres is suggested) toallow the polypropylene fibres to be washed out and to rise to the surface. Pass the resultant slurry through a5 mm mesh sieve to ensure that any fibres still trapped are collected.

D.2.4 Collect all the polypropylene fibres and carry out any further washing that may be required prior todrying the collected fibres. Drying may be carried out by first rinsing in methylated spirit and then drying forapproximately 30 min in an oven at not higher than 80 0 C . Alternatively, the washed fibres could be dried outin a vacuum dessicator.

D.2.5 Establish the volume of the collected fibres using either a weighing/calculation technique orpreferably, if available, using apparatus normally employed in powder metallurgy to measure the volume ofmetallic powders.

D.2.6 Calculate the percentage volume of polypropylene fibres as compared with the original samplevolume of mix.

D.3 DRY METHODD.3.1 Obtain a specimen that has cured for not less than 12 h, from either a test cube, a core cut from thecoated component or a quantity collected from a test plate at the time of coating. If the coating is applied tothe component in more than one application, collect a specimen representative of each application.

D.3.2 Weigh the sample to an accuracy of 1 g (a specimen size of between 500 g and 1000 g issuggested).

D.3.3 Reduce the sample to approximately walnut size with a hand hammer, endeavouring to minimizethe fragmentation or loss of polypropylene fibres. A convenient method is to use a steel tray with three sidewalls to stop pieces flying out.

D.3.4 Immerse the pulverized mix in dilute hydrochloric solution (1 part HCI to 10 parts H 2 0) and allow

to stand for not less than 12 h. The application of gentle heat may prove beneficial.

D.3.5 Wash the mix (i.e. polypropylene fibres that may have risen to the surface and the sediment) anddry.

D.3.6 Collect the polypropylene fibres, examining the dry residue for any residual fibres.

D.3.7 Weigh the polypropylene fibres and calculate the percentage weight of fibres compared with theoriginal dry sample.