gbe-cw6 part-1-1993

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GBE/CW6: PART 1

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GBE/CW6: PART 1

CONTENTS

Page

FOREWORD v

AMENDMENT RECORD AND BRIEF HISTORY vi

SECTION ONE - GENERAL REQUIREMENTS

1. SCOPE 1

2. REFERENCES 1

3. DEFINITIONS 2

4. COATING MATERIALS 2

4.1 -Acceptable materials 2

4.2 Identification of materials 3

4.3 Production data sheets 4

4.4 Toxicity and handling 4

5. VARIANTS 4

SECTION TWO - BASIC PROPERTIES AND TESTS FOR

POWDER AND CURED COATING

6. BASIC PROPERTIES OF THE POWDER 5

6.1 General 5

6.2 Infra-red scan 5

6.3 Gel time 5

6.4 Particle size analysis 5

6.5 Density 5

6.6 Moisture content 5

6.7 Thermal analysis 5

6.8 Stability 5

7. BASIC PROPERTIES OF THE DETACHED COATING FILM 6

7.1 General requirements 6

7.2 Micro-sectioning 6

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Page

7.3 Tensile strength 6

7.4 Elongation 6

7.5 Dielectric strength 6

7.6 Water permeability 6

7.7 Water absorption 6

8. BASIC PROPERTIES OF THE CURED APPLIED COATING 6

8.1 Physical performance test requirements 6

8.2 Environmental test requirements 8

8.3 Thermal stability test 8

9. QUALITY CONTROL REQUIREMENTS 9

10. COMPLIANCE 9

SECTION THREE - BASIC PROPERTIES AND TESTS OFMULTI-COMPONENT LIQUID COATINGMATERIALS AND CURED COATING

11. BASIC PROPERTIES OF UNMIXED COATING MATERIALS 11

11.1 General 11

11.2 Total non-volatile content 11

11.3 Viscosity 11

11.4 Relative density 11

11.5 Mixing ratio 11

11.6 Pot life 11

11.7 Flash point 11

11.8 Stability 11

12. BASIC PROPERTIES OF DETACHED COATING FILM 12

12.1 General requirements 12

12.2 Micro-sectioning 12

12.3 Tensile strength 12

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Page

12.4 Elongation 12

12.5 Dielectric strength 12

12.6 Water permeability 12

Water absorption 12

13. BASIC PROPERTIES OF CURED APPLIED COATING 12

13.1 Physical performance test requirements 12

13.2 Environmental test requirements 13

13.3 Thermal stability test 14

14. QUALITY CONTROL REQUIREMENTS 14

15. COMPLIANCE 15

APPENDICES

A METHODS FOR THE EVALUATION OF THE THERMAL CHARACTERISTICS

OF POWDER AND CURED COATING 17

B FLEXIBILITY TEST 28

c HOLIDAY DETECTION OF COATINGS 32

D EVALUATION OF RESISTANCE TO IMPACT 33

E EVALUATION OF RESISTANCE TO WATER IMMERSION 36

F EVALUATION OF RESISTANCE TO CATHODIC DISBONDING 38

G STRAIN /POLARIZATION TEST 42

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GBE/CW6: PART 1

FOREWORD

This Gas Business Engineering Technical Specification having been approved by the Materials andConstruction Group as document MCG 92/779 is published under the authority of British Gas plc for

use throughout the Company.

This Gas Business Engineering Technical Specification, which has been amended to accord with therequirements of the EC Utilities Directive, is a revision of BGC/PS/M6: Part 1 (dated January 1985),which is hereby superseded.

This Gas Business Engineering Technical Specification forms Part 1 of a two-part series of specifications dealing with the performance requirements and methods of test of materials that can beused for the protective external coating on steel line pipe and associated fittings.

The other part of this series (GBE/CW6: Part 2) specifies requirements for factory applied coatings.

Requirements for field applied coatings formerly specified in BGC/PS/CW6: Part 3 (now withdrawn)are specified in BG/PS/M5.

This Gas Business Engineering Technical Specification is intended for use by British Gas and if it isused where British Gas is not involved then care shall be taken to ensure that the TechnicalSpecification is correctly applied.

Compliance with this Gas Business E ' ngineering Technical Specification does not confer immunityfrom compliance with any legal or statutory obligations.

Contract requirements

A Gas Business Engineering specification does not purport to include all the necessary provisions of acontract.

Contractors and other users external to British Gas pie should direct their requests for further copies of this Gas Business Engineering Technical Specification in the first instance to the departmentresponsible for the initial issue of their contract documentation.

Comments regarding the technical content of this Technical Specification should be directed to:

Standards GroupDesign Standards DepartmentBritish Gas plc326 High HolbomLondon WC1 V 7PT

Application for further copies of this Technical Specification should be directed to:

Standards Production UnitBritish Gas plcOperational CentreBrick Kiln StreetCoventry RoadHirickleyLeicestershire LE10 ONA.

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REVISION OF GAS BUSINESS ENGINEERING SPECIFICATIONS

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GBE/CW6: PART 1

Gas Business Engineering specifications are revised, when necessary. by the issue of amendments or of rev~ editions. it is important that users should ascertain that they are in possession of the latestamendments or edition& Any person who, in the course of using a Gas Business Engineeringspecification, encounters any inaccuracy or ambiguity is requested to notify the Standards Groupwithout delay in order that the appropriate action may be taken.

Amendment record

Incorporated into text

Amendment Number DatedName Initials

Brief history

First published as BGC/PS/CW6: Part 1 January 1985

Re-issued as GBE/CM: Part 1 January 1993

© British Gas plc 1993

This Gas Business Engineering specification is copyright and must not be reproduced in whole or inpart by any means without the approval in writing of British Gas plc.

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SECTION ONE

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GBE/CW6: PART 1

GAS BUSINESS ENGINEERING

TECHNICAL SPECIFICATION FOR

THE EXTERNAL PROTECTION OF STEEL LINE PIPE AND FITTINGS

USING FUSION BONDED POWDER AND ASSOCIATED COATINGSYSTEMS

PART 1 - REQUIREMENTS FOR COATING MATERIALS

AND METHODS OF TEST

SECTION ONE - GENERAL REQUIREMENTS

1. SCOPE

This Part 1 of Gas Business Engineering Technical spec ication* GBE/CW6 specifies materials for use as anti-corrosion coatings on steel line pipe and fatings. It deals specifically with the propertiesand performance tests to establish suitability for use with Part 2 of this Specification, which deals withfactory applied coatings, and for use with BG/PS/CWS for certain field applied coatings.

Section One of this Specification covers general requirements. Section Two covers fusion bondedpowder and Section Three covers multi-component liquid coating materials.

2. REFERENCES

This Specification makes reference to the documents listed below. Unless otherwise specified the

latest editions of these documents, including all addenda and revisions, shall apply.

Statutes and Regulations

- Classification, Packaging and Labelling of Dangerous SubstancesRegulations 1984

. Control Of Substances Hazardous to Health (COSHI-1) Regulations

- The Health and Safety at Work etc. Act 1974

British Standards

BS 1387 - Specification for screwed and socketed steel tubes and tubulars and for

plain end steel tubes suitable for welding or for screwing to BS 21 pipethreads

BS 2015 - Glossary of paint terms

Hereinafter referred to as ‘this Specification'.

SECTION ONE

BS3900 - Methods of test for paints:Part B2 - Determination of volatile matter and nonvolatile matter Part F2 - Determination of resistance to humidity (cyclic

condensation)

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PartF3 - Resistance to artificial weathering (enclosed carbon arc)Part F4 - Resistance to continuous salt spray

BS 7079 Preparation of steel substrates before application of paints and relatedproducts

American Society for Testing and Materials

ASTM G 14-77 - Test for impact resistance of pipeline coatings - (Failing weight test)

British Gas specifications

BG/PS/CM2 - Specification for internal coating materials for steel line pipe and finings

3G/PS/CW - Code of practice for the selection and application of field applied externalpipework coatings

GBE/CW6 - Technical specification for the external protection of steel line pipe andfittings using fusion bonded powder and associated coating systems:

Part 2 - Factory applied coatings.

3. DEFINITIONS

For the purposes of this Specification the following definitions shall apply:

British Gas: British Gas plc.

British Gas representative: the person appointed from time to time by British Gas andnotified in writing to the Contractor to act as British Gas representative for the purposes of the Contract.

Contractor: the person, firm or company with whom British Gas enters into a contract to

which this Specification applies, including the Contractor's personal representatives.successors and permitted assigns.

Manufacturer: the producer of the coating material being offered for test or his appointedagents or assigns.

Quality Assurance: the Quality Systems and Quality Audits Department of British Gas.

4. COATING MATERIALS

4.1 Acceptable materials

4.1.1 Coating systems

Only coating systems conforming to this Specification shall be considered for application inaccordance with GBE/C~ Part 2. Coating systems may include the use of primer or chemicalpretreatment of the steel surface to enhance adhesion. In such cases. the pretreatment and coatingmaterial shall be clearly specified as a combined system.

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GBE/CW6: PART 1

SECTION ONE

Where recycled material is used, the ratio Of recycled to virgin material shall be stated. Any coatingsystem made up with a recycled material mix shall meet the requirements of this Specification.

Fusion bonded powder shall also meet the requirements of Part 1 of this Specification without the useof chemical pretreatment.

4.1.2 Compliance With this Specification

The Contractor shall be responsible for ensuring that all coating materials and equipment comply withall of the provisions specified in this Specification and Quality Assurance may make any investigationnecessary, by way of testing, batch sampling and manufacturing inspection, to satisfy itself of compliance by the Contractor.

4.1.3 Application of this Specification

It is intended that this Specification be used to encourage and stimulate the development of

progressively better external pipeline coatings. Thus, where certain minimum performance values arestated and should future coating material test submissions yield better performance than the specifiedrequirements then, after economic evaluation, these new values may be adopted as the minimumrequirements and the Specification would be up-graded accordingly.

4.1.4 Supply of data

The Contractor shall furnish, on request and in confidence, such details as may be required by BritishGas, which may include formulations, typical physical constants, manufacturing tolerances andapplication data associated with the coating materials being used. British Gas also reserve the right of direct communication with the Manufacturer should the need arise.

Any change of formulation, or manufacturing supply route, of a material may be proposed for consideration as a variant by British Gas and supply of the modified material shall not be implemented

until such time as the revised procedure qualification trials have been completed.

4.2 Identification of materials

All materials supplied for coating operations shall be suitably marked giving the following information:

a) Manufacturer's name, initials or identification mark.

b) Name of material.

c) Batch number.

d) Date of manufacture and 'use by' date.

e) Storage temperature limits.

f) Safety data sheet (included with delivery).

Containers and any associated packaging shall, where appropriate, be marked in accordance with theClassification. Packaging and Labelling of Dangerous Substances Regulations 1984

The Contractor shall require the Manufacturer to supply certificates confirming that tests specified inthis Specification have been carried out on the batches supplied and that the materials meet thespecified requirements. These certificates shall be made available for examination by British Gas onrequest.

SECTION ONE

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GBE/CW6: PART 1

4.3 Production data sheets

The Contractor shall be responsible for obtaining data sheets from the Manufacturer which shallinclude values for all the basic properties of the material as specified in the 'Basic properties' clause inthe appropriate Section of this Specification.

4.4 Toxicity and handling

Any hazard including toxic, corrosive risks and fire risks, associated with coating materials offered for use to meet the requirements of this Specification shall be specified by the Manufacturer, together withhis recommendations for safe handling in accordance with the requirements of the Health and Safetyat Work etc. Act 1974 and the COSHH Regulations.

Containers and associated packages shall be marked with their weights and, where appropriate, beprovided with handling points. e.g. handles or handholes.

5. VARIANTS

A contractor shall only propose variants to this Specification where the text indicates that variantswould be considered by British Gas.

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SECTION TWO

SECTION TWO - BASIC PROPERTIES AND TESTS FOR POWDER AND CURED COATING

6. BASIC PROPERTIES OF THE POWDER

6.1 General

The Contractor shall obtain from the Manufacturer specified and qualified ranges of values for allproperties listed in 6.2 to 6.8 inclusive that will ensure an acceptable coating. The frequency of testingshall be in accordance with 9.2.

6.2 Infra-red scan

An infra-red spectrogram, preferably made by using a standard potassium bromide (KBr) disc, shall beobtained from a typical batch of the powder. This shall subsequently be used for comparison with typespectrograms.

6.3 Gel time

A hot plate technique shall be used to obtain values of the gel time. and the values obtained of eachbatch shall be used for comparison with values originally quoted.

6.4 Particle size analysis

The particle size distribution of the powder shall be the optimum to suit the particular method of application.

Particle size range shall be quoted in the production data sheet. Each batch shall be checked for conformity with the values originally quoted.

6.5 Density

The density of the powder shall be measured for all batches produced, and the values shall conformwith the value originally specified.

6.6 Moisture content

The moisture content of the powder shall be less than 0.5% by weight and shall be checked for everybatch.

6.7 Thermal analysis

Thermal analysis data for each batch shall be made available showing, by use of a DifferentialScanning Calorimeter (DSC), the glass transition of the raw powder and also the enthalpy of the curingpowder. The glass transition temperature of the fully cured powder shall also be quoted. The reference

curve shall be provided as part of the production data sheet (see 4.3). The limiting values of AH, Tg,and T 92 (see Appendix A) shall be identified by the Manufacturer.

6.8 Stability

After ageing for 120 days at 25 +1 OC in a sealed container, the powder shall not exhibit anysignificant change from the properties identified in 6.2 to 6.7 inclusive.

SECTION TWO

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GBE/CW6: PART 1

7. BASIC PROPERTIES OF THE DETACHED COATING FILM

7.1 General requirements

The Contractor shall ensure that the tests specified in 7.2 to 7.7 inclusive are carried out by theManufacturer in accordance with 9.4. The tests shall be carried out on detached coating samples. 400

pm to 450 gm thick. which have been prepared by application on to polished steel plates. 6 mm thick.previously coated with polytetrafluoroethylene (PTFE).

7.2 Micro-sectioning

A cross-section of the cured film shall be examined at a magnification of X1 00 and shall be seen tobe homogeneous and essentially free of voids, foaming or other defects.

7.3 Tensile strength

Test specimens of detached coatings shall be tested at an extension rate. of 1 mm/min. Values for tensile strength shall be quoted in MN/m 2 as maximum strength and strength at break.

7.4 Elongation

When tested in accordance with 7.3, the elongations at 'yield' and 'break' shall be quoted by theManufacturer.

7.5 Dielectric strength

The dielectric strength of the cured material shall be quoted by the Manufacturer as kV/mm together with the method of test.

7.6 Water permeability

The water permeability of the cured material, expressed as g/24 h m 2 /mm thickness shall bespecified by the Manufacturer together with the method of test.

7.7 Water absorption

The quantity of water absorbed after three months immersion at 20 OC shall be quoted by theManufacturer.

8. BASIC PROPERTIES OF THE CURED APPLIED COATING

8.1 Physical performance test requirements

8.1.1 General requirements

The Contractor shall ensure that the tests specified in 8.1.2 to 8.1.9 inclusive are carried out induplicate by the Manufacturer in accordance with 9.3 and results of the tests, demonstratingcompliance, made available.

The tests shall be carried out on sections of 6 mm thick laboratory coated standard steel plate, asappropriate to the test requirement. Prior to coating, the steel surface shall be blast cleaned using G34grit to BS 7079 Sa 3 quality and surface profile of between 50 microns and 100 microns peak to troughheight. The coating thickness shall be in the range 400 microns to 450 microns. A destructive filmthickness test shall be carried out to verify the accuracy of the coating thickness measurementtechnique employed.

SECTION TWO

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GBE/CW6: PART 1

Testing of applied coatings shall be Carried out seven days after application of the coating in respectof 8.1.6, 8.2.3 and 8.2.5.

8.1.2 Cissing and pinholing test

The coating shall not show signs of cissing or pinholing when applied to a prepared steel panel. In

cases of doubt, a further test may be carried out by applying the coating to a grit roughened glasspanel and examining it by viewing over a bright light source.

8.1.3 Blistering and appearance test

The coating shall not show signs of blistering and shall exhibit uniform appearance when examined byeither of the tests specified in 8.1.2.

8.1.4 Sagging test

The coating shall not exhibit sagging when applied to a steel panel in the vertical plane prepared inaccordance with 8. 1. 1.

8.1.5 Thermal analysis - coating cure test

Thermal analysis shall be carried out, in accordance with Appendix A, on samples taken fromlaboratory prepared panels which are to be used for subsequent performance testing.

The values of Tg, and T 92 specified by the Manufacturer shall be in a range to ensure the coating isadequately cured to meet subsequent performance tests.

The Contractor shall obtain complete results of all thermal analyses from the Manufacturer for recordpurposes. British Gas shall have the right to examine the results on request.

8.1.6 Flexibility test

Steel plates, 50 mm x 300 mm x 6 mm thick, shall be coated to a film thickness of 400 pm to 450 gmand be properly cured. After bending in accordance with clause 13.1 (at a deflection rate of 25mm/min) over appropriate sized mandrels, the coating shall not crack, disbond or pinhole and shallpass a holiday test in accordance with Appendix C.

8.1.7 Impact resistance test

Impact resistance shall be determined in accordance with Appendix D using plate specimens. Themethod of statistical analysis described in ASTM G 14-77 shall also apply.

The coating shall withstand a minimum mean impact value of 1.5 J without resulting in a breakdown or loss of adhesion of the coating.

8.1.8 Adhesion test

The adhesion test procedure shall be as specified in clauses E.5 and E-6 and the results assessed inaccordance with clause E.7.

8.1.9 Hardness test

The Manufacturer shall specify the method used to test coating hardness and shall quote the valuesobtained.

SECTION TWO8.2 Environmental test requirements


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GBE/CW6: PART 1

The Contractor shall ensure that the tests specified in 8.2.2 to 8.2.8 inclusive are carried out induplicate by the Manufacturer and the results of the tests, demonstrating compliance, made available.

The Contractor shall be responsible for ensuring that the range of values for any material under consideration will be capable of providing a finished product in compliance with the relevant Sectionsof GBE/C~ Part 2.

All tests shall be carried out on coatings properly cured and in the thickness range 400 microns to 450microns.

8.2.2 Cathodic disbondment test

Sample panels shall be tested by the procedure specified in Appendix F. The coating, when subjectedto an impressed current at a negative voltage of 1500 mV at 20 OC, shall not disbond for greater than5 mm radius from the edge of the damaged coating after 28 days.

8.2.3 Strain/polarization cracking test

The sample panels shall be subjected to a bend strain at 20 OC and then polarized and tested asspecified in Appendix G with the test area selected on the minimum radius of the bend, i.e. area of maximum strain.

8.2.4 Water immersion test

The sample panels shall be subjected to a water ' immersion test as specified in Appendix E. The testshall not show loss of adhesion greater than 3 mm after 28 days.

8.2.5 Humidity resistance test

Coated steel test plates shall be exposed for 2000 h in accordance with BS 3900: Part F2. The coatingshall not lose adhesion and no underfilm corrosion or blistering of the film shall occur.

8.2.6 Salt spray resistance test

Coated steel test plates shall be cross-cut and exposed for 2000 h to continuous salt spray conditionsin accordance with BS 3900: Part F4. The coating shall not lose adhesion, and no underfilm corrosionor blistering of the film shall occur.

8.2.7 Artificial weathering test

Coated steel test plates shall be exposed for 2000 h to artificial weathering, in accordance with BS3900: Part F3, and shall show no signs of deterioration, apart from superficial chalking.

8.3 Thermal stability test


The Contractor shall ensure that the test specified in 8.3.2 is carried out in duplicate by theManufacturer and the results of the test, demonstrating compliance. made available.

8.3.2 Test conditions

Coated steel test plates shall be exposed to dry heat at 50 OC for three months to determine thermalstability and shall still meet the full requirements of this Specification.

SECTION TWO

9. QUALITY CONTROL REQUIREMENTS

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GBE/CW6: PART 1

9.1 Before dispatch from the factory, the Manufacturer shall carry out sampling and testing of themanufactured material covered by this Specification In accordance with 9.2, 9.3 arid 9.4.

9.2 During the production of each separate batch of powder or twice every 8 h of continuousproduction (whichever is the more frequent), the tests specified in 6.2 to 6.7 Inclusive shall be carriedout.

9.3 At least once every 8 h of continuous production. the tests specified in 8. 1.2 to 8.1 .9 inclusiveshall be carried out. 1

9.4 The tests specified in 7.2 to 7.7 inclusive arid in 8.2.2, 8.2.3 and 8.2.4 and the requirements of 6.8 shall be carried out once per year.

9.5 Any time a production, source, process or formulation change is made to the coating system,the tests specified In 7.2 to 7.7 Inclusive, 8.2.2 to 8.2.8 Inclusive and the requirements of 6.8 shall becarried out.

10. COMPLIANCE

The coating material shall not be dispatched until it has been demonstrated that the Manufacturer's

inspection and testing complies with the requirements of this Specification.

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GBE/CW6: PART 1

SECT1ON THREE

SECTION THREE - BASIC PROPERTIES AND TESTS OF MULTI-COMPONENT LIQUID COATING

MATERIALS AND CURED COATING

11. BASIC PROPERTIES OF UNMIXED COATING MATERIALS

11. 1 General

This Section Three covers multi-component liquid systems suitable for both spraying and brushapplication.

The Contractor shall obtain, from the Manufacturer, specified and qualified ranges of values for allproperties, listed in 11.2 to 11.8 inclusive, that will ensure an acceptable coating. The frequency of testing shall be in accordance with 14.2.

11.2 Total non-volatile content

The total non-volatile content shall be specified by the Manufacturer for each individual materialcomponent as supplied. The method of test shall be in accordance with the method given in BS 3900:

Part B2.

11.3 Viscosity

The viscosity of each material component as supplied, and that of the mixture when prepared for usein the correct ratio, shall be specified by the Manufacturer, together with the method of test.

11.4 Relative density

The relative density of each material component as supplied, and that of the mixture when preparedfor use in the correct ratio, shall be specified by the Manufacturer, together with the method of test.

11.5 Mixing ratio

The mixing ratio of material components shall be specified by the Manufacturer, both by weight and byvolume.

11.6 Pot life

The pot life measured in accordance with the definitions contained in BS 2015 shall be quoted by theManufacturer.

11.7 Flash point

The flash point of each material component as supplied, and that of the mixture when prepared for use, shall be specified by the Manufacturer.

11.8 Stability

The separate material components when stored at 20 OC to 25 OC for a period of 6 months shall:

a) Show no signs of hard settlement.b) Show no deterioration in application properties.c) Show no deterioration in curing properties.

The separate material components, when stored in closed containers approximately 75 mm diameter x 75 mm high, two-thirds full at 20 OC to 25 OC for 24 h, shall not show signs of skinning or other deterioration.

SECTION THREE

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GBE/CW6: PART 1

12. BASIC PROPERTIES OF DETACHED COATING FILM

12.1 General requirements

The Contractor shall ensure that the tests specified in 12.2 to 12.7 inclusive are carried out by theManufacturer at the frequency specified in 14.4. The tests shall be carried out on detached coating

samples which have been prepared by application on to polished steel plates, 6 mm thick. previouslycoated with PTFE. The coating shall be applied to give a minimum dry film thickness of 1.5 mm andallowed to cure at 20 OC to 25 OC and 60% to 70% relative humidity for a period of seven days. toachieve optimum properties before test. Samples shall be of uniform thickness for all tests.

12.2 Micro-sectioning

A cross-section of the cured film shall be examined at magnification of X100 and shall be seen to behomogeneous and essentially free of voids or other defects.

12.3 Tensile strength

Test specimens of detached coatings shall be tested at an extension rate of 1 mm/min. Values for tensile strength shall be quoted in MN/m2 as maximum strength and strength at break.

12.4 Elongation

When tested in accordance with 12.3, the elongations at 'yield' and 'break' shall be quoted by theManufacturer.

12.5 Dielectric strength

The dielectric strength of the cured material shall be quoted by the Manufacturer as kV/mm together with the method of test.

12.6 Water permeability

The water permeability of the cured material, expressed as g/24 h m21mm thickness shall bespecified by the Manufacturer together with the method of test.

12.7 Water absorption

The quantity of water absorbed after three months immersion at 20 OC shall be quoted by theManufacturer.

13. BASIC PROPERTIES OF CURED APPLIED COATING

13.1 Physical performance test requirements


Coating materials shall develop adequate handling properties within 24 h of application to suit factoryor field conditions.

The Contractor shall ensure that the tests specified in 13.1.2 to 13.1.7 inclusive are carried out induplicate by the Manufacturer in accordance with 14.3 and the results of the tests, demonstratingcompliance, made available.

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GBE/CW6: PART 1

SECTION THREE

The tests shall normally be carried out on standard steel surfaces which have been blast cleaned,using G34 grit, to BS 7079, Sa 3 quality to produce a profile of between 50pm and 100 pm peak totrough height. Coating application shall normally be by a suitable technique with pre-heating of components, where necessary. The coating shall be applied to give a dry film thickness of not less

than 1.5 mm and allowed to cure at 20 OC to 25 OC and 60% to 70% relative humidity for a period of 24 h to achieve optimum properties before test.

Testing of applied coatings shall be carried out seven days after the coating application.

13.1.2 Closing and pinholing test

The coating shall show no signs of cissing or pinholing when applied to a prepared steel panel. Incases of doubt, a further test may be carried out by applying the coating to a grit roughened glasspanel and examining it by viewing over a bright light source.

13.1.3 Blistering and appearance test

The coating shall show no signs of blistering and shall exhibit uniform appearance when examined by

efther of the tests specified in 13.1.2.

13.1.4 Sagging test

The coating shall not exhibit sagging when applied to a steel panel in the vertical plane prepared andcoated in accordance with 13.1.1 and which, immediately subsequent to coating, has been placed in avertical position and has remained in that position until the coating is dry.

13.1.5 Flexibility test

Steel plates, 50 mm x 300 mm x 6 mm thick, shall be coated in accordance with 13.1.1 and beproperly cured. After bending in accordance with clause B. 1 (at a deflection rate of 25 mm/min) over appropriate sized mandrels, the coating shall not crack, disbond or pinhole and shall pass a holidaytest in accordance with Appendix C.

13.1.6 Impact resistance test

Coated steel plates shall be tested in accordance with Appendix D.

The coating shall withstand a minimum impact of 5 J without resulting in a breakdown or loss of adhesion of the coating.

13.1.7 Adhesion test

The adhesion test procedure shall be as specified in clauses E.5 and E.6 and the results assessed inaccordance with clause E.7.

13.1.8 Hardness and cure of coating

The hardness and degree of cure of the coating shall be determined and the Manufacturer shallspecify the hardness range to indicate the correct degree of cure of the coating.

13.2 Environmental test requirements

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GBE/CW6: PART 1

13.2.1 General

The Contractor shall ensure that the tests specified in 13.2.2, 13.2.3 and 13.2.4 are carried out induplicate by the Manufacturer in accordance with 14.4 and the results of the tests, demonstratingcompliance, made available.

The tests specified in 13.2.5 to 13.2.8 Inclusive shall be carried out once to provide evidence of satisfactory long term performance.

13.2.2 Cathodic disbondment test

Sample panels shall be tested by the procedure specified in Appendix F. The coating, when subjectedto an impressed current at a negative voltage of 1500 mV at 20 OC, shall not disbond for greater than5 mm radius from the edge of the damaged coating after 28 days.

13.2.3 Strain/polarization cracking test

The sample panels shall be subjected to a bend strain at 20 OC and then polarized and tested asspecified in Appendix G with the test area selected on the minimum radius of the bend, i.e. area of maximum strain.

13.2.4 Water immersion test

The sample panels shall be subjected to a water immersion test as specified in Appendix E. The testshall show no loss of adhesion greater than 3 mm after 28 days.

13.2.5 Humidity resistance test

Coated steel test plates shall be exposed for 2000 h in accordance with SS 3900: Part F2. Coatingshall not Jose adhesion and no underfilm corrosion or blistering of the film shall occur.

13.2.6 Salt spray resistance test

Coated steel test plates shall be exposed for 2000 h to continuous salt spray conditions in accordancewith SS 3900: Part F4. Coating shall not lose adhesion and no underfilm corrosion or blistering of thefilm shall occur.

13.2.7 Artificial weathering test

Coated steel test plates shall be exposed for 2000 h to artificial weathering, in accordance with SS3900: Part F3, and shall show no signs of deterioration, apart from superficial chalking.

13.3 Thermal stability test

13.3.1 General

The Contractor shall ensure that the test specified in 13.3.2 is carried out in duplicate by theManufacturer and the results of the test, demonstrating compliance, made available.

13.3.2 Test conditions

Coated steel test plates shall be exposed to dry heat at 50 OC for three months to determine thermalstability and shall still meet the full requirements of this Specification.

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SECTION THREE

14. QUALITY CONTROL REQUIREMENTS

14.1 Before dispatch from the factory, the Manufacturer shall carry out sampling and testing of the manufactured material covered by this Specification in accordance with 14.2,14.3 and 14.4. themanufactured material covered by this Specif

14.2 During the production of each separate batch or twice every 8 h of continuous production(whicheveris the more frequent), the tests specified in 11.2, 11.3 and 11.4 shall be carried out. Therequirements of 11.5 to 11.8 inclusive shall also be met.

14.3 At least once every 8 h of continuous production, the tests specified in 13.1.2 to 13.1.7inclusive shall be carried out.

14.4 The tests specified in 12.2 to 12.7 inclusive and in 13.2.2,13.2.3 and 13.2.4 (considered astype tests) and the requirements of 11.8 shall be carried *out once per year or at any time aproduction, source. process or formulation change is made to the coating system.

15. COMPLIANCE

The coating material shall not be dispatched until it has been demonstrated that the Manufacturer'sinspection and testing complies with the requirements of this Specification.

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APPENDIX A

METHODS FOR THE EVALUATION OF THE THERMAL CHARACTERISTICS OF POWDER AND

CURED COATING

A.1 INTRODUCTION

This appendix details methods by which the thermal characteristics of a powder (see clause A-2) andthe thermal characteristics of cured coating (see clause A3) can be evaluated.

A.2 EVALUATION OF THERMAL CHARACTERISTICS OF POWDER

A.2.1 Principle

The method for the determination of powder reactivity and glass transition temperatures of powder consists of heating the powder at a constant rate in a DSC. A first trace is made which records thermalchanges in the sample between ambient temperature and some point after full cure. When full cure isachieved, the sample is cooled rapidly to ambient temperature and a second DSC run is carried out.

Values for glass transition temperature and heat of cure can be derived from the trace. Confirm theaccuracy of both axes by calibration before powder testing is carried out.

A.2.2 Apparatus

The apparatus used shall be a DSC* with sufficient calorimetric sensitivity to respond to the glasstransition temperature of the powder (the thermal analysis curve shall be capable of displaying theheat flow rate at a sensitivity of not less than 400 gW/cm). Additionally, the following accessories willbe required:

a) Aluminium sample pans.

b) Quench cooling accessory.

c) Analytical balance capable of weighing to an accuracy of 0.1 mg.

d) Liquid nitrogen or other cooling fluid. Alternatively, a DSC with a built-in cooling device isacceptable provided it can cool the sample rapidly at the rate required in the method.

A further device is required to measure the area under the cure exotherm (see A.2.5.6).

A.2.3 Calibration of the Differential Scanning Calorimeter

A.2.3.1 Temperature axis calibration

A method suitable for checking the temperature axis calibration is as follows:

a) Calibrate the upper temperature scale of the DSC using samples of pure indium, tin and

lead which have melting points of 156.6 OC, 231.9 OC and 327.4 OC respectively.

b) Melt the metal samples in open pans in either static air or under inert gas purge,depending on the test procedure being followed.

c) Take the melting point as the intersection of the leading edge of the fusion endotherm withthe projected baseline.

There are a number of DSC machines available and correlation shall be demonstrated.

The results obtained are influenced by the scan rate, therefore adjust the instrument such that thesevalues are correct at the scanning rate employed in the test, i.e. 20 OC/min.

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In practice, melting points are usually within 2 OC to 3 OC of the accepted values when determined ata 20 OC/min scan rate and this is found to be adequate for Tg measurements of the coating film. It themeasured value differs from the true value by more than 2 OC to 3 OC, recalibrate the temperatureaxis.

A.2.3.2 Theory of calorimetric calibration

The mV signal which drives the pen in the Y direction is a measure of the rate of heat absorbed or evolved and is derived from the following equation:

dh = K1 δydt

where δY = - difference in Y-axis deflection between the sample and empty pan curves at thetemperature of interest, measured in units of length (centimetres, inches, etc.).

K1 = proportionality constant, made up of:

a) The signal attenuation setting on the Y-axis, i.e. q. (Y-axis range in mW or equivalent).

b) The cell calibration coefficient E (dimensionless).

The cell calibration coefficient E can be determined at any given temperature through the use of amaterial of known specific heat (e.g. sapphire (A12 03)) using the following equation:

E CP Hr m (1)

qs δY

where Cp = specific heat of sample at the temperature of interest.

Hr = heating rate.

m = sample mass

Equation (1) is derived from another equation (2), which relates the heat release (or absorption) to thearea of the event on the thermogram, ie:

H = A (B E qs)m (2)

where H = heat released

A = area of the exotherm

B = time base setting (see A.2.5.3 e)

The heat release is a function of the specific heat of the test material and equal to:

H = CpHr AB 1 (3)

δY

Therefore, 9 this is substituted in equation (2) and transposed. we arrive at the equation for E.

Alternatively, the cell constant may be determined by relating the latent heat fusion of the pure material(e.g. iridium) to the area produced from the melting endotherm.

A.2.3.3 Method for determining the cell coefficient E

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A-2.3.3.1 Place two empty pans in the DSC cell and run a temperature programme betweenambient temperatureand 300 'C. If the trace is not almost horizontal, the baseline slopecontrol shall be adjusted until the best line is achieved. A typical temperature calibrationchart is shown in FigureA1.

A.2.3.3.2 Load the sample pan with a weighed sapphire disc for a second run. Heat the pan up to

the initial ambient temperature and hold until equilibrium is obtained. This shall beachieved by setting the starting temperature to ambient temperature and running inisothermal mode.

A.2.3.3.3 Run a second trace using the same final temperature as is used in A.2.3.3.1.

A.2.3.3.4 Measure several values for &Y, the vertical difference between the traces, to calculate Evalues at these points. The average of E over the range of interest shall be used.

A.2.4 Sampling

When it is necessary to sample large amounts of powder from the sample batch (e.g. several kilogramboxes), take representative amounts (approximately 50 g) from each container, mix together andsample by coning and quartering. Analyse different batches separately.

Take a final sample (approximately 250 g) and store it in an airtight container, at a temperature nothigher than 0 OC, in case subsequent testing is required. When the cold sample is taken from coldstorage, allow at least 30 min in its closed container to reach ambient temperature. Take powder for DSC tests directly from the 250 g sample.

When amounts of powder less than 1 kg are involved, coning and quartering or riffle sampling is notnecessary.

Record the following information for each sample:

a) Dateb) Timec) Powder lot number/batch number

A.2.5 Test procedure

A.2.5.1 Instrument setting

The test procedure and instrument settings depend upon the design of equipment employed.However, there are certain essential features in the test method which shall be followed W consistentand comparable results are to be obtained.

Where applicable, select a baseline slope setting which gives a virtually horizontal line when thereference and sample pans are loaded identically. This is normally carried out with empty pans.

A.2.5.2 Preparation of test samples

Weigh out accurately between 10 mg and 15 mg of powder into an aluminium sample pan. Heavier weights (up to 25 mg) may be used, if needed, to give adequate sensitivity. The accuracy of weighingshall be + 0. 1 mg.

A.2.5.3 Standard air test

Carry out the standard air test under the following conditions:

a) Use open pans throughout.

b) Use an empty aluminium pan for the reference.

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c) No purge gas is employed; carry out the test in static air at atmospheric pressure.

d) Appropriate experimental data recording conditions.

e) If exothermal areas are to be recorded accurately, it may be necessary with some Instrumentsto change from a temperature base on the abscissa to one of time before the onset of cure.

f) Heat the sample from ambient temperature to 280 OC at a rate of 20 OC/min and record thetrace. Rapidly cool the sample to ambient temperature. Repeat this procedure for the secondrun, except that this run may be terminated at approximately 20 OC in excess of the secondrun glass transition temperature (Tg2).

The test temperature of 280ºC may be subject to change depending on the type of coatingmaterial under test. It should be advised by the powder manufacturer.

A.2.5.4 Inert gas test

Carry out the inert gas test as for the standard air test (see A.2.5.3), using an inert gas purge insteadof static air throughout the test. A flow rate of 40 ml/min shall be used.

A.2.5.5 Measuring the glass transition temperature

The glass transition temperature (Tg) is defined as that temperature (or temperature range) at whichthe coating polymer is transformed from a hard and often brittle material (the glass) into a tough,rubber-like material.

The glass transition temperature of the cured material is visible on the DSC trace as a baseline shift,resulting from a marked step-like change in specific heat at Tg, the step usually covering severaldegrees. It is conventional to take Tg as the point of intersection of the extrapolated baseline at the lowtemperature end and the tangent of the curve at the inflection point (see Figure A.2). For raw powders,the Tg usually takes the form of a baseline shift with a superimposed endothermic peak (see Figure A.3).

A.2.5.6 Measuring the heat released during cure

It is necessary to measure the area under the curing exotherm either in the determination of thermalstability, or when the quality of oversprayed powder is in question.

There are several ways of measuring the exothermal area which vary in their accuracy. These are:

a) Electronic integration using a computer or a dedicated integrator

b) Planimeter

c) Cut out the exothermal area marked on the chart paper, weigh it and compare it with theweight of a known area of the same paper

d) Count the squares within the exothermal area marked on the chart paper

One of these, or a similar method, shall be selected for use with the DSC.

The points at which the cure exotherm commences and ends are used to calculate the heat release.They are usually determined by drawing in the baseline to the exotherm using a rule. Care must betaken to distinguish between the onset of cure (Toc) and the onset of flow (Tof) and to commence thebaseline at Toc (see Figure A.3).

A.3 MEASUREMENT OF DEGREE OF CURE OF POWDER COATING

A.3.1 Principle

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The method of assessment of the cure of the powder coating film cure by measurement of its glasstransition temperature consists of heating a ground coating sample at a constant rate in a DSC. A firsttrace is made which records thermal changes in the sample between ambient temperature and somepoint after full cure as defined by the powder manufacturer. The sample is cooled to ambienttemperature and a second run carried out. The glass transition temperatures before and after heatingare determined and are used to assess the degree of cure. It is essential that samples are initiallypretreated in the calorimeter to remove moisture and to confer a uniform thermal history.

A.3.2 Apparatus

The apparatus used shall be a DSC with sufficient calorimetric sensitivity to respond to the glasstransition temperature of the materials under test (the thermal analysis curve should display the heatflow rate at a sensitivity of 400 pW/cm minimum). Additionally, the following accessories will berequired:

a) Aluminium sample pans.

b) Quench cooling accessory.

c) Analytical balance capable of weighing to an accuracy of 0.1 mg.

d) Liquid nitrogen or other cooling fluid. Alternatively, a DSC with a built-in cooling device isacceptable provided it can cool the sample rapidly at the rate required in the method.

e) Hammer and cold chisel.

f) Microhammer mill or equivalent

A.3.3 Temperature axis calibration

The method to be used for checking the temperature axis calibration is as follows:

a) Calibrate the upper temperature scale of the DSC using samples of pure indium, tin and leadwhich have melting points of 156.6 OC, 231.9 OC and 327.4 OC respectively.

b) Melt the samples in open pans in either static air or under an inert gas purge, depending on thetest procedure being followed.

c) Take the melting point as the intersection of the leading edge of the fusion endotherm with theprojected baseline.

The results obtained are influenced by the scan rate, therefore adjust the instrument such thatthese values are correct at the scanning rate employed in the test, i.e. 20 OC/min.

In practice, melting points are usually within 2 OC to 3 OC of the true values when determinedat a 20 OC/min scan rate and this is found to be adequate for Tg measurements of thecoating film. When the temperature deviation is higher than this, it is necessary to adjust thesample thermocouple reference junction.

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If adjustment has been necessary to bring within limits. carry out a further calibration to demonstrate that theinstrument is calibrated accurately.

A.3.4 Sampling

Remove coating film samples from the coated component using a hammer and cold chisel. This produces fuded

coating flakes. Care should be taken to remove samples of full film m thickness. but at the same time avoid theinclusion of steel debris.

Sample a component at several points along Its length and around Its circumference. Take samples from testpanels in a similar manner.

Collect the coating flakes in a plastics bag and identity. Grind the flakes to pieces small enough to pass througha 2.8 mm aperture sieve in a microhammer mill. Record the following information for each sample:

a) Date

b) Time

c) Component number

d) Sequence number

e) Powder lot number/batch number

f) Location of sample on component

A.3.5 Test procedure

A.3.5.1 Instrument setting

The test procedure and instrument settings used depends upon the design of equipment involved. However,there are certain essential features in the test method which shall be followed if consistent and comparableresults are to be obtained.

Where applicable, select a baseline slope setting which gives a virtually horizontal line when the reference andsample pans are loaded identically. This is normally carried out with empty pans.

A.3.5.2 Preparation of test samples

Weigh out accurately between 10 mg and 15 mg of ground coating into an aluminium sample pan. Heavier weights (up to 25 mg) may be used, 9 needed, to give adequate sensitivity. The accuracy of weighing shall be+0.1 mg.

A.3.5.3 Standard air test

Carry out the standard air test under the following conditions:

a) Use open pans to assist the release of moisture from the sample during pretreatment

b) Use an empty aluminium pan for the reference

c) No purge gas is employed; carry out the test in static air at atmospheric pressure

d) Appropriate experimental data recording conditions

e) It will normally be necessary to subject the coating sample to thermal pretreatment beforeassessment of its degree of cure. Pretreatment is designed to remove any absorbed moisturefrom the coating because moisture is known to influence glass transition temperaturemeasurements. Such pretreatment shall not significantly advance the cure of the coatingsample.

The powder Manufacturer should specify the thermal pretreatment required for the product.This will typically require heating the sample in the DSC cell from ambient temperature (i.e. 20

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OC to 25 OC) to some defined temperature higher than 1 W OC, probably in the range 1 WOC to 150 OC. This required temperature Will typically be attained within 120 s and held for aperiod up to 60 s. Immediately cool the sample to ambient temperature with liquid nitrogen or a suitable cooling fluid; alternatively, a DSC with a built-in cooling device is acceptableprovided K can cool the sample rapidly at the rate required in the method.

Make a suitable record of the pretreatment run.

f) Heat the sample from ambient temperature to a temperature specified by the Manufacturer, ata rate of 20 OC/min, so that the sample achieves full cure, but avoids significant degradation.Rapidly cool the sample to ambient temperature using liquid nitrogen or a suitable coolingfluid. This establishes the first glass transition temperature (Tgl).

Repeat the procedure for the second run, except that this run may be terminated atapproximately 20 OC higher than the second glass transition temperature (T92),

Make pen records of both (Tgl) and (T 92) runs.

A.3.5.4 Inert gas test

Carry out the inert gas test as for the standard air test (see A.3.5.3), using an inert gas purge insteadof static air throughout the test. Use a flow rate of 40 milmin throughout the test.

A.3.5.5 Measuring the glass transition temperature

The glass transition temperature (Tg) is defined as that temperature (or temperature range) at whichthe coating polymer is transformed from a hard and brittle material (the glass) into a tough, rubber-likematerial.

The glass transition temperature is visible on the DSC trace as a baseline shift, resulting from amarked step-like change in specific heat at Tg, the step usually covering several degrees. It isconventional to take Tg as the point of intersection of the extrapolated baseline at the low temperatureend and the tangent of the curve at the inflection point (see Figure A.2).

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APPENDIX B

FLEXIBILITY TEST

B.1 LABORATORY PREPARED TEST PANELS

B.1.1 Apply the coating to steel plates 50 mm x 300 mm x 6 mm thick and properly cure. Bend (at adeflection rate of 25 mm/min) over appropriate sized mandrels (see 8.1.2) at two substrate testtemperatures (5 OC and 20 OC). After bending, the coating shall not crack, disbond or pinhole whenholiday tested in accordance with Appendix C. Inspect plates immediately after bending and againafter 24 h at 20 OC.

B.1.2 Select mandrel sizes according to the following formula:

D = t(l - S)S

where D = mandrel diameter, in mm (see Figure B.1).

t = plate thickness. in mm.

S = one of the values in clause B.3 depending on the intended coating application and thetemperature of the test.

The are length of the mandrel shall be fixed at 225 ± 25 mm.

B.1.3 Set the panel support gap set according to the following formula:

Support gap = M + 2t + 4 mm,

where m = chord length across the mandrel arc. in mm (see Figure B.1).

t = plate thickness. in mm.

Bend the panel until it makes contact with the entire surface area of the mandrel.

B.1.4 During bending, peaking (point at which a gap occurs between the mandrel and the panel) maybe observed at the centre of the panel. In this case, the area of the panel where the gap exceeds0.254 mm (0.010 in.) shall be disregarded in evaluating the test results. This area shall not exceed25% of the mandrel surface area.

B.2 TESTS ON PIPE SPECIMENS

B.2.1 Cold cut test specimens 356 mm long x 50 mm wide from a pipe section with the long axisin the circumferential direction. Where seamless pipe is being tested, select specimens which show aminimal variation in pipe wall thickness, particularly within the test area (i.e. middle 75 mm to 100 mmof specimen). Bend the test specimens over appropriate sized mandrels at two substrate testtemperatures (5 OC and 20 OC). After bending. the coating shall not exhibit visible signs of cracks,

disbonding or pinholes and shall pass a holiday detection test when tested in accordance with Appendix C. Inspect specimens immediately after bending and again after 24 h at 20 OC.

B.2.2 Select mandrel sizes according to the following formula:

1D1 = - t

S + 1

1 Do - t

where D1 = mandrel diameter, in mm.

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DO = original specified pipe outside diameter, in mm.

t = pipe wall nominal thickness, in mm.

S = one of the values specified in clause B.3 depending on the intended coatingapplication and the temperature of the test.

B.2.3 The arc length of the mandrel shall be fixed at 225 ~L 25 mm.

B.2.4 For specimens from pipes having an outside diameter in the range 406 mm to 1219 mm,set the panel support gap according to the following formula:

Support gap = M + 2t + 4 mm

where M = chord length across the mandrel arc, in mm (see Figure B.1).

t = plate thickness, in mm.

Bend the specimen until contact is made with 75 + 10% of the mandrel area.

B.2.5 For specimens from pipes having an outside diameter in the range 305 mm to 405 mm,set the panel support gap according to the following formula:

Support gap = M + 2t + 29 mm

where M = chord length across the mandrel arc. in mm (see Figure B. 1).

t = plate thickness, in mm.

Bend the specimen until it makes contact with the entire surface area of the mandrel.

Test specimens from pipes having an outside diameter below 305 mm by an appropriate method.

B.2.6 During bending, peaking (point at which a gap occurs between the mandrel and the panel) may

be observed at the centre of the panel. In this case, the area of the panel where the gap exceeds0.254 mm (0.010 in.) shall be disregarded in evaluating the test results. This area shall not exceed25% of the mandrel surface area.

B.3 S VALUES

B.3.1 For coatings intended for use on fittings, the following S values shall apply:

S = 0.005 at a temperature of 5ºC

S = 0.01 at a temperature of 20ºC

B.3.2 For coatings intended for use on line pipe, the following S values shall, apply:

S = 0.02 at a temperature of 5 OC.

S = 0.03 at a temperature of 20 OC.

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B.4 TESTING AT 5 OC

Testing at 5 OC may be carried out by pre-cooling the panel in a refrigerator to a temperature slightlylower than 5 OC and carrying out the bending operation when the panel temperature reaches 5 + 2OC. Alternatively, an environmental chamber which controls the temperature in the bending apparatusmay be used. The test specimens shall not be immersed in any liquefied coolant to achieve the testtemperature.

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APPENDIX C

HOLIDAY DETECTION OF COATINGS

C.1 EQUIPMENT

Holiday detection shall be carried out using dc, non-pulsing holiday detection equipment on surfaces attemperatures below 90 OC and free from moisture.

C.2 OPERATING VOLTAGE

The operating voltage shall be 125 V per 25 pm of coating thickness.

The rate of travel of the probe over the surface shall not exceed 300 mm/s.

C.3 ELECTRODE TYPE

For all coating systems the wire brush type of electrode shall be used, suitably curved to conform tothe contour of the coated surface.

C.4 IDENTIFICATION METHOD

All holidays shall be identified with a waterproof marker.

C.5 EQUIPMENT CALIBRATION

All holiday detectors shall be calibrated at the beginning of every working day and, additionally, whenrequested by British Gas.

ge 32 APPENDIX C

Delete the existing text of clause C.3 and substitute the folloylling:

For all coating systems the wire brush typeof electrode shall be used,suitably curved to conform to the contour of the coated surface of pipe.For fittings, a suitable procedure shall be agreed with the coatingapplicator and shall normally be the one that is approved within theprocedure qualification.

CW6:1 AMD No 1

Dec `993

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APPENDIX D

EVALUATION OF RESISTANCE TO IMPACT

D.1 GENERAL

The procedures specified in clauses D.2 to D.6 inclusive serve to assess the comparative resistanceof coatings to impact damage.

D.2 TEST EQUIPMENT

The following test equipment will be required:

a) A variable impact tester (ASTM G14-77, paragraph 4.2 or equivalent) with punch hammer typeindentor modified as shown in Figure D. 1 to accommodate a 14.3 mm diameter ball bearingand equipped with a minimum impact mass of 1 kg

b) A sufficient supply of 14.3 mm diameter ball bearings manufactured from EN31 steel with aVickers hardness of 800 to 930

c) A holiday detector (see Appendix C)

d) A thickness gauge

e) Repair materials

D.3 TEST PROCEDURE ON COMPONENTS

D.3.1 Check the test site to ensure that it is free from holidays with the holiday detector set at therequired voltage for the particular coating film (see clause C.2).

D.3.2 Position the impact tester on a holiday free site 300 + 50 mm from one end of the component.

D.3.3 Drop the impact weight from a height calculated to impart the specified impact energy to the

coating. The impact height may be calculated using the following formula:

H = J

9.81W

where H = impactor height, in m.

W = impactor mass, in kg.

J = impact energy, in joules.

D.3.4 Retest the impact area for holidays using the detector set at the required operating voltage.

D.3.5 Repeat D.3.2, D.3.3 and D.3.4 at four more locations evenly spaced over the surface of the

component.

D.3.6 Rotate the ball bearing after each impact.

D.3.7 After every 20 impacts fit a new ball bearing.

D.3.8 If a holiday is caused by the impact test, check the coating thickness in the test area using athickness gauge.

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D.4 REPAIR PROCEDURE FOR COMPONENTS

Repair any holiday caused by impact testing using repair materials.

D.5 TEST PROCEDURE ON PANELS

D.5.1 Test sample panels (300 mm x 50 mm x 6 mm) and test panels (300 mm X 50 mm) cold cutfrom component in the longitudinal direction according to the procedure detailed in ASTM G l 4-77,paragraphs 6 to 9, using the apparatus detailed in clause D.2 a). The additional modifications to the ASTM procedure specified in D.S.2 to D.5.6 inclusive shall apply.

D.5.2 Test impact areas for failure using the holiday detector set at a voltage of 125 V per 25 gm of coating thickness (this relates to coating thickness before impact damage).

D-5.3 The minimum spacing between impacts along the centre line of the specimen shall be 25 mm.

D.5.4 Rotate the ball bearing after each impact.

0.5.5 After every 20 impacts fit a new ball bearing.

D.5.6 Increase the height by an increment of 10 mm between impacts.

D.S.7 There shall be no disbonding at the minimum impact energy. Verity this by testing inaccordance with clause E.6 and report in accordance with clause E.7.

D.6 REPORTING RESULTS

D.6.1 If the coating withstands the specified impact energy without forming a holiday, the test shall berecorded as a 'Pass'. If a holiday is formed at the specified impact energy. the test shall be reported as'Fail at thickness of ...'and the measured coating thickness shall be recorded.

D.6.2 The impact strength shall be converted to impact energy in joules and this value shall bereported. (A typical calculation is shown in Figure D. 1).

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APPENDIX E

EVALUATION OF RESISTANCE TO WATER IMMERSION

E.1 GENERAL

The equipment and procedure detailed in clauses E.2 to E.7 inclusive shall be used to assess thecomparative resistance of coatings applied to components (free of holidays) to loss of adhesion due towater absorption.

E.2 EQUIPMENT

The following equipment will be required:

a) A water bath which shall be maintained at a temperature of 50 + 2 OC.

b) A holiday detector.

c) Internal pipe coating material (complying with BG/PS/CM2).

d) 6 mm diameter twist drill.

e) Pointed sharp knife, e.g. Stanley type or similar.

f) 5 mm diameter steel rod 450 mm long.

g) Elastomeric adhesive for repairing test areas, e.g. Sillastic silicone-rubber, grades RTV 738 or RTV 732 or equivalent.

E.3 SAMPLE PREPARATION

E.3.1 Laboratory prepared specimens

Prepare 300 mm x 50 mm x 6 mm panels under conditions of application and cure similar to those for

a coated component.

E.3.2 Specimens taken from components

Cold cut 300 mm x 50 mm specimens from a sample pipe or, in the case of a fitting, from the pipe pupwhich has been coated as a test piece.

E.4 PREPARATION OF TEST AREA

E.4.1 To ensure freedom from holidays, test the prepared panels for holidays with the holiday detector set at the required voltage (see clause C.2).

E.4.2 Drill a 6 mm diameter hole through the test panel within 25 mm of one end.

E.4.3 Protect the bare metal of the panel with internal coating material (see clause E.2 c)).

E.5 INITIAL TEST PROCEDURE

E.5.1 Carry out an initial adhesion test as described in clause E.6.

E.5.2 Using the steel rod fitted through the 6 mm diameter hole, suspend the specimen panel in thewater bath immersing all but the top 50 mm of the panel.

E.5.3 At intervals of 24 h, remove the panel from the water bath and allow it to cool to ambienttemperature.

E.5.4 Test the coating adhesion as specified in clause E.6.

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E.S.5 Repair the test area using elastomeric adhesive.

E.5.6 Return the panel to the water bath immediately.

E.5.7 If, after seven days immersion, the coating is retested and is found to be satisfactory, return thepanel to the water bath and repeat the adhesion test at intervals of seven days up to a total immersion

time of 28 days.

E.6 INVESTIGATION PROCEDURE

E.6.1 Use one or other of the following procedures (E.6.2, E.6.3) as appropriate.

E.6.2 For all coated components and coatings on panels equal to or less than 600 pm thickness, usethe following procedure:

a) Using a sharp pointed knife (e.g. Stanley knife or similar), make two incisions approximately13 mm long through to the metal surface to form a V with an angle of approximately 300 at theintersection point.

b) Starting at the point of intersection force the coating from the steel substrate using the sharp

pointed knife. Take care to protect the eyes and hands when carrying out this operation.

E.6.3 For laboratory panels with coatings greater than 600 pm thickness use the following procedure:a) Using a small hacksaw blade (e.g. 'Junior' type or similar) make two incisions through to the metalsurface to form an X with an angle of approximately 300 at the point of intersection.

b) Draw a sharp knife along the cut lines to ensure that the hacksaw blade has reached themetal surface.

c) Starting at the point of intersection, force the coating from the steel substrate using the sharppointed knife. Take care to protect the eyes and hands when carrying out this operation.

E.7 REPORTING RESULTS

Refusal of the coating to peel or a cohesive failure within the coating shall be recorded as a 'Pass'.

Cohesive failure, caused by voids leaving a honeycomb structure on the specimen surface, shallconstitute a 'Fail' condition.

For the purpose of this test, cohesive failure will be recorded where some coating material remains onthe metal surface and where difficulty in coating removal has been experienced.

The extent of the adhesive failure between the coating and the metal substrate shall be recorded.

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APPENDIX F

EVALUATION OF RESISTANCE TO CATHODIC DISBONDING

F.1 GENERAL

The procedures detailed in clauses F.2 to F.8 inclusive serve to assess the comparative resistance of damaged pipe coatings to disbonding when exposed to cathodic protection in potentially corrosivesoils.

F.2 TEST REQUIREMENT

F.2.1 Apparatus

The following apparatus will be required:

a) A stabilized dc power unit having a voltage output of 12 V and a capability to supply 20 mAsimultaneously to each test area in circuit. A suitable circuit is shown in Figure F. 1 a).

b) Digital voltmeter, range 1.9W V (3.5 digit), input impedance 103 M Q. Accuracy of 0.1 % + 1

digit at 20 +1 OC.

c) Variable resistor, range 1 k Q :110%, 1 W (one required for each specimen).

d) 75 mm length of 0.8 mm diameter platinum wire, or similar length of 6 mm wide, 1.5 mm thickplatinized titanium strip (one required for each test area).

e) Holiday detection equipment.

f) Reference electrode of the saturated calomel type, constructed from glass or plastics withporous plug. The diameter should be not greater than 10 mm.

g) 6 mm diameter twist drill with included cutting angle of 1600.

h) Equipment for maintaining the temperature of the specimens and test area at 20 +2 OC.

i) A length of rigid plastics pipe per test area to be used as a solution container (approximatedimensions 60 mm long x 50 mm nominal bore).

j) Elastomeric adhesive for fixing the plastics pipe to the test surface, e.g. a silastic siliconerubber grade RTV 738 or RTV 732 or equivalent material.

k) Fixed resistor, 1Q +2%, 1 W (one required for each test area).

F.2.2 Reagent

An electrolyte comprising a sodium chloride (NaCI) solution, (3% W/V). 30 g of NaCt should bedissolved in distilled water and made up to 1 litre.

F.3 PREPARATION OF TEST PANELS

F.3.1 Laboratory prepared specimens

Sample panels 300 mm X 50 mm x 6 mm shall be prepared simulating the conditions of application for a factory coated pipe.

F.3.2 Specimens taken from components

Test panels 300 mm x 50 mm shall be cut from a sample production coated pipe.

F.4 PREPARATION OF TEST AREAS

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F.4.1 Test the prepared panels for holidays with the holiday detector set at the required voltage (seeclause C.2).

F.4.2 Fix two lengths of rigid plastics tube perpendicular to the coated surface using a suitableelastomes ric adhesive (see Figure F. 1). Place them with their centres on the centre line of the panel width and equidistant from the panel ends and each other and leave for a period of

12 h to allow the adhesive to fully cure.

F.4.3 Drill a 6 mm diameter hole through the coating to the metal surface in the centre of each testarea using the drill specified in F.2.1 g).

F.5 INITIAL TEST PROCEDURE

F.5.1 Fill each plastics tube with NaCI electrolyte to a depth of approximately 50 mm (see F.2.2)with the apparatus set up as shown in, Figure F. 1 a). Bring the temperature of the specimensand test area to 20 + 2 OC. Maintain this temperature throughout the test period.

F.5.2 Connect a voltmeter and reference electrode to each test rig in turn as shown in Figure F. 1b). With the tip of the calomel reference electrode positioned approximately 10 mm from thecentre of the hole, adjust the voltmeter reading to read a negative voltage of 1500 mV withrespect to the calomel electrode. Carry this out using the variable resistance shown in FigureF. 1 a).

F.5.3 Record, at intervals of 24 h, the voltmeter indication for each test area and adjust the variableresistor to correct any drift from the negative voltage setting of 1500 mV. Also record, every 24h, the current flow by measuring the voltage drop across the 1 Q fixed resistor.

F-5.4 Every 24 h check the plastics tubes for loss of electrolyte and restore the level with distilledwater as necessary.

F.6 INVESTIGATION PROCEDURE

F.6.1 After seven days, remove the electrolyte and plastics tube from one test site and removeexcess moisture.

F.6.2 Use one or other of the following procedures (F.6.3, F.6.4) as appropriate:

F.6.3 For coatings up to and including 600 um use the following procedure:

a) Using a sharp-pointed knife (e.g. Stanley type or similar), make two incisions approximately 13mm long through to the metal surface extending radially from the 6 mm hole and at an angleof approximately 300 to each other to form a truncated V.

b) Starting at the base of the truncated V, force the coating from the steel substrate using thesharp pointed knife. Take care to protect the eyes and hands when carrying out this operation.

F.6.4 For all coatings in excess of 600 g m thickness use the following method:

a) Using a small hacksaw blade (e.g. 'Junior' type or similar make two cuts across the 6 mm holeat an angle of approximately 300 to each other to form a truncated W. Make the cuts throughto the metal surface and to extend radially from the 6 mm hole.

b) To ensure that the hacksaw blade has reached the metal surface. draw the point of the sharpknife along the cut lines.1

c) Starting at the base of the truncated V, force the coating from the steel substrata using thesharp pointed knife. Take care to protect the eyes and hands when carrying out this operation.

F.6.5 Repeat the investigation procedure at the second test site after 28 days

F.7 REPORTING OF RESULTS

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The amount of disbonding shall be quoted as the radial distance from the edge of the pre-damage towhich the coating peels easily from the metal surface.

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APPENDIX G

STRAIN/POLARIZATION TEST

G.1 Bend the test sections In accordance with the method detailed in Appendix B using a value of S =0.02 for line pipe powders and S = 0.005 for fitting powders at a temperature of 20 +2 OC.

G.2 Polarize the specimens, as detailed in Appendix F, with a single test site selected on the minimumradius of the bend. i.e. area of maximum strain. After 28 days polarization, remove the electrolyteandplastics tube and remove excess moisture.

G.3 The area of coating exposed to the electrolyte shall not exhibit signs of cracks, disbondment or pinholes and shall pass a holiday detection test as detailed in Appendix C.

gbe-cw6 part-1-1993

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