October 2009 Vol. 236 No. 10

Features

Efforts Continue To Develop International Coating Standards

As previously reported in these pages (“Efforts Seek To Develop International Coating Standards,” by K. Coulson, P&GJ, August 2008) the International Standards Organization (ISO) in 2001 resolved at its TC67/SC2 Plenary meeting on Pipeline Transportation Systems in Bratislava to start developing external pipeline coating standards for adoption and utilization by the global market.

Consequently, the ISO Technical Committee ISO/TC67 formed a Work Group WG14 (Petroleum And Natural Gas Industries, Subcommittee SC2, Pipeline Transportation Systems) to identify which coatings standards were needed to best serve the requirements of the pipeline community. This work is now coming to fruition and in the last two years ISO has issued pipeline-coating standards for fusion bonded epoxy and – most recently – for field-applied girth-weld coatings.

While this article references and discusses in some manner the milestones for future publications and standards, it deals more specifically with the most recently published ISO standard on field-applied girth-weld coatings.

The ISO Technical Committee TC67/SC2 in 2001 laid out a program to identify which pipeline coatings required an internationally acceptable coating standard or specification. It was recognized that a need existed for standards for the following:

• Three-Layer Polyethylene and Polypropylene Coatings;
• Fusion Bond Epoxy (FBE);
• Field Joint (Girth-Weld) Coatings;
• Two-Layer Polyethylene; and
• Concrete Coatings.

TC67/SC2 formed Work Group Fourteen (WG14) and Matt Dabiri of Williams (now with El Paso Pipelines), was appointed the coordinator of this entire program. However, as the WG14 program rapidly expanded, it became apparent that additional project management was required. In 2006, Tom Weber of Trenton was approached to work with Dabiri as the coordinator of WG14. (See Table 1 for a listing of Work Group Leaders, Coordinators and the ISO Editorial Committee (EDC).)

Development Stages
As detailed in the August 2008 article, the development, review and voting for all ISO Coatings standards involves four distinct stages. These are:

1. CD: Committee Draft.
2. DIS: Draft International Standard.
3. FDIS: Final Draft International Standard.
4. IS: International Standard.

Status Of ISO Coating Standards
By 2008, the five ISO petroleum and natural gas industries external-coating standards for buried or submerged pipeline used in pipeline transportation systems were either in preparation or had been published. Their status is as follows:

1. WG14-1:ISO/DIS 21809-1 – Part 1: Polyolefin Coatings (three-layer PE and three-layer PP); Denis Grimshaw (UK). At Draft International Standard Stage. Publication anticipated in 2010.
2. WG14-2: ISO 21809-2 – Part 2: Fusion-Bonded Epoxy Coatings, Keith Coulson (Canada). Published Dec. 15, 2007.
3. WG14-3: ISO/FDIS 21809-3 – Part 3: Field Joint Coatings, Marcel Roche (France). Published Dec. 15, 2008.
4. WG14-4: ISO/DIS 21809-4 – Part 4: Polyethylene Coatings (two-layer PE), Dennis Wong (Canada). FDIS to be issued for vote shortly. Publication anticipated by early 2010.
5. WG14-5: ISO/DIS 21809-5 – Part 5: External Concrete Coatings, Betty Friedman (U.S.). FDIS to be issued for vote shortly. Publication anticipated by early 2010.

Field Joint Coating
This part of ISO 21809 specifies requirements for field joint coating of seamless or welded steel pipes for pipeline transportation systems in the petroleum and natural gas industries as defined in ISO 13623. It details requirements for the qualification, application and testing of the corrosion protection coatings applied to steel surfaces left bare after the pipes and fittings (components) are joined by welding (Figure 1). It does not, however, address additional mechanical protection, thermal insulation or joint in-fills for concrete weight-coated pipes.

The work on the field joint coating precipitated wide interest from the international pipeline community. Representatives of Brazil, Canada, France, Germany, Holland, Italy, Mexico, Norway, United Kingdom, and the U.S. were invited to participate and support the work group’s activities.

The priority was to identify the various types of field joint coatings available in the market and to determine their level of acceptance within the pipeline industry. From that review, the following comprehensive list of coatings was deemed of sufficient importance to be included in the 21809-3 standard:

1. Hot-applied bituminous tapes.
2. Petrolatum tapes.
3. Wax tapes.
4. Cold-applied polymeric tapes.
5. Heat-shrinkable materials, polyethylene-based.
6. Heat-shrinkable materials, polyethylene-based, applied over a liquid or fusion-bonded epoxy layer.
7. Heat-shrinkable materials, polypropylene-based, applied over a liquid or fusion-bonded epoxy layer.
8. Single-layer fusion-bonded epoxy powder.
9. Two-layer fusion-bonded epoxy powder.
10. Liquid epoxy or derivatives.
11. Liquid polyurethane or derivatives.
12. Fibre-reinforced epoxy.
13. Fibre-reinforced vinylester.
14. Cast polyurethane.
15. Flame-sprayed polypropylene powder applied over an epoxy layer.
16. Polypropylene tapes/sheets hot-applied over an epoxy layer.
17. Injection-moulded polypropylene over an epoxy layer.
18. Flame-sprayed polyethylene powder applied over an epoxy layer.
19. Polyethylene tapes/sheets hot-applied over an epoxy layer.
20. Thermal spray aluminum (TSA).
21. Hot-applied microcrystalline wax coatings.
22. Elastomeric coatings, polychloroprene-based.
23. Elastomeric coatings, EPDM-based.

The work group (WG14-3) immediately focused on the need for application and procedure qualifications, pre-production qualifications and pre-production trials. The harmonization of test methods and test criteria, along with more concise document control, inspection and test report procedures, were also identified as critical parameters in the successful application of a field coating. To ensure that all those aspects were covered in the standard, the following clauses were developed:

• Application procedures and qualification.
• Application procedure specification (APS).
• Coating materials.
• Procedure qualification trial (PQT).
• Pre-production trial (PPT).
• Qualification of coating and inspection personnel.
• Production testing and inspection.
• Certificates of compliance and traceability.

Each of the girth-weld coatings was categorized specifically into one of the following coating types:

• Bituminous, petrolatum, wax and polymeric tapes (Clause 10 of ISO 21809-3).
• Heat-shrinkable coatings (Clause 11).
• Fusion-bonded epoxy powder coatings (Clause 12).
• Liquid coatings (Clause 13).
• Polyolefin-based coatings (Clause 14).
• Thermal spray aluminum (TSA) coatings (Clause 15).
• Hot-applied microcrystalline wax coatings (Clause 16).
• Elastomeric coatings (Clause 17).

Each coating category had detailed requirements relating to the coating identification and descriptions. Specific surface preparation requirements were defined because, obviously, each coating type will require different types of substrate preparation. For instance, while some coatings only require hand-tool cleaning, others can only provide an optimum performance if applied over abrasive-blasted surfaces. These requirements are clearly identified and described in the new ISO pipeline coating standard.

Finally, the application parameters and quality-assurance testing techniques are addressed for each particular coating category. Items such as pre- and post-heating and any post-cure requirements are itemized along with specific testing parameters and protocols. The requirements should ensure that the designer, after having selected a specific coating, obtains those specific characteristics on the final field-applied coating. This ultimately will provide full confidence that the coating system is totally “fit for purpose.”

Future Work
A significant number of additions are being planned for the ISO Pipeline Coating program. These are:

1. The contents of ISO 21809-1 (Three-layer PO Coatings) were revised to include not only extruded systems but also powder-application polyolefin coatings. This now encompasses not only the more traditional three-layer extruded PE/PP coatings, but the powder/powder/powder (PPP) coatings which have gained wide-scale acceptance in North America in the last decade.
2. It is proposed that the scope of the FBE Standard 21809-2 be revised to include both dual-layer FBE coatings and high-temperature systems.
3. A proposal was accepted to undertake the preparation of an additional ISO coating standard to cover the requirements for wet thermal insulation coatings for pipelines, flow lines, equipment and sub-sea structures.

Conclusion
Field Joint Coatings Standard 21809-3 is the second in a series that will represent the industrial integration of external coating standards to be published through ISO for use on buried or submerged pipelines.

Under the Vienna agreement with ISO and CEN (European Committee for Standardization, Central Secretariat, Rue de Stassart 36, B-1050, Brussels, Belgium) this standard will be adopted as a European standard. As an international standard, the 21809-3 documents will bring a much-needed consistent and uniform approach to the qualification, application and testing of globally applied field-joint coatings.

This consistency of approach will help define the necessary requirements for material composition, dimensional tolerances and performance in regard to an internationally accepted set of criteria and allow objective comparisons and the elimination of the unnecessary variances in quality that the pipeline industry has encountered in the last few decades.

The introduction of addition pipeline-coating standards, such as Three-Layer Polyolefin and External Concrete Coatings, will go even further in providing operating pipeline companies with optimum external coating systems for use on their domestic and non-domestic pipeline projects.

Author
Keith E.W. Coulson has spent more than 30 years in the pipeline industry with NOVA Gas Transmission and TransCanada Pipelines in Calgary and then Jotun Powder Coatings (Norway). Since 2006, he has served as a technical consultant with Dragon Pipeline Specialists. He was Chairman of the Canadian Standards Association Coatings Committee that published Z245.20/21 (FBE and Polyethylene Coatings). He also was the work group leader of the ISO group that developed and published the first ISO external pipeline coating standard (21809-2 on FBE) and was head of the Canadian delegation to ISO on pipeline materials from 1998-2008. He has authored more than 25 technical papers on pipeline activities. He is a registered Professional Engineer in Alberta (APEGGA) and a certified Corrosion Specialist with NACE, as well as being licensed as a Chartered Engineering (UK) and as a European Engineer (Eur Ing). He was recently made a Life Fellow of the Institute of Corrosion. He was educated at the University College of Swansea (Wales) and Aston University (England). E-mail: keithcoulson@shaw.ca.