Field joint coatings | technical report Luc Perrad and Nathan Muncaster consider the performance of
polymeric backed mesh coatings against heat shrinkable polyolefi n (3LPE) and polymeric tape coatings tested to ISO 21809-3
Comparing performance of fi eld-applied coatings
Pipeline operators have many fi eld joint coating options available to them. For most of them, the reference standard used in their selection and specifi cation development is the international standard ISO21809-3 (edited in December 2008). Applicable to pipeline operators in the oil, gas and water sectors, the standard describes nine fi eld joint coating systems and details the required performance for each system: 1. Bituminous, petrolatum, wax and polymeric tapes 2. Heat-shrinkable coatings 3. Fusion bond epoxy (FBE) powder coatings 4. Liquid coatings 5. Polyolefi n-based coatings 6. Thermal spray aluminum (TSA) coatings 7. Hot applied microcrystalline wax coatings 8. Elastomeric coatings 9. Non-crystalline low viscosity polyolefi n tapes. Polymeric-backed mesh coatings, such as the RD-6
product manufactured and marketed by Polyguard Products, have been successfully used since 1988 and are included in many reference standards – including NACE standard SPO 169-2009 (Control of External Corrosion on Underground or Submerged Metallic Piping Systems) – but they are not listed in ISO21809-3. Polyguard Products has been participating in ISO
committees to add a tenth fi eld joint coating system to the ISO21809-3 standard: Polymeric backed mesh coatings. To assist the ISO committee in qualifying the required performances to be included in ISO21809-3 for this new system, the Polyguard RD-6 coating system has been tested by the independent laboratory KTA Tator, based in Pittsburgh, Pennsylvania. The tests were conducted according to current ISO21809-3 test methods for heat shrinkable coatings (3LPE) and cold applied polymeric tapes. This article compares the performances required by ISO21809-3 for heat shrinkable coatings and polymeric tapes with the results of the tests conducted by KTA Tator in December 2012 and November 2014. As the
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standard EN12068 (edited in August 1998) is still used today by some major oil & gas companies outside North America, the comparison also includes the required performances of EN12068 Class C50 (test methods of ISO21809-3 and EN12068 are so similar that they can be considered the same). The comparison includes the following short and long term performances: Short term performance (punctual tests conducted 24 hours after application of the coating): Impact and indentation (penetration) resistance, peel strength (adhesion), and lap shear resistance. Long term performance (tests conducted during a relatively long period of time): Cathodic disbondment resistance and hot water immersion.
Short Term Performance Impact Resistance - The objective of the test is to simulate a mechanical impact on the coating such as a
September 2015 | PIPELINE COATING 25
Above: Polymeric
backed mesh coatings are not specifi cally covered in
reference FJC standards but boast a proven track record
and tests show they meet key requirements
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