The root cause of premature breakdown of coatings at the field joint area usually stems from a lack of detail within the Field Coating Specifications in terms of technical requirements when compared to the rigorous attention given to factory-applied coatings. Evidence would suggest that unless practical attention is given to the variances induced by local environmental factors, which require systematic planning to negate, then poor workmanship/inspection could result. To ensure the entire pipeline coating system withstands the ingress of corrosion throughout its design life the importance of the field joint coating system is paramount.
Factory-applied coatings to pipelines are carefully specified with known variances in surface preparation and application controlled and keenly monitored by any number of inspection bodies who have a stakeholding in the finished project. The lifetime design protection is assured through pre-qualification and process qualification activities to ensure the coating plant can repeat 100% compliance in a production environment. In essence the field joint coatings should match the performance and design criteria of the factory-applied coating to provide one homogeneous layer protection system along the length of the entire pipeline.
ISO 21809-3 provides a prescribed method to confront the vagrancies of field joint coatings. So, for each coating classification there is attention to pre-qualification and process qualification to mirror the rigour given to factory-applied coatings. Pipeline Protection can provide materials compliant to ISO21809-3 and also field joint services compliant to the same standard.
According to ISO 21809-3 Field Joint Coatings can be classified in groups and designated codes as demonstrated in the following table;
| Code | Type of Field Joint Coating |
| 1A | Hot Applied Bitumen Tape |
| 1B | Petrolatum Tapes |
| 1C | Wax Tapes |
| 1D | Cold Applied Polymeric Tapes |
| 2A | Heat Shrinkable materials – PE Based |
| 2B | Heat Shrinkable materials – PE based, applied over primer |
| 2C | Heat Shrinkable materials – PP based, applied over primer |
| 3A | Single Layer Fusion Bonded Epoxy powder |
| 3B | Dual Layer Fusion Bonded Epoxy powder |
| 4A | Liquid Epoxy |
| 4B | Liquid Polyurethane |
| 4C | Fibre-reinforced epoxy |
| 4D | Fibre-reinforced vinylester |
| 4E | Cast Polyurethane |
| 5A | Flame-sprayed polypropylene powder over epoxy layer |
| 5B | Polypropylene tapes/sheets hot applied over epoxy layer |
| 5C | Injection Moulded polypropylene over an epoxy layer |
| 5D | Flame sprayed polyethylene powder applied over an epoxy layer |
| 5E | Polyethylene tapes/sheets hot applied over an epoxy layer |
| 6 | Thermally Sprayed Aluminium (TSA) |
| 7 | Hot-applied microcrystalline wax coatings |
| 8A | Elastomeric coatings, Polychloroprene |
| 8B | Elastomeric coatings, EPDM |