The Trikote trilaminate coating consisted of 150 µm of fusion bonded epoxy, 100 µm of copolymer adhesive and 1,600 µm of high density polyethylene (HDPE) providing a total composite coating thickness of 1,850 µm.

APC Socotherm believes that Trikote coating provides excellent corrosion resistance and flexibility properties as well as being extremely resistant to soil stress due to its excellent adhesion to the steel substrate. The coating also offers superb impact and abrasion resistant properties, and therefore is an ideal coating to handle the rigour of pipeline installation and multiple handling required to transport coated pipe over 1,200 km from the coating contractor to the construction site.

The coating also has the benefit of providing a distinct anti-corrosion coating layer and mechanical protection layer with the ability to adjust each layer thickness to suit specific project requirements. Epic took advantage of this when designing the final coating specification to include the HDPE mechanical protection layer at 1,600 µm.

Recently, APC Socotherm modified its coating facility to process externally coated longer length line pipe. Epic Energy utilised the benefits of this upgrade to have 19.3 m length line pipe coated by APC Socotherm. While the extended pipe length still allows the pipe to be transported by rail wagon and trucks within the same current regulations of 18 m line pipe, the 19.3 m option provided some key benefits to the project: namely, a reduction in the amount of pipe joints handled, transported, welded, inspected and joint coated.

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The longer lengths also offer the potential to increase the total amount of lineal metres of pipe laid per day. The QSN Link project is the first major pipeline project in Australia to take advantage of increased line pipe length, and therefore has set a key milestone in Australia by demonstrating how construction costs may be reduced in future oil and gas projects without compromising installation standards.

The project also utilised concrete weight coating (CWC) for key parts of the pipeline route that may be subject to future water flow by normally dry or seasonal creeks and rivers. The 30 mm CWC was applied by compression method to the 18 m line pipe.