Yellow Jacket XL is a significantly improved Yellow Jacket product which meets or exceeds all of the materials and performance property requirements of AS/NZS1518:2002. Yellow Jacket XL has many similar performance characteristics as a 3-Layer HDPE coating system, including resistance to damage from storage and handling, while at the same time maintains advantages of the standard Yellow Jacket coating system including compatibility with readily available field joint coating systems.

Yellow Jacket XL development history

Yellow Jacket has been applied at Bredero Shaw’s Kembla Grange facility for over 30 years and has been a mainstay anti-corrosion coating for the Australian onshore gas market since 1968. Over this period of time, Bredero Shaw’s Yellow Jacket product has evolved to accommodate the changing needs of the Australian market, including a new adhesive sealant in 1985 to accommodate higher operating temperatures and a tougher HDPE outer layer in 1996 to provide better resistance to damage from handling and storage.

During the 2002 review of AS1518 it was recognised that Australia’s varied environment provides some unique challenges to pipe coatings during handling, stockpiling and transportation over long distances. High ambient temperatures and direct sunlight has resulted in coating surface temperatures recorded as high as 70°C on yellow colour coating. As a result, a revised AS/NZS 1518 standard introduced stringent property requirements to ensure that the adhesive used retained minimum performance parameters at contact points with timber supports during stockpiling.

The performance of standard Yellow Jacket is often challenged by the new minimum performance parameters. A 3-Layer HDPE system is able to retain the minimum performance parameters at contact points, however it is a more complex coating to apply than Yellow Jacket in that it requires a more thoroughly prepared and cleaned bare pipe surface and much higher energy consumption in order to achieve the desired performance, which results in additional manufacturing costs.

In 2006 Bredero Shaw, began a program to develop an improved Yellow Jacket product that could address handling, stockpiling and transportation concerns raised by its clients in the Australian marketplace. The primary parameters provided to the design team were for a robust coating system:

* Having similar impact, damage resistance and mechanical properties to 3-Layer HDPE, especially for handling and stockpiling in hot conditions; * Capable of use for operating temperatures up to 70°C typically encountered near compressor stations; * Suitable for all soil conditions; and, * Which is cost competitive.

Performance characteristics

Yellow Jacket XL pipe coating system is applied using proven Yellow Jacket technology that has been specially modified to achieve desired performance characteristics, including hardness for resisting penetration and flow under stockpile compression and lap shear properties approximately ten times that of standard Yellow Jacket. Being a 2-Layer system makes the choice of a compatible field joint coating system more straightforward than for a 3-Layer HDPE system. Also, that fact that Yellow Jacket XL is a simpler coating system to apply, there exists a manufacturing cost advantage over 3-Layer HDPE.

Yellow Jacket XL complies with AS1518-2002, however, as the adhesive is much higher strength there will be relatively no shrink back at the coating cutback which allows brushed back chamfered ends to be applied similar to 3-Layer HDPE, therefore providing a smooth transition profile between pipe and HDPE coating for improved field joint coating.

Table 1, compares the lap shear strength of the various HDPE based system while Table 2 demonstrates the properties of the Hybrid Yellow Jacket XL adhesive when tested against the criteria for an adhesive complying with AS1518.

Pipes are frequently cold field bent to enable the pipeline to follow the terrain. As demonstrated in Table 2 the Yellow Jacket XL system has a high level of flexibility. For this test strips of steel 200 mm x 25 mm were cut from along the length of the coated test pipe and bent using a 4-point bending machine. This test demonstrates that both the adhesive and HDPE are flexible enough to be bent severely without cracking.

Bredero Shaw has always enjoyed a healthy involvement with the Australian Pipeline Industry by participating in industry research programs and formulation and re-assessment of Australian and International Standards.

Part of this involvement means taking notice of feedback from end users and pipeline engineers regarding the various needs regarding coatings and other products suitable for the diverse conditions encountered in Australia.

Bredero Shaw has developed a new hybrid adhesive, combining key benefits from mastic products and copolymer adhesives, commonly used in associated divisions of the company, for use with the tried and tested Yellow Jacket application system to provide superior ability for both peel and lap shear strengths, impact resistance and indentation resistance.

This provides greater confidence for handling, transportation and stockpiling, under any ambient condition applicable in Australia, coupled with the ability to run continually at operating temperatures up to 70°C while also providing a cost advantage to the user over 3-Layer systems.