Offset ball joints are installed at fixed points between risers and flowline and protect the pipe from movement caused by thermal expansion, shock, seismic and torsional forces.

The simple, precision ball-in-socket design can handle an angular flex ranging from 15 to 40 degrees and 360 degree rotation. Ball joints have been used successfully in up to 1200 degrees F and 10,000 psi and are available in pipe size from ½" to 48" in steel, alloy and NACE materials.

The Australian distributor, Clipper Enterprises, said there were significant advantages from cost, weight and operational criteria. The joints were less costly than laminated flexible pipe, and saved space, weight and installation labour costs.

With a projected life of 40 years, Clipper executive, Phil Martin, said the joints were maintenance free as they had redundant sealing with zero leakage.

Some other applications for the ball joints were for the protection of turret swivels on FPSOs, platform and subsurface flowlines, distribution and gathering lines and piggable pipelines.

They were installed on the Terra Nova FPSO, Petrobras' Albacore FPSO, Philips' Ekofisk 2 and a number of other US-based facilities. Clipper Enterprises can be found at www.clipperenterprises.com.au