Small diameter X70 and X80 linepipe for high pressure gas transmission

The Australian natural gas transmission system is characterized by relatively small markets for gas located at long distances from the sources of supply. The need to deliver gas to these markets at internationally competitive energy costs in competition with other fuels has led to the development of unique ERW pipeline designs comprising: a relatively high design pressure of 15MPa compared to 10MPa or less that is characteristically used in most parts of the world; the transmission of rich gas which places special demands upon fracture toughness; small diameter typically 18" (DN450); high strength levels typically X70 moving to X80; relatively thin wall thickness; and an expected move from 72 to 80% design factor. The needs generated by these design parameters have stimulated developments in steel making and hot strip production to achieve sufficient strength, weldability and toughness suitable for ERW pipe production. Parallel developments have also occurred in girth welding, control of HACC without preheat at very high production rates, girth weld defect tolerance, and other areas relevant to pipeline construction and operation. (AU)