Development of standards & specifications for high strength line pipe

The needs of the international gas industry to transport bulk gas from remote gas fields to market have prompted the development of ultra-high strength line pipe which will be required for the economic construction of future long distance, high pressure gas pipelines. Until recently, the conventional limiting grade for such line pipe was API 5L Grade X80 or its ISO 3183 equivalent Grade L555. Joint private development programmes between oil/gas companies and major steel pipe manufacturers have resulted in new higher strength pipes; principally grades X90 (625), X100 (L 690) and X120 (L830). The steel makers and pipe mills have designed alloy compositions and pipe processing routes to optimise mechanical properties in the line pipe, including high toughness for fracture control for arctic use. The oil and gas companies have conducted forming and girth welding trials on these new pipes together with extensive mechanical property evaluation and assessment of fracture arrest behaviour. The industry is now ready to translate results of the long development programmes into national and international codes and standards for line pipe production and pipeline construction. This paper describes current work within API and ISO to standardise these ultra high strength grades of line pipe for industry use. (AU)