Hashemi - The University of Birjand , Department of Mechanical Engineering Birjand , IRAN
Jalai - Sadid pipe and Equipment Company, Tehran ,IRAN

Around 75% of the world energy resources are located in remote areas far from the end users. In order to transport energy from the production sites to the market highpressure gas pipelines and networks are used. The trend in gas companies has been towards the use of more efficient piping systems for a greater transportation capacity of richer gases. This requires the use of higher toughness steel pipelines with larger outside diameters to minimise the cost of the weight per meter of the linepipe and to reduce pipe laying costs by the use of thinner wall pipes. These pipelines are now commercially avilable due to recent developments in steel making technology, new manufacturing techniques and modern pipe forming processes. As a result, large diameter pipes up to 56” (1422mm) O.D with different range of wall thicknesses have been produced using 550 MPa steel (grade API X80). The application of grade 690 and higher (grade X100 and X120) is recently under review. The X120 linepipes requires far higher production technology than X60 or X80 pipes does concerning its material design, steelmaking, casting, plate production and pipe forming. This paper gives an overview of some of the challenges faced by pipeline engineers (in the design, production and application processes of such pipeline materials) with an emphasise on the recent manufacturing technologies leading to the production of ultar high-strength high-toughness linepipe steels.

Steel manufacturing, Linepipe technology, API X80, X100, X120