Recent construction of pipelines in Canada has seen a trend towards higher operating pressures with greater wall thicknesses and/or higher strength pipe. At the same time, Grade 550 linepipe is becoming accepted as the standard for new construction. The production of high strength grades in wall thicknesses over 12.5 mm presents a new challenge. The increased wall thickness and higher strengths tax manufacturing equipment to the fullest. IPSCO has recently completed the production of 1150 km of 14.2 mm spiral-welded Grade 483 linepipe for the Alliance Pipeline. This paper will examine the technical issues associated with the production of this pipe at the Regina steel mill. Successful production trials at IPSCO’s new steel mill in Montpelier, Iowa, which incorporates new process technology, are also described. Production of linepipe with strength exceeding 550 MPa will also be examined.

Steel for a large-scale commercial production of X80 (550 MPa) gas transmission linepipe was made in a scrap-based, electric arc furnace shop. Thermo-mechanical processing of skelp was completed in a Steckel mill. Successful pipe manufacture (1219 mm OD, 12.0 mm WT) and efficient field construction demonstrated that suitable steel making and processing controls can eliminate potential detrimental effects of residual chemical elements in electric steel.

New large diameter pipeline projects for transmission of gas from western Canada propose the use of operating pressures as high as 12kPa (1740 psi). These operating pressures will require linepipe with increased wall thickness. As well, X80 grades are now an economic alternative to X70 for these major projects. X80 was first commercially produced in North America by IPSCO in 1994. However, to extend IPSCO’s capability to heavier gauges, a significant metallurgical development program was necessary. Particular attention has focussed on achieving more demanding impact toughness requirements. This program has resulted in the successful production of X80 linepipe in gauges as heavy as 15.3 mm. The paper will review the experimental development of heavy gauge linepipe.

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The Electric Resistance Welding (ERW) process is a highly efficient means of producing linepipe. Historically, this process has been applied to grades X70 (Grade 483) and less. However, recent upgrades to IPSCO’s 24 Inch ERW pipe mill have facilitated the production of X80 (Grade 550) material. This paper briefly describes the development trials and mill upgrades and highlights the properties achieved during the commercial production of 10 km of 24″ outside diameter × 0.250″ wall thickness X80 material with particular emphasis on the weld properties.