L51663 Seam-Weld Quality of Modern ERW-HFI Pipe

Major advances have been made in recent years in the production of electric resistance-welded (ERW) and high-frequency induction (HFI)-welded line pipe, particularly in the area of automated process control procedures designed to ensure uniform, high-quality seam welds. ERW/HFI pipe produced from microalloyed, controlled-rolled steels can be obtained in larger diameters and heavier wall thicknesses than were formerly available, and with reportedly excellent seam-weld quality as well as pipe body properties. Thus, it is feasible to consider the application of ERW/HFI pipe in a number of additional applications in gas-transmission lines. The lower cost of the ERW/HFI pipe compared with double submerged arc welded (DSAW) pipe of comparable size has resulted in increased interest in the greater use of this product. This work was undertaken to determine whether the seam weld quality of modern ERW/HFI pipe has been improved to justify more widespread use, particularly in critical locations, with resultant reductions in construction costs. The report describes the test protocol and results from six samples ranging from X60 through X70 pipe provided by PRCI member companies. Variations in weld zone properties in one of the samples are reviewed and attributed in some detail.