Effects of sour crude oil on fatigue properties of steel plates for shipbuilding Ouchi, H., Kohavashi, J., I.shikawa, J. Takezawa. H., 1-tiara, R. and Yamada, Y. Paper No. 218, NACF international, PO) Box 218340, Houston, TX 77218, USA (1994) 14 pp

Abstract

This chapter discusses the usage of various high-strength steel linepipes, including X70 linepipe, X80 linepipe, and grades above X80 and describes the standard welding techniques for high-strength linepipes. Grade X70 is now widely used for high-pressure transmission lines in many countries, for example, the Oman–India gas pipeline. The code requirements for the installation of the Oman–India gas pipeline are based on the American Society of Mechanical Engineers (ASME) B31.8. Grade X80 carbon steel linepipe is accepted onshore. Higher grades are currently under active development. X100 grades are being actively developed by several companies, but at present, no project use has been identified/indicated. Views of the future developments toward high-strength steel up to X100 are given by a consortium of companies and documented in Graf and Hillenbrand. The range of welding techniques used for pipeline construction includes shielded metal arc welding (SMAW), gas metal arc welding (GMAW), submerged arc welding (SAW), flux cored arc welding (FCAW), and gas tungsten arc welding (GTAW). When welding higher strength grades of linepipe (X70 and above), special techniques are generally specified to avoid defects in high-strength welds. Some of the additional measures that are necessary include the control of joint preparation and lineup; using adequate preheat; additional inter-run griding; a careful selection of electrical characteristics; and no movement of the pipe until completion of the root pass.