OVERVIEW

Carbon steel and to a much lesser extent stainless steel are the materials of choice in the great majority of pipelines, flow lines, risers, casings and other onshore and offshore applications of tubulars. The needs are such that during the last 30 years, pipe and tube manufacture has become a technological discipline of its own accord. Industrial production of linepipe and oil well tubulars amounts to several billion dollars per year. While pipe manufacturing companies are spread around the globe, the main centers are in Japan (Nippon Steel, NKK, Sumitomo, etc.), Europe (Corus, Europipe, Tenaris, Vallourec & Mannesmann Tubes, etc.), South America (Tenaris), and North America (US Steel, Lone Star Steel, Oregon Steel Mills, etc.).

The mechanical property requirements of tubulars vary with the application. Pipeline steel requirements are usually the most stringent, as they include high strength, high ductility, high toughness, high corrosion resistance and good weldability [3.1]. For offshore pipelines, these must be met along with the heavy wall thickness required to resist collapse due to external pressure [3.2]. These difficult-to-meet requirements have made pipeline steel the "prince" of steels, and its production a truly high-tech endeavor. The required properties are achieved by carefully controlled alloying and thermo-mechanical processing during the production. Furthermore, each length of pipe is monitored at every manufacturing step, from the casting of steel rounds and slabs, through the rolling steps, to dispatch. A significant amount of non-destructive testing is performed, including ultrasonic, magnetic particle, and X-ray for through-thickness and weld defects. In...