If "ultrasteel" means a steel with superior properties pushed up to the extreme limits of attainability for a particular field of application, either as a single one or as an entire set, then this is exactly what is aimed for a very high strength linepipe steel. The high demanding and stringent requirements for large diameter (O.D. > =20") and extremely high pressure (> =100 bar) gas pipelines, now designed and under construction in the world for large transportation distances (> = 2.000 Km) and harsh environments, calls indeed for materials with exceptional performances, which can be summarise, at a pipe level, as optimum weldability, good ductility and very high fracture resistance with a yield strength equal or even higher than 700 Mpa (API grade > = X100 ).
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