Weldable Seamless Heavy Wall Line Pipes

摘要

The achievement in heavy wall line pipes of proper combinations of strength, toughness, maximum hardness and weldability, typical of the most challenging environments, is critical because of the necessity to guarantee adequate steel hardenability to achieve the mechanical properties at mid thickness and to optimize alloying and micro-alloying additions to ensure low hardness after welding in low heat input processes. The present work focuses on recent improvements obtained in the manufacturing of 273.1 mm OD x 49 mm WT pipes and in the development of GMAW narrow groove welding procedures for offshore production with sour service requirements. Good strength-toughness combinations were achieved in the pipes; full scale welded joints confirmed the good hardness control of the selected steels in the HAZ.