Research of heavy wall X65MOS submarine pipeline steel key process strategy

Abstract

In recent years, there has been development of several significant pipeline projects for the transmission of oil and gas from deep water environments. The production of gas transmission pipelines for application demands heavy wall, high strength, good lower temperature fracture toughness, low yield ratio and good corrosion resistance. To overcome the difficulties of producing excellent performance in heavy wall X65MOS pipe Shougang Steel Research in cooperation with the Shougang Steel Qinhuangdao China (Shouqin) 4.3m heavy wide plate mill research was conducted.This paper describes the background, composition design, key process strategy to produce excellent performance in heavy wall X65MOS plate. The importance of recrystallized rolling process, the tensile property change during pipe making and the corrosion resistance change by “pre-stretching + bend” deformation simulate pipe making in the lab will be discussed. The results showed the per pass reductions during recrystallized rough rolling should be increased in a steady fashion, with special emphasis on the reduction of the final two roughing pass prior to the intermediate hold (transfer thickness for finishing) should be more than 20%. The tensile properties change rule and the reasonable pipe expansion process should be determine during pipe making. The crack length ratio(CLR) internal control criteria of the plate should be less than 6%, it helps to ensure the HIC performance of the pipe can meet the technical specification(CLR≤15%).