X120 UOE Linepipe With Improved Properties and Varied Sizes

Nippon Steel has developed X120 UOE linepipe as a part of joint development program with ExxonMobil. After establishment of the basic production technology of X120, the mechanical properties have been improved, especially to increase the suitability to strain based design application and the size range has been expanded. The combination of heavily deformed austenite grains and a mild accelerated cooling to lower cooling stop temperatures (MAC) achieves the aim to lower the yield strength (YS) and the yield to tensile (Y/T) ratio for the B-containing chemistry that was decided to meet the CG-HAZ toughness target. The properties of MAC pipes met the targets and the pipes with OD from 28” to 48” and WT from 13mm to 20mm were made for test purpose.