... buy and wholesale high quality oil casing pipes, oil casing steel pipe, oil well casing pipe, oil well casing steel pipe from our factory ... and gas transportation.It includes petroleum drill pipe, oil casing, tubing.Oil casing pipe is mainly used in the drilling process and ... and gas transmission to the ground. Oil casing pipe main grade:H40,J55,K55,M65,L80,C90,N80,C90,C95,T95,P110 ...