... Steel typeSteel gradeannual output/t1Oil casing Pipe, joint materialJ55,K55,N80-11000002Oil line pipe B,X42~X60(L245~L415) ... of seamless steel tubes10#~45#,40Mn2,35Cr,35CrMo500007Hydraulic pillar tube, cylinder sleeve etc.45#,27SiMn20008pipes for high-pressure ... typeSteel gradeAnnual output/t1Oil casing Pipe, joint materialJ55,N80,L80,C90,P110850002Oil casing Pipe, joint materialJ55,N80,L80-1 ...