j55 Tubing and Casing Fitting API oil well Perforated screen pipe In API 5CT standard, casing and tubing are divided into 4 groups and 19 steel grades. According to the manufacturing method, it is divided into seamless steel pipe and welded pipe. Except L80-9Cr and LJ80-13CI In addition to the 6 steel grades C90-1, C90-2, T95-1, T95-2, etc., which are limited to use seamless steel pipes, other steel grades can not only use seamless steel pipes, but also use straight seam welded pipes produced by resistance welding or electric induction welding. his For the heat treatment process, except for the three steel grades in the first group, 14 steel grades in the first group N80Q, the second, third and fourth groups must be subject to full length quenching+tempering, and the minimum tempering temperature is specified for the eight steel grades in the second group. Only the maximum values of S and P content are specified for the 7 steel grades in Group 1, Group 2 and Group 3, but no other…