Casing perforation nipple for oil drilling

Hot Rolled Casing perforated pup joint Tube For Oil Drilling Tubing sub is classified into three types according to its function. (a) Both ends of the double male subs are outer letty, outer thickened and non thickened subs, outer thickened and non thickened and non thickened and non thickened and non thickened and non thickened and non diameter subs of any kind. (b) Conversion sub. One end is outer letty, the other end is internal thread, and the outside thickened to non-thickened sub, outside thickened to non-thickened diameter sub, outside thickened to non-thickened diameter sub, the same diameter sub, and non-thickened to non-thickened diameter sub are threaded. (c) Adjusting the length of the sub varies, according to the engineering needs design, one end is external thread, the other end is internal thread, outside thickened and not thickened sub, outside thickened and variable diameter sub, the same diameter sub and not thickened and variable diameter sub screw coll…