All the oil and gas lines (including the underground injecting material of any formation) need to be cased with material of high strength. Casing and tubing are the important aspects of any well construction. Casing and tubing are key portions of OCTG. Casings are those pipes supporting the wall of oil and gas well. It is mainly divided in 3 major categories- the surface, protection and production casing. Tubing is a distinct pipe, installed in production casing after well cementing to allow the oil and gases flow to the ground