Oil casing is the lifeline of oil well operation. Due to different geological conditions, the underground stress state is complicated, tensile, compressive, bending and torsional stress act on the pipe body, which puts forward higher requirements on the quality of the casing itself.

According to the strength of the steel itself, the casing can be divided into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150 and so on. Different well conditions, well depth, the use of steel grades are also different. In the corrosive environment, the casing itself is also required to have corrosion resistance. In the place of complex geological conditions, it is also required that the casing has the performance of anti-collapse.