Special petroleum pipe is mainly used for oil and gas well drilling and oil and gas transmission. It includes oil drilling pipe, oil casing and oil pumping pipe. The oil drill pipe is used to connect the drill collar to the drill bit and transfer drilling power. Oil casing is mainly used to support the well wall during drilling and after completion, so as to ensure the drilling process and the normal operation of the whole well after completion. The pumping pipe mainly transfers the oil and gas from the bottom of the well to the surface.

Oil casing is the lifeline of oil well operation. Due to different geological conditions, underground stress state is complex, tensile, compressive, bending and torsional stress act on the pipe body, which puts forward higher requirements on the quality of casing itself. If the casing itself is damaged for some reason, the entire well can be reduced production or even abandoned.

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, etc. Different well conditions, well depth, the use of steel grade is also different. The casing itself is also required to have corrosion resistance in corrosive environment. In the place of complex geological conditions, casing is also required to have the ability to resist collapse.