Petroleum special pipe is mainly used for drilling of oil and gas wells and transportation of oil and gas. It includes petroleum drilling pipe, petroleum casing, and sucker pipe. Oil drill pipe is mainly used to connect drill collar and drill bit and transmit drilling power. Oil casing is mainly used to support the borehole wall during and after drilling to ensure the normal operation of the entire oil well during and after the drilling. The sucker pipe mainly transports oil and gas from the bottom of the well to the surface.

Oil casing is the lifeline to maintain oil well operation. Due to the different geological conditions and the complex state of the downhole force, the combined effects of tensile, compression, and torsional stresses on the pipe body put forward higher requirements for the quality of the casing itself. Once the casing itself is damaged for some reason, it may lead to reduced production of the whole well or even scrap.

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 good conditions and depths also use different steel grades. In a corrosive environment, the casing itself is also required to have corrosion resistance. Where geological conditions are complex, the casing is also required to have anti-collapse performance.