Special oil pipes are mainly used for drilling oil and gas wells and transporting oil and gas. It includes an oil drilling pipe, oil casing, and oil pumping pipe. Oil drill pipe is mainly used to connect drill collars and drill bits and transmit drilling power. Oil casing is mainly used to support the well wall during the drilling process and after well completion to ensure the drilling process and the normal operation of the entire oil well after completion. The pumping pipe mainly transports oil and gas from the bottom of the oil well to the surface.

Oil casing is the lifeline to maintain the operation of oil wells. Due to different geological conditions and complex stress conditions downhole, tension, compression, bending, and torsion stresses act comprehensively on the pipe body, which places higher requirements on the quality of the casing itself. Once the casing itself is damaged for some reason, the entire well may be reduced in production or even scrapped.

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 and well depths require different steel grades. In corrosive environments, the casing itself is also required to have corrosion resistance. In places with complex geological conditions, the casing is also required to have anti-collapse properties.