Oil special pipe is mainly used in oil and gas well drilling and oil and gas transmission.It includes petroleum drill pipe, oil casing, tubing.Oil drill pipe is mainly used to connect the drill collar and bit and drilling.Oil casing pipe is mainly used in the drilling process and after the completion of borehole wall support, to ensure that the drilling process and after completion of the normal operation of the oil Wells.Main pipe will be well at the bottom of the oil and gas transmission to the ground. Oil casing is to maintain the lifeblood of any oil Wells.Due to different geological conditions, underground stress state is complex, tension, pressure, bending, torsion stress combination on the pipe body, which put forward higher requirements about the quality of the casing itself.Once the casing damage due to some reason itself, may lead to the whole production of the well, or even scrapped. According to the strength of the steel itself casing can be divided into different steel grade, namely the J55, K55, N80, L80, C90, T95, P110 and Q125, V150, etc.Different well conditions, hole depth, the grade of steel are also different.In corrosive environment also requires casing itself has corrosion resistance.In the complicated geological conditions where also calls for casing collapse resistance.