OCTG is mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drill pipe, casing, pumping tubing. Oil drilling pipes are mainly used to connect the drill collar and bit and pass the drilling power. Oil casing is mainly used for drilling and completion of the sidewall of the support in order to ensure the normal operation of the wells in the conduct and completion of the drilling process. The pumping tubing wells at the bottom of the oil and gas transmission to the ground.
  Oil Casing is the lifeline to maintain a well run. Due to different geological conditions, underground stress state of tension and compression, bending, and the combined effects of torsional stress acting on the tube, which has put forward higher requirements on the quality of the casing itself. Once the casing is damaged for some reason, may lead to the production of the wells, or even scrapped.
   According to strength of steel,casing can be divided into different grade of steel, that is, J55, K55, N80, L80, C90, the T95, P110, Q125, V150. And so on. Well conditions, different depth of the steel grade is also different. Also requires the casing in corrosive environments with corrosion resistance. Casing with anti-collapsing performance in complex geological conditions.