The drill pipe is a tail with a threaded pipe for connecting the drill ground equipment and drilling equipment in drilling bottom or bottom hole device. The drill pipe is the use of drilling mud transported to drill, and drill to improve, reduce or rotary hole device. The drill pipe must be able to withstand huge internal and external pressure, distortion, bending and vibration. In the process of oil and gas extraction and refining, the drill rod can be used many times. The drill rod is divided into three types: square drill rod, drill rod and aggravated drill rod. The connection order is the square drill rod (1) + drill rod (n root, determined by the depth of the well) + aggravated drill rod (n root, decided by the combination design of the drill tool). The classification of drill rod, drill rod joint, drill rod specification and steel grade and strength of drill rod are 

introduced in detail.

The drill pipe is the tail of the steel pipe is provided with a threaded connection, for drill ground equipment and is located in the bottom of the drilling drilling and grinding equipment or bottom hole device. The drill pipe is the use of drilling mud transported to drill, and drill to improve, reduce or rotary hole device. The drill pipe must be able to withstand huge internal and external pressure, distortion, bending and vibration. In the process of oil and gas extraction and refining, the drill rod can be used many times.

The drill rod is divided into three types: square drill rod, drill rod and aggravated drill rod. The connection order is the square drill rod (1) + drill rod (n root, determined by the depth of the well) + aggravated drill rod (n root, decided by the combination design of the drill tool).

The light pipe and the original steel pipe are made into a drill rod after a number of machining steps. First of all, through the pipe thickening process processing, light tube outer surface of bend, pipe wall thickening. In the next step, the thread is machined and plated with copper that can increase the strength. Then the non destructive quality control test was carried out, and then the welded joint of the tube body was welded. Then, the pipe experience has experienced the welding heat treatment and welding final treatment to eliminate the residual stress of the welding. Other tests should be carried out on the finished steel tube before the finished drill pipe is painted and packed, including the hardness test, the pressure test and the non destructive test.

The length of the drill pipe is usually about nine meters.

The steel grade of the drill rod refers to the grade of the drill rod and steel, which is determined by the yield strength of the drill rod and steel. API (American Petroleum Institute) divides the steel grade of drilling rod into five levels: D, E, 95 (X), 105 (G), 135 (S). The higher the steel level of the drill pipe, the greater the yield strength of the pipe, the greater the strength of the drill rod. In the strength design of the drill string, the method of improving the steel grade is recommended to improve the strength of the drill string without the method of increasing the thickness of the wall.