Pipe end thread

Steel pipe in the production, the single length is usually less than 14m, and some of the length of service in the steel pipe is often much more than this length. For example, in geological drilling and oil drilling, drilling depth is usually above 1000m, up to 7000m; for conveying oil, natural gas, water, alkali, minerals and other transport lines up to several kilometers or even hundreds of kilometers. To this end, the need for both ends of the steel pipe thread, the use of the corresponding coupling (take over) to connect the steel pipe. Threaded connection requires high connection strength, good air tightness, to prevent the fracture of steel and transport media leakage. In order to meet the needs of a variety of uses, the world has developed a variety of forms of thread, but the main use of the following three:

(1) Dome triangular thread. It is characterized by simple thread processing. But the thread is uneven and deformation, so the connection strength is low, only the side of the thread seal, sealing performance is poor.
(2) Spiral trapezoidal (britters) thread. It is characterized by high thread precision, high processing requirements, high connection strength; rely on the side of the thread and the top compression seal, sealing performance is relatively high.
(3) Straight type connection thread. Its characteristics are not to take over, but the tube side to be thickened, one end of the car thread, the other end of the car thread, processing more difficult. High precision thread, high connection strength; rely on the top and side seal, sealing performance.