How to prevent thread teeth from breaking by friction welding drill pipe.

Thread cracking failure accounts for about 70% of drill pipe failure. According to the analysis of the causes of thread cracking failure, the following preventive methods can effectively reduce the incidence of such failure: (1) When machining threads, it is necessary to prevent the generation of imperfect threads at the end of threads (at the tool withdrawal position) and prevent the stress of drill pipe from concentrating there, which will lead to fatigue failure of thread teeth. (2) Proper sealing methods should be adopted for the bottom of the coupling and the inner end of the external thread of the friction welding drill pipe, so as to prevent the fluid in the pipeline from entering the threaded joint as far as possible, reduce corrosion and wear, and prevent the threaded teeth from rusting and lack of structural strength. (3) Stop nondestructive testing such as X-ray testing or magnetic particle testing for the processed thread, find the surface and internal defects of the pipeline thread in time, and prevent the defective thread from being tightened. (4) Tighten the thread with proper torque, so as to prevent the pre-tightening force from exceeding the strength limit of the thread data and causing the thread teeth to crack.