The circular thread top and bottom arcs have the following advantages: Improve the resistance of the thread due to abrasion when tightening When tightening the thread, the interdental gap provides a controlled gap for foreign particles and dirt This arc-shaped crest is not sensitive to local scratches or dents Round threads are easy to process, have good tightness, have a certain connection strength, are simple to maintain and use on site, and have a convenient price. Suitable for use in bushing connections The coupling of the coupling is almost controlled according to the withholding torque, and there is also a control based on the J value, but it must reach the specified small torque. | 
