Research on the Calculation Method of Tightening Torque on P-110S Threaded Connections

Tightening torque is one of the main factors that could affect the connection quality in threaded connections. On the basis of elastic mechanics and thick cylinder theory, this paper established a new analytical model based on the geometric parameters of thread tooth and the calculation method of tightening torque on P-110S threaded connections was also obtained by calculating the frictional torque on each threaded surface. In this paper, the friction coefficient on the real contact thread tooth was measured by the developed experimental equipment that could be used to simulate the contact of threaded surfaces approximately. By applying the new method on P-110S threaded connection and comparing the results obtained by analytical model with the true make-up torque in application, it could be found that the analytical model and the calculation method proposed in this paper are reasonable. The new method was also validated by using the finite element analysis method to the same sample. The new method proposed in this paper is practical and convenient because it can be applied to calculate the tightening torque just with geometric parameters and thread numbers, which is easier to implement in application.