Numerical and experimental distribution of stress fields for double shoulder tool joint

A two dimensional axisymmetric finite element analysis (FEA) numerical model was established, by which the mechanical property of double shoulder tool joint (DST) could be analyzed under combined loads such as axial load, internal and external pressures and make-up torque. An elastic–plastic FEA software was developed on the basis of the model, and the wider tolerance ranges in API standard for thread were optimized with the software including tolerances of length, pitch, taper and thread angle, and the relevant standard tolerances were determined. A new tool joint was processed based on these optimized tolerances, and on which the make and break tests and hydraulic sealing tests were performed. The FEA model and make-up torque of the newly processed DST were validated by comparing the numerical results with experimental data, which can provide references for further developing the tool joint.