What effect does a pin shoulder makeup against a box face have on a connection?
The pin neck is stressed in tension in proportion to the makeup torque applied, and the average neck stress is increased at the juncture of the neck and the shoulder by the stress concentration factor as is well known. If both the juncture radius and the applied torque are controlled carefully such that the concentrated stress from makeup is substantially less that the yield stress but greater that the sum of combined neck stress from all operating loads, then improvement in fatigue strength may occur. However if not, then rupture in service may occur.
