Effect of Helix Angle on the Bending Capacity of a 5 Inch API-Style Threaded Flange

Abstract

This paper investigates the effect of helix angle on the structural bending capacity of an API 5-1/8 inch 15,000 psi rated threaded flange under internal pressure and external tension and bending. The three-dimensional finite element flange connection is analyzed with and without the helix angle, and API 17TR8 criteria is selected as a standard to calculate capacity. It was found that the helix angle model predicts a more conservative bending capacity with low internal pressure when compared to the model without a helix angle. At higher bore pressures, the roles reverse and the bending capacity predicted by the helix angle model is less conservative than the non-helix angle model. This disparity is diminished as external tension is increased.