Enhancing Thread Load Distribution Methodology

Abstract The thread load distribution methodology outlined in ASME Section VIII, Division 3, E-220, “Thread Load Distribution,” provides guidance for determining the load distribution in threaded end closure connections [1]. However, it lacks explicit direction on how to incorporate the thread angle when applying loads in Finite Element Analysis (FEA). This omission can lead to inaccuracies in the calculation of both horizontal and vertical force components within threaded joints, potentially resulting in misrepresentations of load distribution and, ultimately, the performance of pressure vessels and other equipment. This paper proposes an enhancement to the existing methodology by integrating the thread angle into the load distribution calculation. By explicitly considering the angular orientation of the threads, the proposed approach improves the accuracy of force balance, both vertically and horizontally, within threaded connections. This refinement ensures a more realistic simulation of load behavior, capturing the full impact of thread geometry on load transfer. The paper explores the theoretical foundation of this enhanced methodology and demonstrates its practical application through numerical examples involving a common thread geometry. This example highlights how the revised approach provides a more precise representation of force distribution across threads, offering engineers a more reliable tool for designing and evaluating threaded joints in pressure vessels and other critical applications.