The Calculation of Foot Bolt Group Connection for Pressure Vessels Under Action of Nozzle Loads

Abstract The computation of bolts in pipe flange connections has received significant attention in engineering practice. However, few studies have systematically been done to compute member stiffness in the design of tie bolts under nozzle loads. This paper focuses on the critical problem of foot bolt group connections in pressure vessels subjected to nozzle loads, particularly when these loads exceed standard requirements. A method based on the translation of spatial force systems is proposed to determine the equivalent loads on bolt groups. Four primary failure modes including faying translation, faying rotation, angle separation, and parallel separation are analyzed, and corresponding calculation procedures are established. Two distinct methods are proposed to further evaluate the bolt group's strength, and calculation examples and contrast analysis are performed to verify their applicability at different development stages.