摘要：Threaded connections applied for high pressurevessel covering must have adequate mechanical strengthand good leak tightness. Often in gasketed flanges the var-iations of internal pressure, temperature and deformationof joined-up elements cause cyclic bending of these ele-ments and threaded connections also [1-7]. Due to the highstress concentrations at thread roots and cyclic loadingthese connections are prone to fatigue failure.Low fatigue strength of important threaded con-nections is defined in accordance with the ASME code [6]or Russian Federation standard [7]. These methods requirethe maximum stress concentration in thread root to beevaluated and this can be done without using a knowledgeof the load distribution along the thread helix.More exact analitical calculation of the stress atthe thread roots can be achieved by direct using of loaddistribution data.
