Evaluation and Completion the Design Methods of Pressure Vessels Flange Joints

Abstract

We have provided a comparative analysis of the current international computing standards (European Standard EN 13445-3; ASME-Code, Section VIII, Division 2; British Standard (PD 5500: 2009)) that take into consideration only the static loading of flanges and bolts, if the temperatures of the flanges, bolts and sealing gasket are equal to each other and lower than creep temperature. The paper has put forth relations for completion the calculation method for flange joints in situations not taken into consideration by standards, namely: -static loading if flange temperature and bolt temperature are different; -thermal transient loading; -creep stress; -fatigue loading in the general case of a sequence of blocks of normal stresses. Furthermore, relationships have been proposed for the calculation of the maximum allowable difference between a flange and a bolt so as to ensure both the tightness and the mechanical strength of the flange joint.

A Method Based on the Principle of Critical Energy for Calculating Flange Joints

“…where F(ΔT) is calculated with the relation given in works [8][9][10]. The total force in the bolts in service, becomes,…”

“…. (10) d. Flange stress loading. First (Fb,0), the force in the bolts is applied during pre-clamping -the internal pressure is introduced, the stress loading caused by it emerges, which generates the bending moment (Mb,H).…”

“…The maximum flange bending stress can be calculated with some relationships to be found in works [10][11][12][13]. For example, if:…”