Design considerations for rectangular bolted full face flanged joints for surface condensers

Abstract

Rectangular bolted full face flanged joints are widely used in surface condensers within the power generation industry including the nuclear one. In order to design these components, it is necessary to analyze the flanged joint from the point of view of structural strength and leak tightness. This work presents an analytical procedure applied to a rectangular bolted flange to determine the thickness of the flange, the bolt stresses and leak tightness conditions. First, the proposed analytical procedure is validated by comparing its results with those from finite element analysis (FEA) using non-linear approach considering the behavior of the materials, gasket and contacts. In addition, the proposed procedure is applied to the design of a rectangular flanged joint of a steam surface condenser using two different gaskets: compressed non-asbestos fiber gasket and NBR elastomer gasket. The obtained results show a better performance of the NBR elastomer gasket in comparison with compressed fiber gasket: better sealing condition, reduction of the flange thickness and reduction of the bolt stresses. It is important to highlight there are practically no references of procedures for design of non-circular full face flanged joints.