Development of a New Bolt Spacing Formula

Abstract

Bolted flange joints are extensively used to connect pressure vessels and piping equipment together. They are simple structures that offer the possibility of disassembly. However, they often experience leakage problems due to a loss of tightness as a result of a nonuniform distribution of gasket contact stresses in the radial and circumferential directions. Many factors contribute to such a failure; the flange and gasket stiffness, bolt spacing or a combination of them are to name a few. In our recent papers, the effect of bolt spacing was investigated based on the theory of circular beams on linear elastic foundation and on the theory of rings on nonlinear elastic foundation. The variations of the contact stress between bolts were of a concern. This paper is an extension of the work in which an analytical solution, based on the theory of circular beams resting in a linear elastic foundation, has been developed to determine a formulae for flange bolt spacing. The relationship between bolt spacing, gasket compression modulus, and flange thickness is deduced from an analysis that considers a maximum tolerated gasket contact stress difference between any two bolts.