Comparative study of the behaviour of conventional gasketed and compact non-gasketed flanged pipe joints under bolt up and operating conditions

Bolted flanged joints comprise an assembly of a number of important individual components, which are required to perform well together in service. The ideal requirement for a bolted flange joint is a 'zero-leak' condition. However, whilst recommended design procedures for bolted flange joints are available in international codes and standards, leakage problems are still faced by industry. These are common in both normal operating (internal pressure loading) and critical event conditions. The drive is, therefore, to find a flange joint assembly, which provides 'zero-leak condition' and requires little or no maintenance and handling. Considerable investigation in the area of optimised bolted joints has been in progress for the past 10 years comparing traditional gasketed joints and 'compact non-gasketed' joints, using both analytical and experimental approaches. In this present study, two-dimensional non-linear finite element studies have been performed for both gasketed and non-gasketed bolted flange pipe joints. Based on the stress results for the flange and the bolt and the flange rotation/displacement, compact non-gasketed flange joints are shown to be a viable and preferable alternative to the conventional gasketed flange joints. Recommendations are made for a best-fit flange model for static load conditions with 'zero-leak' sealing in a flange joint.