Behavior of bolted joints with metal-to-metal contact type gaskets under bolting-up and loading conditions

摘要

A floating-type joint applies the entire bolt load to the gasket to generate sealing contact stress, and is prone to leak due to the bolt load loss. Different with the floating type one, a metal-to-metal contact type joint applies only part of the bolt load to the gasket to achieve seating stress, and applies the additional bolt load to the metal-to-metal contact to compensate for the unloading effects due to internal and external loadings. Due to this advantage, metal-to-metal contact type joints are gradually used in chemical industries, nuclear power industries, etc. A flange joint together with a metal-to-metal contact type gasket forms the metal-to-metal contact type joint studied in this article. A three-dimensional nonlinear finite element model is developed to highlight the complex behavior of the flange joint under bolting-up, pressure loading and thermal loading conditions. Despite the common perception that gasket stress in a metal-to-metal contact type joint stays constant, reduced gasket stress is concluded due to flange rotation and joint thermal expansion.