Application of Plastic Region Bolt Tightening to Flange Joint Assembly: Behavior of Compact Flanged Joint Subjected to Thermal Load

Abstract

In the past study the plastic region tightening has been applied to the compact flange joint and its advantages have been demonstrated. However, behavior of the compact flange joint subjected to the thermal load is not investigated. There are reduction of the gasket stiffness, the flange rotation, and difference in the thermal expansion among the members making up the flange joint. It is well known that these problems cause the change in axial bolt force. The present paper describes the behavior of the compact flange joint subjected to the thermal load under the plastic region tightening. Since there is a difference in temperature between the compact flange joint and the bolts, the axial bolt force increases as the temperature of the internal fluid increases. The additional axial bolt force is positive when the thermal loads are applied to the compact flange joint. However, the additional axial bolt force was approximately 3% of the bolt yield force at maximum and the bolt had a sufficient margin for the allowable limit. Additionally, the load factor depends on the change in the elastic modulus due to change in temperature of the internal fluid.