Pretightening Range of Flange Joints in Pipeline Considering Nonlinear Compression Resilience of Gaskets

Abstract

The analytical pretightening force range of flange joints in a pipeline was deduced based on the allowable gasket stress and flange rotation angle considering the nonlinear compression resilience behavior of gaskets. Relationships between pretightening force and working pressure or gasket stress were established. The results show that the corresponding relationship between bolt pretightening stress and gasket stress under different internal pressures is different due to the nonlinear compression resilience performance. Moreover, the region enclosed by the minimum bolt load under initial pretightening, the minimum bolt load under working pressure, and the maximum bolt load corresponding to the limit flange rigidity in the diagram of bolt pretightenting force versus working pressure can be treated as the effective sealing region for flange joints in a pipeline. Additionally, the bolt pretightening range can be defined as [max{SbA,SbB}, SbC] in a diagram of bolt pretightenting stress versus gasket stress. These are simple and effective strategies to define a reasonable pretightening range of flange joints for engineering design and assembly in a pipeline system.