Standard Practice for Evaluating Flat-Faced Gasketed Joint Assemblies

Gasket compressions produced by bolt loads in a flanged joint are important in the application engineering of a joint assembly. They are related to the ability of a gasket to seal, to maintain tightness on assembly bolts, and to a variety of other gasket properties that determine the service behavior of a joint assembly. Thus, being able to determine the degree of compression in a gasket under the bolt loading will permit one to make qualitative predictions of the behavior of a joint assembly when it comes in contact with the application or service environment. With the plug test, bending of a flange facing between bolt centers can be measured; however, in a few highly distortable flanges the maximum bending between bolt centers may not be detected.

The variation in gasket compressions at selected points in a flat-face joint assembly reveals the degree of flange distortion or the ability of the flange to distribute satisfactorily the compressive forces from bolt loads throughout the gasket.