How Does a Ring Joint Gasket Work?

Ring joint gaskets work by creating a seal between the two flange faces under the compressive loading of the flange bolts. When under load the gasket deforms and flows into the microstructure irregularities of the flange groove in which the RTJ gasket sits. This creates a very tight metal-to-metal seal. Since its material can only flow so much into the flange mating surface, attention must be given to the flange groove and gasket to make sure there are no defects that will cause the sealing mechanism to fail. Imperfections could include scratches, dents, rough surface finish, or out-of-tolerance dimensions. Allowable defect limits can be described by standards; API6A, ASME B16.5, ASME B16.47 Series A, or BS1560. If flange defects are found a flange-facing tool can be used to remove some material from the face to bring it back into tolerance.