The octagonal metal ring gasket is installed in the trapezoidal ring groove on the flange surface. When the connecting bolt is tightened, it is axially tightened and the upper and lower trapezoidal grooves are tightened, resulting in plastic deformation, forming an annular sealing belt and establishing an initial seal. After boosting under the action of medium pressure, the ring gasket radially expands. The gasket and the inclined surface of the trapezoidal groove are more tightly attached, resulting in a self-tightening effect.

The rise of the medium pressure will also deform the flange and the connecting bolts, resulting in a relative separation between the sealing surfaces, and the gasket sealing ratio is relatively reduced. Therefore, the ring gasket can be considered as a semi-self-tight seal, and the octagonal metal ring gasket and the The matching of the flange groove is mainly surface contact. Compared with the oval ring gasket, it is not easy to get close to the flange groove, but it can be used again, and it is easy to process because the cross section is composed of straight lines.

At the same time, the hardness of the octagonal metal ring gasket should be lower than that of the flange surface. Application range of octagonal metal ring gasket: usually used in high temperature and high pressure steam, gas, solvent pipe flange, tower tank, pressure vessel, high speed joint surface, high temperature and high pressure valve cover.

Wellhead installation in oil and natural gas media and sealing metal ring gaskets on Christmas trees were first used in boilers in the 1920s, and later used for manhole covers, sealing of other windows in autoclaves, and later in petroleum and oil refining. attention in the industry. As the temperature and pressure of steam powered installations increase, the usefulness of metal ring gaskets becomes more and more common.