Octagonal gasket is a kind of Ring joint gasket with octagonal cross-section shape made of metal materials by forging, heat treatment and machining .It has the function of radial self-tightening seal. It is a kind of standard R-type Ring joint gasket. Its working principle is the contact between the backing sheet and the inside and outside (mainly the outside side) of the flange ladder groove, and the sealing effect is formed by pressing.
The octagonal Ring joint gasket is installed in the ladder ring groove on the flange surface. When the connecting bolts are tightened, they are tightly attached to the upper and lower ladder groove under axial compression, resulting in plastic deformation, forming an annular sealing belt, and establishing the initial seal.
After boosting, the Ring joint gasket expands radially under the action of medium pressure. The gasket is more closely attached to the inclined plane of the trapezoidal groove, resulting in self-tightening effect. However, the increase of medium pressure will also deform the flange and connecting bolt, resulting in the relative separation between the sealing surfaces and the relative decrease of gasket sealing ratio. Therefore, the ring gasket can be considered as a semi self-tightening seal.
Octagonal Ring joint gasket and flange groove match is mainly face contact, compared with oval ring gasket, although it is not easy to close with flange groove, but it can be used again, and because the section is composed of straight lines, it is easy to process. At the same time, octagonal metal ring gasket material should be selected, and its hardness should be lower than 15 ~ 20hb of flange face.
Characteristics Octagonal Ring joint gasket
1. High temperature and high-pressure resistance, suitable for high pressure flange;
2. The sealing is durable and reliable.
3. Adapt to the working condition of pressure and temperature fluctuation.
Scope of application of Octagonal Ring joint gasket
Usually used in high temperature and high-pressure steam, gas, solvent pipe flange, tower trough, pressure vessel, high speed joint surface, high temperature and high-pressure valve, cover.
Octagonal Ring joint gasket originated from the United States. It was first used in the field of boiler in the 1920s. Later, it was used to seal manhole cover, autoclave, and other windows. Later, it was paid more attention in oil filed production and refining industry. With the increase of steam power plant temperature and pressure, the use of metal ring gasket is more and more widely.