The ring joint gasket can be used in the range from vacuum to 700 kgf/cm2 for ordinary piping of process lines that are exposed to high temperature/high pressure steam, oil, gases, and solvents as well as high-pressure containers, vessels, and valve bonnets.
Major shapes of the ring joint gasket are ‘oval’ and ‘octagonal.’ The RX and BX types are ideal for high pressure conditions over 700 kgf/cm2.
The flange groove deformation is more significant in the case of oval gaskets than octagonal gaskets. This is because the bolt extendibility creases and the gasket is also deformed as the flange connecting pressure increases, causing the change from the linear contact to the surface contact. Thus, the initial sealing performance is excellent but the gasket deformation is significant on the other hand. As the octagonal gasket involves internal pressure, the pressure in contact with the flange increases up to the point of sealing. Because the surface contact occurs in the early stage of connection, a high level of connecting pressure is required.
It is difficult to judge which type is better when it comes to seal characteristics. In general, however, the octagonal form is common used.
Material | m | y |
---|---|---|
Iron or soft steel | 5.50 | 18,000psi |
Monel or 4%~6% chrome | 6.00 | 21,800psi |
Stainless steels and nickel-base alloys | 6.50 | 26,000psi |
Material | Hardness (Max. HB) | Material | Hardness (Max. HB) | Material | Hardness (Max. HB) |
---|---|---|---|---|---|
Soft iron | 90 | SS321 | 160 | Inconel 600 | 200 |
Low carbon steel | 20 | SS347 | 160 | Inconel 625 | 200 |
SS304 | 160 | 5Cr-1/2Mo | 130 | Inconel 800 | 200 |
SS304L | 160 | Monel | 140 | Inconel 825 | 160 |
SS316 | 160 | Titanium | 160 | Duplex | 230 |
SS316L | 160 | Hastelloy C276 | 180 | Super Duplex | 240 |