The hardness of the ring gasket should always be 30% lesser than the hardness of the flanges to prevent flange deformation
Dimensions and Tolerances for Ring Joint Gaskets and Grooves are covered in API 6A and ASME B16.20.
Ring type joint gaskets(RTJs) are designed for high pressure applications. They are available in a variety of forms to suit different flange formats . RTJs can be used for very high and/or fluctuating pressures (up to 1500 bar), depending on the profile selected. Material selection determines use for high temperatures (up to i000°C) and in aggressive media. To ensure proper sealing the surfaces of contact between the gaskets and flange have to be carefully processed. The small sealing area and high contact pressure results in excellent sealability.
| Common Materials |
| Material | HB Hardness | Temperature Limitations | Identification |
| Soft Iron | 90 | -60 to +400 °C | D |
| Low carbon steel | 120 | -40 to +500°C | S |
| 4%-6% Cr ½% Mo:F5 | 130 | -125 to +500°C | F5 |
| Stainless steel 304/304L | 160 | -250 to +650°C | S304 or 304L |
| Stainless steel 316/316L | 160 | -196 to +800°C | S316 or 316L |
| Stainless steel 321 | 160 | -250 to +870°C | S321 |
| Stainless steel 347 | 160 | -250 to +870°C | S347 |
| Stainless steel 410 | 170 | -20 to +500°C | S410 |
| Inconel 625 | – | 1000°C | 625 |
| Incoloy 825 | – | 1000°C | 825 |
| Hastelloy C-276 | – | 1000°C | C-276 |
| Duplex | – | 800°C | S31803 |
| Titanium | – | 540°C | TI |
In order to reduce turbulent flow in adjoining flanges and prevent gasket/flange erosion Goodrich Gasket offers SPECIAL R, RX type joints with PTFE inserts. We also offers Nitrile Rubber coated ring joint gaskets (RTJ gasket) used in pressure testing applications and as a protection for flange grooves and surfaces. Ring joint flanges with different ring groove diameters are sealed by Transition Ring joints, a different size and same PCD combination rings. Blind Ring joints, a standard ring joint with integral solid metallic centers blanks off flanges and pipe work. Flange Guards of closed cell neoprene foam readily compress under load protecting outside diameter of Ring joints in corrosive environments.
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