Oval and octagonal Ring Type Joint (RTJ) gaskets are high-pressure, metallic sealing rings designed for ASME B16.5, B16.20, and API 6A flanges, used extensively in oil, gas, and petrochemical industries. They create a metal-to-metal seal through plastic deformation when tightened, with octagonal offering better efficiency and oval providing better compatibility.
Key Features and Description
Design & Function: Both types seal by seating in a groove, ensuring high-pressure integrity. The octagonal ring has a higher sealing contact surface and is generally preferred for its superior efficiency, while the oval is often used in older, rounded-bottom grooves.
Interchangeability: While they have similar functions, an octagonal ring cannot always be used in some pre-existing, older installations designed for oval gaskets.
Materials: Gaskets are manufactured with a lower hardness than the flange material (usually by at least 50 BHN) to ensure the gasket deforms rather than the flange groove. Common materials include soft iron, low carbon steel, and stainless steel (304, 316, 347).
Pressure Ratings: Standard oval/octagonal gaskets are designed for pressures up to 5,000 PSI, while specialized variations (e.g., BX) can handle up to 20,000 PSI.
Standards: These gaskets are manufactured in accordance with API 6A and ASME B16.20 standards.