Ring Joint Gasket

A ring joint gasket (RJG) is a precision-machined metallic sealing element designed for use with API ring-type joint (RTJ) flanges. Unlike soft or semi-metallic gaskets, ring joint gaskets achieve a seal through plastic deformation of the metal ring against the machined grooves of mating flanges, making them ideal for extreme pressure and temperature service.

Cross-Section Variants

Ring joint gaskets are manufactured in two standard cross-section profiles:

• Oval Cross-Section: The original RTJ profile, featuring a rounded cross-section that contacts the flange groove along a narrow line. Suitable for both flat-bottom and tapered grooves.
• Octagonal Cross-Section: A flat-sided profile that provides greater contact area with the flange groove, offering improved sealing efficiency. Compatible only with flat-bottom grooves and generally preferred for higher-pressure applications.

Materials

Ring joint gaskets are available in a range of metallic materials selected to match the hardness and corrosion-resistance requirements of the service environment:

• Soft Iron: Low hardness (HB ≤ 90), suitable for general-purpose and lower-alloy flange materials.
• Stainless Steel 304 (SS 304): Good corrosion resistance for general chemical and process applications.
• Stainless Steel 316 (SS 316): Enhanced resistance to chlorides and acidic media, preferred in offshore and marine environments.
• Inconel: Nickel-chromium superalloy offering exceptional resistance to high temperatures, oxidation, and aggressive corrosive media.

Standards Compliance

Ring joint gaskets are manufactured in accordance with internationally recognised standards to ensure dimensional accuracy and interchangeability:

• API 6A: Specification for wellhead and Christmas tree equipment, governing ring groove dimensions and gasket hardness requirements.
• ASME B16.20: Metallic gaskets for pipe flanges — ring-joint, spiral-wound, and jacketed, covering dimensional and material requirements for RTJ gaskets used with ASME flanges.

Pressure Ratings

Ring joint gaskets are rated for use across the full range of ASME pressure classes, from Class 150 through to Class 2500, as well as API pressure ratings (2000, 3000, 5000, 10000, 15000, and 20000 psi working pressure). Their all-metal construction makes them the preferred choice for the most demanding high-pressure, high-temperature (HPHT) applications.

Typical Applications

Ring joint gaskets are widely used across industries where reliable sealing under extreme conditions is critical:

• Oil and gas exploration and production (wellheads, Christmas trees, manifolds)
• Petrochemical and refinery piping systems
• High-pressure steam and process pipelines
• Subsea and offshore equipment
• Power generation and industrial process plants

Installation Notes

Correct installation is essential to achieve a reliable seal with ring joint gaskets:

• Inspect flange grooves for damage, corrosion, or tool marks before installation. Grooves must be clean and free of debris.
• The gasket hardness must always be lower than the flange groove hardness to ensure proper plastic deformation and sealing.
• Ring joint gaskets are single-use components and must never be re-used after a joint has been made up and broken.
• Apply bolt torque in a cross-pattern sequence to ensure even seating of the gasket in the groove.
• Verify the ring number (R, RX, or BX designation) matches the flange groove specification before assembly.