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Quick Answer: A custom ring joint gasket is a metallic RTJ gasket produced to a non-standard ring number, dimension, material, or cross section. Buyers should confirm the flange standard, ring number, groove dimensions, material, and hardness before ordering. CORASEALS can quote a custom ring joint gasket once the flange standard, ring number, material, and required quantity are provided.
RTJ stands for ring type joint. A custom ring joint gasket is not a rubber or sheet gasket. It is a solid metallic gasket that fits into RTJ grooves on ASME, API, and other high pressure flanges. CORASEALS supplies custom ring joint gaskets within its industrial gasket range. Standard ring joint gaskets follow ASME B16.20, API 6A, or an equivalent flange specification. A custom ring joint gasket becomes necessary when a standard ring number does not match a non-standard groove, when the flange surface is worn or repaired, or when the service medium requires a special material.
Most RTJ flanges accept standard R, RX, or BX ring numbers. A custom ring joint gasket is needed in several situations. The flange may be manufactured to a non-standard pitch diameter or groove width. The flange may have been remachined and no longer matches the original ring number. The service may require a material that is not easily available in a standard size. The gasket may need a special coating, a controlled hardness range, or a non-standard oval or octagonal section.
For these cases, the buyer should not guess the size. Send the flange standard, nominal pipe size, pressure class, and groove measurements. CORASEALS can cross-check the dimensions against ASME B16.20, API 6A, or the flange drawing.
R ring gaskets are used in ASME flanges and some API flanges. They have oval or octagonal cross sections. RX ring gaskets have a pressure-energized geometry and are used in some API high pressure flanges. BX ring gaskets are used in API 6BX flanges with pressure ratings up to 20,000 psi depending on the flange design. Each ring type has different dimensional rules and tolerances.
Do not assume that similar ring numbers are interchangeable. R, RX, and BX gaskets have different geometry. Always confirm the ring type from the flange drawing, flange marking, or groove inspection.
Material selection depends on the fluid, temperature, pressure, and flange groove hardness. Common ring joint gasket materials include:
ASME B16.20 defines material markings and hardness limits for standard ring joint gaskets. The gasket hardness must be lower than the flange groove hardness. The lower hardness allows the gasket to deform and seal without damaging the flange.
A custom ring joint gasket is not specified by ID, OD, and width in the same way as a rubber gasket. The critical dimensions are the ring number, pitch diameter, width, height, and oval or octagonal cross section. The pitch diameter is measured at the center of the gasket ring cross section. The groove dimensions must be compared with the gasket dimensions to confirm the correct fit.
If a ring number is unknown, provide the groove OD, groove width, groove depth, and pitch diameter from the flange drawing or a measurement report. A hand measurement of a used gasket alone is not enough because a crushed gasket may not reflect the original dimension.
Send the following information for a custom ring joint gasket quote:
Send the flange standard, ring number, material, and dimensions to CORASEALS for a custom ring joint gasket quotation. If a flange drawing or sample photo is available, include that file with the inquiry.
A standard RTJ gasket matches a published ring number in ASME B16.20 or API 6A. A custom ring joint gasket is made to a special pitch diameter, groove dimension, material, hardness, or cross section when a standard ring number is not suitable.
Inconel 625 is commonly specified for sour gas and seawater service. The final material must meet the requirements of the applicable service standard, such as NACE MR0175 or ISO 15156. Send the H2S partial pressure and chloride content to confirm the selection.
The flange type determines the ring type. R ring gaskets are used in ASME and some API flanges. RX ring gaskets are used in API high pressure flanges. BX ring gaskets are used in API 6BX flanges. Check the flange marking and drawing first.
The gasket hardness must be lower than the flange groove hardness. The lower hardness allows the gasket to deform under bolt load and fill the groove. A gasket that is too hard can damage the flange seating surface.
Send the ring number, material, dimensions, and required quantity. CORASEALS can quote custom ring joint gaskets for single replacement pieces, project orders, and regular resupply programs.
For a custom ring joint gasket quote, send the gasket type, material, pitch diameter, groove dimensions, pressure, temperature, flange standard, drawing, sample photo, and required quantity.
