RX Ring Joint Gasket

RX Ring Joint Gasket — Self-Energizing Metal Seal for API 6B Flanges up to 15,000 PSI

RX Ring Joint Gasket — machined to API 6A / ASME B16.20, pressure-energized for high-pressure wellhead and process service.

The RX ring joint gasket is a pressure-energized, metal-to-metal sealing ring developed from the standard octagonal R gasket. Its 23° outer bevel and pressure-responsive cross-section let line pressure increase the sealing contact force, which is why RX rings are specified for high-pressure wellhead, Christmas tree and manifold connections in API 6B flanges.

What Is an RX Ring Joint Gasket?

An RX ring joint gasket is a solid machined metal ring with a modified octagonal cross-section, manufactured to API 6A and ASME B16.20. It seals by metal-to-metal contact between the ring and the machined grooves of the mating flange faces. Unlike a sheet gasket, it carries no compressible filler — sealing starts as an initial line contact and develops into a controlled wedging action as the bolts are tightened.

The defining feature of the RX design is that it is pressure energized in the radial direction. The geometry of the ring guides the contained fluid pressure onto the sealing faces, so that as system pressure rises, the ring is pressed harder against the groove walls. This self-energizing effect is why RX gaskets hold tightness well beyond the range where a plain octagonal ring would begin to leak, and why they are specified for wellhead and process duties up to 15,000 PSI.

Because the seal is entirely metallic, RX gaskets suit the full temperature envelope of the selected alloy — from cryogenic service around −200 °C up to approximately +650 °C for high-alloy grades — and resist aggressive media including sour gas (H2S), CO2, condensate and produced water.

RX vs. R (Oval / Octagonal) vs. BX vs. SRX / SBX — Which Ring Do You Need?

All ring joint gaskets seal on the same principle, but the cross-sections are not interchangeable between flange types. Confirm the correct series before ordering:

Groove sealing surfaces must be finished to 63 µin (1.6 µm) Ra or smoother and be free of ridges, tool marks and chatter. Ring hardness must always be lower than flange hardness to protect the groove from deformation.

Material & Hardness Selection

Material choice is driven by the process medium, operating temperature and the hardness of the mating flange. Our technical team will confirm the correct grade against your service conditions before production.

Every ring is marked with size, material grade, heat number and standard, and is supplied with an EN 10204 3.1 material certificate so that your QA department can trace the heat back to the mill.

Typical Applications

• Oil and gas wellheads, Christmas trees and production manifolds (API 6B)
• High-pressure gathering lines, flowlines and test lines
• Refinery and petrochemical process piping with ring joint flanges
• Valve bonnets and bodies with API 6B ring grooves
• Offshore platforms and subsea wellhead / tree equipment (SRX, SBX)
• High-pressure gas storage, hydrogen and CO2 handling systems
• Power plant and high-temperature steam service with alloy rings

Installation & Bolting Guidance

Ring joint gaskets are a one-time-use sealing element. Correct groove condition and controlled bolt-up are what deliver a leak-free joint:

• Inspect the groove before assembly — it must be clean, dry and free of scratches, burrs, corrosion or old gasket residue.
• Verify the ring number, material and hardness; ring hardness must be lower than flange hardness.
• Apply a thin film of the specified rust-preventive oil or lubricant. Do not pack the groove with grease.
• Seat the ring squarely in the groove by hand — never hammer on the sealing face.
• Tighten bolts in a cross / star pattern in three to four incremental passes to the specified torque.
• Do not re-use a gasket that has already been compressed. Replace it on every break-out.

Need the torque sequence for your flange size and pressure class? Send us the flange specification and we will return the recommended bolt-up procedure.

Why Buy RX Ring Joint Gaskets from Kaxite Sealing

We are the manufacturer, not a trading company

Ningbo Kaxite Sealing Materials Co., Ltd. operates its own machining, heat treatment and inspection facility in Ningbo, China. RX rings are turned, marked and measured in-house, which means we control lead time, tolerances and material traceability directly — and we can quote a genuine factory price.

Quality control on every batch

• Incoming raw material verified by spectrometer analysis before production
• In-process dimensional checks on groove angle, ring height and diameter
• 100% final inspection with recorded measurements before packing
• Hardness tested against API 6A / ASME B16.20 requirements
• EN 10204 3.1 material certificate issued with each shipment
• Third-party inspection (SGS, BV, TUV) arranged on request

Engineering support, not just order taking

We supply ring joint gaskets to oil and gas, petrochemical, power and marine customers worldwide, including OEM and ODM programmes. Our technical sales engineers will confirm the correct RX number, material and hardness for your flange, medium and temperature before you commit to a purchase order.

Terms that suit project procurement

• No minimum order quantity on stock sizes — sample and trial orders welcome
• Stock sizes ship in 7–15 days; custom materials and non-standard sizes in 15–25 days
• Export packing with rust-preventive protection, carton plus plywood case or pallet
• 24 hours × 7 days after-sales response

What to Send for an Accurate RX Gasket Quotation

Frequently Asked Questions