Kaxite BX ring joint gasket is a metal-to-metal sealing ring machined from a solid forging on CNC equipment to ASME B16.20 and API 6A. The BX profile is pressure-energised and carries a pressure relief vent hole drilled through the ring face, so that trapped pressure between the ring and the groove can equalise during make-up. BX rings are used on API 6BX flanges and 16BX hubs for wellhead, Christmas tree, choke manifold and high-pressure well service where the pressure class runs from 5,000 PSI up to 20,000 PSI. The BX series sits above RX in the API family; compare the two on the RX ring joint gasket page, or see the full range on the ring joint gaskets page.
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| Dimension | Tolerance | Inspection method |
|---|---|---|
| Width of ring | +0.20 / -0.00 mm | Calipers, three positions per ring |
| Height of ring | +0.20 / -0.00 mm | Height gauge against the BX table |
| Outside diameter | +0.00 / -0.15 mm | Outside micrometer |
| Hole size (vent hole) | ±0.5 mm | Pin gauge |
| Groove angle | 23° ± 0° 15' | Angle gauge, comparator |
| Radius | 8%–12% of ring height | Radius gauge, visual comparator |
| Hardness | Per material specification | Portable hardness tester, batch record |
| Surface condition | Free of cracks, pits, tool marks and rust | Visual, 100% inspection |
Dimensional records and hardness records travel with every batch. Third-party dimensional inspection is available on request for wellhead and manifold packages.
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| Material group | Grade | Typical hardness (HB) | Notes |
|---|---|---|---|
| Carbon and soft iron | Soft iron, low carbon steel | 90 / 120 | Standard for non-sour, lower-alloy BX service |
| Stainless steel | SS304, SS304L, SS316, SS316L, SS321, SS347, SS410, 316Ti | 160–170 | Chloride, process and moderate corrosive service |
| Duplex and 3CR12 | Duplex, 3CR12, 310 | Per grade | Chloride stress and elevated temperature options |
| Nickel alloys | Monel 400, Nickel 200, Inconel 600, 625, 718, X-750, Incoloy 800, 825 | 150 typical | High temperature, sour, and aggressive media |
| Specialty alloys | Hastelloy B2, Hastelloy C276, titanium, zirconium, copper | Per grade | Seawater, strong acids and exotic process media |
| Non-metal | PTFE (inner rings only) | — | Only used for the inner ring component, never as the BX sealing ring body |
The ring hardness must stay below the flange groove hardness; if the ring is harder than the groove, the groove deforms instead of the ring and the joint leaks. Sour service is governed by NACE MR0175 / ISO 15156, and the final grade depends on H2S partial pressure, chloride content and temperature. Send the media data and Kaxite will return a matching hardness and alloy.
| Feature | R-oval / R-octagonal | RX | BX (this page) |
|---|---|---|---|
| Flange family | ANSI B16.5, ASME B16.47 Series A | API 6B | API 6BX and 16BX hub only |
| Pressure ceiling | Class 150 – 2,500 | Up to 5,000 PSI | 5,000 – 20,000 PSI |
| Vent hole | No | No | Yes — pressure relief hole on the ring face |
| Interchangeability | R-oval and R-octagonal are interchangeable on the same groove | Interchangeable with R-oval / R-octagonal on API 6B | Not interchangeable with R or RX |
| Typical service | Refinery, chemical, general process | Wellhead, manifold, 6B high-pressure | 6BX wellhead, 20,000 PSI well service, choke manifold |
See the oval ring joint gasket and octagonal ring joint gasket pages for the R profiles, and the API ring joint gasket page for the full API family.
Kaxite Sealing machines BX ring joint gaskets in Ningbo, Zhejiang, on the same CNC line as the R-oval, R-octagonal and RX rings, so a mixed wellhead package can be shipped from one facility with one set of certificates. Sizes follow the ASME B16.20 BX table; non-standard groove drawings and special alloy rings are quoted from drawings. Free samples are available for qualified projects, with the mill certificate attached to the sample shipment. Factory visits and video audits are welcome by appointment; ISO 9001 certificate details are available on request.
Request a BX ring joint gasket quote
Tell us flange size, API 6BX or 16BX pressure class, BX number, material grade and working media. Free samples and full dimensional records available for qualified projects.
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No. 432 Zhenhai Middle Road, Luotuo Street, Zhenhai District, Ningbo City, Zhejiang China
