Kaxite R-octagonal ring joint gasket is a metal-to-metal sealing ring CNC-machined from solid forging to ASME B16.20. It fits the same octagonal groove as an R-oval ring of the same nominal size, but the octagonal cross-section provides a better sealing line on modern flanges because the 23° faces make continuous contact across the ring. That makes the R-octagonal ring the default choice for ASME B16.5, ASME B16.47 Series A and API 605 flanges, Class 150 to Class 2500, on refinery, petrochemical and high-pressure process piping. Compare the R-oval profile on the oval ring joint gasket page, or see the full R, RX and BX range on the ring joint gaskets page.
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| Dimension | Tolerance | Inspection method |
|---|---|---|
| Width of ring | ±0.2 mm | Calipers, three positions per ring |
| Height of ring | ±0.4 mm | Height gauge against the ASME B16.20 table |
| Pitch diameter | ±0.18 mm | Inside and outside micrometers |
| Groove angle | 23° ± 0.5° | Angle gauge, comparator |
| Surface condition | Free of cracks, pits, tool marks and rust | Visual, 100% inspection |
| Hardness | Per material specification | Portable hardness tester, batch record |
| Ring flatness | Within 0.1 mm at the sealing face | Surface plate and dial gauge |
The ring hardness must stay below the flange groove hardness; if the ring is harder than the groove, the groove deforms first and the joint leaks. Dimensional records and hardness records travel with every batch. Third-party dimensional inspection is available on request for refinery and petrochemical packages.
Soft iron (90 HB), low carbon steel (120 HB). The default grades for Class 150–600 non-sour, non-oxidising service where the flange is carbon steel.
SS304, SS304L, SS316, SS316L, SS321, SS347, SS410, 310, 316Ti, 3CR12 and duplex, 160–170 HB. SS304 and SS316 are the everyday stainless grades; SS347 is used for high-temperature cycling; SS410 suits mild wear resistance.
Monel 400, Nickel 200, Inconel 600, Inconel 625, Inconel X-750, Incoloy 800, Incoloy 825, 150 HB typical. Sour service follows 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 grade.
Hastelloy B2, Hastelloy C276, titanium, zirconium, copper, and PTFE (inner rings only, never as the R-octagonal sealing body). For seawater, strong acids, high-purity processes and other exotic media.
The R-octagonal profile covers the same flange range as R-oval. For API 6B flanges use RX; for API 6BX flanges and 16BX hubs use BX. See the RX ring joint gasket and BX ring joint gasket pages for those families, or the API ring joint gasket page for the full API range.
Kaxite Sealing machines R-octagonal ring joint gaskets in Ningbo, Zhejiang, on the same CNC line that produces R-oval, RX, BX and lens rings, so a mixed project package can be shipped from one facility with one set of certificates. Standard sizes follow the ASME B16.20 table. Non-standard groove dimensions 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. For soft-gasket alternatives on non-RTJ flanges, compare the spiral wound gasket range.
Request an R-octagonal ring joint gasket quote
Tell us flange size, pressure class, ring 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
