Ring Joint Gaskets — R, RX & BX

What is a Ring Joint Gasket?

A ring joint gasket is a precision-machined metal ring that sits in a groove on each flange face. When bolts are tightened the ring deforms slightly into the groove walls, forming a metal-to-metal line seal. The ring must be softer than the flange groove, typically 15 to 20 HB lower, so the ring deforms and not the groove. Ring joints are used for high pressure, high temperature and wellhead service where a soft gasket could blow out.

Key features

• Type R oval and octagonal for ASME B16.5, B16.47 Series A and API 6B flanges
• Type RX pressure-energised rings for API 6B flanges
• Type BX rings with pressure-balance hole for API 6BX flanges
• Materials from soft iron to nickel alloys, hardness controlled
• Ring number and material stamped on each ring

Specification

Applications

• Class 900–2500 process flanges
• Wellhead and Christmas tree equipment
• High-pressure gas and hydrocracker service
• High-temperature steam and refinery piping

R vs RX vs BX ring gasket

Type R rings (oval or octagonal) are the general ring joint for ASME B16.5 / B16.47 and API 6B flanges. RX rings fit the same grooves as octagonal R but have an asymmetric profile that uses internal pressure to improve sealing. BX rings are for API 6BX flanges only, with a pressure-balance hole, and are not interchangeable with R or RX.