Ring Gaskets / RTJ-BX
BX Type Metal Ring Gasket
API 6A compliant metallic ring gasket for extreme pressure and temperature service. Used in wellhead and Christmas tree assemblies.
Technical Specifications
Key Features
- Ultra high pressure rated
- API 6A certified design
- Controlled compression
- High temperature resistance
- Corrosion resistant materials
- Offshore certified
Applications
- Wellhead equipment
- HTHP wells
- Offshore platforms
- Acid gas service
- Christmas tree assemblies
- Subsea systems
Dimension Table
| Size | Outside Diameter (mm) | id | Width (mm) | Groove |
|---|---|---|---|---|
| 2-1/16" | 82.6 | 52.4 | 11.2 | BX-150 |
| 3-1/16" | 107.9 | 77.8 | 11.2 | BX-150 |
| 4-1/16" | 133.4 | 103.2 | 11.2 | BX-150 |
| 7-1/16" | 200.0 | 169.9 | 11.2 | BX-150 |
| 9" | 244.5 | 214.3 | 11.2 | BX-150 |
Technical Notes
- 01Single use recommended.
- 02Surface cleaning is essential before installation.
- 03API 6A certification required.
- 04Traceability documentation mandatory.
Other Types
What is a ring joint gasket (RTJ)?
A ring joint gasket (RTJ) is a metallic sealing ring that seals flange connections at high pressure and temperature. The R series (oval and octagonal cross-sections) is made to ASME B16.20; the pressure-energized BX and RX series to API 6A. It is used with RTJ-faced flanges in pressure classes 150#–2500#.
How RTJ gaskets work and which type goes where
The RTJ gasket sits in a trapezoidal groove machined into the flange face; as the bolts are tightened the ring deforms plastically, creating line contact against the groove walls — a metal-to-metal joint that stays tight even at very high pressure. The gasket material is therefore always chosen softer than the flange (soft iron, low-carbon steel, 304/316 stainless, alloys): the gasket must deform, not the groove. The oval section also suits older round-bottom grooves; the octagonal section seals better in modern flat-bottom grooves. RX is a pressure-energized type that fits the standard R groove; BX serves API 6A wellhead and christmas-tree applications up to 20,000 psi. RTJ gaskets are standard in oil & gas, refining and petrochemicals.
Frequently Asked Questions
Oval vs octagonal ring gasket — what is the difference?+
They differ in cross-section: oval also fits older round-bottom grooves; octagonal gives wider contact and a better seal in modern flat-bottom grooves. Both are R-series and share the same groove dimensions (B16.20).
Where are BX ring gaskets used?+
BX is for high-pressure API 6A wellhead and christmas-tree flanges; it provides pressure-energized sealing up to 20,000 psi and fits only BX-grooved flanges.
Can an RTJ gasket be reused?+
No. Sealing relies on plastic deformation of the ring, so a removed gasket has lost its dimensions and surface finish; a new gasket is fitted at every assembly.
How is RTJ gasket material selected?+
The gasket must be softer than the flange so deformation happens in the gasket, not the groove. Typical picks: soft iron/low-carbon steel for carbon steel flanges, 304/316 for stainless systems, suitable alloys for corrosive service.
Related Blog Posts
Technical articles, guides and industry analyses
Flange Types Guide: The 7 Main Flange Types and How to Choose
We explain weld neck, slip-on, blind, socket weld, threaded, lap joint and orifice flanges — their construction, facing types (RF/FF/RTJ), pressure classes and selection criteria.
ASME B16.5 Flange Standard: Comprehensive Technical Guide
Comprehensive technical guide to the ASME B16.5 flange standard. Pressure classes, flange types, material groups, and pressure-temperature ratings explained in detail.