Ring Gaskets / RTJ-OCT
Octagonal Ring Gasket
High-performance ring gasket with octagonal cross-section as an alternative to oval types. Provides more balanced compression and easier alignment.
Technical Specifications
Key Features
- Octagonal cross-section
- Superior sealing capability
- Controlled contact surface
- Easy alignment
- Long service life
- High pressure compatibility
Applications
- Power generation plants
- Chemical process lines
- Steam piping
- Boiler connections
- High temperature service
- Turbine systems
Dimension Table
| Size | Outside Diameter (mm) | id | Width (mm) | Groove |
|---|---|---|---|---|
| 1" | 60.5 | 35.1 | 11.2 | OCT-11 |
| 2" | 79.2 | 53.8 | 11.2 | OCT-11 |
| 4" | 127.0 | 101.6 | 11.2 | OCT-11 |
| 8" | 200.2 | 174.8 | 11.2 | OCT-11 |
| 12" | 269.9 | 244.5 | 11.2 | OCT-11 |
Technical Notes
- 01Used as an alternative to oval rings.
- 02Provides better alignment.
- 03Balanced compression force.
- 04Performs well at high temperatures.
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.
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