Standards
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 925 Rings (UNS N09925)
Seamless rolled rings, forged rings, machined rings — wellhead spool rings, RTJ gaskets, flange rings
Incoloy 925 rings (UNS N09925) are circular forged components produced either by ring rolling (seamless ring up to 4 m OD), open-die ring forging (smaller diameters with simpler tooling), or machined-from-disc forging. Rings serve five distinct functions in oilfield + pressure-equipment service: (1) RTJ (ring-type-joint) gaskets per API 6A / ASME B16.20; (2) wellhead spool gasket rings; (3) flange ring blanks (rough rings machined into flange forgings); (4) bearing rings + retainer rings for rotating-equipment service; (5) tube-sheet retaining rings in heat exchangers. The seamless rolled-ring process is the preferred manufacturing route for high-load oilfield service because it gives circumferential grain flow that aligns with the ring's principal hoop stress, resulting in superior fatigue + burst strength compared to machined-from-plate or welded-ring alternatives. TorqBolt manufactures Incoloy 925 rings in OD 50 mm to 4000 mm, wall thickness to 200 mm, in the solution-annealed and aged condition with hardness controlled within the 35 HRC NACE MR0175 sour-service cap.
Need Incoloy 925 rings? Email info@torqbolt.com with OD × ID × height, ring type (RTJ / spool / flange / bearing / retainer), quantity, applicable standards. WhatsApp +91-22-66157017.
Ring Variants Manufactured
| Variant | Description | Use |
|---|---|---|
| Seamless rolled ring | Hot-rolled on ring-rolling mill from preform billet; circumferential grain flow | Wellhead spool rings, large flange blanks, bearing races |
| RTJ gasket ring (R / RX / BX) | Machined ring per API 6A / ASME B16.20 dimensional spec; oval (R) / octagonal (RX) / pressure-energized (BX) | API 6A wellhead + Christmas tree flange sealing |
| Forged ring (open-die) | Hot-forged ring from billet; near-net shape with downstream machining | Smaller-volume custom rings; compact-flange retainers |
| Machined ring (from disc forging) | Bored and faced from solid disc forging | Small ID / OD ratio rings; precision tolerance |
| Welded ring | Plate rolled into ring + welded longitudinal seam (per welding spec) | Lower-cost large-diameter non-critical service |
RTJ Gasket Ring Standard Sizes
Per API 6A / ASME B16.20, RTJ gaskets in Incoloy 925 are commonly supplied in R-series (oval), RX-series (octagonal), and BX-series (pressure-energized) profiles, ring sizes coded by R-number indicating flange + pressure class. Common sizes:
| R-number | Flange Size + Class | OD × ID × H (R-oval) |
|---|---|---|
| R-20 | 1-13/16" 5K wellhead | 2.84" × 1.86" × 0.49" |
| R-24 | 2-9/16" 5K wellhead | 3.81" × 2.84" × 0.49" |
| R-26 | 2-9/16" 10K | 3.94" × 2.84" × 0.59" |
| R-37 | 4-1/16" 5K | 5.69" × 4.13" × 0.55" |
| R-39 | 4-1/16" 10K / 15K | 5.94" × 4.13" × 0.69" |
| R-44 | 5-1/8" 10K | 6.81" × 5.13" × 0.69" |
| R-46 | 7-1/16" 5K | 9.24" × 7.13" × 0.55" |
| R-49 | 7-1/16" 10K | 9.50" × 7.13" × 0.69" |
| R-53 | 9" 10K | 11.50" × 9.13" × 0.69" |
| R-57 | 11" 10K | 13.75" × 11.13" × 0.69" |
| BX-150 to BX-180 | 2-1/16" to 16-3/4" 10K–20K (pressure-energized) | ASME B16.20 / API 6A spec |
Mechanical Properties (Aged)
Tensile 165 ksi min / Yield 110 ksi min / Elongation 18% min / Hardness 32–35 HRC (NACE cap). For RTJ gasket rings specifically, the hardness must be CONTROLLED to be 5–10 HRC SOFTER than the mating flange-groove material so the ring deforms preferentially during make-up, sealing the joint, specify the flange material at RFQ stage so the ring hardness can be matched.
Standards
- ASTM B805, UNS N09925 forgings & ring stock
- API 6A / ASME B16.20, RTJ gasket ring dimensional standards (R / RX / BX series)
- API 6A annex K, gasket-ring hardness control
- API Specification 6A, Wellhead and Christmas tree equipment
- API 17D, Subsea wellhead and tree
- ASME B16.5, Pipe Flanges + Flanged Fittings
- NACE MR0175 / ISO 15156-3 Table A.10, sour service
- NORSOK M-630 MDS A30; EN 10204 3.1 / 3.2
Manufacturing Sequence (Seamless Rolled Ring)
- Billet input per ASTM B805 (cylindrical preform sized for ring rolling)
- Pre-heat to forging temperature (1900°F / 1040°C)
- Upset to disc + pierce center hole, produces "doughnut" preform
- Ring rolling on mill: idler + drive rolls reduce wall thickness while expanding OD, circumferential grain flow develops
- Solution anneal + age cycle per heat-treatment specification
- Rough machine to drawing dimension; finish machine after age cycle
- For RTJ gasket rings: precision machine to ASME B16.20 / API 6A profile + dimensional spec
- Final inspection: dimensional CMM, 100% UT (ASTM E2375), 100% MT (ASTM E709), 100% Rockwell hardness, dye-penetrant on RTJ groove surface
- Marking: heat number + UNS N09925 + ASTM B805 + RTJ R-number + NACE stamp + softness-vs-mating-flange certification
Frequently Asked Questions
Why is RTJ gasket hardness softer than the flange? The RTJ joint seals by metal-to-metal deformation: the gasket ring partially compresses against the flange grooves during bolt-up. If the ring is harder than the flange grooves, the FLANGE deforms instead of the gasket, ruining the joint sealing surface. RTJ gaskets are deliberately controlled to be 5–10 HRC softer than the mating flange material. Specify the flange material at RFQ stage.
Seamless rolled ring vs welded ring? Seamless rolled rings have no weld and develop circumferential grain flow during rolling, superior fatigue + burst strength for pressure-cycled service. Welded rings are cheaper for large diameters but the weld zone is a fatigue + corrosion initiation site. For sour-service oilfield use, prefer seamless rolled.
Lead time? RTJ gasket rings (standard R-number sizes): 6–8 weeks. Custom rolled rings: 10–14 weeks. Forged rings (open-die): 8–12 weeks. Large diameter (above 1500 mm OD): 14–18 weeks, mill capacity for large-diameter ring rolling is limited.
Documentation Package & Related Products
EN 10204 3.1 MTC (3.2 with TPI on request); chemistry, tensile, 100% hardness, 100% UT + MT, dye-penetrant on RTJ surface, dimensional CMM report, NACE MR0175 reference, API 6A PSL stamp, hardness-vs-mating-flange certification (RTJ rings). Related: forgings, bars, wellhead hangers, full datasheet.
Request a Quote
Email info@torqbolt.com · Phone +91-22-66157017 · WhatsApp +91-22-66157017. Specify ring type (rolled / RTJ / forged / machined / welded), OD × ID × height, R-number for RTJ, quantity, applicable standards (API 6A / ASME B16.20 / NACE MR0175 / NORSOK MDS A30), mating-flange material (RTJ rings), MTC level.
References: ASTM B805; ASTM B564; API 6A / ASME B16.20 (RTJ gaskets); API Specification 6A annex K; API 17D; ASME B16.5; ASTM E2375 / E709 / E18; NACE MR0175 / ISO 15156-3 Table A.10; NORSOK M-630 / M-650; EN 10204. INCOLOY® is a registered trademark of Special Metals Corporation.
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