Incoloy 925 (UNS N09925) is the standard choice for surface safety valve (SSV), subsurface safety valve (SSSV) and Christmas-tree valve internals exposed to high-velocity sour gas streams. The combination of 110 ksi minimum yield strength (aged), NACE MR0175 Table A.10 qualification to 1000 psi H₂S, erosion-corrosion durability under chloride + CO₂ gas flow, and API 6A PSL-3 / PSL-3G / PSL-4 documentation compatibility covers the operating envelope of every commercial wellhead valve. The alloy is used for valve stems, bonnets, body bolting, trim cages, gate / seat carriers, choke internals and stem extensions. TorqBolt manufactures Incoloy 925 valve components and bolting per ASTM B805 + API 6A with EN 10204 3.1 / 3.2 MTC including hardness map, Charpy at design temperature and NACE-stamped certification.
Need Incoloy 925 valve components? Email info@torqbolt.com with valve manufacturer / model, component drawing, applicable PSL level and any TPI witness requirement. WhatsApp +91-22-66157017.
Valve Components Manufactured in Incoloy 925
| Component | Function | Why Incoloy 925 |
|---|---|---|
| Valve stems / stem extensions | Transmit actuator load to gate / plug | 110 ksi YS + sour-service Cl-SCC immunity + non-galling vs bonnet bushings |
| Bonnet flange + bonnet bolting (stud bolts / nuts) | Pressure-containing closure | API 6A bolting strength + sour qualification |
| Gate carriers / seat retainers | Hold gate + seat assembly | Strength + corrosion under sealing-fluid exposure |
| Trim cages, plugs, sleeves | Flow control + erosion barrier | Erosion-corrosion durability in high-velocity sour gas |
| Choke trim | Adjustable orifice + flow conditioning | Hardfacing-compatible base material; sour resistance |
| Body bolting (high-strength studs) | Body-bonnet pressure boundary | API 6A PSL-3G compliant with NACE stamp |
| Stem packing follower / gland | Holds stem packing in sealed condition | Strength + non-galling against bonnet bushings |
Why Incoloy 925 for Valve Service
- Bolting strength: 110 ksi minimum yield (aged) supports the high-preload bolted joints required for body-bonnet pressure boundaries to API 6A PSL-3 (15,000 psi) and PSL-4 (20,000 psi).
- Sour-service envelope: NACE MR0175 Table A.10 qualified to 1000 psi H₂S partial pressure at 400°F, covers virtually every commercial sour wellhead service.
- Erosion-corrosion: The age-hardened gamma-prime structure resists erosion better than solid-solution alloys at the high gas velocities through choke trim and orifice plates.
- Non-galling: Incoloy 925 stems run reliably against Incoloy 718 or Stellite-coated bushings without seizure, a common failure mode for stainless-on-stainless valve stems.
- Charpy toughness: 40 J min at -46°C (NACE MR0175 sour-service) and 27 J min at -101°C (API 6A PSL-3G cryogenic) qualified per mechanical properties spec.
- Hardfacing compatibility: Stellite 6 or 21 hardfacing on gate / seat surfaces bonds well to Incoloy 925 substrate via standard PTAW / GTAW deposition.
API 6A PSL Documentation Levels
| PSL Level | Pressure Class | Documentation Required | Charpy Test Temp |
|---|---|---|---|
| PSL-1 | 2,000–5,000 psi | Mill MTC + heat-lot mechanical | Not required |
| PSL-2 | 5,000–10,000 psi | + NDE (UT or MT) | Not required |
| PSL-3 | 10,000–15,000 psi | + Charpy + 100% UT | -29°C (-20°F) |
| PSL-3G | 10,000–15,000 psi (gas / cryogenic) | + Charpy at low temperature + tensile + grain size | -46°C (-50°F) or -101°C (-150°F) |
| PSL-4 | 15,000–20,000 psi | + TPI witness + full traceability | -46°C (-50°F) |
TorqBolt manufactures Incoloy 925 valve components to all five PSL levels with documentation packages assembled per the API 6A Annex M heat-treatment requirements. PSL-4 orders include third-party witness (DNV, Bureau Veritas, ABS, Lloyd's) at the heat-treatment, mechanical-test and final-inspection stages.
Common Valve OEM References
Incoloy 925 valve components and bolting commonly supplied for:
- Cameron / Schlumberger: Wellhead valves, BOP rams, choke valves
- FMC / TechnipFMC: Subsea Christmas tree valves, manifold valves
- Dril-Quip: Subsea wellhead valves, mudline suspension
- Halliburton: Surface safety valves, completion equipment
- NOV / National Oilwell Varco: Drilling chokes, BOP-stack components
- Parker: High-pressure ball valves, instrument valves
- Velan / Cameron / KSB: Industrial sour-service gate / globe / check valves
Components are made to OEM drawings under reverse-engineered specifications; original-OEM customer license / approval may be required for some applications.
Heat-Treatment Status & QA
All valve components are supplied in the SOLUTION-ANNEALED + AGED condition per heat-treatment specification. The age cycle is run in calibrated furnaces with continuous chart-recorder traceability; charts are retained 5 years ASTM B805 Section 7. Hardness is 100% inspected per ASTM E18 with values reported per piece. Sample tensile + Charpy per heat / per heat-treatment lot.
For PSL-3G cryogenic service, additional Charpy at -101°C is performed and reported. For hardfacing-coated trim, the PTAW / GTAW Stellite deposit is dye-penetrant tested 100% post-grinding to verify no cracks at the base-metal interface.
Frequently Asked Questions
Why is Incoloy 925 chosen over Inconel 718 for valve stems? Two reasons: (1) Inconel 718's NACE Table A.13 H₂S limit of 15 psi disqualifies it from most sour wellhead service; (2) Inconel 718 over-ages above 1200°F, Incoloy 925 is stable to 1100°F continuous service. For high-strength applications below 15 psi H₂S where strength matters more than sour envelope, Inconel 718 is the alternative; for typical sour wellhead, Incoloy 925 is the standard.
Can Incoloy 925 stems be supplied with Stellite hardfacing? Yes, PTAW (plasma-transferred-arc welding) Stellite 6 or 21 deposit on Incoloy 925 substrate is standard for high-wear sealing surfaces (gate / seat interface). The deposit is ground to dimension and dye-penetrant inspected before final age cycle. Hardness of the Stellite layer is 38–42 HRC; the underlying base metal remains within the 35 HRC NACE cap.
What thread compound for Incoloy 925 bonnet bolting? Sulfur-free, copper-free anti-seize compounds, e.g. Loctite 8009 (high-purity nickel anti-seize) or Henkel Permabond Antiseize 8023. Avoid copper-bearing compounds (galvanic) and graphite-bearing compounds (galvanic with stainless flanges). Apply to bolt threads + nut bearing surface for accurate torque-to-tension correlation.
How does TorqBolt prove API 6A heat-treatment compliance? Per API 6A Annex M, every Incoloy 925 valve component is supplied with: (1) furnace chart-recorder trace for solution anneal + age cycles, (2) work-zone thermocouple data per AMS 2750, (3) post-anneal hardness, (4) post-age 100% hardness inspection, (5) sample mechanical results per heat / per heat-treatment lot. PSL-4 orders include third-party witness on the heat-treatment cycle.
Related Pages
- Downhole oil & gas applications
- NACE MR0175 sour-service envelope
- Tubing & casing hangers
- Drill-string tool joints
- API 6A wellhead specification
Request a Quote
For Incoloy 925 valve internals + bolting per API 6A PSL-3 / PSL-3G / PSL-4:
- Email: info@torqbolt.com
- WhatsApp: +91-22-66157017
- Component drawing or 3D STEP file required for quoting
Specify component (stem, bonnet, gate carrier, trim cage, body bolting), drawing, applicable PSL level (PSL-1 to PSL-4), service environment (H₂S partial pressure / temperature / chloride), TPI witness requirement (DNV / BV / ABS / Lloyd's), and any hardfacing or surface-treatment specification.
References: Special Metals Corporation: INCOLOY® alloy 925 Technical Bulletin. ASTM B805; API Specification 6A Wellhead and Tree Equipment, Annex M Heat-Treatment Requirements. NACE MR0175 / ISO 15156-3 Table A.10. AMS 2750 Pyrometry. EN 10204 inspection certification 3.1 / 3.2. INCOLOY® is a registered trademark of Special Metals Corporation.
