Incoloy 925 (UNS N09925) is the standard CRA for wellhead tubing hangers, casing hangers and mandrel hangers in sour HPHT service. The hanger sits at the wellhead interface where structural load (suspended weight of multiple casing / tubing strings, sometimes thousands of metres long), pressure (well shut-in pressure, often 15,000–20,000 psi for HPHT), sour gas (H₂S to 1000 psi partial pressure), brine (formation water with chloride to saturation) and erosive sand all converge simultaneously. The combination of 110 ksi minimum yield (aged), NACE MR0175 Table A.10 qualification, chloride-pitting resistance, and qualified envelope to 400°F covers the operating window. Lower-cost alloys fail one or more of these requirements: carbon steel by SSC; duplex 2205 by sour-service envelope; Incoloy 825 by strength shortfall. TorqBolt manufactures Incoloy 925 hanger forgings and machined hangers per ASTM B805 + API 6A with full PSL documentation including NACE-stamped MTC, hardness map and Charpy at design temperature.
Need Incoloy 925 wellhead hangers? Email info@torqbolt.com with hanger drawing, OEM reference, applicable PSL level and TPI witness requirement. WhatsApp +91-22-66157017.
Hanger Types Manufactured in Incoloy 925
| Hanger Type | Function | Typical Service |
|---|---|---|
| Tubing hanger (single completion) | Suspends production tubing string; pressure-isolation | Single-zone production wells |
| Tubing hanger (dual completion) | Suspends two parallel tubing strings; isolates two zones | Multi-zone production / injection wells |
| Tubing hanger (triple / multi-completion) | Three or more parallel strings + control lines | Complex multi-zone HPHT wells |
| Casing hanger (multiple string suspension) | Lands and seals each casing string at the wellhead | All wellhead designs |
| Mandrel hanger | Solid-body mandrel with slip assembly; high-strength suspension | HPHT wells with heavy completion strings |
| Slip-and-seal hanger | Slip-engagement load support + seal energiser | Adjustable suspension; subsea wellheads |
| Boll-weevil hanger | Emergency-recovery hanger for stuck casing | Workover / completion contingency |
| Subsea horizontal tree hanger | Seals and suspends production tubing in subsea XT | Deepwater subsea production |
| Hanger lockdown screws / bolting | Holds hanger in spool; pressure-energised | All wellhead types |
Why Incoloy 925 for Wellhead Hangers
- Suspended-string load capacity: 110 ksi YS minimum supports the weight of long casing strings (10,000+ ft of 9-5/8" casing weighs ~470,000 lb, the hanger must transfer this load without yielding).
- Pressure containment: The hanger seal area sees full well pressure when the BOP is removed. Aged Incoloy 925's tensile minimum (165 ksi) gives the safety margin for 15,000 / 20,000 psi service.
- Sour-service envelope: NACE MR0175 Table A.10 qualified to 1000 psi H₂S at 400°F, the hanger sits in produced fluid (not gas alone) so it sees the worst H₂S exposure of any wellhead component.
- Chloride pitting: Mo + Cu package gives qualified resistance to brine + chloride completion fluids that pit lower-PREN alloys.
- Erosion resistance: Age-hardened gamma-prime structure resists sand erosion better than solid-solution alloys at the high gas velocities through the hanger seal area.
- Compatible hardfacing: Stellite 6 / 21 hardfacing on slip teeth and seal landings bonds well to Incoloy 925 substrate via PTAW deposition.
- API 6A PSL compliance: Aged Incoloy 925 meets PSL-3 (-29°C Charpy), PSL-3G (-46°C / -101°C Charpy for cryogenic) and PSL-4 (third-party witness) documentation requirements.
API 6A PSL Documentation per Wellhead Pressure Class
| Pressure Class | PSL Level | Charpy Requirement | NDE |
|---|---|---|---|
| 2K (2,000 psi) | PSL-1 | Not required | Visual |
| 5K (5,000 psi) | PSL-2 | Not required | UT or MT |
| 10K (10,000 psi) | PSL-3 | 27 J at -29°C | 100% UT |
| 10K (gas / cryogenic) | PSL-3G | 27 J at -46°C or -101°C | 100% UT + grain size |
| 15K (15,000 psi) | PSL-3 or PSL-4 | 40 J at -46°C | 100% UT + TPI witness |
| 20K (20,000 psi) | PSL-4 | 40 J at -46°C + tensile | 100% UT + 100% MT + TPI witness |
TorqBolt manufactures Incoloy 925 hangers across all 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 heat-treatment, mechanical-test and final-inspection stages.
Manufacturing Sequence
- Forging: Incoloy 925 bar / billet (per ASTM B805) is hot-forged to near-net hanger shape on open-die or closed-die press. Forging temperature 1900°F; finishing temperature 1700°F minimum to prevent cracking.
- Solution anneal: 1900°F (1040°C) hold + water quench, removing forging stresses and dissolving any second-phase precipitates.
- Rough machining: Bore + OD turning to 0.1" oversize. Stress-relief at 1100°F × 4h optional for thick-section hangers prone to distortion in the age cycle.
- Age cycle: 1365°F (740°C) × 8h + slow furnace cool to 1150°F + 1150°F × 8h + air cool. Furnace-chart trace recorded.
- Finish machining: Bore, OD, seal grooves, slip pockets to final dimension after age cycle (avoids dimensional drift from the age cycle distorting the finish-machined surfaces).
- Hardfacing (optional): Stellite 6 / 21 PTAW or GTAW deposit on slip teeth + seal landings; ground to final dimension; dye-penetrant inspected.
- Final NDE + inspection: 100% UT volume inspection per ASTM E2375; 100% hardness per ASTM E18 (in 35 HRC NACE cap); CMM dimensional inspection; Charpy + tensile sample testing.
- Marking + MTC: Heat number, UNS N09925, ASTM B805, API 6A PSL level stamping. EN 10204 3.1 / 3.2 MTC issued with all documentation.
Common Wellhead OEM References
- Cameron / Schlumberger: Standard / customised tubing and casing hangers
- FMC / TechnipFMC: Subsea horizontal tree hangers, multi-bore hangers
- Dril-Quip: SS-15 / SS-20 / DX-2 subsea wellhead hangers
- Aker / Aker Solutions: Subsea production system hangers
- OneSubsea: Subsea horizontal tree hangers, monobore hangers
- NOV: Surface wellhead hangers and adapter spools
- BHGE / Baker Hughes: Surface and subsea hangers
Components are made to OEM drawings under reverse-engineered specifications; original-OEM customer license / approval may be required for some applications.
Frequently Asked Questions
Why not 4145H modified or 8630 low-alloy steel for hangers? The standard low-alloy carbon steels (4145H, 8630) used for non-sour wellhead bodies cannot meet NACE MR0175 sour-service requirements above ~22 HRC, which gives only ~80 ksi YS, insufficient for HPHT hanger loading. For sour HPHT service, Incoloy 925 (or a CRA cladding on a low-alloy substrate) is required.
Can Incoloy 925 hangers be supplied with hardfacing? Yes, Stellite 6 / 21 PTAW (plasma-transferred-arc) deposit on slip teeth and seal landings is standard. The hardfacing is ground to final dimension and dye-penetrant inspected. Hardness of the Stellite layer is 38–45 HRC; the underlying base metal remains within the 35 HRC NACE cap.
What's the difference between mandrel and slip hangers? A mandrel hanger has a solid-body design that lands directly in a profile in the wellhead spool, preferred for HPHT because the load path is straightforward. A slip-and-seal hanger uses radial slips that engage the spool ID under axial load, preferred for adjustable suspension or where the casing length must be set in the field. Both are available in Incoloy 925 with appropriate hardfacing.
How does TorqBolt verify HPHT hanger compliance? Every hanger MTC includes: (1) chemistry within UNS N09925 limits, (2) heat-treatment chart recorder traces, (3) 100% post-age hardness (in 35 HRC NACE cap), (4) sample tensile + Charpy at room temp + design temperature, (5) 100% UT volumetric NDE per ASTM E2375, (6) NACE MR0175 Table A.10 reference, (7) API 6A PSL-3 / PSL-3G / PSL-4 documentation pack. PSL-4 orders include TPI witness at heat-treatment, mechanical-test and final-inspection.
Related Pages
- Downhole oil & gas applications
- NACE MR0175 sour-service envelope
- Surface safety valves (SSV)
- Drill-string tool joints
- API 6A wellhead specification
- Incoloy 925 forgings
Request a Quote
For Incoloy 925 wellhead hangers per API 6A PSL-3 / PSL-3G / PSL-4:
- Email: info@torqbolt.com
- WhatsApp: +91-22-66157017
- Drawing or 3D STEP file required for quoting
Specify hanger type (tubing single / dual / triple, casing, mandrel, slip-and-seal), drawing, applicable PSL level (PSL-1 to PSL-4), well environment (BHT, BHP, H₂S / CO₂ / chloride concentration), TPI witness requirement, 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. ASTM E2375 (UT inspection). AMS 2750 Pyrometry. EN 10204 inspection certification 3.1 / 3.2. INCOLOY® is a registered trademark of Special Metals Corporation.
