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
Super Duplex 2507 in Oil and Gas
Super Duplex 2507 (UNS S32750 / EN 1.4410) is a primary corrosion-resistant alloy across the upstream oil and gas chain: wellhead christmas trees, manifolds, downhole completion tools, surface flowlines, choke bodies, and topside production manifolds. PREN above 41 lets the alloy ride out the chloride content of typical formation brines, and the qualified hardness ceiling of 28 HRC per NACE MR0175 / ISO 15156-3 keeps it inside the sour-service envelope for many fields.
TorqBolt supplies 2507 forgings, fasteners, pipe, fittings, and flanges to API 6A PSL3 / 3G surface wellhead specifications and API 17D subsea production specifications. Mill test certificates per EN 10204 Type 3.1 are standard; Type 3.2 third-party-witnessed (DNV, Lloyd's, BV, ABS) is available where the project specification calls for witnessed inspection.
Why Super Duplex 2507 in Oil and Gas
Upstream service conditions stack four corrosion drivers on a single component: chloride from formation brine, H2S partial pressure (sour service), CO2 partial pressure (sweet corrosion), and temperature. 2507 is selected when:
- Chloride and CO2 combination exceeds the limit for 13Cr martensitic and standard 22Cr duplex (2205). 2507 PREN above 41 vs 2205 PREN of 34 to 38.
- H2S partial pressure stays inside the ISO 15156-3 envelope for solution-annealed 25Cr super duplex (zone classification per Table A.30 of ISO 15156-3).
- Operating temperature sits between minus 50 degrees Celsius (subsea minimum design metal temp) and about 250 degrees Celsius continuous. Sigma-phase risk above 300 degrees Celsius is the long-term ceiling.
- Mechanical strength is required at higher levels than austenitic CRA. 2507 minimum yield is 550 MPa, roughly twice that of 316L. Wall-thickness reduction on subsea hardware drives lift-and-handling savings.
- Cost target rules out Alloy 625 / 825 cladding or solid Alloy 925.
Super Duplex 2507 Oil and Gas Design Data
| Parameter | Value | Reference |
|---|---|---|
| PREN | 41 to 43 | Cr + 3.3 times Mo + 16 times N |
| CPT (ASTM G48 Method E) | Greater than 50 degrees Celsius | ASTM G48-11 |
| Hardness limit (sour service) | 28 HRC max | NACE MR0175 / ISO 15156-3 |
| Ferrite content | 35 to 55 percent (base), 35 to 65 percent (weld) | NORSOK M-630 |
| Minimum design metal temperature | Down to minus 46 degrees Celsius (impact tested at minus 46) | NORSOK M-630, API 6A |
| Maximum continuous service temperature | 250 degrees Celsius (sigma-phase risk above 300) | NORSOK M-630 |
| Wellhead specification | API 6A PSL3 / 3G | API Spec 6A 21st ed |
| Subsea production | API 17D | API Spec 17D 2nd ed |
| Bolting standard | ASTM A1082, API 20F | API Spec 20F 1st ed |
Where Super Duplex 2507 Is Specified in Oil and Gas
- Surface wellhead christmas trees per API 6A PSL3 / 3G. 2507 forged tree bodies, valve blocks, gate-valve stems, and connector housings.
- Subsea christmas trees and tubing hangers per API 17D. 2507 in flow-loop wetted parts where temperature and chloride combination accept the alloy.
- Manifolds on production gathering lines and water-injection headers.
- Downhole completion hardware: subsurface safety valves (TR-SSSV) bodies, packer mandrels, sliding sleeves, where temperature is below 250 degrees Celsius continuous.
- Surface flowlines from wellhead to manifold or test separator. 2507 pipe to ASTM A790 or solid 2507 tubing to ASTM A789.
- Choke bodies and trims for production and injection chokes. Erosion combined with chloride is a known failure mode; 2507 holds up where 17-4PH or 13Cr would fail by chloride pitting.
- Pumps and rotating equipment trims in produced-water reinjection and water-flood service.
- Topside production manifolds and heater-treater piping where wet hydrocarbon contains formation water.
- Bolting on flange connections, valve covers, and subsea connectors per ASTM A1082 / API 20F.
Super Duplex 2507 vs Competing Alloys in Oil and Gas
| Alloy | PREN | NACE Hardness | Cost Index | Oil and Gas Verdict |
|---|---|---|---|---|
| 13Cr (S41000, S42000) | ~13 | 22 HRC max | 1.0 | Sweet service only; CO2 + chloride limit |
| Super 13Cr (modified martensitic) | ~17 | 27 HRC max | 1.4 to 1.6 | Wider sweet service envelope; not for sour |
| 2205 duplex (S31803 / S32205) | 34 to 38 | 32 HRC (NORSOK), 28 HRC (ISO 15156) | 1.5 to 1.8 | Many sweet and mildly sour duties; pits faster than 2507 |
| Super Duplex 2507 (S32750) | 41 to 43 | 28 HRC max | 2.0 to 2.5 | Standard for harsher CRA duty inside the ISO 15156-3 envelope |
| Zeron 100 (S32760) | 41 to 44 | 28 HRC max | 2.2 to 2.7 | Equivalent envelope; choice often dictated by project spec |
| Alloy 825 (N08825) | ~30 | 35 HRC max (sour with limits) | 3.0 to 3.5 | Used at higher H2S partial pressure than 2507 envelope |
| Alloy 625 / 925 (Ni-base) | 50+ | 35 to 40 HRC | 4.0 to 6.0 | Reserved for hot, sour, high-chloride service beyond the 2507 envelope |
Super Duplex 2507 Installation Notes for Oil and Gas
- Welding per NORSOK M-601 with filler ER2594 (overmatching) or ER2553 (matching); heat input 0.5 to 2.5 kJ per millimetre, interpass below 150 degrees Celsius. Argon plus 2 to 5 percent nitrogen shielding for GTAW root.
- Hardness survey on every weld and HAZ for sour-service items. 28 HRC max per NACE MR0175 / ISO 15156-3 (or per project specification, which is sometimes tighter at 25 HRC).
- Ferrite count per ASTM E562 point counting or ASTM E1245 image analysis. 35 to 55 percent base, 35 to 65 percent weld. ASTM A923 Methods A and B for sigma-phase detection on critical heats.
- Hydrotest with low-chloride water (less than 30 ppm), full drain plus dry-out within 24 hours.
- Bolting per ASTM A1082 / API 20F in matching S32750 chemistry. PTFE or molybdenum disulfide thread lubricant on assembly.
- Subsea cathodic protection: 2507 is compatible with sacrificial anode CP systems; isolate high-strength bolting from over-protection to avoid hydrogen embrittlement.
- Hot dip / pickling after fabrication per ASTM A380 to remove iron contamination from carbon-steel tools.
Recommended TorqBolt 2507 Products for Oil and Gas
- 2507 pipe: ASTM A790 seamless / welded for surface and subsea flowlines
- 2507 fittings: ASTM A815 WP-S32750 buttweld elbows, tees, reducers
- 2507 flanges: ASTM A182 F53 weld neck and blind, RTJ for high-pressure gas duty
- 2507 stud bolts: ASTM A1082 / API 20F for wellhead and flange connections
- 2507 heavy hex nuts: ASTM A1082 in matching S32750 chemistry
- 2507 forgings and bar: ASTM A479 / A182 F53 for tree bodies, valve blocks, connectors
- ASTM A182 F53 forgings: flanges, blocks, hubs
Related Application Pages
- Sour service (NACE MR0175): H2S partial pressure and zone classification
- Marine and offshore: subsea hardware, NORSOK supply
- Seawater applications: sea-chest, fire-water, lift systems
- Chemical processing: dilute HCl, H2SO4, HF service
- NACE MR0175 compliance: hardness and ferrite limits
Super Duplex 2507 Oil and Gas FAQ
Is Super Duplex 2507 qualified for API 6A PSL3 / 3G wellhead service?
Yes. API Spec 6A lists 25Cr super duplex (UNS S32750) as an acceptable material category for tree bodies, valve blocks, and connectors at PSL3 (and PSL3G when gas-tightness testing applies). Material is supplied solution-annealed at 1040 to 1100 degrees Celsius and water quenched, with mechanical, hardness, ferrite, and impact testing per the API Spec 6A material classification.
What H2S partial pressure can Super Duplex 2507 handle?
ISO 15156-3 Table A.30 sets the limits for solution-annealed 25Cr super duplex by zone. Above 0.05 psi (0.0035 bar) H2S partial pressure the service is classified sour and the alloy must be qualified per the table, with hardness 28 HRC max and ferrite within 35 to 65 percent. Specific limits depend on the H2S / chloride / temperature combination of the application zone. Check ISO 15156-3 Table A.30 row by row against the project envelope.
Can 2507 be used in subsea production trees?
Yes, per API 17D. 2507 is widely used for subsea tree bodies, choke bodies, and valve trims where chloride and temperature combination is acceptable. The minimum design metal temperature for North Sea subsea is typically minus 46 degrees Celsius, which 2507 covers with Charpy impact testing per NORSOK M-630. Cathodic protection compatibility is good; high-strength bolting must be isolated from CP overprotection to avoid hydrogen embrittlement.
What is the maximum operating temperature for 2507 in oil and gas service?
250 degrees Celsius continuous per NORSOK M-630. Above 300 degrees Celsius long-term exposure can precipitate sigma phase, which cuts Charpy toughness by 80 percent or more and removes pitting resistance. For sustained service above 250 degrees Celsius, austenitic CRAs (Alloy 825, Alloy 625) are the next step up.
Is 2507 acceptable for downhole tubular service?
2507 OCTG is offered for selected downhole completion components (subsurface safety valves, packer mandrels, sliding sleeves) within the ISO 15156-3 sour-service envelope and below the 250 degrees Celsius temperature ceiling. For full-string OCTG in deep, hot, sour wells, Alloy 825 or Alloy 925 is more common. The alloy choice is driven by the reservoir temperature, H2S partial pressure, and chloride content, evaluated against ISO 15156-3 Table A.30.
Which welding filler should be used for 2507 in oil and gas?
ER2594 (overmatching, slightly higher PREN than the base) per AWS A5.9 is the standard pick for sour service. ER2553 (matching) is acceptable for sweet service. Heat input 0.5 to 2.5 kJ per millimetre, interpass below 150 degrees Celsius. Argon plus 2 to 5 percent nitrogen shielding for GTAW root pass to maintain austenite balance in the weld metal. Hardness survey on every weld and HAZ to confirm 28 HRC max for sour-service items.
What bolting standard applies to 2507 in oil and gas service?
ASTM A1082 / A1082M for general 2507 bolting and API Spec 20F for petroleum and natural gas service. PSL ratings (PSL-1 through PSL-4) cover increasing levels of inspection and certification. Hardness 28 HRC max for sour service. PTFE or molybdenum disulfide thread lubricant on assembly to prevent galling. TorqBolt supplies stud bolts and heavy hex nuts in matching S32750 chemistry with NACE MR0175 / API 20F certification on request.
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