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 Lock Washers
From TorqBolt (Mumbai, India): Super Duplex 2507 lock washers in UNS S32750, split-spring (Grover), internal-tooth, external-tooth, and conical Belleville types, prevent fastener loosening under vibration. Material per A479 / A276 in S32750 chemistry. Note: hardened spring temper is not applicable to super duplex; the spring force comes from the duplex microstructure's inherent stiffness.
The dedicated standard for super duplex bolting is ASTM A1082/A1082M (high-strength precipitation hardening and duplex stainless steel bolting material), supplemented by API 20F for corrosion-resistant bolting in petroleum and natural gas service. TorqBolt manufactures under WPS qualified to NORSOK M-650 at the Mumbai facility, with hardness restricted to 28 HRC max for NACE MR0175 / ISO 15156-3 sour-service compliance.
Super Duplex 2507 Lock Washers Size Range
| Type | Standard |
|---|---|
| Split spring (Grover) | ASME B18.21.1, DIN 127B |
| Internal / external tooth | ASME B18.21.1, DIN 6797 |
| Belleville (conical) | DIN 6796 / 2093 |
Super Duplex 2507 Lock Washers Standards
| Standard | Scope |
|---|---|
| ASTM A1082 / A1082M | Dedicated standard, High-Strength Precipitation Hardening and Duplex Stainless Steel Bolting Material. Covers UNS S32750 (Type 2507) explicitly. |
| API 20F | Corrosion-Resistant Bolting for Petroleum and Natural Gas Industries (BSL-2, BSL-3) |
| ASTM A962/A962M | General requirements for stainless steel bolting (A1082 §1.2 companion) |
| ASTM A479 | Bar stock chemistry and properties (raw stock for machining) |
| ASTM A276 | Bar and shapes (alternate raw stock) |
| ASME B18.21.1, DIN 127B / 6796 / 6797 | Dimensional specification |
| ASME B1.1 / ISO 261 | Inch / metric thread call-outs |
| NORSOK L-005 | Compact flange connections (NCS reference) |
| NORSOK M-630 | Material data sheet (MDS D55, D57) |
| NORSOK M-650 | Manufacturer qualification (QTR) |
| NACE MR0175 / ISO 15156-3 | Sour-service compliance, 28 HRC max |
| API 6A PSL 3 / 3G | Wellhead and christmas tree fasteners |
| API 17D | Subsea wellhead and tree fasteners |
Super Duplex 2507 Mechanical Properties (per ASTM A1082)
| Property | Minimum | Typical |
|---|---|---|
| Tensile strength | 800 MPa (116 ksi) for ≤ 2 in. / 760 MPa (110 ksi) for > 2 in. | 800 to 1000 MPa |
| Yield strength (0.2 percent offset) | 550 MPa (80 ksi) for ≤ 2 in. / 515 MPa (75 ksi) for > 2 in. | 620 to 720 MPa |
| Elongation in 4D | 15 percent | 25 to 35 percent |
| Reduction of area | 33 percent | 40 percent |
| Hardness (A1082) | 310 HBN max | 250 to 300 HBN |
| Hardness (NACE sour-service) | 28 HRC max | 25 to 28 HRC |
| Charpy V-notch at minus 46 degrees Celsius | 45 J min | 60 to 100 J |
| PREN | 40 min | 41 to 43 |
Heat Treatment
Solution annealing at 1025 to 1125 degrees Celsius per A1082 (NORSOK M-630 narrows to 1040 to 1100 degrees Celsius), followed by rapid water quench. There is no aging or precipitation hardening; strength comes from the duplex austenite-ferrite microstructure itself. Final hardness check confirms 28 HRC maximum for NACE MR0175 compliance.
Super Duplex 2507 Chemistry per ASTM A1082
| Element | A1082 Min % | A1082 Max % |
|---|---|---|
| Carbon | (no min) | 0.030 |
| Manganese | (no min) | 1.20 |
| Phosphorus | (no min) | 0.035 |
| Sulfur | (no min) | 0.020 |
| Silicon | (no min) | 0.80 |
| Chromium | 24.0 | 26.0 |
| Nickel | 6.0 | 8.0 |
| Molybdenum | 3.0 | 5.0 |
| Nitrogen | 0.24 | 0.32 |
| Copper | 0.50 max, residual, not intentional | |
Companion Products
All companion components in matching UNS S32750 chemistry per A1082.
- Bolts, A1082 in S32750
- Stud bolts, A1082 in S32750, ASME B18.31.2
- Heavy hex nuts, A1082 in S32750, 8MA pattern
- Flat washers, UNS S32750, F436 dimensional pattern by special order
- Mating flanges, ASTM A182 F53
Super Duplex 2507 Lock Washers Applications
- Oil and gas, wellhead christmas trees, manifolds, pipeline flanges per API 20F
- Subsea and offshore, production trees, jumpers, BOP, riser flanges per API 17D
- Seawater service, sea-chest flange bolting, ballast piping, fire-water systems
- Desalination, high-pressure brine pipework flanges, RO membrane housings
- FGD, wet absorber tower flange bolting in chloride-rich flue gas
- Chemical processing, heat exchanger tubesheet bolting, reactor flanges
Super Duplex 2507 Lock Washers FAQ
What is the standard for lock washers in Super Duplex 2507?
ASTM A1082/A1082M for the bolting material, plus the relevant dimensional standard (ASME B18.21.1, DIN 127B / 6796 / 6797). For petroleum and natural gas service, additionally cite API 20F.
Are lock washers in Super Duplex 2507 NACE MR0175 compliant?
Yes, when hardness is restricted to 28 HRC maximum and ferrite content is within 35 to 65 percent. Specific H2S partial pressure and chloride limits depend on the application zone classification under ISO 15156-3. NACE compliance certification accompanies every order on request.
What is the heat treatment for Super Duplex 2507 lock washers?
Solution annealing at 1025 to 1125 degrees Celsius per A1082 (NORSOK M-630 narrows to 1040 to 1100), followed by rapid water quench. There is no aging, precipitation hardening, or temper. Strength comes from the duplex austenite-ferrite microstructure. Final hardness check confirms 28 HRC max for sour-service compliance.
What is the lead time for Super Duplex 2507 lock washers?
Stock sizes ship in 3 to 7 working days from Mumbai. Custom sizes from solution-annealed bar stock typically 4 to 6 weeks including heat-treatment confirmation, dimensional inspection, and EN 10204 Type 3.1 certification. Type 3.2 third-party-witnessed certification adds 1 to 2 weeks.
What marking is on Super Duplex 2507 lock washers?
UNS designation (S32750 or 2507), the A1082 designation when supplied to that standard, plus the manufacturer mark and heat number traceable to the mill test certificate. Marking depth and location follow ASME B18.21.1, DIN 127B / 6796 / 6797 conventions.
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