Patriot Bolt machines Super Duplex 2507 stud bolts from certified round bar for seawater, subsea and sour service. Super Duplex 2507 (UNS S32750) is a 25% chromium ferritic-austenitic stainless steel with a pitting resistance equivalent number (PREN) above 40.
We make 2507 studs to the specification on your purchase order or to your drawing. Every order ships with mill test reports traceable to the heat.
Super Duplex 2507 Stud Bolts at a Glance
- Also called
- SAF 2507 · UNS S32750 · F53 · W.Nr. 1.4410
- Material specs
- ASTM A479 / A276 bar · ASTM A1082 bolting · NACE MR0175 / ISO 15156-3
- Strength
- 116 ksi min tensile, 80 ksi min yield (2 in. and under)
- Corrosion
- PREN above 40; resists pitting and chloride SCC
- Configurations
- Fully threaded, double-end and tap-end
Why Engineers Specify Super Duplex 2507 Stud Bolts
Super Duplex 2507 sits between stainless steel and nickel alloys. It is stronger than 316 and resists seawater far better, at lower cost than Inconel.
- Seawater resistance. A PREN above 40 is the usual threshold for long-term seawater exposure.
- Strength. An 80 ksi minimum yield is more than double that of A193 B8 Class 1.
- Chloride stress-corrosion cracking. The duplex structure resists the cracking that affects austenitic stainless.
- Sour service. Listed in NACE MR0175 / ISO 15156-3, within the limits that standard sets.
Super Duplex 2507 Stud Bolt Specifications
2507 bar is produced to ASTM A479 or A276. ASTM A1082 covers duplex stainless steel bolting for pressure vessel and piping service.
| Size | Tensile, min | Yield, min | Elong., min | Hardness, max |
|---|---|---|---|---|
| 2 in. and under | 116 ksi | 80 ksi | 15% | 33 HRC |
| Over 2 in. | 110 ksi | 75 ksi | 15% | 33 HRC |
Values per ASTM A1082 for UNS S32750. Duplex steels lose toughness at high temperatures and are generally kept below about 600 °F. Check your design code for the limit.
Super Duplex 2507 Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 24.0–26.0 |
| Nickel | 6.0–8.0 |
| Molybdenum | 3.0–5.0 |
| Nitrogen | 0.24–0.32 |
| Manganese | 1.20 max |
| Silicon | 0.80 max |
| Copper | 0.50 max |
| Carbon | 0.030 max |
| Phosphorus | 0.035 max |
| Sulfur | 0.020 max |
| Iron | Balance |
PREN = %Cr + 3.3 × %Mo + 16 × %N. The mill test report for your heat is the controlling document.
Stud Configurations
- Fully threaded studs, threaded end to end, for flange bolting where grip length varies.
- Double-end studs, threaded on both ends with an unthreaded center.
- Tap-end studs, with one end made to thread into a tapped hole.
Duplex stainless can gall. Use a compatible thread lubricant.
Applications and Industries
- Subsea and offshore: Seawater, firewater and subsea flange studs. See Oil & Gas.
- Chemical and desalination: Chloride-bearing process and brine systems. See Petrochemical & Refining.
- Industrial and marine: Pumps, valves and seawater cooling. See Industrial & Manufacturing.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each Super Duplex 2507 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
Compare Super Duplex 2507 with other bolting grades in our Fastener Materials Matrix.
Super Duplex 2507 Stud Bolt FAQ
What is the PREN of Super Duplex 2507?
2507 is specified with a PREN above 40, calculated as %Cr + 3.3 × %Mo + 16 × %N.
How does 2507 compare with 2205 duplex studs?
2507 has more chromium, molybdenum and nitrogen, so it is stronger and resists pitting better. It is chosen when chloride levels or temperatures are too high for 2205.
Is 2507 a good alternative to Inconel 625?
For many seawater applications, yes. It is stronger in yield and costs less, but 625 handles higher temperatures and harsher acids.
Do you make matching nuts?
Yes. We also machine Super Duplex 2507 nuts.
Request a Quote
Send us the stud configuration, diameter, length, thread, specification and quantity, or upload your drawing. Our team will confirm the material and lead time. Call (281) 581-0176 or request a quote.
Also in Super Duplex 2507: Heavy hex bolts · Nuts · All stud bolts