Super Duplex Steel Fasteners Supplier in Mumbai, India
Nicorex Alloys is an ISO 9001 and ISO 14001 certified importer, stockist, and supplier of Super Duplex Steel fasteners in Mumbai, India. We stock grades S32750 (SAF 2507), S32760 (Zeron 100), S32550, and S39274.
Super Duplex steels are dual-phase alloys with 50% austenite and 50% ferrite and a PREN above 40. All shipments carry EN 10204/3.1B mill test certificates.
We stock a wide range of Super Duplex Steel Fasteners in multiple grades, including:
Super Duplex Steel Fastener Specifications
The specifications of Super Duplex Steel fasteners, like standards, dimensions, thread forms, conditions, and finishes, are stated below:
| Standards | ASTM A182 (F53, F55, F61) |
|---|---|
| Size Range | M6 to M100 |
| Thread Forms | UNC, UNF, Metric Coarse, Metric Fine, BSW, BSF, 8UN |
| Finishes | Pickled and passivated, PTFE/Xylan coated, bright annealed |
| Supply Condition | Solution annealed and quenched |
| Testing | Ferrite 40–60% (ASTM E562), ASTM G48 pitting test, max 36 HRC (NACE MR0175), impact at −46°C (NORSOK) |
| Forms | Hex Bolts, Stud Bolts, Cap Screws, Hex Nuts, Washers, Threaded Rods, U-Bolts, Set Screws, Eye Bolts, Anchor Bolts |
What Are Super Duplex Steel Fasteners?
Super Duplex Steel fasteners are joining hardware from dual-phase stainless steels rich in chromium, nickel, molybdenum, and nitrogen. A PREN above 40 places them above standard Duplex in chloride resistance. Where 316L bolts fail from pitting and stress corrosion cracking above 60°C, Super Duplex fasteners hold with a minimum yield of 550 MPa.
Types and Forms of Super Duplex Steel Fasteners
Super Duplex Steel fasteners are stocked in 10 types for offshore, chemical, subsea, and marine bolting.
Super Duplex Hex Bolts
Super Duplex Stud Bolts (Double-End Studs)
Super Duplex Socket Head Cap Screws
Super Duplex Hex Nuts (Heavy Hex, Lock, Flange)
Super Duplex Washers (Flat, Spring, Belleville)
Super Duplex Threaded Rods
Super Duplex U-Bolts
Super Duplex Set Screws
Super Duplex Eye Bolts
Super Duplex Anchor Bolts
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Available Grades of Super Duplex Steel Fasteners
Nicorex Alloys stocks Super Duplex Steel fasteners in 4 grades.
Super Duplex S32750 / SAF 2507 Fasteners
S32750 is the most common grade with PREN of 42.5 and minimum yield of 550 MPa. It resists chloride pitting up to 75–80°C per ASTM G48. Covered under ASTM A182 F53 and NORSOK MDS D45.
Super Duplex S32760 / Zeron 100 Fasteners
S32760 adds tungsten and copper for better crevice resistance in hot seawater per NORSOK MDS D56.
Super Duplex S32550 / Ferralium 255 Fasteners
S32550 contains 1.5–2.5% copper for sulfuric acid resistance under ASTM A182 F61.
Super Duplex S39274 Fasteners
S39274 is a high-molybdenum, tungsten-bearing grade with PREN of 42–44 for extreme sour service.
Industries and Applications of Super Duplex Steel Fasteners
Super Duplex Steel fasteners serve 7 industries:
- Offshore Oil and Gas: Flange studs, wellhead fasteners, and splash zone bolting.
- Subsea Engineering: Manifold bolting and subsea tree studs per API 6A/17D.
- Chemical Processing: Reactor bolts and heat exchanger studs.
- Desalination: RO housing bolts and brine pump fasteners.
- Marine and Shipbuilding: Seawater piping bolts and FPSO piping studs.
- Pulp and Paper: Digester bolts and bleaching equipment studs.
- Mining: Leach pad bolts and slurry pipeline studs.
Frequently Asked Questions
What types of Super Duplex Steel fasteners does Nicorex Alloys supply?
Nicorex Alloys stocks and supplies Super Duplex Steel fasteners like hex bolts, stud bolts, socket head cap screws, heavy hex nuts, flat and spring washers, belleville washers, threaded rods, U-bolts, anchor bolts, set screws, and eye bolts in grades like Super Duplex S32750, S32760, S32550, and S39274 with UNC, UNF, metric, 8UN, BSW, and BSF thread forms.
Why are Super Duplex bolts preferred over 316L stainless steel bolts for offshore and subsea service?
316L has a PREN of 24 and fails from chloride pitting above 20–25°C. Super Duplex S32750 (PREN 42.5) resists pitting up to 75–80°C with minimum yield of 550 MPa.
What is the difference between Super Duplex S32750 and S32760 fasteners?
Both are 25Cr Super Duplex grades with PREN above 40. S32760 adds tungsten and copper for better crevice resistance in hot seawater. S32750 is more widely stocked.
Are Super Duplex Fasteners Suitable for Sour Service?
Yes. Both grades in solution annealed condition meet NACE MR0175/ISO 15156 when hardness stays below 36 HRC and ferrite is within 40–60%.
What ferrite content is required for Super Duplex fasteners?
NORSOK M-630 and most offshore specifications require 40–60% ferrite for Super Duplex fasteners.
What is the maximum service temperature for Super Duplex fasteners?
Do not use above 250°C (482°F) continuously. Exposure at 300–550°C causes 475°C embrittlement. Sigma phase forms above 600°C.
What size range is available for Super Duplex fasteners?
Standard stud bolt sizes are M6 (1/4″) to M64 (2-1/2″) per ASTM A193 B8MLCuN. Larger sizes up to M100 (4″) are machined from ASTM A479 S32750 or S32760 bar. Heavy-hex 8UN stud bolts are available for ASME B16.5 / B16.47 flanges, with metric sizes M6–M100 and custom sizes available.