High-Performance Duplex & Super Duplex Steel Fasteners
Neelkamal Alloys LLP is a premier manufacturer, stockist, and global exporter of high-grade Duplex Steel Fasteners based in Mumbai, India. Designed specifically to excel under extreme mechanical stress and aggressive corrosive environments, our duplex nut bolts, studs, and screws provide unmatched performance in critical offshore, petrochemical, and marine applications.
Duplex stainless steel features a dual-phase microstructural balance combining approximately equal proportions of austenitic and ferritic stainless steel. This unique structure grants UNS S31803 / UNS S32205 (2205 Duplex) and UNS S32750 / UNS S32760 (2507 Super Duplex) fasteners nearly twice the yield strength of conventional 316L stainless steel, along with exceptional resistance to pitting, crevice corrosion, and chloride stress corrosion cracking (SCC).
Technical Specifications & Material Standards
Every batch of duplex steel fasteners manufactured by Neelkamal Alloys LLP adheres strictly to internationally recognized manufacturing and material standards including ASTM, ASME, DIN, ISO, and BS specifications.
| Parameter | Technical Standard / Capability |
|---|---|
| Material Grades | Duplex 2205 (UNS S31803 / S32205 / 1.4462), Super Duplex 2507 (UNS S32750 / 1.4410), Super Duplex Zeron 100 (UNS S32760 / 1.4501) |
| Standard Specifications | ASTM A479, ASTM A182, ASTM A276, ASME SA479, ASME SA182 |
| Dimensional Standards | ASME B18.2.1 (Bolts), ASME B18.2.2 (Nuts), DIN 931, DIN 933, DIN 934, DIN 912, ISO 4014, ISO 4017 |
| Size Range | Metric: M6 to M64 | Imperial: 1/4" to 2-1/2" (Custom sizes & drawing-based manufacturing available) |
| Thread Profiles | UNC, UNF, UNEF, Metric Coarse, Metric Fine (Class 2A/2B, 6g/6H) |
| Testing & Certification | EN 10204 3.1 MTC, PMI Testing, Microstructure Analysis, Hardness, Tensile, Impact Test (-40°C), 3rd Party Inspection (TUV, BV, SGS) |
Chemical & Mechanical Properties Overview
Our engineering team ensures rigorous melt-heat control so that all manufactured fasteners achieve optimal ferrite-austenite balance (40% - 60% ferrite range) and maximum corrosion resistance (PREN > 34 for 2205; PREN > 42 for Super Duplex 2507).
| Grade | Tensile Strength (MPa) Min | Yield Strength 0.2% (MPa) Min | Elongation (%) Min | Hardness (HB) Max |
|---|---|---|---|---|
| Duplex 2205 (UNS S32205) | 620 - 880 | 450 | 25 | 290 |
| Super Duplex 2507 (UNS S32750) | 750 - 1000 | 550 | 15 | 310 |
| Super Duplex (UNS S32760) | 750 - 1000 | 550 | 25 | 310 |
Comprehensive Duplex Fastener Product Range
We produce a complete line of standard and custom-machined fastening components for high-pressure piping, valves, heat exchangers, and structural installations:
- Duplex Steel Hex Bolts & Heavy Hex Bolts: Precision forged and thread-rolled for maximum fatigue resistance in heavy-duty structural and flange joint assemblies.
- Duplex Steel Stud Bolts & Threaded Rods: Continuous threaded and double-end stud bolts manufactured according to ASME B16.5 flange pressure-rating demands.
- Duplex Steel Heavy Hex Nuts & Lock Nuts: Engineered to pair seamlessly with high-tensile alloy studs, eliminating thread galling under load.
- Duplex Steel Socket Head Cap Screws & Machine Screws: High-precision internal drive fasteners ideal for space-constrained machinery and subsea hardware.
- Duplex Steel Flat & Spring Washers: Precision stamped load-distributing washers offering supreme pitting resistance in marine splash zones.
Strict Quality Control & Export Testing Protocols
At Neelkamal Alloys LLP, product reliability and buyer trust are paramount. All outgoing shipments pass through an extensive Quality Assurance Plan (QAP):
- Positive Material Identification (PMI): 100% verification of alloy composition prior to processing.
- Mechanical & Metallurgical Testing: Tensile strength, yield proof, impact toughness, and microstructural ferrite count testing.
- Corrosion Resistance Testing: Pitting corrosion testing in accordance with ASTM G48 Method A.
- Traceability & Certification: Full heat-number traceability mapped directly to EN 10204 3.1 Inspection Certificates provided with export documentation.
- Seaworthy Packaging: Heavy-duty plastic wrapping, anti-corrosion barrier packing, and sturdy wooden crates to prevent transit damage.
Industrial Applications
Our export-grade duplex steel fasteners are routinely specified by EPC contractors, plant operators, and stockists across demanding industry sectors:
- Offshore & Subsea Oil & Gas: Riser clamps, subsea trees, wellhead equipment, and marine piping flanges.
- Desalination & Seawater Systems: High-pressure pumps, RO membranes, and saltwater intake structures.
- Chemical & Petrochemical Processing: Organic acid reactors, chloride processing units, and storage tanks.
- Marine Engineering: Propulsion shafts, rudder hardware, and coastal defense installations.
Global Supply & Export Capabilities
Neelkamal Alloys LLP maintains a strong export footprint, shipping high-strength fasteners to over 105 countries including the United States, United Kingdom, United Arab Emirates, Saudi Arabia, Germany, Singapore, Qatar, Oman, Canada, Australia, and Brazil. Our export logistic team handles fast customs clearance, competitive freight pricing, and on-time global site deliveries.
Need Precision Duplex Steel Fasteners for Your Project?
Contact our technical engineering sales team today to request material quotes, weight charts, or custom drawing-based production estimates.
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