Duplex Steel Stud Bolts
ASME B18.31.2 & B16.5 continuous-thread and double-end stud bolts for high-pressure flanged joints.
High-Performance Fastening Solutions
ASME SA479 / ASTM A182 Duplex Steel Fasteners (UNS S31803 / S32205)
Stud Bolt India is an ISO 9001:2015 certified manufacturer, stockist, and global exporter of high-precision Duplex Steel Fasteners. Engineered from premium-grade austenitic-ferritic dual-phase stainless steel, our UNS S31803 and UNS S32205 (Duplex 2205) bolting components deliver exceptionally high yield strength (nearly double that of standard austenitic stainless steel) combined with superior resistance to chloride stress corrosion cracking, pitting, and crevice corrosion.
We manufacture a full range of high-tensile duplex hex bolts, heavy hex nuts, full-thread stud bolts, plain and spring washers, socket head cap screws, and cut-to-length threaded rods. Designed for high-stress applications in offshore oil & gas platforms, marine engineering, chemical processing, seawater desalination, and subsea pipelines, all items are produced under strict quality management systems complying with ASME, ASTM, DIN, and ISO specifications.
Types of Duplex Steel Fasteners Manufactured
Duplex Steel Hex Bolts
Heavy hex bolts to ASME B18.2.1 and DIN 931/933 with hot-forged strength and CNC precision threads.
Duplex Steel Heavy Hex Nuts
High-tensile nuts conforming to ASTM A194 Grade 8M/Duplex standards for high load bearing.
Duplex Steel Threaded Rods
DIN 975 / DIN 976 fully threaded bars available in standard 1m to 3m lengths or custom cut lengths.
Duplex Steel Washers
Flat washers, spring lock washers, and heavy-duty structural washers to DIN 125 and ASME B18.21.1.
Duplex Socket Screws
Precision socket head cap screws, countersunk screws, and set screws according to DIN 912 and ISO 4762.
Technical Specifications & Material Standards
| Parameter | Standard Specifications |
|---|---|
| Material Specifications | ASTM A240, ASTM A479, ASTM A182, ASME SA240, SA479 |
| Duplex Grades | UNS S31803 (F51), UNS S32205 (F60 / Duplex 2205), UNS S32550, UNS S32750 (Super Duplex 2507) |
| Size Range | Metric: M3 to M100 | Imperial: 1/8" to 4" (Custom sizes up to 5 meters in length) |
| Dimensional Standards | ASME B18.2.1, B18.2.2, B18.31.2, DIN 931, DIN 933, DIN 934, DIN 975, ISO 4014, ISO 4017 |
| Surface Coatings | Plain Bright Finish, PTFE / Xylan Coated, Zinc Plated, Hot-Dip Galvanized (HDG), Cadmium Coated |
| Quality Certification | EN 10204 3.1 MTC, NACE MR0175 / ISO 15156 Compliant, PMI Test Report, 3rd Party Inspection |
Chemical Composition & Mechanical Properties
Chemical Composition (UNS S31803 / S32205)
| Grade | Cr (%) | Ni (%) | Mo (%) | N (%) | C (Max) | Mn (Max) | Si (Max) | P (Max) | S (Max) |
|---|---|---|---|---|---|---|---|---|---|
| UNS S31803 | 22.0 – 23.0 | 4.50 – 6.50 | 3.00 – 3.50 | 0.14 – 0.20 | 0.030 | 2.00 | 1.00 | 0.030 | 0.020 |
| UNS S32205 | 22.0 – 23.0 | 4.50 – 6.50 | 3.10 – 3.50 | 0.14 – 0.20 | 0.030 | 2.00 | 1.00 | 0.030 | 0.020 |
Mechanical Properties
| Grade | Tensile Strength (MPa) | Yield Strength 0.2% Proof (MPa) | Elongation (%) | Hardness (Rockwell C) | PREN Value |
|---|---|---|---|---|---|
| Duplex 2205 (S31803 / S32205) | 655 – 880 MPa (min 116 ksi) | ≥ 450 MPa (min 65 ksi) | ≥ 25% | ≤ 32 HRC | ≥ 34 |
Stringent Quality Management
100% Positive Material Identification (PMI) Spectro Analysis
Tensile, Yield, Impact (Charpy V-Notch), and Elongation Testing
Intergranular Corrosion (IGC) Test per ASTM A262 Practice E
Hydrostatic and Hardness Testing (Brinell / Rockwell)
Complete EN 10204 3.1 Material Test Certificates provided
E-E-A-T Certified Quality Assurance
Every batch of Duplex Steel Fasteners produced at our Mumbai manufacturing facility undergoes rigorous multi-stage quality checks. We strictly verify microstructural phase balance (50/50 ferrite-austenite matrix) to ensure optimal corrosion resistance and mechanical integrity.
Export Packaging & Seaworthy Logistics
To safeguard threads and surface integrity during international transit, our duplex fasteners are individually wrapped, bundled, and packed in heavy-duty wooden crates, ISPM 15 compliant heat-treated pallets, or reinforced corrugated boxes with protective shrink wrap.
Global Supply Network
Stud Bolt India regularly exports certified Duplex Stainless Steel Fasteners to project locations, stockists, and EPC contractors across international markets including:
United States & Canada
United Arab Emirates (Dubai, Abu Dhabi, Sharjah)
Saudi Arabia & Kuwait
Qatar, Oman & Bahrain
Germany, United Kingdom & Netherlands
Singapore, Malaysia & Australia
Brazil, South Africa & South Korea
Frequently Asked Questions
What makes Duplex Steel UNS S32205 suitable for marine environments?
Duplex 2205 contains 22% Chromium, 3% Molybdenum, and 0.18% Nitrogen, giving it a PREN (Pitting Resistance Equivalent Number) of over 34. This chemical composition provides outstanding resistance to pitting and crevice corrosion in warm seawater and saline environments compared to standard 304 or 316 stainless steels.
Can Duplex Fasteners be used in sub-zero or high-temperature service?
Duplex steel fasteners perform excellently in ambient and moderately high temperatures. However, due to potential embrittlement phase transformations (475°C embrittlement), their recommended service temperature range is typically restricted between -50°C (-58°F) and +300°C (+572°F).
Do you offer customized sizes and non-standard pitch threads?
Yes. In addition to standard metric and imperial sizes, our CNC machining division produces customized studs, extra-long hex bolts, and special pitch threads manufactured strictly according to engineering drawings and project datasheets.
Need a Fast Quote on Duplex Steel Fasteners?
Connect directly with our technical sales engineers for immediate stock availability, custom manufacturing lead times, and competitive FOB/CIF pricing.