Stainless steel fasteners are precision iron-chromium-nickel alloys formulated with a minimum of 10.5% chromium. When exposed to oxygen, chromium spontaneously develops an invisible, self-healing chromium oxide passive film that confers exceptional resistance to atmospheric corrosion, oxidative chemicals, and pitting in chloride environments.
At TorqBolt Inc., we process high-grade austenitic bar stock to engineer bolts, studs, nuts, screws, and washers engineered for chemical processing, marine structures, power plants, and cryogenic storage. By controlling alloying additions such as molybdenum (316/316L), titanium (321), and niobium (347), our fasteners maintain structural integrity and stress-rupture resistance across an operating envelope spanning -196°C to 800°C.
TorqBolt engineers standard austenitic, strain-hardened high-tensile, and cryogenic-certified stainless steel fasteners to international design codes including ASME Boiler & Pressure Vessel Code (BPVC) Sections II and VIII.
The standard 18-8 Cr-Ni stainless alloy offering versatile resistance against fresh water, atmospheric exposure, and mild process media. Low-carbon 304L prevents intergranular carbide precipitation during welding.
Alloyed with 2.0% - 3.0% Molybdenum to resist chloride pitting, crevice corrosion, and dilute sulfuric acid. The international benchmark for offshore platforms, marine hardware, and chemical plants.
Stabilized with Titanium (321) or Niobium/Tantalum (347) to eliminate chromium carbide precipitation in the 427°C to 816°C sensitization zone. Ideal for exhaust systems and refinery reactors.
High chromium (25%) and nickel (20%) alloy delivering remarkable resistance to oxidation, carburization, and thermal shock up to 1100°C in continuous industrial furnace service.
Cold-worked to achieve elevated tensile strength (up to 860 MPa) and high proof stress while retaining austenitic corrosion integrity. Widely specified for high-pressure ASME B16.5 flanges.
Controlled chemistry ensuring Charpy V-notch impact toughness exceeding 27 J at -196°C. Certified for cryogenic LNG storage, refrigeration units, and sub-zero Arctic pipeline installations.
Reference data for high-tensile strain-hardened austenitic bolting per ASTM A193 and low-temperature bolting per ASTM A320.
| Grade / Class | Base Material | Tensile Min (MPa / ksi) | Yield 0.2% Min (MPa / ksi) | Elongation Min (%) | Hardness Max | Typical Service Conditions |
|---|---|---|---|---|---|---|
| ASTM A193 Gr. B8 Cl. 1 | AISI 304 (Solution Annealed) | 515 / 75 | 205 / 30 | 30% | 96 HRB | Standard pressure vessels, flanges, valves |
| ASTM A193 Gr. B8 Cl. 2 | AISI 304 (Strain Hardened) | 690 - 860 / 100 - 125 | 550 - 690 / 80 - 100 | 15 - 28% | 35 HRC | High pressure piping, structural joints |
| ASTM A193 Gr. B8M Cl. 1 | AISI 316 (Solution Annealed) | 515 / 75 | 205 / 30 | 30% | 96 HRB | Corrosive chemical & marine installations |
| ASTM A193 Gr. B8M Cl. 2 | AISI 316 (Strain Hardened) | 655 - 760 / 95 - 110 | 515 - 655 / 75 - 95 | 15 - 25% | 35 HRC | Offshore topsides, sour service bolting |
| ASTM A193 Gr. B8T Cl. 2 | AISI 321 (Strain Hardened) | 655 - 860 / 95 - 125 | 515 - 690 / 75 - 100 | 15 - 25% | 35 HRC | Elevated temperature flanges and turbines |
| ASTM A193 Gr. B8C Cl. 2 | AISI 347 (Strain Hardened) | 655 - 860 / 95 - 125 | 515 - 690 / 75 - 100 | 15 - 25% | 35 HRC | Refinery cat crackers, heat exchangers |
| ASTM A320 Gr. B8 Cl. 1/2 | AISI 304 (Low-Temp Tested) | 515 - 860 / 75 - 125 | 205 - 690 / 30 - 100 | 15 - 30% | 35 HRC | LNG, liquid oxygen, sub-zero services (-196°C) |
| ASTM A320 Gr. B8M Cl. 1/2 | AISI 316 (Low-Temp Tested) | 515 - 760 / 75 - 110 | 205 - 655 / 30 - 95 | 15 - 30% | 35 HRC | Cryogenic marine valves and arctic piping |
Every stainless fastener manufactured at our Rajkot facility undergoes rigorous multi-stage quality verification to assure absolute reliability in severe service.
TorqBolt supplies comprehensive documentation with every consignment. All parts carry distinct head markings indicating material grade, class, and TorqBolt manufacturer identification for complete lifecycle accountability.
Standard documentation includes certified EN 10204 Type 3.1 Material Test Reports (MTRs) detailing heat chemistry, solution annealing parameters, and lot testing. Where contractual specifications dictate third-party verification, we facilitate EN 10204 Type 3.2 witnessed testing through internationally recognized bureaus including TÜV Rheinland, DNV, Lloyd's Register, Bureau Veritas, and SGS.
Connect directly with our engineering team to review material selection, project specifications, dimensional prints, and delivery schedules.
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