Manufacturer, Supplier & Global Exporter of ASTM A193 / ASME SA193 Certified Fasteners
Engineered for marine, offshore, oil & gas, and chemical environments, Unifit Fastener manufactures high-integrity molybdenum-alloyed 316-series bolts that resist pitting, crevice corrosion, and chloride attack — shipped worldwide with full material traceability.
Stainless Steel 316 bolts (AISI 316) are austenitic bolts manufactured from a chromium–nickel–molybdenum alloy with exceptional corrosion resistance in salt water, acidic and industrial environments. The 316 grade is the preferred choice for coastal, marine and petrochemical installations, due to the addition of 2–3% molybdenum which provides significantly greater resistance to pitting and crevice corrosion through chlorides. In the family, 316L has a low-carbon structure that provides resistance to weld zone sensitization, 316H has a higher carbon content for better high temperature strength, and 316Ti is stabilized with titanium to resist intergranular corrosion between 425 and 815°C.
Each 316-series bolt produced at Unifit Fastener is to ASTM A193 / ASME SA193 standards and is accompanied by the EN 10204 3.1 mill test certificate. From standard DIN 933 hex bolts to heavy hex structural bolts, our fasteners are engineered to ensure your tensile strength, ductility, and long-service requirements — so you can specify with confidence.
| Parameter | Details |
|---|---|
| Standards | ASTM A193 / ASME SA193, DIN, BS, IS, EN, JIS |
| Dimensions | DIN 931, 933, 934, 976, 7991, 125; ASME B18.2.1 |
| Size Range | M3 – M56 | 3/16″ to 2″ | custom sizes |
| Length | 3 mm to 200 mm | custom lengths |
| Thread | Rolled, cut or tapped — UNF, UNC, BSW, BSF, Metric |
| Form | Hex, square, round, threaded as per gauge |
| Test Certificate | EN 10204 3.1, PED 97/23/EC, AD 2000 W2 |
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N |
|---|---|---|---|---|---|---|---|---|---|
| 316 | 0.08 | 2.0 | 0.75 | 0.045 | 0.030 | 16–18 | 2.0–3.0 | 10–14 | 0.10 |
| 316L | 0.03 | 2.0 | 0.75 max | 0.045 | 0.030 | 16–18 | 2.0–3.0 | 10–14 | 0.10 |
| 316H | 0.04–0.10 | 2.0 | 0.75 | 0.045 | 0.030 | 16–18 | 2.0–3.0 | 10–14 | 0.10 |
| 316Ti | 0.08 | 2.0 | 0.75 | 0.045 | 0.030 | 16–18 | 2.0–3.0 | 10–14 | – |
Values shown are maximums unless a range is given. 316Ti additionally contains Ti ≈ 5×C, min 0.70% max.
| Property | A240 base (316/316L) | A193 B8M Cl.1 bolt | A193 B8M Cl.2 bolt (≤¾″) |
|---|---|---|---|
| Tensile min (MPa) | 515 / 485 | 515 | 655 |
| Yield 0.2% min (MPa) | 205 / 170 | 205 | 450 |
| Elongation min (%) | 40 | 30 | 25 |
| Hardness max | 95 HRB / 217 HB | 96 HRB / 223 HBW | 35 HRC / 321 HBW |
| Grade | UNS No. | EN Numeric | EN Symbolic | JIS | British BS |
|---|---|---|---|---|---|
| 316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS 316 | 316S31 |
| 316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS 316L | 316S11 |
| 316H | S31609 | 1.4919 | – | – | 316S51 |
| 316Ti | S31635 | 1.4571 | X6CrNiMoTi17-12-2 | SUS 316Ti | 320S31 |
| Nominal Size | Body Dia (max) | Head Height (max) | Width Across Flats (max) | Width Across Corners (max) |
|---|---|---|---|---|
| M10 | 10.00 | 6.63 | 17.00 | 18.48 |
| M12 | 12.00 | 7.76 | 19.00 | 20.78 |
| M16 | 16.00 | 10.32 | 24.00 | 27.71 |
| M20 | 20.00 | 12.88 | 30.00 | 34.64 |
| M24 | 24.00 | 15.44 | 36.00 | 41.57 |
| M30 | 30.00 | 19.48 | 46.00 | 53.12 |
| M36 | 36.00 | 23.38 | 55.00 | 63.51 |
| M48 | 48.00 | 31.07 | 75.00 | 86.60 |
| M56 | 56.00 | 36.20 | 85.00 | 98.15 |
The corrosion resistance and temperature tolerance of 316-series bolts make them indispensable across demanding sectors:
| Industry | Typical Uses |
|---|---|
| Oil & Gas / Offshore | Wellheads, pipelines, subsea flanges, valve assemblies |
| Petrochemical & Refining | Reactors, columns, heat-exchanger bolting |
| Marine & Shipbuilding | Deck fittings, propeller shafts, hull hardware |
| Chemical Processing | Acid tanks, dosing systems, corrosive fluid handling |
| Power Generation | Turbine housings, boiler mounts, exhaust systems |
| Food & Pharmaceutical | Hygienic equipment, clean-room assemblies |
| Pulp, Paper & Fertilizer | Digesters, evaporators, high-humidity structures |
| Property | SS 304 Bolts | SS 316 Bolts | SS 316Ti Bolts |
|---|---|---|---|
| Molybdenum | None | 2–3% | 2–3% |
| Chloride/Pitting Resistance | Moderate | High | High |
| Weld Sensitization Resistance | Low | Good (316L) | Excellent |
| High-Temp Performance | Fair | Good | Excellent |
| Best For | General use | Marine / chemical | Sustained heat + corrosion |
Our fasteners are produced from premium raw material sourced from reputed mills, then thread-rolled for maximum fatigue strength. Each batch passes a structured inspection regime before dispatch:
| Standard Category | Applicable Standards |
|---|---|
| ASTM / ASME | ASTM A193, ASTM A194, ASTM F593, ASTM F594, ASTM A320 (where applicable), ASME SA193, ASME SA194 |
| ISO | ISO 4014, ISO 4017, ISO 3506-1, ISO 3506-2, ISO 4032, ISO 4762, ISO 7380, ISO 8676, ISO 8765, ISO 7412 |
| DIN | DIN 444, DIN 558, DIN 580, DIN 605, DIN 607, DIN 608, DIN 610, DIN 931, DIN 933, DIN 960, DIN 961, DIN 976-1, DIN 6914, DIN 6915, DIN 6921, DIN 6922, DIN 7990 |
| ANSI / ASME | ANSI B18.2.1, ASME B18.2.3.1M, ASME B18.3, ASME B18.31.2 |
| BS | BS 1083, BS 1768, BS 1769 |
| IS | IS 1363, IS 1364, IS 2585, IS 3138, IS 3640, IS 3757, IS 6639, IS 10238 |
We offer a wide range of industrial Stainless Steel 316, 316L Bolts that are in compliance with IS, BS and DIN standards at best market prices in India. To know more about the latest price of Stainless Steel 316/316L Bolts.
Please call at 91 22 66518521 or Send an Email to chirag@unifitmetalloys.com
| Metric Size | Imperial Size | Thread Pitch (Coarse) | UNC/UNF Thread | Available Length |
|---|---|---|---|---|
| M3 | 3/16" | 0.50 mm | — | 6–30 mm |
| M4 | 1/4" | 0.70 mm | 1/4"-20 / 1/4"-28 | 6–50 mm |
| M5 | — | 0.80 mm | — | 8–60 mm |
| M6 | 1/4" | 1.00 mm | 1/4"-20 / 1/4"-28 | 10–100 mm |
| M8 | 5/16" | 1.25 mm | 5/16"-18 / 5/16"-24 | 12–150 mm |
| M10 | 3/8" | 1.50 mm | 3/8"-16 / 3/8"-24 | 16–200 mm |
| M12 | 1/2" | 1.75 mm | 1/2"-13 / 1/2"-20 | 20–250 mm |
| M16 | 5/8" | 2.00 mm | 5/8"-11 / 5/8"-18 | 25–300 mm |
| M20 | 3/4" | 2.50 mm | 3/4"-10 / 3/4"-16 | 30–350 mm |
| M24 | 1" | 3.00 mm | 1"-8 / 1"-14 | 40–400 mm |
| M30 | 1-1/8" | 3.50 mm | 1-1/8"-7 / 1-1/8"-12 | 50–450 mm |
| M36 | 1-1/2" | 4.00 mm | 1-1/2"-6 / 1-1/2"-12 | 60–500 mm |
| M42 | 1-5/8" | 4.50 mm | 1-5/8"-5.5 / 1-5/8"-8 | Up to 500 mm |
| M48 | 2" | 5.00 mm | 2"-4.5 / 2"-8 | Up to 500 mm |
| M56 | 2-1/4" | 5.50 mm | Custom Threads Available | Up to 500 mm |
In the annealed condition, 316 bolts are essentially non-magnetic because of their austenitic structure. Cold working during forming can induce slight magnetism, but they remain far less magnetic than martensitic grades.
The key difference is carbon content. 316L is limited to 0.03% carbon, which prevents chromium-carbide formation during welding and preserves corrosion resistance in the heat-affected zone. Standard 316 allows up to 0.08% carbon and offers marginally higher strength.
Yes. The molybdenum content gives 316 excellent resistance to chloride pitting, making it a standard choice for marine and coastal applications. For prolonged full immersion with stagnant conditions, super-duplex grades may be considered.
316H bolts are designed for elevated-temperature service and retain useful creep and rupture strength well above 500°C, which is why they are specified for boilers and high-temperature piping.
Unifit Fastener supplies 316-series bolts from M3 to M56 (3/16″ to 2″) in lengths from 3 mm to 200 mm, with custom sizes, threads and coatings available on request.
Yes. Every order is supplied with EN 10204 3.1 mill test certificates, and PMI or additional third-party inspection can be arranged on request.