Mill-certified austenitic nuts engineered for corrosion resistance, high-temperature strength and clean-weld integrity — manufactured and stocked by Unifit Fastener.
ASTM A194 Certified • M3–M56 • Hex, Heavy-Hex, Nylon-Insert & Coupling Nuts • Shipped to 45+ Countries
At Unifit Fastener, we manufacture, stock and export a complete range of Stainless Steel 304, 304H and 304L nuts trusted across oil & gas, petrochemical, marine, construction and food-processing projects worldwide. Grade 304 is the most widely used austenitic stainless steel, prized for its balance of strength, formability and outstanding resistance to atmospheric and chemical corrosion. Its two variants extend that versatility: 304L, an extra-low-carbon grade that resists weld-zone sensitisation and performs reliably in cryogenic service, and 304H, a controlled higher-carbon grade delivering superior creep strength at elevated temperatures up to 800 °C and beyond. Every Unifit Fastener nut is produced to ASTM A194 / ASME SA194 and DIN standards, cold-forged or CNC-machined for precise thread engagement, and supplied with EN 10204 3.1 mill test certificates. From a single M3 hex nut to bulk M56 heavy-hex orders, we combine in-house inventory, tight tolerances and fast global dispatch so your assembly never waits on hardware.
Stainless steel 304 nuts are internally-threaded fasteners forged from an 18/8 austenitic alloy — nominally 18% chromium and 8% nickel — that forms a self-healing passive oxide layer to resist rust, staining and pitting. The three grades share the same chromium-nickel backbone but differ in one decisive element: carbon content.
SS 304 nuts (UNS S30400 / DIN 1.4301) offer excellent all-round corrosion resistance, high tensile strength and easy cold-working. They are the default choice for general structural, architectural and food-grade assemblies operating at ambient to moderate temperatures.
SS 304L nuts (UNS S30403 / DIN 1.4307) cap carbon at 0.03% to prevent chromium-carbide precipitation during welding, eliminating intergranular corrosion in the heat-affected zone. Their excellent low-temperature toughness makes them ideal for cryogenic tanks, LNG lines and food-processing equipment operating below –100 °C.
SS 304H nuts (UNS S30409 / DIN 1.4948) hold carbon between 0.04% and 0.10% and require a coarser grain size to deliver improved creep and rupture strength above 500 °C. They are specified in refinery, boiler and pressure-vessel service where high-temperature mechanical performance is critical.
| Attribute | Specification |
|---|---|
| Material Grades | SS 304, 304H, 304L (Austenitic) |
| Standards | ASTM A194 / ASME SA194 (nuts), DIN 934, ISO 4032; matching studs to ASTM A193. |
| Size Range | M3 to M56 | 3/16" to 2" | 3 mm to 200 mm |
| Thread | Metric coarse & fine, UNC / UNF, BSW (custom) |
| Form | Hex, Heavy Hex, Nylon Insert (Nyloc), Coupling, Square, Cap, Wing, Lock, Flange |
| Surface Finish | Bright, self-colour, passivated, electro-polished, PTFE-coated |
| Tolerance Class | 6H (internal thread), custom on request |
| Test Certificate | EN 10204 3.1 / 3.2 mill certificate |
| Grade | C | Mn | Si | P | S | Cr | Ni | N |
|---|---|---|---|---|---|---|---|---|
| 304 | 0.08 max | 2.0 max | 0.75 max | 0.045 max | 0.030 max | 18.0–20.0 | 8.0–10.5 | 0.10 max |
| 304L | 0.030 max | 2.0 max | 0.75 max | 0.045 max | 0.030 max | 18.0–20.0 | 8.0–12.0 | 0.10 max |
| 304H | 0.04–0.10 | 2.0 max | 0.75 max | 0.045 max | 0.030 max | 18.0–20.0 | 8.0–10.5 | — |
| Grade | Tensile Strength (MPa min) | Yield Strength 0.2% (MPa min) | Elongation (% min) | Hardness Rockwell B (max) | Brinell (HB max) |
|---|---|---|---|---|---|
| 304 | 515 | 205 | 40 | 92 | 201 |
| 304L | 485 | 170 | 40 | 92 | 201 |
| 304H | 515 | 205 | 40 | 92 | 201 |
| Property | Value |
|---|---|
| Density | 8000 kg/m³ |
| Elastic Modulus | 193 GPa |
| Thermal Expansion (0–100 °C) | 17.2 µm/m·°C |
| Thermal Expansion (0–538 °C) | 18.4 µm/m·°C |
| Thermal Conductivity (at 100 °C) | 16.2 W/m·K |
| Specific Heat (0–100 °C) | 500 J/kg·K |
| Electrical Resistivity | 720 nΩ·m |
| Standard | UNS | WERKSTOFF | EN | JIS | BS | AFNOR |
|---|---|---|---|---|---|---|
| SS 304 | S30400 | 1.4301 | X5CrNi18-10 | SUS 304 | 304S31 | Z7CN18-09 |
| SS 304L | S30403 | 1.4306 / 1.4307 | X2CrNi18-9 | SUS 304L | 304S11 | Z3CN18-10 |
| SS 304H | S30409 | 1.4948 | — | SUS 304H | — | — |
We offer a wide range of industrial Stainless Steel 304, 304L, 304H Nuts 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 304/304H/304L Nuts
Please Call 91 22 66518521 or Send an Email to chirag@unifitmetalloys.com
| Nut Type | Metric Size Range | Inch Size Range | Thread Type | Common Standards |
|---|---|---|---|---|
| Hex Nuts | M2 – M100 | 1/4" – 4" | Metric, UNC, UNF, BSW, BSF | DIN 934, ISO 4032, ANSI B18.2.2 |
| Heavy Hex Nuts | M6 – M100 | 3/8" – 4" | Metric, UNC, UNF | ASTM A194, ANSI B18.2.2 |
| Thin (Jam) Nuts | M3 – M64 | 1/4" – 2" | Metric, UNC, UNF | DIN 439, DIN 936 |
| Nylon Insert Lock Nuts | M3 – M36 | 1/4" – 1-1/2" | Metric, UNC, UNF | DIN 985, ISO 10511 |
| Flange Nuts | M5 – M30 | 1/4" – 1-1/4" | Metric, UNC, UNF | DIN 6923 |
| Dome (Cap) Nuts | M3 – M24 | 1/4" – 1" | Metric, UNC | DIN 1587 |
| Wing Nuts | M3 – M20 | 1/4" – 3/4" | Metric, UNC | DIN 315 |
| Square Nuts | M4 – M36 | 1/4" – 1-1/2" | Metric, UNC | DIN 557, DIN 562 |
| Coupling Nuts | M6 – M64 | 1/4" – 2" | Metric, UNC, UNF | DIN 6334 |
| Eye Nuts | M6 – M48 | 1/4" – 2" | Metric, UNC | DIN 582 |
| Weld Nuts | M4 – M20 | 3/16" – 3/4" | Metric, UNC | DIN 929, DIN 928 |
| Custom & Special Nuts | M2 – M100 | 1/4" – 4" | Metric, UNC, UNF, BSW, BSF | As per ASTM, DIN, ISO, ANSI & Customer Drawings |
| Factor | SS 304 | SS 304L | SS 304H |
|---|---|---|---|
| Carbon Content | ≤ 0.08% | ≤ 0.03% (low) | 0.04–0.10% (high) |
| Best For | General purpose | Welding & cryogenics | High-temperature service |
| Corrosion Resistance | Excellent | Excellent (weld zones) | Very good |
| High-Temp Strength | Good | Moderate | Superior (creep) |
| Tensile (min) | 515 MPa | 485 MPa | 515 MPa |
| Typical Service Temp | Ambient–425 °C | Below –100 °C | Up to 800 °C+ |
Every Unifit nut passes through a controlled, traceable production route:
A. The core difference is carbon content. Standard 304 contains up to 0.08% carbon, while 304L is capped at 0.03%. The lower carbon in 304L prevents chromium-carbide precipitation during welding, protecting the heat-affected zone from intergranular corrosion. 304L also performs better at very low (cryogenic) temperatures, whereas standard 304 offers slightly higher strength for general use.
A. Choose 304H when the fastener will operate continuously above roughly 500 °C. Its controlled higher carbon content and coarser grain size give improved creep and rupture strength, making it the preferred grade for boilers, refinery equipment and high-temperature pressure vessels.
A. In their annealed condition 304 nuts are essentially non-magnetic because of their austenitic structure. Heavy cold-working during forming can induce slight magnetism, but this does not affect corrosion resistance or mechanical performance.
A. Unifit Fastener supplies 304, 304H and 304L nuts from M3 to M56 (3/16" to 2"), in metric coarse, metric fine, UNC, UNF and BSW threads. Custom sizes and non-standard threads are produced to order.
A. Stainless steel nuts are typically manufactured to ASTM A194 / ASME SA194 (Grade 8 for 304, 8M for 316), while the matching bolts follow ASTM A193. We supply nuts fully certified to these specifications.
A. Yes. Every order ships with an EN 10204 3.1 mill test certificate showing chemical composition and mechanical properties, with heat-number traceability. 3.2 third-party certified reports (SGS, BV, TUV) are available on request.
