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Stainless Steel 304H Nuts are high-carbon variants of austenitic stainless steel fasteners designed specifically for elevated temperature service where standard 304 grades lose mechanical stability. These nuts are widely used in boiler assemblies, petrochemical plants, heat exchangers, power generation systems, and pressure equipment where sustained temperature exposure demands superior creep strength and structural reliability.
Manufactured in compliance with DIN, ISO, and ASTM standards, Stainless Steel 304H Nuts provide a balance of corrosion resistance and thermal strength, making them suitable for critical fastening applications under continuous thermal stress. The “H” grade indicates higher carbon content, improving tensile strength at elevated temperatures without significantly compromising corrosion resistance in controlled environments.
KK Fasteners supplies these nuts to global industrial clients with full material traceability, ensuring consistent quality for high-performance engineering systems across demanding industries.
| Parameter | Specification |
|---|---|
| Material | Stainless Steel 304H (AISI 304H / UNS S30409) |
| Grade Options | 304H, 304, 304L (comparison variants) |
| Size Range | M3 to M64 / 1/8" to 2.5" |
| Thread Type | Metric (ISO), UNC, UNF, BSW |
| Standards | DIN 934, ISO 4032, ASTM A194 (equivalent reference), BS 1768 |
| Surface Finish | Bright, Passivated, Polished, Black Oxide (custom) |
| Type Variants | Hex Nuts, Heavy Hex Nuts, Lock Nuts, Slotted Nuts |
| Tensile Strength | ≥ 515 MPa (typical for 304H condition) |
| Hardness | Up to 201 HB (approx.) |
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
|---|---|---|---|---|---|---|---|---|---|---|
| 304H | min. | 0.04 | – | – | – | – | 18.0 | – | 8.0 | – |
| max. | 0.10 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | – | 10.5 | – | |
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
|---|---|---|---|---|---|
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| 304H | 515 | 205 | 40 | 92 | 201 |
| STANDARD | WERKSTOFF NR. | UNS | JIS |
| SS 304H | 1.4948 | S30409 | SUS 304H |
All measurements in millimeters
Nominal Size or Basic Major Thread Diameter |
F |
G |
H |
||||||
Width Across Flats |
Width Across Corners |
Thickness |
|||||||
Basic |
Max |
Min |
Max |
Min |
Basic |
Max |
Min |
||
1/4 |
.2500 |
1/2 |
.500 |
.488 |
.577 |
.556 |
15/64 |
.250 |
.218 |
5/16 |
.3125 |
9/16 |
.562 |
.546 |
.650 |
.622 |
19/64 |
.314 |
.280 |
3/8 |
.3750 |
11/16 |
.688 |
.669 |
.794 |
.763 |
23/64 |
.377 |
.341 |
7/16 |
.4375 |
3/4 |
.750 |
.728 |
.866 |
.830 |
27/64 |
.441 |
.403 |
1/2 |
.5000 |
7/8 |
.875 |
.850 |
1.010 |
.969 |
31/64 |
.504 |
.464 |
9/16 |
.5625 |
15/16 |
.938 |
.909 |
1.083 |
1.037 |
35/64 |
.568 |
.526 |
5/8 |
.6250 |
1-1/16 |
1.062 |
1.031 |
1.227 |
1.175 |
39/64 |
.631 |
.587 |
3/4 |
.7500 |
1-1/4 |
1.250 |
1.212 |
1.443 |
1.382 |
47/64 |
.758 |
.710 |
7/8 |
.8750 |
1-7/16 |
1.438 |
1.394 |
1.660 |
1.589 |
55/64 |
.885 |
.833 |
1 |
1.0000 |
1-5/8 |
1.325 |
1.575 |
1.876 |
1.796 |
63/64 |
1.012 |
.956 |
1-1/8 |
1.1250 |
1-13/16 |
1.812 |
1.756 |
2.093 |
2.002 |
1-7/64 |
1.139 |
1.079 |
1-1/4 |
1.2500 |
2 |
2.000 |
1.938 |
2.309 |
2.209 |
1-7/32 |
1.251 |
1.187 |
1-3/8 |
1.3750 |
2-3/16 |
2.188 |
2.119 |
2.526 |
2.416 |
1-11/32 |
1.378 |
1.460 |
1-1/2 |
1.5000 |
2-3/8 |
2.375 |
2.300 |
2.742 |
2.622 |
1-15/32 |
1.505 |
1.433 |
1-5/8 |
1.6250 |
2-9/16 |
2.562 |
2.481 |
2.959 |
2.828 |
1-19/32 |
1.632 |
1.556 |
1-3/4 |
1.7500 |
2-3/4 |
2.750 |
2.662 |
3.175 |
3.035 |
1-23/32 |
1.759 |
1.679 |
2 |
2.0000 |
3-1/8 |
3.125 |
3.025 |
3.608 |
3.449 |
1-31/32 |
2.013 |
1.925 |
2-1/4 |
2.2500 |
3-1/2 |
3.500 |
3.388 |
4.041 |
3.862 |
2-13/64 |
2.251 |
2.155 |
2-1/2 |
2.5000 |
3-7/8 |
3.875 |
3.750 |
4.474 |
4.275 |
2-29/64 |
2.505 |
2.401 |
2-3/4 |
2.7500 |
4-1/4 |
4.250 |
4.112 |
4.907 |
4.688 |
2-45/64 |
2.759 |
2.647 |
3 |
3.0000 |
4-5/8 |
4.625 |
4.475 |
5.340 |
5.102 |
2-61/64 |
3.013 |
2.893 |
3-1/4 |
3.2500 |
5 |
5.000 |
4.838 |
5.774 |
5.515 |
3-3/16 |
3.252 |
3.124 |
3-1/2 |
3.5000 |
5-3/8 |
5.375 |
5.200 |
6.207 |
5.928 |
3-7/16 |
3.506 |
3.370 |
3-3/4 |
3.7500 |
5-3/4 |
5.750 |
5.562 |
6.640 |
6.341 |
3-11/16 |
3.670 |
3.616 |
4 |
4.0000 |
6-1/8 |
6.125 |
5.925 |
7.073 |
6.755 |
3-15/16 |
4.014 |
3.862 |
Stainless Steel 304H Nuts are used in high-temperature and heavy-duty engineering environments where mechanical stability and oxidation resistance are critical.
Stainless Steel 304H Nuts are manufactured using a combination of cold forging and precision CNC threading processes to achieve dimensional accuracy and mechanical strength consistency. Raw material billets are heat-treated under controlled conditions before forming to ensure uniform grain structure.
Each batch undergoes dimensional inspection, thread gauge testing, and hardness verification to ensure compliance with DIN and ISO standards. Surface passivation is applied to enhance corrosion resistance by removing free iron contamination. Lot traceability is maintained throughout production for quality assurance and export documentation.
KK Fasteners follows ISO 9001-based quality protocols, ensuring each production lot meets global industrial fastening requirements with verified mechanical performance and consistency.
| Applications | Industries |
|---|---|
| Industrial Machinery | Manufacturing |
| Construction | Construction |
| Automotive | Automotive |
| Aerospace | Aerospace |
| Marine | Marine |
| Oil and Gas | Energy |
| Chemical Processing | Chemical |
| Food and Beverage | Food |
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Stainless Steel 304H Nuts are high-carbon austenitic stainless steel fasteners designed for elevated temperature applications. They offer improved creep strength compared to standard 304 grades and are widely used in boilers, petrochemical equipment, heat exchangers, and power plant assemblies where long-term thermal stability is required.
The main difference is carbon content. 304H contains higher carbon, which increases tensile strength and creep resistance at high temperatures. Standard 304 is suitable for general corrosion resistance, while 304H is specifically chosen for continuous high-heat industrial service.
These nuts are commonly manufactured according to DIN 934, ISO 4032, and ASTM A194 equivalent specifications. These standards ensure proper dimensional accuracy, thread compatibility, and mechanical performance for industrial and structural fastening applications.
They are used in high-temperature environments such as boilers, refinery piping systems, heat exchangers, power plants, and chemical processing units. They are selected where both strength retention and oxidation resistance are critical under continuous heat exposure.
A reliable manufacturer should offer ISO-certified production, material traceability, compliance with DIN/ASTM standards, and proven export capability. Engineering-grade inspection reports and consistent quality control are also key indicators of a trustworthy supplier.
Stainless Steel 304H Nuts are engineered for demanding thermal and structural environments where standard fasteners fail under prolonged heat exposure. With precision manufacturing and strict quality controls, KK Fasteners delivers consistent performance-ready components for global industrial applications.
For technical specifications, bulk pricing, or custom requirements, connect with KK Fasteners to request a detailed quotation or engineering support for your project.
