ASTM A194 Specification
The ASTM A194 specification is an ASTM International standard that governs nuts intended for use in high-pressure, high-temperature service, or both. This standard covers a wide range of carbon, alloy, and stainless steel nuts, available in sizes from 1/4″ to 4″ (and metric sizes M6 through M100 nominal). Specifically, it includes carbon, alloy, and martensitic stainless steel nuts in that full size range, while austenitic stainless steel nuts are covered for sizes 1/4″ and M6 nominal and above. Common grades included in the A194 specification are 2H, 2HM, 3, 4, 6, 7, 7M, 8, 8M, 8T, and 16, among others. These nuts are typically paired with ASTM A193 bolts. The materials used to make these nuts must be hot-wrought bars, which may then undergo further processing like centerless grinding or cold drawing. Austenitic stainless steel materials can be solution annealed or annealed and strain-hardened, with specific care required by the purchaser to understand related requirements (like Supplementary Requirement S1) when ordering strain-hardened material. It’s also important to note that grade substitutions are not permitted without the purchaser’s explicit permission.
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ASTM A194 Fastener Grades
ASTM A194 Material Grades
| Grades | Materials |
| A194 Grade 2H | Carbon Steel |
| A194 Grade 4 | Carbon Molybdenum Steel |
| A194 Grade 7 | Chromium Molybdenum Alloy Steel Type 4140 / 4142 / 4145 / 4140H / 4142H / 4145H |
| A194 Grade 8 | AISI 304 Stainless Steel |
| A194 Grade 8C | AISI 347 Stainless Steel |
| A194 Grade 8M | AISI 316 Stainless Steel |
| A194 Grade 8S | UNS S21800 Stainless Steel |
| A194 Grade 8T | AISI 321 Stainless Steel |
| B7 |  |
Hex bolts, screws, stud bolts, double ended studs, full thread rods, full threaded studs |
| B7M |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B16 |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8 |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8M |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8T |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
ASTM A194 Nuts, Fasteners and Bolts Supplier for High and Low Temperature Industrial Applications
Jade Alloys is a leading supplier and exporter of high-quality ASTM A194 fasteners, which include ASTM A194 nuts, studs, and ASTM A194 bolts. These products strictly adhere to the rigorous ASTM A194 specification for carbon, alloy, and stainless steel nuts used in high-pressure and high-temperature service. Key A194 material grades supplied are Grade 2H, Grade 4, Grade 7, and Grade 8, essential for critical applications in the oil and gas, petrochemical, and power generation sectors, such as pressure vessels and flanges. We maintain a vast, quality-certified inventory, ensuring exceptional strength, durability, and corrosion resistance to meet urgent and bulk orders efficiently while providing expert technical support globally.
We also specialize in supplying High Tensile Nut Bolts across India, known for their exceptional strength and durability crucial for critical, high-load applications in construction, automotive, manufacturing, and heavy machinery. These fasteners are manufactured from premium A194 material like alloy steel, carbon steel, and stainless steel, and are offered in high-performance metric grades 8.8, 10.9, and 12.9. Grade 12.9 offers the highest tensile strength for the toughest environments. Our entire range of high tensile nut bolts meets international standards including ISO, DIN, ASTM, and BS, ensuring reliable quality and global compatibility for your projects.
ASTM A194 Fasteners Mechanical Properties
| Specification | Material | Nominal Size, In. | Tempering Temp. °F | Proof Load Stress, ksi | Hardness Rockwell min – max | See note |
| ASTM A194 Grade 2 | Medium Carbon Steel | 1/4 – 2004 | 1000 | 150 | 159 – 352 | 1,2,3 |
| ASTM A194 Grade 2H | Medium Carbon Steel, Quenched and Tempered | 1/4 – 2004 | 1000 | 175 | C24 – C38 | 1,2 |
| ASTM A194 Grade 2HM | Medium Carbon Steel, Quenched and Tempered | 1/4 – 2004 | 1000 | 150 | 159 – 237 | 1,2,3 |
| ASTM A194 Grade 4 | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 – 2004 | 1100 | 175 | C24 – C38 | 1,2 |
| ASTM A194 Grade 7 | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 – 2004 | 1100 | 175 | C24 – C38 | 1,2 |
| ASTM A194 Grade 7M | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 – 2004 | 1100 | 150 | 159 – 237 | 1,2,3 |
| ASTM A194 Grade 8 | Stainless AISI 304 | 1/4 – 2004 | – | 80 | 126 – 300 | 4 |
| ASTM A194 Grade 8M | Stainless AISI 316 | 1/4 – 2004 | – | 80 | 126 – 300 | 4 |
ASTM A194 Nuts Chemical Composition
| Element | 2, 2H | 7 | 8 (AISI 304) | 8M (AISI 316) |
| Carbon | 0.4% min | 0.37 – 0.49% | 0.08% max | 0.08% max |
| Manganese | 1.0% max | 0.65 – 1.1% | 2.0% max | 2.0% max |
| Phosphorus, max | 0.04% | 0.035% | 0.045% | 0.045% |
| Sulfur, max | 0.05% | 0.04% | 0.03% | 0.03% |
| Silicon | 0.40% max | 0.15 – 035% | 1.0% max | 1.0% max |
| Chromium | 0.75 – 1.2% | 18.0 – 20.0% | 16.0 – 18.0% | |
| Nickel | 8.0 – 11.0% | 10.0 – 14.0% | ||
| Molybdenum | 0.15 – 0.25% | 2.0 – 3.0% |
ASTM A194 Hex Nut Dimensions
| Nut Size | Heavy Hex Nut | Heavy Hex Jam Nut | ||
|---|---|---|---|---|
| A | B | A | C | |
| 1/4″ | 1/2 | 15/64 | 1/2 | 11/64 |
| 5/16″ | 9/16 | 19/64 | 9/16 | 13/64 |
| 3/8″ | 11/16 | 23/64 | 11/16 | 15/64 |
| 7/16″ | 3/4 | 27/64 | 3/4 | 17/64 |
| 1/2″ | 7/8 | 31/64 | 7/8 | 19/64 |
| 9/16″ | 15/16 | 35/64 | 15/16 | 21/64 |
| 5/8″ | 1-1/6 | 39/64 | 1-1/16 | 23/64 |
| 3/4″ | 1-1/4 | 47/64 | 1-1/4 | 27/64 |
| 7/8″ | 1-7/16 | 55/64 | 1-7/16 | 31/64 |
| 1″ | 1-5/8 | 63/64 | 1-5/8 | 35/64 |
| 1-1/8″ | 1-13/16 | 1-7/64 | 1-13/16 | 39/64 |
| 1-1/4″ | 2 | 1-7/32 | 2 | 23/32 |
| 1-3/8″ | 2-3/16 | 1-11/32 | 2-3/16 | 25/32 |
| 1-1/2″ | 2-3/8 | 1-15/32 | 2-3/8 | 27/32 |
| 1-5/8″ | 2-9/16 | 1-19/32 | 2-9/16 | 29/32 |
| 1-3/4″ | 2-3/4 | 1-23/32 | 2-3/4 | 31/32 |
| 1-7/8″ | 2-15/16 | 1-27/32 | 2-15/16 | 1-1/32 |
| 2″ | 3-1/8 | 1-31/32 | 3-1/8 | 1-3/32 |
| 2-1/4″ | 3-1/2 | 2-13/64 | 3-1/2 | 1-13/64 |
| 2-1/2″ | 3-7/8 | 2-29/64 | 3-7/8 | 1-29/64 |
| 2-3/4″ | 4-1/4 | 2-45/64 | 4-1/4 | 1-37/64 |
| 3″ | 4-5/8 | 2-61/64 | 4-5/8 | 1-45/64 |
| 3-1/4″ | 5 | 3-3/16 | 5 | 1-13/16 |
| 3-1/2″ | 5-3/8 | 3-7/16 | 5-3/8 | 1-15/16 |
| 3-3/4″ | 5-3/4 | 3-11/16 | 5-3/4 | 2-1/16 |
| 4″ | 6-1/8 | 3-15/16 | 6-1/8 | 2-3/16 |
Applications of ASTM A194 Nuts
The superior material quality and manufacturing under the ASTM A194 specification make these fasteners indispensable in industries where failure is not an option. ASTM A194 nuts are specifically designed to maintain secure joint integrity under extreme conditions, including high and low temperatures, intense pressure, and corrosive environments. They are the go-to solution for high-stress connections across various critical sectors.
Nuts produced according to ASTM A194 find use in highly technical fields where mechanical or environmental stresses are significant:
- Oil & Gas: Used for critical connections in flanges, valves, pipelines, and high-pressure equipment where temperature and media resistance are paramount.
- Petrochemical: Essential components for securing reactors, heat exchangers, distillation columns, and piping systems that handle corrosive chemicals.
- Thermoelectric Plants: Applied in high-temperature fittings, boilers, turbines, and steam lines where continuous thermal cycling occurs.
- Marine Industry: Utilized in structural applications and accessories subject to high humidity and salt spray, requiring excellent corrosion resistance (especially stainless grades).
- Infrastructure and Tunnels: Employed for structural fixings, bridge components, and tunnel supports subject to heavy vibration, seismic activity, or wet atmospheres.
Advantages of Using ASTM A194 Nuts
Selecting fasteners manufactured to the ASTM A194 specification provides distinct operational and safety benefits, positioning them as the superior choice for critical, high-stress applications. Choosing ASTM A194 certified nuts means:
Enhanced Plant Safety: Utilizing reliable and tested materials significantly increases plant safety, minimizing the risk of failure in high-pressure or high-temperature systems.
Superior Durability: The specialized A194 material grades ensure the long-term durability and integrity of the bolted joint, even when exposed to extreme temperature, pressure, or corrosive environments.
Guaranteed Traceability: We provide complete documented traceability, typically via EN 10204 3.1 certification, guaranteeing material origin and quality testing.
Regulatory Compliance: Using ASTM A194 nuts ensures compliance with rigorous international regulations and standards during critical procurement, construction, and inspection phases.
These core benefits combined with the high-performance of the ASTM A194 bolts and fasteners directly translate into lower overall maintenance costs, reduced downtime, and greater long-term operational efficiency for your facility.
Looking for ASTM A194 Nuts?
Contact us today for more information about ASTM A194 nuts and receive expert assistance in choosing the right bolt + nut combination for your specific industrial project. Our technical team is ready to guide you through material selection (e.g., Grade 2H, 7, or 8) and dimensional requirements to ensure optimal joint integrity and performance under your operating conditions.
Frequently Asked Questions About ASTM A194
The ASTM A194 specification covers a wide range of carbon, alloy, and stainless steel nuts intended for high-pressure and/or high-temperature service. Common grades include 2H, 4, 7, and 8. Grade 2H nuts, in particular, are designed for demanding operating conditions and are typically supplied in a plain (uncoated) finish. These nuts can be easily identified by the permanent “2H” marking embossed on the face of the nut.
ASTM A193 is the standard specification for bolts and studs, whereas ASTM A194 is the standard specification for the corresponding nuts. Both standards are intended for high-temperature and high-pressure applications and are designed to be used together. ASTM A193 focuses on tensile strength and material composition for bolts and studs, while ASTM A194 specifies hardness, material composition, and proof load requirements for nuts. Together, they ensure a reliable and high-integrity bolted joint.
ASTM A194 nuts are available in a wide range of sizes to suit various industrial applications. The specification covers sizes from 1/4" through 4" in inch dimensions, and M6 through M100 in metric sizes. These nuts are specifically intended for use in high-pressure, high-temperature environments, or applications requiring both conditions.
