More about ASTM A 194
The ASTM A194 specification covers carbon, alloy, and stainless steel nuts intended for use in high-pressure and/or high-temperature service. Unless otherwise specified, the
American National Standard Heavy Hex Series (ANSI B 18.2. 2) shall be used.
Nuts up to and including 1-inch nominal size shall be UNC Series Class 2B fit
Nuts over 1-inch nominal size shall be either UNC Series Class 2B fit or 8 UN Series Class 2B fit
High strength ASTM A194 grade 2H nuts are common in the marketplace and are often substituted for ASTM A563 grade DH nuts due to the limited availability of DH nuts in certain diameters and finishes.
ASTM A194 in various Grades as bellow:
American National Standard Heavy Hex Series (ANSI B 18.2. 2) shall be used.
Nuts up to and including 1-inch nominal size shall be UNC Series Class 2B fit
Nuts over 1-inch nominal size shall be either UNC Series Class 2B fit or 8 UN Series Class 2B fit
High strength ASTM A194 grade 2H nuts are common in the marketplace and are often substituted for ASTM A563 grade DH nuts due to the limited availability of DH nuts in certain diameters and finishes.
ASTM A194 in various Grades as bellow:
Gr.2 : Carbon steel for Heavy Hex Nuts
Gr.2H : Quenched & tempered carbon steel heavy hex nuts
Gr.2HM : Quenched & tempered carbon steel heavy hex nuts, 100% hardness tested
Gr.4 : Quenched & tempered carbon-molybdenum heavy hex nuts (withdrawn in 2017)
Gr. 7 : Quenched & tempered alloy steel heavy hex nuts
Gr.7M : Quenched & tempered alloy steel heavy hex nuts, 100% hardness tested
Gr.7L : Quenched & tempered alloy steel heavy hex nuts, Charpy impact tested
Gr.8 : Stainless AISI 304 heavy hex nuts
Gr.8M : Stainless AISI 316 heavy hex nuts
To access standard ASTM A194 please click here
A194 Mechanical Properties
| Grade Identification Marking5 | Specification | Material | Nominal Size, In. | Tempering Temp. °F | Proof Load Stress, ksi | Hardness Rockwell | See Note | |
|---|---|---|---|---|---|---|---|---|
| Min | Max | |||||||
 | ASTM A194 Grade 2 | Medium Carbon Steel | 1/4 - 4 | 0 | 150 | 159 | 352 | 1,2,3 |
 | ASTM A194 Grade 2H | Medium Carbon Steel, Quenched and Tempered | 1/4 - 4 | 850 | 175 | C24 | C38 | 1,2 |
 | ASTM A194 Grade 2HM | Medium Carbon Steel, Quenched and Tempered | 1/4 - 4 | 1150 | 150 | 159 | 237 | 1,2,3 |
 | ASTM A194 Grade 4 | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 - 4 | 1100 | 175 | C24 | C38 | 1,2 |
 | ASTM A194 Grade 7 | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 - 4 | 1100 | 175 | C24 | C38 | 1,2 |
 | ASTM A194 Grade 7M | Medium Carbon Alloy Steel, Quenched and Tempered | 1/4 - 4 | 1150 | 150 | 159 | 237 | 1,2,3 |
 | ASTM A194 Grade 8 | Stainless AISI 304 | 1/4 - 4 | - | 80 | 126 | 300 | 4 |
 | ASTM A194 Grade 8M | Stainless AISI 316 | 1/4 - 4 | - | 80 | 126 | 300 | 4 |
