ASTM A307 Screws, Threaded Rod, Grade A, B
ASTM A307 screws, threaded rod and studs are the most commonly used fasteners, covering two grades of chemical and mechanical requirements from 0.25 to 4 inches in size.
- ASTM A307 Grade A : Suitable for bolts, pins and screws for general applications, with a minimum tensile strength of 60 ksi.
- ASTM A307 Grade B : Heavy-duty bolts, pins and screws, with tensile strength of 60-100 ksi, used for flange connections in piping systems with cast iron flanges.
Note: This standard does not cover anchor bolts.
Product marking
All A307 screw heads, one end of studs 3/8 inch and larger, and studs smaller than 3/8 inch, where feasible, shall be marked with the following classification mark:
- Grade A: 307A
- Grade B: 307B
A307 threaded rod will be exempt from the marking requirements of the relevant material specifications unless otherwise specified by the purchaser. Packaging and labeling requirements are mandatory in the applicable material specifications. If markings are required, they shall be located at both ends of the threaded rod and shall be raised or lowered according to the manufacturer's choice.
Specifications
The following tables show the class properties and specifications of ASTM A307 bolt and threaded rod (data sheet), including chemical composition, mechanical properties, etc.
Chemical Composition of A307 Steel
The chemical requirements for A307 steel, grade 307B and 307A screws, threaded rod and studs are listed in the following table.
| Chemical Requirements | |||||
| Grades | W | Mn | P | s | Illness |
| ASTM A307 Grade A | 0.29 | 1.2 | 0.04 | 0.15 | Heat Analysis |
| 0.33 | 1.25 | 0.041 | Product Analysis | ||
| ASTM A307 Grade B | 0.29 | 1.2 | 0.04 | 0.05 | Heat Analysis |
| 0.33 | 1.25 | 0.041 | 0.051 | Product Analysis | |
Mechanical properties
Hardness Requirements for A307 Screw, Stud and Threaded Rod
| Hardness Requirements | |||
| Note | Nominal length, in. | Toughness | |
| Brinell | Rockwell B. | ||
| A307 Gr A | Less than 3 x diameter | 121-241 | 69-100 |
| 3 x diameter and more | ≤241 | ≤100 | |
| A307 Gr B | Less than 3 x diameter | 121-212 | 69-95 |
| 3 x diameter and more | ≤212 | ≤95 | |
Tensile Requirements for ASTM A307 Full-Size Bolts, Studs, and Threaded Rod
| Traction Requirements | ||||
| Bolt size, in. | Threads per inch | Stress Area, in. | Tensile strength, lbf x 10 3 (kN) | |
| Grade A, ≥ | Serie B | |||
| 1/4 | 20 | 0.0318 | 1.9 (8.45) | 1.9-3.18 (8.45-14.16) |
| 05/16 | 18 | 0.0524 | 3.1 (13.79) | 3.1-5.24 (13.79-23.31) |
| 3/8 | 16 | 0.0775 | 4.65 (20.68) | 4.65-7.75 (20.68-34.47) |
| 7/16 | 14 | 0.1063 | 6.35 (28.25) | 6.35-10.63 (28.25-47.28) |
| 1/2 | 13 | 0.1419 | 8.5 (37.81) | 8.5-14.19 (37.81-63.12) |
| 16/09 | 12 | 0.182 | 11 (49) | 11-18.2 (49-81) |
| 5/8 | 11 | 0.226 | 13.55 (60) | 13.55-22.6 (60-100) |
| 3/4 | 10 | 0.334 | 20.05 (89) | 20.05-33.4 (89-148) |
| 7/8 | 9 | 0.462 | 27.7 (123) | 27.7-46.2 (123-205) |
| 1 | 8 | 0.606 | 36.35 (161) | 36.35-60.6 (161-269) |
| 1 1/8 | 7 | 0.763 | 45.8 (204) | 45.8-76.3 (204-339) |
| 1 1/4 | 7 | 0.969 | 58.15 (230) | 58.15-96.9 (230-431) |
| 1 3/8 | 6 | 1,155 | 69.3 (308) | 69.3-115.5 (308-514) |
| 1 1/2 | 6 | 1,405 | 84.3 (375) | 84.3-140.5 (375-625) |
| 1 3/4 | 5 | 1.9 | 114 (507) | 114-190 (507-845) |
| two | 4 1/2 | 2.5 | 150 (667) | 150-250 (667-1112) |
| 2 1/4 | 4 1/2 | 3.25 | 195 (867) | 195-325 (867-1445) |
| 2 1/2 | 4 | 4 | 240 (1067) | 240-400 (1067-1779) |
| 2 3/4 | 4 | 4.93 | 295.8 (1316) | 295.8-493 (1316-2193) |
| 3 | 4 | 5.97 | 358.2 (1593) | 358.2-597 (1593-2655) |
| 3 1/4 | 4 | 7.1 | 426 (1895) | 426-710 (1895-3158) |
| 3 1/2 | 4 | 8.33 | 499.8 (2223) | 499.8-833 (2223-3705) |
| 3 3/4 | 4 | 9.66 | 579.6 (2578) | 579.6-966 (2578-4297) |
| 4 | 4 | 11.08 | 664.8 (2957) | 664.8-1,108 (2957-4928) |
| Tensile Requirements for Machined Specimens | |||
| Grades | Tensile strength, ksi | Yield point, min ksi | Elongation by 2 in.,% |
| ASTM A307 Gr A | 60, ≥ | – | 18 |
| ASTM A307 Gr B | 60-100 | – | 18 |
For inspection, sample size and acceptance number of hot-dipped or mechanically deposited zinc coated threads
| Lot size | Sample size | Acceptance number |
| 2 to 90 | 13 | 1 |
| 91 to 150 | 20 | two |
| 151 to 280 | 32 | 3 |
| 281 to 500 | 50 | 5 |
| 501 to 1,200 | 80 | 7 |
| 1,201 to 3,200 | 125 | 10 |
| 3,201 to 10,000 | 200 | 14 |
| 10,001 ≥ | 315 | 21 |
