Technical specifications and application scope of the ASTM A307 standard
The ASTM A307 specification establishes strict chemical and mechanical requirements for carbon steel fasteners — bolts and studs with a nominal diameter ranging from 1/4 to 4 inches. In the EV Group China product line, these items are classified according to their strength characteristics and intended purpose:
| Grade | Technical description |
| A | Bolts, studs, and threaded rods with a tensile strength of 60 ksi. An optimal solution for general engineering tasks and general-purpose metal structures. |
| B | Fasteners with a tensile strength from 60 to 100 ksi. A specialized series for flange connections in piping systems used with cast iron valves and fittings. |
| C | Obsolete grade, replaced by the current F1554 Gr.36 specification. |
Important note: Production of Grade B threaded rods is not standard, however, EV Group China can supply these items according to the customer’s individual technical requirements.
This standard does not cover metric screws, self-tapping fasteners, anchor equipment, and specialized threaded parts that do not comply with the ASTM A307 specification.
To ensure the reliability of the assembly, the selection of nuts must be carried out in accordance with the A563 standard. The table below shows the compliance specification for fasteners and nuts:
| Bolt size and characteristics | Recommended nut type (ASTM A563) |
| 1/4 to 1 1/2 inches | Hex standard |
| Over 1 1/2 to 4 inches | Heavy hex |
| Grade B, 1/4 to 4 inches | Heavy hex |
Technical note: It is permitted to use nuts of higher strength grades, provided their load-bearing capacity meets the requirements of A563.
All measurements in the specification are provided in the inch-pound system, which is the reference system for this standard. If welding of bolts is required, the customer must specify the mandatory S1 requirement, which regulates additional restrictions on chemical composition and joining technology. Terminology for the products fully complies with the international standard F1789.