ASME B18.31.2 Standard specification.
ASME B18.31.2 – Continuous Thread Stud, Double-End Stud, and Flange Bolting Stud (Stud Bolt) (Inch Series)
This standard covers the dimensional and material requirements for continuous-thread and double-end threaded studs, used primarily for bolting flanged connections, valves, pressure vessels, and other industrial applications
ASME B18.31.2 Scope
ASME B18.31.2 provides specifications for:
- Continuous Thread Studs (Fully Threaded Rods):
Threads run the full length of the stud. - Double-End Studs:
Threads on both ends, with a plain (unthreaded) center portion. Used when bolted parts are removed frequently.
Dimensions and specification
| Feature | Details |
|---|---|
| Thread Series | UNC (Coarse) and UNF (Fine) as per ASME B1.1 |
| Nominal Diameters | 1/4 inch through 4 inches |
| Stud Lengths | Specified in inches, typically from 1″ up to 48″ |
| End Configuration | Chamfered ends, optional radius or 45° bevel |
| Unthreaded Center (Double-End) | Minimum 1.5 × diameter between threaded portions |
Dimensions for Continuous thread studs
Stud bolt Materials made according to ASME B18.31.2
| ASTM A307 | Grade A & B |
| ASTM A320, A320M | Grade L7, L7M, B8, B8M |
| ASTM A325, A325M | Grade 8.8 |
| ASTM A490, A490M | Grade 10.9 |
| ASTM A193/A193M | Grade B7, B7M, B8, B8M, B16 |
Customised Coating Systems on stud bolt
Zinc + Fluorocarbon / PTFE
Cadmium + Fluorocarbon /PTFE
Zinc Nickel + Fluorocarbon /PTFE
Zinc Plating + Xylan 1424 Blue coated stud bolt
Xylar 2 + Xylan 1070 Blue coated stud bolt
Standard reference
| Standard | Description |
|---|---|
| ASME B1.1 | Unified Inch Screw Threads (UNC/UNF) |
| ASME B18.2.1 | Hex Bolts and Screws |
| ASME B18.2.2 | Hex Nuts |
