Stud Bolt
Bolts · stud bolt · continuous thread stud · flange stud
Definition: A stud bolt is a headless, fully threaded fastener used with two nuts to join flanged connections, most often in piping and pressure vessels.
Anatomy
■ Head■ Shank■ Threads■ Point
Governing standards: ASME B18.31.2 · ASTM A193
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 1/2-13 | M12 | — | 2–12 long |
| 3/4-10 | M20 | — | 3–18 long |
| 1-8 | M24 | — | 4–24 long |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| B7 | Cr-Mo alloy steel, Q&T | 125,000 | B7 stamped |
| B8 | 304 stainless, strain-hardened | 75,000 | B8 stamped |
| B16 | Cr-Mo-V alloy steel | 125,000 | B16 for high temp |
Materials
- B7 alloy steel
- B8 stainless steel
- B16 alloy steel
Pros & Cons
Pros
- Even clamping around a flange
- Easy to replace without disturbing the flange
- Standardized grades for temperature and pressure
Cons
- Two nuts to torque per stud
- Corrosion on exposed thread ends
- Requires correct engagement on both ends
Typical Uses
- Pipe flanges and valve bodies
- Pressure vessels
- Heat exchangers
- Pumps and compressors
Alternatives & Related
- Threaded Rod — General-purpose rod for hanging and bracing
- Structural Bolt — Headed bolt for structural steelwork
Where to Buy
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FAQ
Stud bolt vs threaded rod?
A stud bolt is an engineered flange fastener with specified grades (B7/B8) and thread lengths; threaded rod is general-purpose all-thread. Use stud bolts for piping and pressure work.
What is B7 stud bolt?
A chromium-molybdenum alloy steel stud, quenched and tempered, rated for high-temperature service and standard for ASME flanged joints.