KEVOS® MAKEOS · Fasteners
Working Strength of Bolts in Packed (Gasketed) Joints
What external load can this bolt safely carry in a packed joint after allowing for the tightening load?
Empirical working strength of studs and bolts in packed or gasketed joints (where the gasket is more elastic than the bolts) by the handbook’s Cornell formula W = S_t (0.55 d² − 0.25 d), and by the alternative using the thread root area, with the bolt count for a total load.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Nominal bolt diameter | mm | Nominal outside diameter of the bolt or stud. |
| Area at the thread root | mm² | Root (minor diameter) area of the thread, for the alternative formula. |
| Allowable working stress in tension | MPa | Allowable tensile working stress you use for the bolt material. |
| Total external load on the joint | kN | Total separating load on the joint (pressure × area), to find the bolt count. |
Method and formulas
- W = S_t (0.55 d² − 0.25 d), with W in pounds, S_t in psi and d in inches (converted here).
- Alternative: W = S_t (A − 0.25 d), with A the thread root area in square inches.
- Handbook example: a 1-in. bolt at 10,000 psi has a working strength of about 3,000 lb.
- Example: a 25.4 mm bolt at 68.95 MPa carries about 13.345 kN in a packed joint.
Limitations
- Empirical rule for hand-tightened bolts in gasketed joints; bolts under 5/8 in. (16 mm) are not recommended for tight joints.
- Pressure equipment must be designed to its code (for example ASME VIII Appendix 2).
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check studs on a gasketed cover or cylinder head
- Choose the number of bolts for a flange load
- Compare a legacy design rule with a modern joint analysis
Who it is for
- Design engineers
- Maintenance engineers
- Pressure equipment technicians
What you get
- Working strength per bolt (both formulas)
- Bolts needed for the load
- Formula in the handbook units
Interpreting the result
- The 0.25 d term allows for the extra load put on by tightening; it penalises small bolts most.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1535–1536. Topic reference; no source tables or recommended settings are reproduced.
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Open the Working Strength of Bolts in Packed (Gasketed) Joints calculator
