Joint
Assembly
Service
Bolt load
TENSION PER BOLT
—
BOLT STRESS
—
F = T / (K·D)
Sg = (n·F − FH) / Ag
ΔSg = M / (π·R²·w)
Sg = (n·F − FH) / Ag
ΔSg = M / (π·R²·w)
Verdict
| Stage | low side | nominal | high side |
|---|---|---|---|
| Seating only | |||
| − end force (no relaxation) | |||
| bolt ×0.80, then end force | |||
| ± moment |
Low / high side here are the ±scatter band combined with the moment: the worst
bolt on the unloading side, and the luckiest bolt on the loading side. A joint only works when
both columns sit inside the window.
Method & assumptions
Bolting per ASME B16.5; studs ASTM A193 B7 (yield 725 MPa up to 2½″). Spiral-wound sealing
element taken as a 12.7 mm annulus inside the raised face; kammprofile 12 mm; sheet and PTFE as
the full B16.21 raised-face annulus (pipe OD to RF OD); RTJ as a 3.5 mm contact strip on the
B16.20 octagonal ring pitch diameter.
Gasket windows are indicative teaching values — real minimum seating and crush limits come from the gasket manufacturer or ASME PCC-1 Appendix O, and vary with filler, facing, thickness and temperature.
The moment term treats the gasket as an elastic annulus, ΔSg = M/Zg with Zg = π·R²·w. Real behaviour includes flange rotation and loss of contact once the low side reaches zero — so this model is optimistic near the leak boundary, not conservative.
Gasket windows are indicative teaching values — real minimum seating and crush limits come from the gasket manufacturer or ASME PCC-1 Appendix O, and vary with filler, facing, thickness and temperature.
The moment term treats the gasket as an elastic annulus, ΔSg = M/Zg with Zg = π·R²·w. Real behaviour includes flange rotation and loss of contact once the low side reaches zero — so this model is optimistic near the leak boundary, not conservative.