Pressure Vessel Wall Thickness
Required wall thickness of a cylindrical shell under internal pressure, per the ASME Boiler and Pressure Vessel Code Section VIII Division 1, UG-27. Both circumferential (longitudinal seam) and longitudinal (circumferential seam) stress are checked.
Required thickness t (incl. CA)4.25mm
- From hoop stress t_c
- 2.75 mm
- From longitudinal stress t_l
- 1.36 mm
- Suggested plate thickness
- 5 mm
- MAWP with this plate
- 1.9 MPa
- Hydrostatic test pressure ≈ 1.3·P
- 1.95 MPa
- P ≤ 0.385·S·E — thin-wall formula valid
- t ≤ R/2 — thin-wall assumption
METHOD
How it is calculated
t_c = P·R / (S·E − 0.6·P) t_l = P·R / (2·S·E + 0.4·P) t = max(t_c, t_l) + CA R = D_i / 2 + CA MAWP = S·E·t / (R + 0.6·t)
ASSUMPTIONS & NOTES
- S = 138 MPa is roughly the room-temperature allowable stress of SA-516 Gr. 70; take the value at design temperature from ASME II-D.
- E: 1.0 for full radiography, 0.85 for spot radiography, 0.70 without radiography.
- Plate under-tolerance and heads (torispherical, elliptical) are not included.
Results are for preliminary design and checking; base the final design on the governing standard and safety factors.
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