ASME UG-27 Shell Thickness (Joint Efficiency and Corrosion)
The ASME Section VIII shell thickness. t = PR/(SE - 0.6P) for a cylinder, PR/(2SE - 0.2P) for a sphere.
Example
You enter
- Design pressure (psig) 150
- Inside radius, corroded (in) 24
- Allowable stress at design temp (psi) 17500
- Joint efficiency E (1.00 full RT, 0.85 spot, 0.70 none) 0.85
- Corrosion allowance (in) 0.0625
- Geometry cylindrical
You get
- Allowable stress x joint efficiency S·E (psi) 14875
- Required thickness 0.24349
- T with allowance (in) 0.30599
- MAWP at the required thickness 150
- Pressure limit (psi) 5726.88
Details, formula, and sources
With R the INSIDE radius in the corroded condition and the allowance added after. E is the piece people leave out: choosing not to radiograph drops it from 1.00 to 0.70 and costs about 30% more wall. 150 psi on a 24-in radius at 17,500 psi and E 0.85 needs 0.2435 in, 0.3060 with allowance. Flags both UG-27 validity limits.
Cylinder (circumferential stress, longitudinal joint): t = P R / (S E - 0.6 P). Sphere: t = P R / (2 S E - 0.2 P). Corrosion allowance added after. Validity: t <= R/2, and for the cylinder P <= 0.385 S E.
ASME BPVC Section VIII Division 1, UG-27, shell thickness under internal pressure, by section number; no allowable-stress or joint-efficiency table is reproduced - both are entered.
The UG-27 equations are reproduced across published engineering references and manufacturer design guides; the BPVC itself is available through ASME.
Estimate. AHJ and licensed professional govern.
Field names used by the API: design_pressure_psi, inside_radius_in, allowable_stress_psi, joint_efficiency, corrosion_allowance_in, geometry, se, t_required_in, t_with_allowance_in, mawp_psi, pressure_limit_psi
- Inside radius, corroded R is the inside radius in the corroded condition; the allowance is added to the computed thicknessASME BPVC VIII-1 UG-27
- Validity limits t <= R/2, and P <= 0.385 S E for the cylinder; beyond either, Appendix 1 thick-wall rules governASME BPVC VIII-1 UG-27
- Longitudinal-joint case only the circumferential-joint (longitudinal stress) equation is omitted rather than shipped unverifiedstated scope limit