ASME BPVC Sec VIII Div 2

Key requirements (8)

• Alternative rules — Design by Analysis or Design by Rules (Part 5 vs Part 4).
• Higher allowable stress factor (typically 2/3 of yield, vs 3.5:1 ratio in Div 1) — thinner walls possible.
• Mandatory user's design specification (UDS) certified by registered engineer.
• Mandatory full radiography of butt welds (with limited exceptions).
• Hydrostatic test: 1.25 × MAWP × stress ratio.
• Fatigue analysis required when cyclic conditions are significant (Part 5 screening).
• Class 1 vs Class 2 design — Class 2 allows higher stresses with stricter NDE/inspection.
• Used for high pressure (>3000 psi typical), large vessels, cyclic service, lethal service.