ASME Section VIII

Covers — construction of pressure vessels (Div 1/2/3): design, materials, fabrication, examination, testing, and certification, plus mandatory overpressure-protection rules (MAWP, allowable accumulation, set pressure) that govern relief-device selection.

Does NOT cover (exclusions) — the following are governed elsewhere:

• Sizing/selecting the relief device → API 520; relief loads/system → API 521; PRV dimensions → API 526.
• Piping (not vessels) → ASME B31.3 / B31.1.
• The EN/PED vessel counterpart → EN 13445; European relief devices → ISO 4126.

Section VIII sets the protection requirement and MAWP basis; the API 520-526 family sizes and dimensions the relief device that satisfies it.

Section VIII sets minimum requirements relevant to overpressure protection:

• MAWP — establishes the vessel's maximum allowable working pressure, the basis for relief set pressure.
• Overpressure Protection — mandates protection so pressure cannot exceed MAWP beyond allowed accumulation.
• Set Pressure & Accumulation — rules for relief set pressure and allowable overpressure (single vs multiple devices, fire case).
• Certification — vessel design/fabrication certification (Code stamp) with the relief basis documented.

ASME BPVC Section VIII is the rules for constructing pressure vessels (Divisions 1, 2, and 3). Beyond vessel design, it sets the overpressure-protection framework: every vessel must be protected against exceeding its MAWP, and the code defines MAWP, allowable accumulation, and relief set-pressure rules (including the fire case and multiple-device scenarios).

It establishes the requirement and the pressure basis; the API family then implements it — API 520/521 size the relief device and system, and API 526 fixes PRV dimensions. On the European side, EN 13445 and ISO 4126 play the equivalent roles.

Engineering Note: The relief device set pressure and required capacity flow directly from the Section VIII MAWP and accumulation rules — confirm the vessel MAWP and the governing overpressure scenario before sizing the PSV, since the vessel code, not the valve, sets the protection target.