ASME Section II

Applies to: All ASME construction codes (Section I, III, VIII, B31.1, B31.3, etc.) for material selection, allowable stress lookup, and welding consumable selection; four parts: Part A (ferrous specs), Part B (non-ferrous specs), Part C (welding rods/electrodes/filler metals), Part D (properties and allowable stresses).

Does NOT cover: Material procurement in isolation — Section II supplements but does not replace individual ASTM/ISO material specifications; material suitability for corrosion resistance (consult API RP 571 or project CRA).

• Allowable stress tables at temperature for design calculations (Part D Table 1A/1B)
• P-number and F-number welding material groupings for procedure qualification
• Material specification cross-references between ASME and ASTM/AWS designations
• UNS material number index for alloy identification
• Weld consumable classification and testing requirements (Part C)
• External pressure charts (Part D) for vacuum and external pressure design

ASME Section II is the materials backbone of all ASME pressure codes. Engineers consult Part D tables for allowable stress values at temperature for wall thickness calculations (B31.3, B31.1, Section VIII), and Part A/B for the full material specification that governs procurement. Allowable stress values in Section II differ from ASTM minimum tensile strength because they incorporate code-specific safety factors (typically 3.5× UTS for most ferrous materials, reducing to 3.0× in recent editions).

Engineering note: When a piping material specification lists both an ASTM grade and a Section II allowable stress, always verify the stress is from the current code edition — allowable stress values are updated each ASME biennial cycle and can change between editions. Designers using older stress values on current-edition projects may be conservative or, in rare cases, non-conservative for high-temperature applications.