Allowable stress in ASME codes is typically based on which material property?

Allowable stress in ASME codes is typically based on which material property?

• A. Fraction of yield or tensile strength
• B. Ultimate tensile strength only
• C. Hardness
• D. Modulus of elasticity

Answer: (A)

Allowable stress in ASME codes is determined by applying a safety margin to the material’s strength, typically expressed as a fraction of the yield strength or the ultimate tensile strength at the service temperature. This approach ensures that operating stresses stay within the elastic range and provides protection against uncertainties in material properties, manufacturing, corrosion, wear, and long-term effects like creep. Whether the controlling parameter is yield strength or ultimate tensile strength depends on the material and service conditions, but the design philosophy remains: base allowable stress on a proportion of a strength property at the given temperature. Hardness and modulus of elasticity do not set allowable stresses because they do not directly reflect the material’s strength under load in service.

Allowable stress in ASME codes is determined by applying a safety margin to the material’s strength, typically expressed as a fraction of the yield strength or the ultimate tensile strength at the service temperature. This approach ensures that operating stresses stay within the elastic range and provides protection against uncertainties in material properties, manufacturing, corrosion, wear, and long-term effects like creep. Whether the controlling parameter is yield strength or ultimate tensile strength depends on the material and service conditions, but the design philosophy remains: base allowable stress on a proportion of a strength property at the given temperature. Hardness and modulus of elasticity do not set allowable stresses because they do not directly reflect the material’s strength under load in service.