Which parameter is used to account for weld and geometry discontinuities in piping fatigue analysis?

Which parameter is used to account for weld and geometry discontinuities in piping fatigue analysis?

• A. Design temperature
• B. Stress Intensification Factor (SIF)
• C. Corrosion allowance
• D. Material yield strength

Answer: (B)

Welding and sharp geometry create localized stress concentrations that raise the stress intensity in a small region beyond the nominal stress level. To account for this in fatigue analysis, you use a factor that quantifies how much geometry amplifies the stress near discontinuities. This is the Stress Intensification Factor (SIF). It serves as a geometry-dependent multiplier that links the applied stress to the actual stress intensity at discontinuities or crack tips, reflecting how welds, fillets, and other abrupt features drive higher local stresses and hence reduce fatigue life. The other options don’t capture this localized concentration effect: design temperature relates to thermal cycling, corrosion allowance is about material thinning, and material yield strength is a material property used for general strength limits, not for geometry-induced stress amplification.

Welding and sharp geometry create localized stress concentrations that raise the stress intensity in a small region beyond the nominal stress level. To account for this in fatigue analysis, you use a factor that quantifies how much geometry amplifies the stress near discontinuities. This is the Stress Intensification Factor (SIF). It serves as a geometry-dependent multiplier that links the applied stress to the actual stress intensity at discontinuities or crack tips, reflecting how welds, fillets, and other abrupt features drive higher local stresses and hence reduce fatigue life. The other options don’t capture this localized concentration effect: design temperature relates to thermal cycling, corrosion allowance is about material thinning, and material yield strength is a material property used for general strength limits, not for geometry-induced stress amplification.