1. How is minimum wall thickness calculated?
ASME Section I formula: t=(PD)/(2SE+2yP). P=design pressure, D=outside diameter. S=allowable stress at temperature. E=weld joint efficiency. y=temperature coefficient. Includes corrosion allowance.
2. What safety factors are applied in design?
3.5-4 on ultimate tensile strength. 1.5-2 on yield strength at temperature. Creep rupture criteria for high-temp applications. Fatigue analysis for cyclic service. Must meet all applicable criteria.
3. How is MAWP determined for existing tubes?
Uses same formula with actual dimensions. S-value based on current metal temperature. Accounts for measured wall thinning. Requires UT thickness surveys. Safety margins adjusted for material condition.
4. What are ASME vs EN design differences?
ASME uses nominal wall thickness. EN uses minimum wall thickness. Different temperature derating factors. Varying weld joint efficiency approaches. EN requires more material testing.
5. How does FEA improve tube design?
Identifies high-stress concentrations. Simulates complex loading conditions. Predicts thermal stress patterns. Optimizes support locations. Validates expansion joint needs.
