Pipe Wall Thickness (ASME B31.3)

Engineering calculator reviewed for preliminary design use · Last updated: March 2026

Calculate required minimum pipe wall thickness per ASME B31.3 Process Piping Code. Input design pressure, outside diameter, allowable stress, joint efficiency, and corrosion allowance. Apply to pipe schedule and material selection.

Pipe Wall Thickness Calculation (ASME B31.3)

The minimum required pipe wall thickness is calculated per ASME B31.3 "Process Piping" to ensure adequate strength under design pressure. This is a fundamental check in any piping design project.

Formula (ASME B31.3 Eq. 304.1.2)

t = P × D / [2 × (S × E + P × Y)]

  • t: Minimum required thickness (before corrosion allowance) [mm]
  • P: Design gauge pressure [MPa]
  • D: Pipe outside diameter [mm]
  • S: Allowable stress [MPa] (material and temperature dependent)
  • E: Weld joint efficiency (seamless = 1.0, welded = 0.85–1.0)
  • Y: Temperature coefficient (typically 0.4)

Minimum Wall Thickness

t_min = t + corrosion allowance (typical: 1.5–3.2 mm)

Typical Allowable Stresses (reference)

  • Carbon steel A106-B at 20°C: 117 MPa
  • Stainless steel A312-TP316 at 20°C: 115 MPa

Related: Vessel Wall Thickness Calculator / Head Thickness Calculator

Frequently Asked Questions

What is the difference between this and the Wall Thickness calculator?

Both calculate minimum required pipe wall thickness per ASME B31.3. This calculator may use a slightly different input format or include additional code-specific factors. The underlying formula is the same.

Should I use the calculated thickness directly for procurement?

No. The calculated value is the minimum required thickness. For procurement, you must select the next standard pipe schedule (Sch 40, Sch 80, etc.) that provides adequate thickness after subtracting mill tolerance.

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Editorial Responsibility
  • Last reviewed: March 2026
  • Reviewed by: EngiCompute Editorial Team
  • Intended for preliminary engineering use

These results are preliminary estimates for screening-level design use. They do not replace detailed engineering, code compliance verification, or vendor-certified calculations.