Pipe wall thickness calculation as per ASME B31.3

Enter data as indicated in the form below and click on Submit Button.

The minimum pipe wall thickness including mill tolerance for pipe sizes from 1/2" to 24" will be listed below the Submit Button.

Design Pressure (psi)

Allowable Stress (psi)

Corrosion + Mechanical Allowance (mm)

Mill Tolerance (%)

Weld Joint Quality Factor
Enter 1 for seamless, 0.95 for EFW and 0.85 for ERW pipes


As per section 304.1.2 of ASME B31.3, for a straight pipe under internal pressure, the design thickness shall be calculated as per the following equation:

t = \(\frac{PD}{2(SE + PY)}\)

The minimum thickness of pipe, T shall not be less than tm

where tm = t + c

c = sum of mechanical allowances (thread or groove depth) plus corrosion and erosion allowances

D = Outside diameter of pipe

E = Quality factor from Table A-1A or Table A-1B of ASME B31.3

P = Internal design pressure (gauge)

S = Allowable stress of material from Table A-1A or Table A-1M of ASME B31.3

t = Pressure design thickness calculated as per above formula

W = Weld joint strength reduction factor in accordance with para 302.3.5(e)

Y = coefficient from Table 304.1.1, valid for t < D/6