Pipeline Wall Thickness Calculator

Work out pipeline wall thickness instantly with clear inputs, formula shown and shareable results.

About Pipeline Wall Thickness Calculator

The Barlow equation gives t = P D / (2 S F), where S is specified minimum yield strength and F the design factor set by location class — 0.72 in remote areas down to 0.4 in densely populated ones. A corrosion allowance, commonly 1/16 inch, is added, and the resulting thickness fixes the maximum allowable operating pressure.

Formulas

Barlow equation

t = P x D / (2 x SMYS x F)

MAOP

MAOP = 2 x SMYS x F x t / D

Worked example

With the default values below, Pipeline Wall Thickness Calculator returns Required Wall Thickness of 0.3846. Change any input above and every figure here is recalculated in your browser.

Inputs used

Design Pressureminimum 0.01 psi: 1,440 psi
Outside Diameterminimum 0.01 inches: 20 inches
Specified Minimum Yield Strengthminimum 0.01 psi: 52,000 psi
Design Factoraccepts 0.01–1: 0.72

Results

Required Wall Thickness: 0.3846
Thickness With Corrosion Allowance: 0.4471
MAOP At That Thickness: 1,674.0
Diameter To Thickness Ratio: 44.73

Step by step

1Values used
2Barlow equation
3MAOP
4Required Wall Thickness= 0.3846
5Thickness With Corrosion Allowance= 0.4471
6MAOP At That Thickness= 1,674.0
7Diameter To Thickness Ratio= 44.73

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Pipeline wall thickness and MAOP are safety-critical and legally governed by pipeline codes such as ASME B31.4 or B31.8. Design must be performed and certified by a qualified engineer.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Pipeline wall thickness and MAOP are safety-critical and legally governed by pipeline codes such as ASME B31.4 or B31.8. Design must be performed and certified by a qualified engineer.

Frequently Asked Questions

What sets the design factor?

The applicable pipeline code and the population density class along the route. Higher-consequence areas require lower design factors and therefore thicker wall.

Is Barlow the only check?

No. External pressure and collapse, bending during installation, longitudinal stress, fatigue at cyclic loading, and denting or gouging resistance are all separate checks in a full design.