Pipe Wall Thickness: Worked Example

1. Calculator Inputs

Select units before entering values.

2. Step-by-step Math

Pressure design thickness

t = P D / [2(S E W + P Y)]
t = 300×4.5 / [2(20000×1×1 + 300×0.4)]
t ≈ 0.0335 in

This is the pressure-only thickness before allowance and mill tolerance.

Allowance and mill tolerance

Minimum finished wall = t+c ≈ 0.096 in
T = (t+c)/(1−0.125)
T = 0.109769951718 in ≈ 2.79 mm

Divide by 0.875; adding 12.5% is not the same adjustment.

Equation scope checks

t = 0.033548708 in < D/6 = 0.75 in
P/(S E) = 300/20000 ≈ 0.015 < 0.385

These checks match the calculator’s equation limits; they are not a complete design evaluation.

3. Compare Your Answers

Keep full precision until the final result. Display rounding may differ; compare answers rounded to three significant figures; retain unrounded intermediate values.

Second check

Select the pressure solve mode and enter nominal wall 0.109769951718 in with the same other inputs. The equation returns 300 psi.

4. Assumptions and Method

S, E, W, Y, allowance and tolerance are supplied benchmark values, not verified properties for a particular material, temperature or code edition. This calculation does not select a pipe schedule or establish code compliance; other loads and applicable design requirements need separate evaluation.

Equation definitions and implementation: open calculator. See also calculation methodology.