Pipe Wall Thickness & Pressure Class

The wall thickness needed for internal pressure, the ordering thickness with corrosion and mill tolerance, and the flange pressure class that fits.

Unit system

Inputs

Pipe sizeDesign pressure (absolute)

Design temperatureDesign temperature (direct)

MaterialWeld joint factor

1.0 for seamless. For welded pipe, 0.85–1.0 depending on the level of examination.Corrosion allowance

Mill under-tolerance

12.5 % is typical on seamless pipe. The calculation ADDS this margin into the ordering thickness.

Minimum ordering thickness

1.899mm

Schedule that fits

Sch 10 is enough

Thickness for pressure alone	0.6614 mm
With corrosion allowance	1.661 mm
Flange pressure class that fits	PN 25 (holds 20.9 bar at 201 °C)
Design temperature used	201.4 °C
Allowable stress	1,288 bar a
Flange temperature derating factor	0.8370

The mill under-tolerance is ADDED to the ordering thickness: seamless pipe can arrive up to 12.5 % thin, and the calculation must hold at the thinnest point.
This covers INTERNAL PRESSURE only. Thermal expansion, weight, wind and seismic loads are separate and can increase the thickness.
The allowable stresses are indicative; the project’s material certificate and design code govern.

A PDF carrying the inputs, results, assumptions and the source. A one-time code is sent to your address.

Results are for engineering pre-assessment and are not a product selection commitment. Final responsibility rests with the user.