Is this an ASME B31.3 compliance calculator?

No. It is a transparent screening tool for basic nominal stresses only.

What should I use for effective wall thickness?

Use nominal wall less corrosion allowance, mechanical allowance and applicable manufacturing tolerance as required by your design basis.

Can I add pressure, bending and thermal stress directly?

The page shows a conservative educational sum. Piping codes classify and combine stress categories differently.

What does the restraint factor mean?

It interpolates between free thermal movement and full axial restraint. It is not a substitute for modelling the actual piping geometry.

Drawing No. EH–FM–016 // Fluid Mechanics & Piping

Pipe Stress Screening Calculator

Reviewed August 2026

Calculate basic pressure, bending and thermal-restraint stresses for a straight pipe section and compare them with a user-entered allowable stress.

Scope: Educational and preliminary screening only. Final piping design requires the governing piping code, material allowables, flexibility analysis, support modelling and local stress evaluation.

What problem does this solve?

Screen a straight pipe section for pressure stress, bending stress and fully restrained thermal stress. It helps users understand which load controls before a formal piping flexibility analysis.

1. Enter geometryOutside diameter and effective wall thickness.

2. Enter loadsPressure, bending moment and temperature change.

3. Choose restraintFree expansion and full restraint represent bounding cases.

4. Compare allowableUse an allowable from the applicable code and material table.

Inputs

Outside diameter mm

Effective wall thickness mm

Internal pressure bar(g)

Bending moment kN·m

Temperature change °C

Expansion coefficient µm/m·K

Elastic modulus GPa

Axial restraint factor 0 = free, 1 = fully restrained

A real piping system usually lies between the free and fully restrained bounds and requires flexibility analysis.

User-entered allowable stress MPa

Check the pipe geometry and positive material properties.

Screening results

Hoop pressure stress

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Longitudinal pressure stress

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Bending stress

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Restrained thermal stress

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Simple combined axial stress

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Combined / allowable

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Important: This page does not calculate ASME stress intensification factors, sustained/occasional combinations, displacement stress range, local stresses, support loads, nozzle loads, fatigue cycles or code equations. Use dedicated pipe-stress software and the applicable piping code for design.

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Background

Frequently asked questions

Practical questions about inputs, assumptions and interpretation.