Pressure Measurement · Glossary

What is Design Pressure?

Q: What is Design Pressure?

Design pressure is the pressure used to design equipment, set with a margin above the maximum expected operating pressure.

Q: How much margin is used?

It varies by company practice and pressure level; follow your design basis.

Q: Why do instrument data sheets ask for design pressure?

So the vendor rates the body, seals and process connection for the worst case, not only normal operation.

basis for equipment designPressure Measurement

Design pressure is the pressure used to design equipment, set with a margin above the maximum expected operating pressure.

Design Pressure Explained

Process engineers choose design pressure from the highest pressure the equipment could see in normal and upset conditions, plus a margin. It sets wall thickness, flange rating and instrument ratings.

Instruments, valves and seals in the line must be rated for at least the design pressure at the design temperature.

Design Pressure: Typical Values

Order of values

operating < design ≤ MAWP < test pressure

Calculators for Design Pressure

CalculatorPipe Wall Thickness CalculatorFree online calculator with formula and worked example.CalculatorHydrostatic Test Pressure CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Design Pressure?

Design pressure is the pressure used to design equipment, set with a margin above the maximum expected operating pressure.

How much margin is used?

It varies by company practice and pressure level; follow your design basis.

Why do instrument data sheets ask for design pressure?

So the vendor rates the body, seals and process connection for the worst case, not only normal operation.

Learn more on the blog

Instrumentation and control standards

A practical guide on instrumentationblog.in with more detail on design pressure and how it is applied on real plants.

Read Full Article

More Pressure Measurement Terms

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