Pressure Measurement · Glossary

What is Set Pressure?

relief valve opening pointPressure Measurement

Set pressure is the inlet gauge pressure at which a pressure relief valve is adjusted to start opening.

Set Pressure Explained

The set pressure is stamped on the valve nameplate. It is normally at or below the MAWP of the protected equipment.

Bench tests check that the valve lifts within the set pressure tolerance. Cold differential test pressure (CDTP) corrects the bench setting for back pressure and temperature.

Set Pressure: Typical Values

ASME VIII tolerance

± 2 psi up to 70 psi set, ± 3 % above

Calculators for Set Pressure

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Free Downloads

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Frequently Asked Questions

What is Set Pressure?

Set pressure is the inlet gauge pressure at which a pressure relief valve is adjusted to start opening.

Can set pressure be above MAWP?

Only in special cases allowed by the code, such as additional valves in a multiple valve installation. Normally it is at or below MAWP.

What is cold differential test pressure?

The bench set pressure adjusted for constant back pressure and operating temperature, so the valve opens at the right pressure in service.

Learn more on the blog

Instrumentation and control standards

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

Read Full Article

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