Steam Relief Valve Testing

Steam Relief Valve Testing

Testing the safety relief valve is extremely important to the overall safety of your boiler system. In this post, we’ll be talking about what goes into testing a steam relief valve, but safety valve repairs should only be performed by a company holding a current Certificate of Authorization (VR) from the National Board of Pressure Vessel Inspectors. 


Using certified and calibrated gauges is essential to accurate testing. WARE’s own Rick Walker recommends using two gauges, for maximum accuracy and in case one isn’t properly functioning.

Relief valves need to open and close at very specific pressures, and also need to open smoothly. A smooth opening contains a clean “pop” sound, and not a simmering or chattering sound. Responding to the appropriate pressures and opening and closing cleanly are both important signs a professional maintenance provider will look for in a safety valve. 

Spring into Safety

Safety valves contain a compression screw, which puts pressure on a spring and causes the valve to function. The compression screw is where a maintenance provider will try to dial in your valve’s functionality and make set-pressure adjustments. It’s important to note if a valve is cold it might test higher, but as the valve gets hotter its metal will expand and its innerspring will slightly decompress. 

Once the valve is warm and has stabilized, it’s best to give it more than one test (Rick does three) to make sure the valve is consistent and within ASME code. 

ASME defines a safety valve as properly functioning at 150 psi if it tests within 3% of the set pressure. If your valve tests within 3% of the set pressure three times in a row on properly calibrated gauges, you’re likely good to go.

Ready to Make Steam

Remember, this procedure should only be done by professionals. If you’d like to schedule maintenance for your boiler, need assistance, or just want to learn more, contact us and check out our maintenance and service options at

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