Your pressure relief valves (PRVs) are some of the most important pieces of equipment in your plant. They are what protects your systems from overpressure events that can damage your systems and, in some cases, have catastrophic consequences.
One of the most common questions we get is about relief valve testing frequency. There is no single answer that’s right for every valve or application. It depends on the service conditions, valve condition, and level of performance desired.
A definite time interval between inspection should be established for every pressure relieving device on the operating equipment in order to assure proper performance. This interval may vary from one installation to another depending on the operating experience.
The National Board Inspection Code (NBIC) and API Standard 576 provide recommendations for maintenance schedules. Local jurisdictional bodies, including state or insurance inspectors, may also provide guidance for plant managers to follow.
Pressure relief valve testing frequency
According to API 576, pressure-relieving devices should be inspected / overhauled as often as necessary “to maintain the device in satisfactory operating condition.”
Effort should be made to conduct inspections and testing of pressure relieving devices at the time they become due in accordance with the schedule previously established, assuming that the equipment has been in continuous operation, interrupted only by the normal shutdown.
The required testing frequency depends on the service. For example, a valve used in a corrosive or fouling service needs to be tested more often than the same valve used in a noncorrosive, nonfouling service. Other conditions that call for shorter testing intervals include:
- Pulsating loads
- Low differential between set and operating pressures
It’s also important to look at the valve testing history over time. If the valve consistently passes the test, then it can be tested less often. If the results are inconsistent, then the valve should be tested more often. For new processes, especially those where the service conditions (corrosion, fouling, etc.) can’t be accurately predicted, the initial inspection should be performed “as soon as practical after operations begin to establish a safe and suitable testing interval.”
PRVs should also be tested after every fire event. If a valve pops, it will need to be serviced and the valve seat gasket replaced.
Our valve technicians are factory-trained and ASME and National Board certified to test PRVs from all valve manufacturers. Contact us to learn how we can help you keep your plant up and running.