A relief valve is one of the most crucial pressured system components and often the last device to prevent catastrophic failures in high-pressured systems. That is why it is essential that relief valves are always certified and should work at all times.
Most manufacturers recommend having relief valves tested once a year and may need to be checked more often depending upon the application.
What is a Relief Valve?
Relief valves are pressure valves that are designed to open at a preset pressure and discharge fluid until the pressure drops to a safe and acceptable level. This means the relief valve is the last resort that releases pressure when other components in the system have failed to control the pressure.
Testing, Certification, and Recertification of Relief Valves
Safety is of paramount importance when it comes to dealing with relief valves. So, it's critical for industries to make sure the valves are working as designed.
The only way to do that is through periodic inspection and standardized testing. The standards about relief valves and associated assemblies like boilers and pressured vessels are regulated by ASME, API, OSHA, National Board, and individual State codes.
Standard requirements include periodic inspection, testing, and recertification. Certification assures that a valve's condition and performance are essentially equal to that of a new valve.
Who provides the Certification?
Though ASME is the leading organization governing pressured systems' standards and codes, the body itself does not certify the valves. Certification and recertification of relief valves are done by the National Board (NB).
The National Board certifies two things:
- Valve's capacity
- Valve's compliance with ASME codes
A certificate is then published in the "Red Book" - NB18, along with the actual flow coefficients measured and approved.
Relief Valve Testing Recommendations
Performing periodic testing on relief valves is the best practice to ensure that the valves are in good working condition and the employees and work environment is safe.
However, how often should valves be tested could be a tricky thing to decide.
National Board Inspection Code (NBIC) recommends the following frequency:
- For high-pressure steam boilers greater than 15 psi and less than 400 psi, perform manual checking every six months and pressure test annually.
- For high-pressure steam boilers 400 psi and greater, pressure test every three years, or as determined by operating experience and testing history.
- Perform pressure tests annually for high-temperature hot water boilers (greater than 160 psi and 250 degrees Fahrenheit).
- For low-pressure steam boilers (15 psi and less), manually check quarterly and pressure test annually.
- For hot water heating boilers, manually check quarterly and pressure test annually.
- For water heaters, manually check every two months and replace defective valves with a new valve if a repair or resetting is indicated.
The above recommendations constitute correct inspecting and testing practices for efficient Relief Valve operations and, ultimately, a safe working environment. However, one crucial safety measure is to use a pressure indicator with a full-scale range higher than the valve's relief pressure.
Relief Valve Experts – Testing & Recertification
PFC understands the importance of proper Relief Valve testing and maintenance. We provide industrial valve testing and repair services for companies.
In fact, we believe proper valve inspection, testing, and maintenance is the best investment you make in the safety and security of your company and employees.
Our valve experts focus on getting your old valves tested and recertified for safe use. On top of that, we evaluate the repair condition of every valve and recommend the right solution to manage your equipment better.
Our service includes:
- Relief valves setting, testing, Certification (recertification)
- Relief Valve inspection and testing equipment calibration
- We also provide specialist support for plant commissioning and startup
PFC performs safety relief valve recertification to the following specifications:
|API 576||API 598|