boiler safety valve testing frequency quotation

Safety is of the utmost importance when dealing with pressure relief valves. The valve is designed to limit system pressure, and it is critical that they remain in working order to prevent an explosion. Explosions have caused far too much damage in companies over the years, and though pressurized tanks and vessels are equipped with pressure relief vales to enhance safety, they can fail and result in disaster.

That’s also why knowing the correct way to test the valves is important. Ongoing maintenance and periodic testing of pressurized tanks and vessels and their pressure relief valves keeps them in working order and keep employees and their work environments safe. Pressure relief valves must be in good condition in order to automatically lower tank and vessel pressure; working valves open slowly when the pressure gets high enough to exceed the pressure threshold and then closes slowly until the unit reaches the low, safe threshold. To ensure the pressure relief valve is in good working condition, employees must follow best practices for testing them including:

If you consider testing pressure relief valves a maintenance task, you’ll be more likely to carry out regular testing and ensure the safety of your organization and the longevity of your

It’s important to note, however, that the American Society of Mechanical Engineers (ASME) and National Board Inspection Code (NBIC), as well as state and local jurisdictions, may set requirements for testing frequency. Companies are responsible for checking with these organizations to become familiar with the testing requirements. Consider the following NBIC recommendations on the frequency for testing relief valves:

High-pressure steam boilers greater than 15 psi and less than 400 psi – perform manual check every six months and pressure test annually to verify nameplate set pressure

High-pressure steam boilers 400 psi and greater – pressure test to verify nameplate set pressure every three years or as determined by operating experience as verified by testing history

High-temperature hot water boilers (greater than 160 psi and/or 250 degrees Fahrenheit) – pressure test annually to verify nameplate set pressure. For safety reasons, removal and testing on a test bench is recommended

When testing the pressure relief valve, raise and lower the test lever several times. The lever will come away from the brass stem and allow hot water to come out of the end of the drainpipe. The water should flow through the pipe, and then you should turn down the pressure to stop the leak, replace the lever, and then increase the pressure.

One of the most common problems you can address with regular testing is the buildup of mineral salt, rust, and corrosion. When buildup occurs, the valve will become non-operational; the result can be an explosion. Regular testing helps you discover these issues sooner so you can combat them and keep your boiler and valve functioning properly. If no water flows through the pipe, or if there is a trickle instead of a rush of water, look for debris that is preventing the valve from seating properly. You may be able to operate the test lever a few times to correct the issue. You will need to replace the valve if this test fails.

When testing relief valves, keep in mind that they have two basic functions. First, they will pop off when the pressure exceeds its safety threshold. The valve will pop off and open to exhaust the excess pressure until the tank’s pressure decreases to reach the set minimum pressure. After this blowdown process occurs, the valve should reset and automatically close. One important testing safety measure is to use a pressure indicator with a full-scale range higher than the pop-off pressure.

Thus, you need to be aware of the pop-off pressure point of whatever tank or vessel you test. You always should remain within the pressure limits of the test stand and ensure the test stand is assembled properly and proof pressure tested. Then, take steps to ensure the escaping pressure from the valve is directed away from the operator and that everyone involved in the test uses safety shields and wears safety eye protection.

After discharge – Because pressure relief valves are designed to open automatically to relieve pressure in your system and then close, they may be able to open and close multiple times during normal operation and testing. However, when a valve opens, debris may get into the valve seat and prevent the valve from closing properly. After discharge, check the valve for leakage. If the leakage exceeds the original settings, you need to repair the valve.

According to local jurisdictional requirements – Regulations are in place for various locations and industries that stipulate how long valves may operate before needing to be repair or replaced. State inspectors may require valves to be disassembled, inspected, repaired, and tested every five years, for instance. If you have smaller valves and applications, you can test the valve by lifting the test lever. However, you should do this approximately once a year. It’s important to note that ASME UG136A Section 3 requires valves to have a minimum of 75% operating pressure versus the set pressure of the valve for hand lifting to be performed for these types of tests.

Depending on their service and application– The service and application of a valve affect its lifespan. Valves used for clean service like steam typically last at least 20 years if they are not operated too close to the set point and are part of a preventive maintenance program. Conversely, valves used for services such as acid service, those that are operated too close to the set point, and those exposed to dirt or debris need to be replaced more often.

Pressure relief valves serve a critical role in protecting organizations and employees from explosions. Knowing how and when to test and repair or replace them is essential.

Boiler explosions have been responsible for widespread damage to companies throughout the years, and that’s why today’s boilers are equipped with safety valves and/or relief valves. Boiler safety valves are designed to prevent excess pressure, which is usually responsible for those devastating explosions. That said, to ensure that boiler safety valves are working properly and providing adequate protection, they must meet regulatory specifications and require ongoing maintenance and periodic testing. Without these precautions, malfunctioning safety valves may fail, resulting in potentially disastrous consequences.

Boiler safety valves are activated by upstream pressure. If the pressure exceeds a defined threshold, the valve activates and automatically releases pressure. Typically used for gas or vapor service, boiler safety valves pop fully open once a pressure threshold is reached and remain open until the boiler pressure reaches a pre-defined, safe lower pressure.

Boiler relief valves serve the same purpose – automatically lowering boiler pressure – but they function a bit differently than safety valves. A relief valve doesn’t open fully when pressure exceeds a defined threshold; instead, it opens gradually when the pressure threshold is exceeded and closes gradually until the lower, safe threshold is reached. Boiler relief valves are typically used for liquid service.

There are also devices known as “safety relief valves” which have the characteristics of both types discussed above. Safety relief valves can be used for either liquid or gas or vapor service.

Nameplates must be fastened securely and permanently to the safety valve and remain readable throughout the lifespan of the valve, so durability is key.

The National Board of Boiler and Pressure Vessel Inspectors offers guidance and recommendations on boiler and pressure vessel safety rules and regulations. However, most individual states set forth their own rules and regulations, and while they may be similar across states, it’s important to ensure that your boiler safety valves meet all state and local regulatory requirements.

The National Board published NB-131, Recommended Boiler and Pressure Vessel Safety Legislation, and NB-132, Recommended Administrative Boiler and Pressure Vessel Safety Rules and Regulationsin order to provide guidance and encourage the development of crucial safety laws in jurisdictions that currently have no laws in place for the “proper construction, installation, inspection, operation, maintenance, alterations, and repairs” necessary to protect workers and the public from dangerous boiler and pressure vessel explosions that may occur without these safeguards in place.

The American Society of Mechanical Engineers (ASME) governs the code that establishes guidelines and requirements for safety valves. Note that it’s up to plant personnel to familiarize themselves with the requirements and understand which parts of the code apply to specific parts of the plant’s steam systems.

High steam capacity requirements, physical or economic constraints may make the use of a single safety valve impossible. In these cases, using multiple safety valves on the same system is considered an acceptable practice, provided that proper sizing and installation requirements are met – including an appropriately sized vent pipe that accounts for the total steam venting capacity of all valves when open at the same time.

The lowest rating (MAWP or maximum allowable working pressure) should always be used among all safety devices within a system, including boilers, pressure vessels, and equipment piping systems, to determine the safety valve set pressure.

Avoid isolating safety valves from the system, such as by installing intervening shut-off valves located between the steam component or system and the inlet.

Contact the valve supplier immediately for any safety valve with a broken wire seal, as this indicates that the valve is unsafe for use. Safety valves are sealed and certified in order to prevent tampering that can prevent proper function.

Avoid attaching vent discharge piping directly to a safety valve, which may place unnecessary weight and additional stress on the valve, altering the set pressure.

The primary role of a safety relief valve is to prevent over-pressure situations in pressurized vessels or systems. If the tank’s relief valve fails, it can lead to an accident that destroys property, life, or landscape.

The National Board of  Boiler and Pressure Vessel Inspectors is one of the governing bodies for the testing and/or repair of ASME Safety Relief Valves.

You, as the owner of the valve, can test it, but it must be done in accordance with the National Board Inspection Code and your state’s and/or local regulations.

Based on the National Board Code, which bases their inspection intervals on what type of service the valve is used for, the following intervals are suggested:

Also, keep in mind that this piping should be oriented so that no liquid relieved through this piping can flow back and rest on the ASME safety relief valve’s outlet port.

The ASME relief valves are set to fully open at its “set” pressure but will begin to partially open before then – normally at 10% below its set pressure.

If your valve is allowed to do this, trash and/or corrosion can set in over time which could prevent the valve from either closing completely or from fully opening, either of which is not a favorable solution.

The National Board of Boiler & Pressure Vessel Inspectors is an organization comprised of chief inspectors from various states and territories of the US and Province and territories of Canada. The primary mission is to promote public safety.

We sat down to ask a few clarifying questions with our very own Marianne Brodeur, who was the owner of International Valve and Instrument (IVI), before its purchase by Collins in October of 2019. She also sits on the National Board as Chairperson of the subcommittee on Pressure Relief Devices. IVI has held a VR stamp for the last 34 years.

In 2013, The Boiler Safety Bureau, working with the devoted owners of these historical boilers, adopted the National Boiler Inspection Code for Historical Boilers. This allowed standardized procedures for the inspection and repairs of these boilers.

North Carolina General Statutes Chapter 95 Article 7B states that the Bureau will create and conduct a safety program to provide instruction on how to properly care, maintain, operate, and exhibit historical boilers. The program will also include instruction on how to train an apprentice.

• Range of Capability:​ MVS is able to test and repair a wide range of pressure relief valves installed on smaller 1/2-inch and up to larger 6x8 flange connections.

• Documentation:​ Technicians complete detailedrecord keeping of testing and repair reports.All information is tracked and managed in an online database.

• NBIC VR Certified:​ Test and repair procedures areperformed using calibrated instruments.Technicians can test, repair, and re-certify asrequired. If a valve fails, then it is rebuilt, retested, and repeated until acceptable.

• Capacity:​ 53-foot climate-controlled trailer isdesigned and equipped to accommodate a widerange of valves with temperature-controlled testing and repair conditions.

When it comes to understanding pressure relief valve testing requirements, there’s a lot of information out there, but not all of it seems conclusive. If you’re new to pressure relief valves or are getting started in a new industry, it can be tough to decipher what testing requirements your facility needs to meet.

While we can’t provide the specific testing requirements for every industry, we can offer a few general testing requirements, and point you in the right direction to find the information you need for your facility’s unique testing requirements:

It’s good to keep in mind that every industry and region has unique pressure relief valve testing requirements. Your facility may be required to just bench test pressure relief valves every five years, or you may have to test valves every year, but bench test and repair valves every three to five years. There is a large variance in the testing requirements for pressure relief and safety valves depending on your industry and your region. That said, there are a few general testing requirements we can look at to start with.

The National Board Inspection Code, created by the National Board of Boiler and Pressure Valve Inspectors, makes the following recommendations on the frequency of testing for safety and pressure relief valves, depending on the temperature, psi, and function of your boiler:

High-pressure steam boilers greater than 15 psi and less than 400 psi should be manually checked every 6 months and pressure tested annually to verify nameplate set pressure.

High-pressure steam boilers greater than 400 psi should be pressure tested to verify nameplate set pressure every three years, or as determined by operating experience as verified by testing history.

High-temperature hot water boilers operating at greater than 160 psi and/or 250° F should be pressure tested annually to verify nameplate set pressure.

It’s important to remember that these are general pressure valve testing recommendations. For specific requirements, you’ll have to verify your unique jurisdictional and industry code requirements. See the resources below for more information.

The National Board Inspection Code is an industry-recognized name offering quality information on pressure relief valve testing requirements. Here, you’ll find a wealth of information and testing best practices.

The ASME is another organization setting pressure relief valve testing requirements, and offering the necessary training engineers need to test and understand the testing procedures for pressure relief valves. In addition to testing requirements and standards, the ASME offers a variety of online courses on pressure relief valves, from fabrication and proper installation to inspection and repair.

For specific testing standards, it’s best to check with your industry and your regional jurisdiction. Pressure relief valve testing requirements can vary by state or region and are most often industry-specific. Check your industry’s standards, and check local code requirements to ensure your facility is adhering to the most relevant pressure relief valve testing requirements.

When you’re looking for the pressure relief valve testing requirements relevant to your facility, it’s important to understand the different testing methods that are available to you. It’s likely that regardless of your industry if you have safety and pressure relief valves in use at your facility, you’ll have to bench test those valves at least every five years.

In addition to those bench tests, though, you’ll also have to perform manual or on-site pressure relief valve testing. Here’s a quick look at the three most common pressure relief valve testing methods you’ll see when researching pressure relief valve testing requirements:

The most commonly mandated form of pressure relief valve testing, bench testing is unique in that it requires you completely shut down your facility’s system and remove all pressure relief valves. The valves are then transported to a lab where they are tested and repaired as necessary. Tested valves are then re-installed in your system.

Bench testing is the most involved method of pressure relief valve testing, but as this is how valves are tested when they’re manufactured, the industry considers this to be the most thorough testing method.

Inline testing is another accurate pressure relief valve testing method that doesn’t require the removal of valves or facility downtime. With inline safety relief valve testing equipment, a trained technician can test valves in the system to calculate the real setpoint of a valve in the system.

While inline testing cannot take the place of mandated bench testing, it is a more efficient form of testing for other regular testing requirements. Inline pressure relief valve testing is the ideal choice for any required testing that does not have to be bench testing, as it eliminates the need for downtime while still providing exceptionally accurate results.

Some pressure relief valve testing requirements will call for regular manual testing for freedom of operation. This is a basic test that can be done on-site. To complete an operated-in-place test, the test lever on the valve is manually activated. This test functions to ensure that the valve can open and shut tightly, but it does not verify at what pressure the valve opens and shuts. This is a test that may be required quarterly or bi-annually, to ensure the most basic functionality of safety relief valves.

Pressure relief valve testing is necessary for any facility with safety relief and pressure relief valves. For more information about the equipment you need for pressure relief valve testing, the profitability of certain testing methods, and more, head to the AccuTEST blog. There, you’ll find a variety of resources on everything from implementing inline safety relief valve testing to minimizing plant downtime.

If your company requires regular pressure relief valve testing, you might be interested in AccuTEST’s high-tech equipment. Offering inline testing with accurate, repeatable results, our system is the best on the market. See how our equipment works in real-time — schedule a live webinar demo today.