boiler safety valve testing frequency pricelist

Safety valves or pressure relief valves are pressure regulating devices that are responsible for expelling excess pressure from the system when the maximum pressure levels for which they have been designed are exceeded, usually due to a

Safety valves perform their function when the pressure of the system where the fluid is contained, becomes higher than the maximum set pressure of the valve previously adjusted. When the system pressure is higher than the valve’s set

pressure, this opens, releasing the excess pressure to the atmosphere or to containment tanks, depending on the toxicity of the fluid. After releasing the excess, the valve closes again and the system pressure returns to normal.

To ensure total safety of personnel and installation, make sure that the valves have passed all safety tests and meet the requirements of the system where they are to be installed. All our valves are supplied with certificates of materials, cas-

What is the difference between the instantaneous full opening safety valve AIT (PSV) and the normal opening relief valve AN or progressive opening relief valve AP (PRV)?

The Pressure Safety Valve (PSV) opens instantaneously and fully upon reaching the set pressure for which it is designed, expelling the excess pressure from the system immediately. They are optimised for use with steam or gases.

In contrast, the normally or progressively opening Pressure Relief Valve (PRV) opens gradually as the system pressure rises above the set pressure of the valve above its setting. They are optimised to work with liquids.

At VYC Industrial we are specialists in the design and manufacture of all types of safety valves. We have a wide range of safety valves to cover all the needs of the sector.

The Mod. 496 EN safety valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The Mod. 495 EN pressure relief valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The relief valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open, at the fi rst proportional to the pressure increase, and after instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open, at the fi rst proportional to the pressure increase, and after instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open, at the fi rst proportional to the pressure increase, and after instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open proportional to the pressure increase.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open proportional to the pressure increase.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

The valve works as an automatic pressure releasing regulator activated by the static pressure existing at the entrance to the valve and is characterized by its ability to open instantly and totally.

They are used in places such as power, chemical and petrochemical plants to discharge safety valves, control valves, etc. in pressure lines and equipment that convey compressible substances such as steam, air, carbon dioxide, helium, methane, nitrogen, oxygen and other gases.

Test bench for regular inspections and setting and resetting safety valves. Ideal for distributors, maintenance companies or with in-house maintenance. It allows safety valves to be adjusted, tested and/or checked to the test pressure (setting) Pe wile cold (simulating service conditions), matching the opening pressure Ps and the closing pressure Pc, in accordance with the standard regulations.

Controlled safety pressure relief system CSPRS valves are mainly used where conventional direct-loaded spring action valves cannot guarantee the opening and closing margins that certain specifi c conditions of service demand.

The objective is to help the closure by means of pressure so that the valve remains completely watertight until reaching the set pressure and/or to activate the opening with pressure.

Increase the operating pressure of the system up to 99.9% of the set pressure.The control safety pressure relief system CSPRS device can be used with any safety valve available in the market and in particular, with models VYC Mod. 485, 486, 494, 495 and 496.

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.

After a boiler has been engineered, built and tested for a given operating pressure there is only one reliable way to prevent operation of the boiler above this design pressure.  This is a safety valve.  The safety valve should be sized so that a single valve can handle the maximum steam production rate of the boiler and once open prevent boiler pressure to continue to rise.  Standard operating procedure for the last century has been to install two safety valves on the boiler, one set 3-5 lbs below the design pressure and one valve set at the design pressure.

The 1st valve listed below is a true adjustable differential pop valve.  The differential is adjured through the differential rings lock screw hole, from 3 PSI to whatever the operator desires.  The pressure of the valve can be adjusted from 40 to 200 PSI.

The other valves listed are adjustable for release pressure and have a "pop" action:  The pressure differential is not adjustable on these valves.  If the valves are operated above their nominal pressure, the set-reset differential increases.  If operated at lower pressure, the differential decreases to the point of disappearing about 10-15% below nominal pressure.

At almost every show I attend, I ask a few engine owners and operators if they are satisfied with their new-style safety valves. It would be only a small exaggeration to say that I get just two responses. “I have been using a new-style valve for 15 years and I haven’t had any trouble with it” or “They are junk!” I have cleaned up the second response to spare the reader the unpleasant expletives.

As the result of these conversations, I have attempted to understand why there is such a discrepancy between the reactions to modern safety valves. It now appears that there are a few simple steps we can take when purchasing and installing these valves that might improve our satisfaction with the new-style valves, which are the only ones currently available.

To understand the issues involved in the selection of a safety valve, it is necessary to review the history of safety valves used on hand-fired boilers. I am referring to hand-fired boilers rather than historical boilers because the issues are determined by how the boilers are fired, not how they are constructed or how old they are. The requirements for a modern welded boiler made to the American Society of Mechanical Engineers (ASME) code are the same as for a 100-year-old riveted boiler, if both boilers are hand-fired. The requirements for a safety valve for a boiler that is automatically fired are dramatically different.

With automatic firing, the safety valve’s function as defined by Anderson Greenwood Crosby, a manufacturer of modern safety valves, is to protect life and property if all other safety measures fail. A safety valve on a hand-fired boiler, as defined by ASME almost a hundred years ago, is to give notice of the highest pressure permissible and to give alarm that more water or less fuel is needed. (The evolution of the purpose of the safety valve is summarized in “The Purpose of a Safety Valve,” at the end of this article.)

When hand-fired boilers, such as found on traction engines, steam cranes and locomotives disappeared, most of the boilers that remained were automatically fired. The safety valve manufacturers adapted their designs accordingly. The old-style valves with bottom guided, beveled seats were capable of withstanding vibration and operating near their setpoint, and were replaced by smaller top-guided valves with flat seats.

At the same time, steam system designs were adapted so there was no need to operate within 10 percent of the setpoint of the safety valve. Not all old-style valves had beveled seats, but the ones that didn’t were designed much differently from the modern flat-seated valves.

When I speak of a modern-style safety valve, I am referring to a valve shown in the second diagram of this article’s image gallery. An example of an old-style safety valve can also be seen in the image gallery. Changes in the design of safety valves had a dramatic effect on their capacity in pounds of steam per hour. If a boiler built in 1920 required a valve capable of releasing 1,000 pounds of steam per hour at a pressure of 100 pounds per square inch, it would have been equipped with a 2-inch safety valve. Today, 3/4-inch valves are available to release that much steam at that pressure.

The evolution of the safety valve did not end with the development of the modern, flat-seated valve. In the last 20 years, the design of safety valves has continued to evolve.

In 1985, a new-style 3/4-inch valve set at 150 pounds per square inch could have a capacity of 1,497 pounds of steam per hour. In 2002 this same valve could have a capacity of 1,651 pounds of steam per hour.

From 1914 until 1998, the blowdown allowed by the ASME boiler code was 2 to 4 percent of the setpoint. In 1998, this was changed to allow the blowdown to be as high as 6 percent. Beginning with the 2004 ASME code, there is no limit on blowdown. The code has not required that the amount of blowdown be stamped on a safety valve since 1986.

When I asked owners and operators how well they liked their new-style safety valves, I was not aware of the need to ask about the age of the valve. Instead, I would ask about the amount of blowdown. In almost every case, the people who were satisfied had valves that would blowdown 4 percent or less. It appears that this is almost the same as if I had asked the age of the valve. If the valve were purchased prior to 1998, it would have been set for 4 percent blowdown. If purchased after that date, unless specified otherwise, it would have been set for 6 percent. The change from 4 to 6 percent causes a 50 percent increase in the amount the pressure changes in a boiler each time the valve pops. The resulting increase in the flexing of the components of the boiler may be associated with a corresponding increase in seepage at stay bolts and tubes.

When you order a new safety valve, you will need to provide four pieces of information: the setpoint, the capacity in pounds of steam per hour, the blowdown and the requirement that the valve be stamped with the ASME “V” stamp. If you specify the pipe size, you may get a valve with far too much capacity, as I have already explained. To determine the capacity you need, do not use the capacity stamped on the old valve. First, if the valve has been replaced, it might not be the right capacity. Secondly, the capacity stamped on the valve is probably the capacity of the smallest valve available and might be significantly larger than the required capacity.

Calculating the heating surface of the boiler, in square feet, and multiplying the number by a factor can determine the required capacity. The ASME code requires a factor of 5 pounds of steam per hour per square foot of heating surface. Ohio requires a factor of 7. The heating surface is the area above the grates that is exposed to the fire. This includes the firebox, the tubes and the front tube sheet.

As I talked to many owners, they would offer other comments regarding their valves. One comment I heard from several owners who were satisfied with the new-style valves was that their valves were larger in pounds per hour than the minimum required by the ASME code. I am not certain as to exactly how the capacity affects the operation of the valve. What I do know is the larger the valve, the more force it takes to raise it off its seat. The force of the steam on the boiler-side of the valve cannot overcome the force of the spring in the safety valve until the pressure in the boiler rises to the setpoint of the valve.

When this happens, the valve pops open. It seems the larger diameter, and thus the greater forces, may result in more stable operation of the valve near its setpoint. There is a concern in the boiler code that safety valves should not be so large that water is drawn out of the boiler. It would seem, because of the relatively small size of portable and traction boilers, the pressure would drop so quickly that little water, if any, would be lost. I have seen boilers where the owners have installed modern safety valves of the same pipe size as the old style valves installed by the factory. The capacity of these valves was far greater than I believe anyone would recommend, but I am not aware that they caused water to be discharged from the boiler. It is important to be careful when sizing a safety valve. I suggest owners talk to each other and share their experiences before making such a decision.

If you would prefer to have a top-discharge safety valve, which looks more authentic, shop around. They are available in a few sizes. You might also want to consider specifying that the valve have a non-metallic seat.

When installing a safety valve, do not install any fitting smaller than the inlet to the valve and do not install any kind of valve between the safety valve and the boiler. Examples of what not to do can be seen in the image gallery. Do not use a pipe wrench on a safety valve, it can damage or destroy the valve.

Once you have carefully selected your safety valve and have installed it on your boiler, it is important to verify the setpoint and the blowdown have been set according to your specifications. The first step in this process is to have the accuracy of your steam gauge checked with a dead-weight gauge tester. If your gauge does not agree with the setpoint of your new safety valve do not assume that the gauge is wrong.

Do not use the lifting lever to lift the valve from its seat until the boiler pressure is up to 75 percent of the setpoint of the valve. If the valve is lifted from its seat at a lower pressure, any dirt or foreign material in the valve might not be blown clear of the seat and could damage the seats when the valve closes.

Because new-style safety valves are not designed to be operated within 10 percent of their setpoint, many owners have elected to install the new valve along with an old-style valve. In doing so, the old style valve operates in the range of 5 to 10 percent below the setpoint of the new valve. With this arrangement, the new valve satisfies the code requirements while the old-style valve performs the function for which it was designed. Two possible arrangements can be seen in the image gallery.

In response to complaints from owners of historical boilers who had recently purchased new safety valves, Dean Jagger, Ohio’s chief boiler inspector, requested that the National Board test valves from the manufacturer to determine if the valves complied with the requirements of the ASME boiler code. As a result of these tests the Ohio Department of Commerce issued a safety notice:

“The State of Ohio Boiler Division has been made aware of the fact that some recently purchased Kunkle safety valves, which were assembled by Allied Industries, have been tested by the National Board Testing Laboratory and found not to be in compliance. The tests indicated that the valves blowdown and setpoint pressure settings were out of tolerance as established by Section I of the ASME Boiler Code.”

This may be an indication that all of the problems with modern safety valves are not entirely the result of design issues, but insufficient oversight of manufacturing and quality control processes may also be a factor. A new valve may be “junk” as has been so often alleged.

The errors found by the National Board Laboratories were significant. One of the valves was stamped 165 psi but popped low at 148.8 psi. Another was stamped 150 psi and popped high at 164.5 psi. On the other three valves the pop was consistent with the setting stamped on the valve. The 2001 edition of the ASME Boiler Code specifies that for pressures from 70 to 300 psi the tolerance, plus or minus from the set pressure, shall not exceed 3 percent of the set pressure. The 165 psi valve popped 9.6 percent below the set pressure stamped on the valve, and the 150 psi valve popped 9.7 percent above the set pressure stamped on the valve.

The blowdowns on all of the valves that were tested were out of tolerance. The 2001 edition of the ASME Boiler Code specifies that for pressures from 67 to 250 psi the blowdown shall not be greater than 6 percent of the set pressure. With such a wide range of variations in both setpoint and blowdown, in a sample of just five valves, it seems reasonable to suspect that even greater variations may exist. The results of the tests are shown in the image gallery.

Complaints about quality problems are not limited to the five valves recently tested by the National Board; for example, an engine owner told me of purchasing a new 1-1/4-inch valve stamped 175 psi. When installed on a traction engine, the valve consistently popped at 185 psi and blew down 15 psi. (A pressure of 11.1 psi equals the allowed 6 percent.) The manufacturer told the owner that the valve had been tested properly prior to shipment but accepted it back. The owner had verified the accuracy of the pressure gauge prior to contacting the manufacturer.

The ASME and National Board procedures for safety valves merely confirm the adequacy of the design of the valve and do not assure the adequacy of production and quality control practices. Each boiler owner and operator must carefully confirm the accuracy of the setpoint and blowdown on every safety valve and not rely on the ASME and National Board stamps as assurances of quality. At this time, I have no reason to believe the monitoring of the ASME and National Board requirements at other valve manufacturers and assemblers is any different than what existed at Kunkle and Allied.

One scenario that concerns me is the owner who installs a new safety valve on his boiler and, seeing that the pop does not coincide with the reading on his 80- or 100-year-old gauge, decides that obviously his gauge must be wrong. This is a conclusion I am sure I would have considered when I first began my study of safety valves.

Incorrect settings of safety valves are more likely to be detected when the valves are used on hand-fired boilers than when used on modern boilers. If the controls on a modern boiler are to limit the pressure to 10 percent or more below the setpoint of the safety valve, the valve can be set as much as 10 percent below its rating and the error might not be apparent. Errors above the setpoint also wouldn’t be obvious even if the boiler were operated up to the setpoint stamped on the valve. Also, incorrect setting of the blowdown would not be apparent until the valve had operated.

1909: “The function of the safety valve is two fold: (A) it gives notice of the highest pressure permissible; (B) it gives alarm that more water or less fuel is needed.”

Today: “A PRV (pressure relief valve) is a safety device intended to protect life and property if all other safety measures fail.” – Anderson Greenwood Crosby, 2001 (safety valve manufactuer)

Bob Ferrell, Bob Schuler and Fred Harrison of the National Board of Boiler and Pressure Vessel Inspectors were instrumental in helping to obtain the information from the old editions fo the ASME boiler codes. Their assistance is greatly appreciated.

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.

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:

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.”

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.

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.

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