asme safety valve testing requirements in stock

The ASME Pressure Relief Device (PRD) Testing Laboratory Accreditation Program accredits manufacturers of pressure relief devices and assemblers of pressure relief valves. It is a hybrid program in that it accredits both the manufacturer and specific personnel within the manufacturing organization (the authorized observer). It is operated in conjunction with The National Board of Boiler and Pressure Vessel Inspectors. Therefore, a manufacturer seeking this accreditation submits an application directly to ASME, but details about the program and review process can be found on The National Board of Boiler and Pressure Vessel Inspector"s website.

Companies that have been accredited through the PRD Accreditation Program are operating in accordance with the applicable rules of the associated ASME BPVC, the ASME PTC-25 standard, "Pressure Relief Devices," as well as one of the standards of construction accepted by The National Board of Boiler and Pressure Vessel Inspectors.

Many processes involve the use of high pressure steam, water or air.  Piping systems carrying these fluids must be protected from over-pressures that could cause damage or injury.  A pressure relief valve is a device that opens to vent any pressure higher than the relief valve’s operating set point.  The water heater in your house, for example, has a pressure relief valve set to open at a pressure that is lower than the burst pressure of the heater tank.  That way if pressure inside the tank exceeds the relief valve’s set point pressure, the valve will open and vent the pressure before the tank is damaged – you get a wet floor but you don’t have to replace the heater tank.

Pressure relief valves come in all sizes and pressures and these are critical parts of a high pressure piping system carrying steam in an industrial plants, refineries, power plants, etc.  The ASME has established criteria for the size and set point pressures for relief valves operating in industrial systems.  Additionally, these valve are tested on a regular basis to insure that they open at the correct pressure and do not impede the flow of fluid as the pressure is vented.  The vales are tested at their operating pressures and temperatures, and the opening pressure and pressure drop through the valve as it vents must be measured.

There are testing laboratories that are used to test industrial pressure relief valves by simulating the operating conditions for water, air and steam.  One customer of Validyne has a test lab capable of generating up to 10,000 lbs. per hour of steam at 300 psig, air flows to 3500 SCFM at 500 psig and water flow rates of 500 gpm at 300 psig.  Pressure relief valves are tested depending on their operating conditions, and the valves are instrumented to verify correct operation at their set point pressure.

The Validyne product used to make relief valve measurements is the DP15 pressure transducers.  One transducer is used to measure the pressure upstream of the relief valve, a second DP15 measures the downstream pressure.  These transducers are 300 or 500 psi, depending on the test.    A third DP15 measures the pressure drop across the relief valve when it is flowing and this transducer is typically 100 In H2O full scale.  The DP15s are used because they can be mounted remotely from the control station.  A large steam relief valve, for example, is connected to piping with runs of 25 and 30 feet.  The DP15 can be mounted at the measurement point and the cable to the demodulator can be up to 50 feet with no compromise in calibration.

The pressure transducers are connected to Validyne CD23 demodulator with digital display.  The CD23 features large LED displays that are helpful for the operator to see while opening and closing large control valves during the test.  The display can be given directly in PSIG and the CD23 provides an analog output proportional to pressure that can be connected to a LabVIEW computer to record the pressures during the test. Alternatively the pressure sensors can also be connected to the USB2250 DAQ.

The Validyne CD23s and DP15s have given many years of service in this difficult environment and this reliability, plus the ability to interface to a data acquisition system make it a great solution for relief valve testing.

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.

(1) Boiler safety valves and safety relief valves must be as indicated in PG-67 through PG-73 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see 46 CFR 52.01-1) except as noted otherwise in this section.

(3) On river steam vessels whose boilers are connected in batteries without means of isolating one boiler from another, each battery of boilers shall be treated as a single boiler and equipped with not less than two safety valves of equal size.

(4) (Modifies PG-70.) The total rated relieving capacity of drum and superheater safety valves as certified by the valve manufacturer shall not be less than the maximum generating capacity of the boiler which shall be determined and certified by the boiler manufacturer. This capacity shall be in compliance with PG-70 of section I of the ASME Boiler and Pressure Vessel Code.

(5) In the event the maximum steam generating capacity of the boiler is increased by any means, the relieving capacity of the safety valves shall be checked by an inspector, and, if determined to be necessary, valves of increased relieving capacity shall be installed.

(6) (Modifies PG-67.) Drum safety valves shall be set to relieve at a pressure not in excess of that allowed by the Certificate of Inspection. Where for any reason this is lower than the pressure for which the boiler was originally designed and the revised safety valve capacity cannot be recomputed and certified by the valve manufacturer, one of the tests described in PG-70(3) of section I of the ASME Boiler and Pressure Vessel Code shall be conducted in the presence of the Inspector to insure that the relieving capacity is sufficient at the lower pressure.

(8) Lever or weighted safety valves now installed may be continued in use and may be repaired, but when renewals are necessary, lever or weighted safety valves shall not be used. All such replacements shall conform to the requirements of this section.

(1) (Modifies PG-68.) Superheater safety valves shall be as indicated in PG-68 of section I of the ASME Boiler and Pressure Vessel Code except as noted otherwise in this paragraph.

(2) The setting of the superheater safety valve shall not exceed the design pressure of the superheater outlet flange or the main steam piping beyond the superheater. To prevent damage to the superheater, the drum safety valve shall be set at a pressure not less than that of the superheater safety valve setting plus 5 pounds minimum plus approximately the normal load pressure drop through the superheater and associated piping, including the controlled desuperheater if fitted. See also § 52.01-95(b) (1).

(3) Drum pilot actuated superheater safety valves are permitted provided the setting of the pilot valve and superheater safety valve is such that the superheater safety valve will open before the drum safety valve.

(1) (Modifies PG-71.) Safety valves shall be installed as indicated in PG-71 of section I of the ASME Boiler and Pressure Vessel Code except as noted otherwise in this paragraph.

(2) The final setting of boiler safety valves shall be checked and adjusted under steam pressure and, if possible, while the boiler is on the line and the steam is at operating temperatures, in the presence of and to the satisfaction of a marine inspector who, upon acceptance, shall seal the valves. This regulation applies to both drum and superheater safety valves of all boilers.

(3) The safety valve body drains required by PG-71 of section I of the ASME Boiler and Pressure Vessel Code shall be run as directly as possible from the body of each boiler safety valve, or the drain from each boiler safety valve may be led to an independent header common only to boiler safety valve drains. No valves of any type shall be installed in the leakoff from drains or drain headers and they shall be led to suitable locations to avoid hazard to personnel.

(1) (Modifies PG-72.) The operation of safety valves shall be as indicated in PG-72 of section I of the ASME Boiler and Pressure Vessel Code except as noted in paragraph (d)(2) of this section.

(2) (Modifies PG-73.) The lifting device required by PG-73.1.3 of section I of the ASME Boiler and Pressure Vessel Code shall be fitted with suitable relieving gear so arranged that the controls may be operated from the fireroom or engineroom floor.

Tired of keeping track of your valve inventory’s annual certification records? We offer complete management of your safety relief valves. With an inventory of repair parts and in stock relief valves of all sizes, we can respond to any customer emergency. We offer annual certification services as well as repair of all major brands, including Kunkle, Conbraco, Consolidated, Dresser, Apollo and more.

A: Maintenance should be performed on a regular basis. An initial inspection interval of no longer than 12 months is recommended. The user must establish an appropriate inspection interval depending on the service conditions, the condition of the valve and the level of performance desired.

The ASME Boiler and Pressure Vessel Code does not require nor address testing installed valves. The only thing the code states are design and installation requirements, such as some valves must have a lifting lever. For instance for Section VIII:

“Each pressure relief valve on air, water over 140° F, or steam service shall have a substantial lifting device which when activated will release the seating force on the disk when the pressure relief valve is subjected to a pressure of at least 75% of the set pressure of the valve.”

A: This drain hole is required on some models by the ASME Boiler and Pressure Vessel Code. It is intended to prevent any condensate from accumulating in the body that may freeze or corrode internal valve parts and prevent the valve from opening. The drain hole should be piped away to safely dispose of any discharge or condensate.

A: This is often a confusing topic. The correct installation often looks backwards from what appears to be correct. A paper instruction tag illustrating the proper connection is attached to each valve. Vacuum valves should have the NPT threads that are cast integral to the body attached to the vacuum source. See the assembly drawing for additional clarification.

A: Typically, the valve should be nameplate set to open at the MAWP (Maximum Allowable Working Pressure) of the vessel the valve is intended to protect. There is a tolerance to actual set pressure, which means a valve set at 100 psig nameplate may open slightly above or below 100 psig. Consult the current ASME Boiler and Pressure Vessel Code for tolerance classes and special situations when the set pressure may be different than the MAWP.

A: It is normal for spring-operated safety valves to exhibit leakage or simmer/warn, as the system operating pressure approaches the nameplate set pressure, typically in the 80%-90% range of nameplate set pressure. The ASME Boiler and Pressure Vessel Code does not require a specific seat tightness requirement. A certain level of leakage is allowed per manufacturers’ literature and API-527 Seat Tightness Performance Standards, both of which can be found in the Technical Reference Catalog and in the Data Supplement, summarized as follows:

API-527 Standard Seat Tightness Performance: A Functional Test Report (FTR) is automatically provided for valves ordered to API-527. See API 527 for complete details.

A: Maintain a minimum operating gap of 10% between the system operating pressure and the safety valve’s nameplate set pressure. Since direct spring-operated safety valves may “simmer” or “warn” at 90% of the nameplate set pressure, and since the factory standard leak test is performed at 80% of nameplate set pressure, better seat tightness performance can be expected with an operating gap of 20%.

Variance of set pressure is allowed, i.e., a Section VIII air valve with a nameplate of 100 psig set pressure may open from 97 psig to 103 psig, but will be factory set around 102 psig.

Gage issues may lead to incorrect reporting of set pressure. Ensure the gage is within calibration and is accurate for the pressure being measured. Rapid increases in system pressure (more than 2 psig/second, water hammer, reciprocating pumps) can make the valve appear to be opening early because the gage cannot accurately report the pressure to which the valve is exposed.

A: Yes. Section I valves have more stringent setting blowdown requirements and may be used in Section VIII steam applications since they meet all the requirements as specified in Section VIII UG-125(a) “Pressure Relief Devices,” which states pressure relief devices must be “in accordance with the requirements of UG-125 through UG-137.” In addition, UG-125(b) actually specifies that even unfired steam boilers MUST use a Section I pressure relief device.

A:  Section VIII UG-136(a)(3) states, “Each pressure relief valve on air, water over 140° F (60° C), or steam service shall have a substantial lifting device which when activated will release the seating force on the disk when the pressure relief valve is subjected to a pressure of at least 75% of the set pressure of the valve.”

The user has a documented procedure and an associated implementation program for the periodic removal of the pressure relief valves for inspection and testing, and repair as necessary.

A: Back pressure reduces set pressure on a one-to-one basis, i.e., a valve set at 100 psig subjected to a backpressure at the outlet of 10 psig will not actuate until system pressure reaches 110 psig. Back pressure drastically reduces capacity; typically backpressure of 10% of set pressure will decrease capacity by 50%. Specific capacity reduction should be determined by the user on a case-by-case basis by flow testing. Back pressure in excess of 10% of set pressure is not recommended.

A: The ASME Boiler and Pressure Vessel Code does not have blowdown requirements for Section VIII (or non-code) valves. Blowdown may vary from less than 2% to more than 50%, depending on many factors including: valve design, dimensional tolerance variation, where the set pressure falls in the set pressure range of a spring, spring rate/force ratio, warn ring/guide settings, etc. Typical blowdown for most valves is 15% to 30%, but cannot be guaranteed.  VM

Jim Knox is president, Allied Valve, Inc. (www.alliedvalve.com), a valve repair service company and supplier of Tyco Kunkle and Dresser Consolidated safety valves in the Midwest. Reach him at knoxj@alliedvalveinc.com.

ValvTechnologies and Severn Glocon have reached a partnership agreement that will see collaboration between two of the world’s leading engineering and manufacturing companies specializing in innovative, high-end, severe-service valves.

This article outlines the challenges of lifting large valve assemblies weighing several tons and illustrates the industrial rigging equipment and lifting operations typically used for these valves.

Many people probably know that the National Board operates a capacity certification program and a valve repair program where we test many pressure relief devices. I want to talk about the background and requirements of that program and the applicability of our testing data to reliability for industry. As a result of years of testing, we have accumulated a good deal of data that helps us analyze the quality and reliability of the equipment. We want to use the data to determine what industry can expect when they receive a certified pressure relief device, pressure relief valve, or rupture disk device.

Slides 2-3: The new product certification program starts with a manufacturer. They will test a design and establish an initial rating for it. Next is a production test – a test of two sample pressure relief devices. This test previously occurred on a five-year cycle, but now it"s on a six-year cycle to line up better with the ASME code stamps’ three-year renewal cycle.

Two samples are selected every six years and tested at an ASME-certified lab. All test requirements come from the ASME Boiler and Pressure Vessel Code. Through the code, the National Board has been designated the responsibility to manage and run that certification program using the ASME boiler code rules. National Board inspectors travel to the manufacturers’ sites. We also deal with valve assemblers and rupture disk manufacturers. A big part of their responsibility when visiting the site is to look at the manufacturing, assembly, and test procedures, and make sure we get a good representative sample of what that manufacturer is capable of doing.

In some cases we will actually take valves right from shelf stock, particularly from manufacturers that mass produce their product and have large quantities of valves in stock. One selection technique is to go into the warehouse and say, “Give me one of those and one of those.” Sometimes they will dust off the box, but we are trying to get an accurate sample. Sometimes they are testing a valve they are building for the inspector while he"s there, but in that case they are looking at the assembly and test procedures and trying to see if it’s a good representative sample.

The program for individual design is not meant to be statistical in nature, so we are not testing a certain percentage of devices: just those two products every six years. It may be more than two if a test failure occurs. If there is a failure, the manufacturer has to test two additional samples. If they get past that test and still have a problem, a formal corrective action program is implemented. They have to analyze their failure, report on what happened (the cause), and explain what corrective actions they will take. And potentially, a manufacturer could actually lose the ability to put the code stamp on their product, so it"s an important test. The manufacturers have a lot riding on it because if the product passes, they can produce that valve for a six-year period of time. The tests are conducted at ASME/National Board-certified test labs, which include the National Board Testing Lab in Columbus, Ohio, but there are also about 10 other laboratories that are operated by valve manufacturers and rupture disk manufacturers.

We are involved in an ASME certification process. The labs all compare to one another to show that they can essentially attain the same results; they get the same measured capacity. And when any certification test is done at those labs, our inspector goes to witness the test and ensure it meets our requirements and procedures; so all tests are considered on the same basis. We have collected a lot of test data over the years and I looked for trends and patterns to analyze what the data was telling us.

Slide 5: We analyzed information starting with the year 2000. I chose that year because it gave me a lot of tests, but also the code rules for rupture disk certification went into effect in the "98 code, and by the year 2000, rupture disks were a well-certified device under ASME Code Section 8, and manufacturers had started to certify those devices. So it gave them a wider variety of equipment than we had seen before, because until then we were just testing pressure relief valves, and the non-reclosing devices were not well represented in the formal testing that we did, although they were being used out in the industry. It includes valve repair verification tests.

So although we talked about testing done on new product, as part of the valve repair certification process, the valve repair applicant has to repair several sample valves. Those are sent to a certified test lab and tested to exactly the same procedure that a new device is tested under. And while we always say a goal of the valve repair program is to return the valve to a like-new condition, as far as a user is concerned, if we get a repaired pressure relief valve, you should be able to expect that valve to do exactly what a new valve would do. It"s a certified device to begin with. It"s put through a program to inspect it, repair it as necessary, reset it, and get it back to that like-new condition. So I included all these valve repair verification tests. The typical test program for a repair outfit is doing a steam valve, an air valve, and a water valve, depending on the scope of work. And I threw those into the hopper; I treated those just like any other new valve that would be coming from the manufacturer.

We do tests for research and development projects and informational tests (what we call provisional testing). Provisional testing is the test a manufacturer does when they are first getting their design certified. Those tests are essentially prototypes. They are not valves that have truly gone into production, which doesn"t happen until a two-valve test is performed. So none of that was included, because they are still tweaking their design and getting it to the point at which they think it"s capable of being put through the final tests, and then to the production tests, which are the proof of the pudding.

It doesn"t include what we call investigation tests. I will talk a little bit about some of that test data. We don"t have a lot of it, but we do have enough to draw a couple conclusions, but it"s not indicative of the new product going out the door. Some of the limitations of this information based on the economics represents the lower pressures and smaller sizes of valves. So what we and other test labs can do is go up to three-, four-inch inlet sizes. Our pressures and capacities are necessarily limited because to put a pressure relief valve through a full-flow test, you need a lot of support equipment. We run boilers (we previously ran large air compressors but we"ve switched to a nitrogen system) but we have a lot of capital tied up in that. And as you double the pressure, the costs go up exponentially. So our tests are limited; we don"t do eight- and twelve-inch valves. The theory is that the valves are scaled up appropriately, but most of the testing we do is lower sizes and pressures. Hopefully that reflects more typical industrial equipment. We don"t get super-critical boilers, but there are large numbers of boilers with a 150-pound safety valve, and we have covered those pretty well.

Section III – 12 tests (These Section III valves were likely nuclear valves that got repaired as part of a repair demonstration. We don"t normally test many nuclear valves. They are the same physical equipment as you see in either Section 1 or Section 8.)

This is the bulk of the work we do; a wide variety of all different types of Section 8 pressure relief devices. In regards to test medium used: steam is about 25 percent and air is almost half. Air represents all the industrial gases. And then water tests are at about 25 percent. That represents valves for liquid service.

The test outcomes are based on the criteria we put in our database. After we run a test, we give it a designation as to the outcome of the test. Eighty-five percent of the valves passed. The biggest ones are set pressure failures and failures of capacity, with the next biggest elements, and I will talk a little bit about each category.

What I have is a plot of all the pressure relief valves, looking first at set pressure. Anything we called a failure is a failure to meet the ASME code set pressure tolerance. It"s cut and dried. If you fail it, you have to retest. But what we tried to do is see how wide those failures were, their distribution, and where test failures might potentially affect the pressurized equipment where that valve might be installed.

Slides 11-12: This distribution is the measured set pressure over the nameplate set pressure. The numbers below the 100% line are valves that opened underneath the nameplate set pressure requirement. The little tilted spot in the middle is all the valves that passed. And then as we go up on the right-hand side, those are the valves that failed but where the set pressure was actually high. And that to me is the real area of concern. A valve that opens low indicates an operational issue. But what we don"t want are valves that open high.

One glitch we discovered were a few valves that showed up at 400% above the set pressure. Normally we stop a test essentially at one and a half times the set pressure of the valve.

Occasionally we had some valves where set pressure was in bars, the test pressure was in psi, and if you tried to compare those numbers you didn’t necessarily get the right answer. Then what is the unsafe level? Where should we be concerned? A lot of times when people do this analysis, they will look at the hydrostatic test pressure. I do not believe that is conservative enough. That was good when a pressure vessel or boiler was manufactured.

We did an overload test on it and made sure it was good. But as that equipment goes into service over time, we know it"s degraded and there are other things happening to it. The criteria I used for what I call ‘the real bad actors’ was all of the devices that were over 116 % of the nameplate set pressure. That is the Section 8 overpressure limit for a system with multiple pressure relief devices. And if we get above that, we also reference it in the NBIC as a place for taking up the valve for an inservice test. We are going to stop at that point. I"m concerned with anything above that. So that was my first set of data where I"m thinking these are really not the way we would want them to be.

Then we get to valve capacity. The capacity includes valves that didn"t flow what they were rated to flow. A common cause is when valves are over pressured, they will hit a point where they get a secondary lift, and if someone doesn"t fine tune that valve properly, secondary lift isn"t quite achieved. It’s a test-and-tune issue; it"s not necessarily a design issue, but people really understanding how the equipment works. We do have a number of liquid valves that showed up, and again, if a valve doesn"t meet its rated capacity by the code-specified overpressure, it"s a test failure. But we have a number of liquid valves that would open just above whatever the specified overpressure is, typically 10 percent for a Section 8 valve.

So we did have a number of comments for those. And this also includes rupture disks where the flow resistance, which is the Kr valveor minimum net flow area, did not meet specifications.

Slides 13-14: This is my first graph of the distribution of our valve capacity. These are valves that were designated as failures, and we have the measured capacity divided by what the valve is actually rated for. So you can see, it starts at zero and works its way up. It should end at one but I had two or three tests where we called it a capacity failure, but it actually flowed more than the nameplate. Every so often we do run across valves that are misidentified, and sometimes that can be an issue. What I used as a measuring stick was stuff that was less than half of what it was rated at. That tells me it"s a valve that probably was not just a secondary lift issue. There was something really wrong with it. And that ended up being about a half percent of all the tests that were done.

We had about 1% of tests where we just didn"t have a measured capacity. Many were liquid valves. So we will take that test (the set pressure on those is where it first starts to have a trickling flow) and we will keep increasing the pressure until that valve pops open. And if that pressure occurred more than 10% above the set pressure, that valve was a capacity failure. We had a number of those that were about 12-15% above the set point. That information goes to the manufacturer and it can help them figure out their problem. Those valves were not counted in the case where we knew where they opened. We know that once they did open, they would probably work fine. But if you don"t hit it by that 10%, you have got to go through and do another test and improve your product to make it better. The rupture disk Kr number is used a little bit differently.

Slide 17: We had about two percent of what we reported as blow-down failures. These are not included in the final analysis because in reality we look at blow-down ultimately as more of an operational issue. It"s a concern to the user and to the boiler operator. It took two examples: one, we did have some Section 1 valves that were occasionally flagged. There is a minimum blow-down under Section 1. If it"s less than that, again, it"s a test failure and you have to address it. In most cases the capacity is probably fine in those valves.

Under Section 8 there is a requirement for manufacturers to demonstrate the capability to make certain valves meet a 7% blow-down requirement, and ones that fell in this category were valves that the capacity was fine because we actually do test that in that case, but they could not make that blow-down be less than 7%, which is the Section 8 specification. And that"s only for certain designs that are deemed what we call adjustable.

Slide 18: For whatever reason, they couldn"t adjust it. And in that case, the service condition you see is the valve stayed open a little bit longer. We had about .2 percent that we called failed operation. Mostly this is the adjustment of the lifting lever. It"s a lack of attention to detail when the valve was being put together.

I had about a tenth of a percent of valves that we deemed incorrect lift. This is from valves that are certified primarily in Section 8 where they will have restricted lift design. The manufacturer could make a valve that would pass all the criteria, but if set incorrectly, there would be too much lift and the design would not meet capacity. We don"t want somebody to pass because they put the valve together wrong.

Slide 19: So to summarize, I took what I classified as my bad actors: the set pressures that were more than 16 percent above the set pressure; the valve capacity failures that were less than half; the rupture disk Kr and rupture disk failures to open; and it all adds up to about one percent of our test total. And thus my initial estimate of what"s the reliability of this equipment ultimately to do its overpressure protection job is that it comes to about 99 percent, which is good.

We also compare that to the actual test failures. They were higher, and it obviously shows there is still room for improvement in the industry. We deemed a number of tests ‘investigation tests.’ These were valves that either had been received from chief inspectors in a few cases or received from private organizations to do a test to see if it possibly contributed to an accident.

Slide 20: We had 130 tests. About half of them were not applicable, but about 37 valves actually passed. Some failed set pressures, some failed capacity, a few failed blow-down. In all of the tests I have personally witnessed, the majority of the problems were ultimately due to how it was applied or maintained. I can pick up a valve and look inside the inlet and tell you if it will pass or not. We will put it on the test stand and test it. But if it"s all clogged up with rust or corrosion, or if the outlet is clogged with product, that valve is not capable of doing its job. And it"s nothing to do with how it was built. It was ultimately how it was maintained when it was inservice.

Slides 21-22: Looking at all of this information, what can we take away from it? One, we do want to recognize the value of the ASME code/National Board capacity certification program. It ultimately is a program that makes the manufacturers and organizations toe the line. They have got to work hard to meet the standard, and the standard has some very tight tolerances that are associated with it. They are there for a reason: this is safety equipment. We want it to be available 100 percent of the time. But that tight margin does give us a little bit of leeway. For example, if we get a valve that opens at four percent above the set pressure, that"s not a good thing and we will want the manufacturer to do better than that, but it still is well below the area where potentially we are going to have a problem when that valve goes into service.

To increasing our test capabilities, the National Board Testing Lab has gone through an expansion project. We have up-rated our air testing capabilities specifically. I have also gone through some refitting of our steam system trying to improve our test capabilities. You may be hearing more about that over the next year or so.We are quite proud of the work that"s been done and we hope to improve what we do.

And then, finally, the statistics that we are looking at are new equipment going into service. And the one thing that we don"t account for in this information, other than the stuff we get from the investigation tests, is now once it goes into service, it"s not like wine, it doesn"t get better with age. Ultimately we need to inspect it, we need to look at this equipment periodically and make sure that when the inspections are done, they are not just a visual inspection, but we want to know for pressure relief devices, there needs to be testing associated with that to assure the device is working properly.

Make sure you have good inspection history to know how often we should be looking at these pressure relief devices. Some industry standards have a ten-year inspection period, which to me is way too long, particularly in a lot of the more aggressive services. You really need to look at the pressure relief devices more often because of the important function that they serve. But this preliminary data gives you an idea of how good a valve is once it goes into service, at least from a new product perspective. However, because of the data quirks, I wouldn"t necessarily quote any of this yet and put it into a publication.

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.

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.

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.

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.

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.

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).

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.

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.

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.

Inspection tags are useful tools that help to facilitate and ensure that proper inspection procedures are followed for equipment such as boilers, industrial pressure vessels, and valves. Inspection tags can be used to inform employees when inspection was last conducted on a part or piece of equipment, offering confidence that the equipment is in safe and working order.

Inspection tags can also indicate when a part or piece of equipment is scheduled for maintenance or repairs and can also be used to indicate the status of a current maintenance procedure that’s in-process. Finally, they can be used to communicate hazards and cautions in the workplace, such as denoting equipment that must be inspected prior to operation. And regular inspections aren’t only useful for safety; regular inspections, testing, and repair of leaking pressure safety valves, for instance, results in a cost savings for organizations, in addition to providing environmental benefits.

We’ve created this guide to provide a comprehensive understanding of inspection tags for boilers, industrial pressure vessels, valves, and other parts and equipment, outlining the information you need to know to ensure compliance with inspection requirements and appropriate equipment tags.

Regulations pertaining to the inspection and maintenance of equipment such as boilers, pressure relief valves, and industrial pressure vessels are largely issued on the state and local levels. However, some federal agencies have issued guidance and standards in an effort to guide state and local entities in creating appropriate regulatory requirements. These federal agencies include:

ASME issues standards on testing pressure relief devices and also offers accreditation for laboratories that test pressure relief devices. Additionally, ASME issues standards for the inspection, repair, and alteration of boilers as well as for various types of valves, such as flanged, threaded, and welding end valves.

The Unified Facilities Criteria (UFC), issued by the Department of Defense, offers guidance on the inspection and certification of boilers and unfired pressure vessels, covering the procedures necessary to determine the material condition of this equipment in order to ensure safe, reliable, and efficient operation. It also specifies the frequency of inspection and testing required, the specific items and components that must be tested or inspected, and the forms that must be used.

The National Board of Boiler and Pressure Vessel Inspectors outlines the specific steps required in order to prepare a boiler or pressure vessel for inspection, as well as specific tests and inspection activities to be carried out by inspectors. The American Petroleum Institute issues several standards related to the testing and inspection (and related topics) of pressure relief valves and other equipment, including API Standard 527, Seal Tightness of Pressure Relief Valves, API Standard 620: Design and Construction of Large, Welded, Low-pressure Storage Tanks, and API Standard 526: Flanged Steel Pressure Relief Valves, among others.

According to OSHA, most pressure and storage vessels in use in the United States are designed and constructed in accordance with either ASME Code (or Section VIII of the ASME “Boiler and Pressure Vessel Code”) or with API Standard 620, which establishes rules for lower pressure vessels which are not covered by the ASME Code. Certification of these vessels can only be performed by trained inspectors with the proper qualifications for each code, and certification requires written tests and practical experience.

Pressure vessels must be certified during manufacturing and are required to be stamped with the proper codes issued by ASME. If a manufacturer is accredited by ASME for pressure vessels (under ASME Code Section VIII Div. 1), the manufacturer can stamp nameplates on vessels with the ASME “U” symbol.

Other pressure vessel stamps include U2, Alternative Rules Section VIII, Division 2 (Shop and /or Field) and U3, Manufacturing of High Pressure Vessels (Shop and /or Field). The “UV” symbol is designated by ASME for pressure relief valves.

Note that a Quality Control System must be implemented in accordance with the ASME code quality control manual, with procedures prepared by the manufacturer. Inspection-for-Industry.com offers a useful Inspection and Test Plan for pressure safety valves that can aid in this process. The quality control system (for pressure relief valves, industrial pressure vessels, and boilers, as well as other parts and equipment) should include ongoing inspection and testing plans and procedures – all of which must be documented over time on inspection tags and inspection and testing reports. The inspection procedure is distinct for each equipment type, involving several observations and tests, with each inspection culminating with recording and maintaining the inspection and testing results.

The type of inspection record (safety inspections, general inspection record, or an indicator of the equipment category, such as boiler inspection record or valve inspection record)

Some inspection tags come pre-marked with months and years for inspection record tracking over a specified number of years, such as four years. These tags can also communicate the specific inspection requirements to employees (such as equipment operators) or to auditors.

In addition to inspection tags intended for documenting the performance of periodic inspections and repairs, most equipment requiring inspections also requires the use of compliance tags for the permanent documentation of important processes or procedures, such as operating or maintenance instructions, inspection procedures, and other essential information. Compliance tags are also printed with the equipment manufacturer, serial or model number, date of manufacture, load rating, or electrical specifications, all of which is essential information for performing equipment inspections. Instructional labels are a similar option, documenting equipment maintenance requirements, operating instructions, or safety instructions.

Other inspection tag materials include vinyl, nylon, stainless steel, and some plastics. When selecting an inspection tag for equipment and parts such as industrial pressure vessels, valves, and boilers, consider the operating environment of the equipment and choose inspection tags constructed of durable materials that can withstand these conditions throughout the life of the asset – or at least for the duration of the tag’s usable life (e.g., four years for inspection tags with pre-printed dates designed to track inspections over a four-year period).

Some testing procedures must be carried out in highly controlled environments, meaning the equipment must be taken out of service until testing is complete. Have procedures in place and appropriate signage and tags on hand to address such scenarios.

Additionally, consider the frequency requirements for inspections. Generally, parts and equipment with greater hazard potential require more frequent inspections, meaning boilers, industrial pressure vessels, and valves will require more frequent inspection and testing than other equipment that poses less risk to operators (or is less subject to malfunctions with slight changes in operating conditions). Inspection frequency also depends on factors such as service, which can alter the ideal inspection frequency even for parts that have a broadly accepted, general guideline of “at least every five years.” For this reason, inspection frequency should be established on an individual basis, within the context of manufacturer requirements and an analysis of the actual service the part or equipment is in.

Inspection tags for boilers, industrial pressure vessels, and valves are just one component of overall quality control. To ensure regulatory compliance, inspection tags prove useful tools in ensuring that minimum inspection intervals are met and providing an audit trail of prior inspection and testing activities. Choosing the right inspection tags for your application will ensure that this vital documentation remains intact and readable throughout the lifespan of your assets.

Safety valves are used in a variety of applications, including air/gas, vapor, steam and liquid service.  Flotech has been approved by the National Board of Boiler and Pressure Vessel Inspectors to perform safety and relief valve testing, repair and certification.

Our valve experts will focus on getting your valves tested, repaired and quickly set to the exact specifications.  We evaluate the repair condition of every valve and will recommend the right solution to manage your maintenance program.