Understanding Valves and Their Role in Mechanical Integrity In partnership with Copyright © 2022 by Inspectioneering, LLC 24900 Pitkin Road, Suite 325 Spring, Texas 77386 USA www.inspectioneering.com All rights reserved. No part of this publication may be reproduced, distributed, or transmi ed in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior wri en permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permi ed by copyright law. Inspectioneering would like to thank all of those that contributed to the development of this work, including the authors, Mike Pelezo and Evan Sparks. The photographs used on the cover and in the subject ma er were provided courtesy of Bayport Training & Technical Center. For more downloadable resources, visit inspectioneering.com/downloads. 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DO NOT RELY UPON ANY INFORMATION FOUND IN THIS BOOK WITHOUT INDEPENDENT VERIFICATION. fi tt Inspectioneering.com | Page 2 tt tt tt Understanding Valves and Their Role in Mechanical Integrity CONTENTS Introduction 4 Industry Standards and References 4 Valve Types and Usage 5 Critical Check Valves and Emergency Isolation Valves 8 Mechanical Integrity Considerations 8 Conclusion 12 References 12 Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 3 Introduction Owner/operators who are responsible for the mechanical ASME B16.34 1, Valves—Flanged, Threaded, and Welding End integrity of valves often lack knowledge and background According to ASME: experience in valve anatomy, valve inspection, and valve maintenance. This may be because, at least for API in-service inspection codes commonly required for in-house inspection positions (i.e., 510, 570, 653), valves are described in vague terms and leave many details up to interpretation by the owner/ operator. ASME B16.34 Valves Flanged, Threaded, and Welding End applies to new construction. It covers pressure-temperature ratings, dimensions, tolerances, materials, nondestructive examination requirements, testing, and marking for cast, forged, and fabricated anged, threaded, and welding end and wafer or Valves critical to process safety should require the same attention to detail as any other fixed equipment or piping system components. Often, the responsibility to inspect and maintain valves is delegated to outside valve repair facilities. Owner/ operators typically offer minimal input outside of their standard specifications. It benefits owner/operators to know and angeless valves of steel, nickel-base alloys, and other alloys. Intended for manufacturers, owners, employers, users and others concerned with the speci cation, buying, maintenance, training and safe use of valves with pressure equipment, plus all potential governing entities. [1] understand the details involved with valve inspection and In short, ASME B16.34 is the design book for valves. As it relates maintenance and how it affects their mechanical integrity to inspection, this standard is primarily used as part of the QA/ programs. QC process during manufacturing. Outside of manufacturing, it Even something as simple as an external visual inspection can be more effective with a basic understanding of valve anatomy and common problems associated with them. Understanding how the hardware on the outside affects the hardware on the inside adds value to the external visual inspection. It is hard to is often referred to by engineering during design and project development as it provides dimensions, materials, and pressuretemperature ratings that can be helpful with valve selection. It is not the type of document that is routinely referenced by inspectors, but it can be a helpful reference in certain situations. seen the inside of that type of valve or understanding how the API 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-service Piping Systems internal parts move. Knowing what sounds to listen for, how API 570 is one of the primary standards referenced in internal seals are made, and potential leak points can help mechanical integrity programs for inspection, rating, repair, and inspectors make credible assumptions and recommendations to alteration of in-service piping systems. This code gives general maintain the integrity of valves. guidance for valve inspections, both internal and external. This eBook covers valves and their role in the overall mechanical API Recommended Practice 574, Inspection Practices for Piping System Components visualize what is going on inside of valves without ever having integrity process. First, we will discuss the various valve types, their common uses, and the governing standards and recommended practices that apply. Second, we’ll discuss the common failure mechanisms affecting valves, the potential causes of the failures, and what can be done on-line to detect and/or prevent them from happening in the rst place. API RP 574 discusses inspection practices for piping, tubing, valves, and ttings used in petroleum re neries and chemical plants. This document supplements API 570, going further indepth with the inspection of piping systems, including valves. Section 4.3 goes into great detail about the many types of valves, Industry Standards and References including their operation and internal components. For starters, we will discuss the industry standards and API Standard 598, Valve Inspection and Testing recommended practices that apply to the inspection, testing, and maintenance of valves. API Standard 598 is a supplement to API 570 and API RP 574. It is primarily used by valve manufacturers and valve repair shops when inspecting and testing a nal product, whether new or repaired. In particular, it covers “inspection, examination, fi fi fi fi fl fl fi Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 4 for resilient-seated, nonmetallic-seated (e.g., ceramic), and metalto-metal-seated valves of the gate, globe, plug, ball, check, and butter y types.” [2] Valve Types and Usage Next, let’s discuss the most common valve types. Each valve type is different and serves a speci c need. It is important to know the difference between valve types and their individual anatomies in order to understand the proper application and potential problems associated with each type. Common valve types include gate, globe, plug, ball, diaphragm, butter y, check, and slide valves. They are made in standard pipe sizes, materials, thickness, and pressure ratings. Valve bodies are typically cast, forged, machined, or welded. The seating surfaces can either be integral or made as inserts. Inserts allow for the seat material to differ from the body material. For instance, a carbon steel body ange may have stainless steel seat inserts to minimize wear and tear over time. Valves are either anged, threaded, socket welded, or butt-welded depending on the process conditions and piping speci cations. Figure 1. Gate valve cutaway. Image courtesy of Bayport Training & Technical Center. Gate Valves A gate valve, often referred to as a “block valve,” consists of a tapered, with the taper getting steeper for ne-throttling service. valves are either completely open or closed. They are not Globe valves are typically used in locations where ow control is intended to be used to regulate ow by “throttling,” as that will essential. They are considered uni-directional and must be typically wear and erode the gate and seats. installed in proper relation to the media ow as indicated by the Standard gate valves are the least costly of the valve types and are one of the most common valves in the re ning and petrochemical industry. They are suitable for most services and they can easily be actuated via electric, pneumatic, or piston by “throttling” the valve to the proper position to maintain a speci ed pressure, temperature, or level. Because of their ability to throttle and regulate ow, globe valves are often used as control valves. Since they are typically designed to be open or closed, gate Plug Valves valves are often set in position and left alone until needed for A plug valve consists of a tapered or cylindrical plug maintenance. In some cases, like with site-wide utilities such as snugly into a correspondingly shaped seat in the valve body. water, steam, air, nitrogen, etc., gate valves may remain open or There is an opening in the plug that lines up with the opening of closed inde nitely. the valve body when in the open position. Plug valves can be Globe Valves used for isolation (similar to the gate valve) or with a circular disc that contacts the seat and moves up and down, parallel to the disc axis. Globe valves distribute ow more evenly across the entire seat to reduce wear; therefore, they are fl fi fl fl fi fl fl fl fi fl fi fl fl fi fl fl fl fi Understanding Valves and Their Role in Mechanical Integrity fl ow direction arrow marked on the valve body. Flow is managed style units. A globe valve is a linear motion valve consisting of a valve body fl commonly used to regulate uid ow. The seat can be at or ow. Typically, gate body that contains a gate that interrupts fi fl supplementary examinations, and pressure test requirements tted ow control (similar to the globe valve). The plug is integral to the handle. Because of the design, the valve opens and closes with just one-quarter of a turn. For larger valves, and for valves requiring even distribution during Inspectioneering.com | Page 5 Figure 3. Plug valve cutaway. Image courtesy of Bayport Training & Technical Center. Figure 2. Globe valve cutaway. Image courtesy of Bayport Training & Technical Center. operation, a gear operator can be installed to prevent sideloading. Plug valves are used in many processes and are engineered for high-cycle, low-emissions service. They are used with con dence in applications where tight shutoff and emissions containment are essential. Because of their performance, plug valves are commonly used in HF Alkylation units. Besides HF Figure 4. Ball valve cutaway. Image courtesy of Bayport Alkylation units, plug valves are also used in isomerization, Training & Technical Center. blending, light ends, gas plants, sulfur plants, and crude With pressure-assisted sealing, they have become a preferred desalting. valve for many applications. Critical service ball valves are found Ball Valves in Distillation, Reforming, Fluidized Catalytic Cracking (FCC), A ball valve is another type of quarter-turn valve that is similar Hydrotreating, Hydrocracking, Delayed Coking, Gasi cation, to a plug valve except that the ow restriction in a ball valve is and other re ning units. spherical instead of tapered or cylindrical. Similar to plug and globe valves, ball valves are used as block valves or for ow control. Ball valves are great for quick on/off applications or in A diaphragm valve is a packless valve containing a processes requiring a bubble-tight seal. Typically, ball valves diaphragm on the inside. When the valve is closed, the stem have a coating around the surface of the ball that serves as a pushes down on the diaphragm. The diaphragm presses against sealing medium. the seat or dam to form a seal and block the ow of uid. When fl fl fi fl fl fl fi Understanding Valves and Their Role in Mechanical Integrity fi Diaphragm Valves exible Inspectioneering.com | Page 6 Figure 5. Diaphragm valve cutaway. Image courtesy of Bayport Training & Technical Center. the valve is opened, the diaphragm raises from the seat or dam to resume ow. Figure 6. Butterfly valve cutaway. Image courtesy of Bayport Training & Technical Center. The metallurgy of the diaphragm is chosen based on the process conditions (e.g., corrosivity, abrasiveness). They are ideal for creating a tight seal in abrasive services with some amounts of solids. They are not used in many places, but they are commonly found in uid catalytic cracking (FCC) slurry services. They are not designed for tight shut off; rather, they are designed for erosive and high-temperature service and can be used for both “throttling” or blocking. The most notable application is in the FCC units. FCC slide Butterfly Valves Butter y valves consist of a disc mounted on a stem within the valve body. Similar to a ball valve, butter y valves are a quarterturn valve designed for quick shut off. However, butter y valves are generally favored over ball valves because of the reduced valves will typically have an erosion-resistant overlay or refractory due to the high wear to the internal surface from the catalyst. Check Valves cost. Butter y valves are most often used in low-pressure service Check valves are used to mechanically prevent back ow without for coarse ow control. The seating material is chosen based on human intervention. They are designed to close automatically how tight of a seal is required. when back ow occurs. There are many types of check valves Larger butter y valves are typically found in cooling water service connected to the cooling water pumps and exchangers, and are typically operated mechanically or with a gear operator to prevent the valve from slamming shut while turning. Slide Valves including swing, piston, and spring-loaded wafer check valves. Check valves of all types are used widely throughout the industry. They’re most commonly found on the discharge of pumps to prevent reverse ow and damage to the pump internals. The spring-loaded wafer type check valves are commonly found attached to tank Slide valves are equipped with a at plate that slides within oating roof drain piping within the roof sump. guides on each side to the seat that is similar to a guillotine. fl fl fl fl fl fl fl fl fl fl fl fl fl Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 7 longer a recommendation to inspect or test CCVs; it is a requirement. EIVs are also among the commonly considered engineered safeguards. An EIV is a special category of valve that is dedicated to the purpose of isolating ammable or toxic material from sources or equipment whose relative consequence of signi cant leakage is high. In short, EIVs are valves that absolutely must work when needed, which is usually during an emergency. Any valve type can be classi ed as an EIV, including critical check valves. Identifying these CCVs and EIVs can be done in a few ways. Figure 7. Ball check valve cutaway. Image courtesy of Bayport Training & Technical Center. in an unintended direction (reverse Typically, the identi cation is led by process engineering. Sometimes, a once-through effort takes place to identify CCVs and EIVs to get them into the mechanical integrity program to When a check valve malfunctions, it allows the process to ow ow). In some cases, this isn’t a major problem. For instance, a check valve installed on the discharge of a water pump is usually there to prevent water from backing up when the pump is removed for maintenance. If begin with. In other cases, the identi cation of CCVs and EIVs takes place through attrition during process hazard analysis (PHA). Regardless of how they’re initially identi ed, the recurring PHA is the primary method for keeping the list evergreen. that valve leaks, it is simply going to make a mess and be Once a valve is identi ed as a CCV or an EIV, it should be stored inconvenient for maintenance crews. On the other hand, the in the site's inspection data management system (IDMS) along proper function of some check valves is deemed critical to with the appropriate inspection tasks, as with any other asset. As process safety. These are typically designated as critical check future PHAs and MOCs are carried out, EIVs and CCVs may be valves (CCVs). added or removed; these changes should be re ected within the Critical Check Valves and Emergency Isolation Valves IDMS. Mechanical Integrity Considerations Now that we’ve discussed the basic valve types, we’ll transition Understanding valves, their anatomy, and how they operate, to particular classi cations of valves that belong in the gives the inspector a better sense of what potential problems mechanical integrity program: critical check valves (CCVs) and exist. At the same time, knowing which problems are more emergency isolation valves (EIVs). common to a speci c type of valve allows the inspector to CCVs are any check valves in piping systems that have been identi ed as vital to process safety. CCVs are check valves that connect these dots and formulate an inspection plan that ensures the continued reliability of valves. need to operate reliably in order to avoid the potential for Ideally, all valves should work when needed; but the truth is that hazardous events or substantial consequences should reverse valves fail. While many valve failures may have minimal impact on process safety, there are a number of valves whose failures ow occur. The fourth edition of API 570, released in 2016, addresses CCVs. Section 5.13 states that CCVs “should be adequately inspected or tested to provide greater assurance that they will prevent ow reversals.” [3] The key here is the word “should.” It wasn’t until the May 2017 Addendum to API 570 that the “should” was fl fl fi fi fi fl fl fi fl fi fi fi fi fi Understanding Valves and Their Role in Mechanical Integrity fi fl changed to “shall.” Because of this slight change wording, it is no can potentially domino into safety problems or larger failures of a process unit. EIVs and CCVs are highlighted in industry standards and references because they’re vital to process safety, and they should be included in mechanical integrity programs to be inspected and maintained. However, the owner/operator’s inspection group oftentimes has limited experience in this eld. Inspectioneering.com | Page 8 Valves often seem to fall into the “gray zone” of equipment – globe valves. Installing a globe or check valve backwards may they don’t explicitly belong to one functional group or another. cause damage to the valve or associated piping and equipment. Along with a handful of other miscellaneous assets, valves tend Uni-directional valves have to slip through the cracks of expertise for owner/operators. casting or forging to show the proper direction. They’re typically maintained by third-party valve repair facilities that are experienced and able to specialize in valves. ow arrows built into the body However, not all valves are clearly marked for direction of ow and it’s important to refer to the manufacturer’s instructions With this eBook, we hope to close the gap by discussing the when performing valve installation and startup. Rising stem ball common failure mechanisms of valves and give the inspector an valves, which are common in re ning and petrochemical idea of what to look for during an inspection. For externally applications, are a good example. These valves are designed to be detectable failure mechanisms, we will discuss the on-stream installed with the core seat facing the inlet pressure. The valve inspection methods used to detect premature valve failure and may operate in a reversed ow condition, but over time this can provide guidance for minimizing or mitigating these failures. lead to performance and reliability degradation. Valve Selection/Installation Flaws In addition to the Let’s start where it all begins: the pipe design and valve selection that occurs on the front end, even before the valve is installed. Valve selection includes design aspects such as valve type, metallurgy, orientation, pressure and temperature rating, etc. Issues related to valve selection usually arise when the process conditions or the intended valve function are incorrect or not ow direction, it’s also important to have proper valve orientation. Check valves are especially sensitive to valve orientation. If a swing check valve is installed such that gravity causes the gate to hang away from the seat, then it’s almost certain to not prevent back ow when needed. Similarly, when a spring check is installed upside down, the weight of the plug compresses the spring, thus taking pressure off of the seats. understood during the selection process. For example, installing In short, it’s important to ensure that valves are installed as a 316 stainless steel valve in a service that was not expected to recommended by the manufacturer and per the engineering/ have chlorides can lead to chloride cracking of the valve stem or construction drawings. body. Had the process conditions been fully understood, 316 stainless steel would not have been selected for this application. Pressure and Temperature Ratings As we discuss these common valve issues, you’ll nd that many All valves come with design pressure and temperature ratings of them can be tied to the pipe design and valve selection set by the manufacturer. Typically, these ratings are listed on a process. tag attached to the valve handle or valve bonnet. It’s important that the speci ed pressure and temperature ratings of valves are Metallurgy not exceeded. Doing so could lead to valve failures from either Improper metallurgy selection is one of the most common examples. As stated earlier, the improper metallurgy of valve bodies, stems, seats, etc., usually occurs when the process conditions were misunderstood or not fully considered during selection. It’s important to have an understanding of the normal process chemistry of the system along with any potential upset overpressure or overheating. Similar to direction and orientation, ensure that the ratings on the valve tag matches the engineering/construction drawings. It’s not uncommon to nd a valve of an improper rating installed where it shouldn’t be. conditions that may change that chemistry. This responsibility External Corrosion, Cracking, and Mechanical Damage typically falls on the metallurgist and piping designer. Even when designed properly for the service, valves are not Direction and Orientation immune to damage. External damage mechanisms still exist, Attention should be paid to the correct installation of the valve, and they affect valves of all types. ensuring the valve is installed in the correct ow direction for Carbon steel and low-alloy valves are vulnerable to external the pipework in which it is being used. This is particularly corrosion, especially in low-temperature services. Just like with important for uni-directional valves such as check valves and any other equipment, the coating still requires inspection and fl fi fl fi fl fl fl fi fl fi Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 9 maintenance; and corrosion under insulation (CUI) inspections valves, pro le radiography is a great tool for this and can be need to be a part of the routine inspection plan. External performed while in service. corrosion not only affects the valve body, but it also affects the valve hardware keeping the valve together. For actuated valves, Cracking Cracking is typically found on the internal tack welds, valve the actuator housing should also be inspected. External cracking is not very common, but it exists. Stainless steel valve bodies are susceptible to chloride cracking, typically induced from high chloride water (i.e., rewater, being used to wash down the unit or from chloride leaching from insulation). From an inspection point of view, there isn’t much that can be done to prevent the high chloride water wash aside from operator training, but a good under-insulation coating can help minimize under-insulation cracking. stems, guide pins, check valve hinges, and retainer hardware. Most of the time, a cracked valve stem is identi ed by operations when opening and closing the valve. It’s not uncommon for cracking of internal tack welds to go unnoticed until the equipment is removed for inspections. A simple dye penetrant test (PT) will usually bring these cracks to light. Pro le radiography can be used on smaller valves, while in service, to inspect for valve stem cracking or other hardware anomalies. Mechanical damage is pretty self-explanatory. There are many ways for a valve to inhibit mechanical damage, especially in a re nery or petrochemical setting with heavy equipment moving around. There is also the potential for operator-induced damage. Pipe wrench marks on a manual valve stem are a sign that the valve may be dif cult to actuate or to seal. In many cases, the operator will apply too much torque to the valve stem, which can cause galling on the seating surfaces. During inspection, be on the lookout for bent valve stems or hardware. Bent valve stems Mechanical Damage Internal mechanical damage is caused by conditions such as valve chattering or vibration, process debris, and water hammer. Oftentimes, these will have audible signs that are noticeable while in service. Operations are usually best suited to identify “new” noises in the unit and will often ag these conditions for follow-up inspections. In automated valves, operators can look for erratic/jerky movement or increased opening/closing times can deem the valve inoperable, and damaged hardware can lead during operation as a potential sign of internal damage. to leaks. Typically, mechanical damage to anges isn’t a major Valve chattering and vibration can cause damage to valve gates deal unless it infringes on the gasket area. and seats. The constant contact between the gate, the guide, and Internal Corrosion, Cracking, and Mechanical Damage the seats creates an irregular wear pattern that eventually Corrosion, cracking, and mechanical damage to valve internals can vary widely depending on the service and operating causes the valve to leak. It’s usually pretty obvious, visually, when a valve has been worn in such a manner. Damage from debris is typically easy to spot internally. Debris conditions. can be anything from vessel tray parts, process scale/corrosion Corrosion products, or trash that manages to get into the system during Internal corrosion affects all metallic components, including the shutdowns or maintenance. With check valves, debris can body and trim. A good rule of thumb is that if you have corrosion prevent the valve from stopping reverse ow. Debris is usually in your piping, you likely have corrosion in your valves. A review the result of poor cleanup after maintenance or shutdowns. of corrosion rates from corrosion monitoring locations (CMLs) Sometimes debris can be pushed through the system from an should direct you to potentially problematic valves. upset upstream. For smaller valves, when an obstruction is Pitting on the trim or inside the valve body can be found with visual inspection. When localized corrosion or washout of the suspected, it’s common to perform radiography to con rm whether or not an obstruction exists. valve body is expected, it’s sometimes advisable to take Water hammer is another cause of mechanical damage. It’s a ultrasonic thickness (UT) measurements, since the corrosion very common check valve problem that is caused by a pressure may be too smooth to notice visually. For smaller diameter surge when a liquid or gas is forced to stop or change direction suddenly. Water hammer can result in both noise and vibration. fi fi fl fl fi fl fi fi fi fi Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 10 performance over time allows a preventative maintenance when ow reversal downstream causes the valve to close too strategy to be deployed as opposed to reactive maintenance. quickly resulting in pressure waves throughout the pipe. It’s Recording details like the mean time between failure (MTBF), important for operations to recognize changes to the normal the repair frequency, the repair costs, and other details allow the sounds in the area and to bring up concerns to the inspection operator to address the bad actors within their inventory. group for further investigation. Water hammer can lead to pipe, tting, and valve damage if not mitigated. Water hammer can be minimized, and even eliminated, if the system and valve types are designed properly. Risk-based inspection (RBI) and maintenance strategies are also common. With enough history and operating data, as well as a clear understanding of the valve criticality, a risk-based approach allows the operator to focus more attention on the higher risk Normal Wear and Tear / Leaking Seals Finally, there are issues related to normal wear and tear. Although it’s expected, it’s still worth discussing ways to identify valves. Age becomes a large factor, as the longer a valve remains in service without inspection and testing, the higher the risk of failure. and minimize these issues. Most wear and tear damage is There are many variables affecting valve inspection, testing, and related to a lack of lubrication. maintenance programs. An experienced valve service With actuated valves, degradation of polymeric materials such as valve seals, seats, actuator O-rings, or weather seals could cause the valve to leak internally across the seats, leak to the atmosphere, or lose ef ciency in operation. Degradation of the case weather seals will lead to water ingress and accelerated corrosion buildup in the actuator, which will also have a detrimental effect on performance. Degradation of grease and lubricants can lead to valve seizure or increased friction resulting in the valve failing to operate as intended. With non-lubricated valves, a Te on or soft metal material is typically used as the sealing element. Te on and soft-seat materials require replacement over time. Normal wear and tear organization will be able to assist in the process of determining inspection and maintenance protocols by means of reviewing client data on each tag number in line with process conditions to allow a criticality study to be prepared. On-Line Valve Inspection and Repair While on-line, there are a few ways to potentially detect some of the problems above. External visual inspection is one of the most effective methods. It can be performed by inspectors during regulatory inspections and it can be done during operator rounds, which typically take place multiple times throughout the day. is very dif cult to inspect while in service. Typically, the only The external visual inspection should look for corrosion of the sign of a leaking seal is a leak to the atmosphere. The only way valve body, bonnet, and hardware. Valve body and bonnet to properly inspect all sealing elements is to break the valve corrosion can lead to through-wall failures, but it’s easy to down and rebuild it. mitigate with a simple clean and paint. Valve hardware corrosion can also lead to gasket surface failures. Attention Inspection Practices should be paid to bonnet bolts, adjuster bolts, ange bolts, and Now that we’ve discussed the types of damage to look for, we’ll other applicable hardware. To stay ahead of the problem, review good inspection practices and what should be included in corrective maintenance should be documented and performed at a valve inspection program. the next opportunity. Inspection Intervals Valves in corrosive or erosive service can have on-line thickness Inspection intervals will normally be determined by service, operator requirements, manufacturer recommendations, and regulations which can vary by location. Many operators have extensive programs already in place to measurements or pro le radiography performed while on-line. These two methods can help identify corrosion and erosion within the valve bodies. It is a good practice to review corrosion data from the associated piping circuits. capture valve performance issues. Regular monitoring of valve fl fl fl fi fi fi Understanding Valves and Their Role in Mechanical Integrity fl fi This phenomenon typically occurs in swing type check valves Inspectioneering.com | Page 11 Fugitive emissions testing is a typical practice which can also understanding of the inspection and maintenance demands that help to identify valves with leaking seals, packing, etc. they require. This is especially true for EIVs and CCVs. We hope A common practice for determining EIV performance is to “stroke test” the valve on a set interval. This involves operations that this eBook has provided some insight into the role valves play in the overall mechanical integrity process. fully opening and fully closing the EIV to ensure that it has full References range of motion and will close if needed. Because of their 1. ASME B16.34-2020, 2021, Valves – Flanged, Threaded, and criticality, any issues noted during the stroke testing requires Welding End, The American Society of Mechanical Engineers, maintenance to be performed at the next opportunity. https://www.asme.org/codes-standards/ nd-codes- Off-Line Check Valve Inspection and Repair standards/b16-34-valves- anged-threaded-welding-end. Off-line inspection and repair of EIVs and CCVs require the valve 2. API Standard 598, 2016, Valve Inspection and Testing, Tenth to be removed from the line. This can be performed in the eld Edition, Section 1.1, American Petroleum Institute. or sent to an offsite valve repair facility. The inspection typically 3. API 570, 2016, Piping Inspection Code: In-service Inspection, looks for damage to the body or damaged internal parts. In some Rating, Repair, and Alteration of Piping Systems, Fourth Edition, cases, with erosive or corrosive services, thickness readings may American Petroleum Institute. be performed on the valve body. In addition to the visual and thickness inspection, a simple function test should be performed to identify problems with valve operation. Common ndings include a stuck gate/ apper, excessive play (wiggle room) of the hinges, lack of tension on springs/hinges, etc. Without fully disassembling the valve, there are some components of the valve that will not be fully visible, such as the edges of the hinge, the stem within the bonnet area, the top of the gate and some areas of the seats. Procedures and Documentation For consistency in the inspection and repair process, it’s important to have written procedures that are followed by inspection or operation personnel. Checklists are often used to generate trigger words and ensure a minimum expectation is met. Proper documentation of the inspections, including the details of the valves, services, etc., allow for detailed analysis of the results to be used during future inspection planning. This allows for pattern detection where, for example, a particular style or valve manufacturer is not performing well in a speci c service. Conclusion Valves are crucial to the ongoing operation of process facilities, and yet they are oftentimes overlooked from a reliability perspective. While it is true that some valves are more important to process safety than others, it’s necessary to have a holistic fi fl fi fi fi fl Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 12 Preserving Asset Integrity in Every Stage Inspections are vital to achieving asset integrity, but at TEAM, they’re just step one. We go beyond identifying potential problems to deliver the solutions you need, when you need them. That means supplementing our inspection expertise with maintenance and repair services that ensure the protection of your most critical assets. After we’ve inspected your valves, your pipelines or your tanks, trust TEAM to provide innovative maintenance and repair solutions to keep those assets up and running. To learn more about how we can contribute in every stage of asset integrity. Visit us today at TeamInc.com Understanding Valves and Their Role in Mechanical Integrity Inspectioneering.com | Page 13