Inspection of valves: key aspects of valve testing
Julie (jonloovalve)
Valve Expert| Valve Manufacturer| We supply the best solution for pipeline systems worldwide
Various kinds of valves, including check valves, are used in industrial facilities to regulate fluid flow, which is essential for the continuation of multiple manufacturing processes. Industrial valves are designed and manufactured in accordance with a variety of codes and standards to guarantee their longevity, effectiveness, and maintainability as well as to prevent valve failure.
Key Points
Occasional pressure relief assessments are necessary in manufacturing and industrial processes because these valves experience repetitive stress and strain from changes in temperature and pressure. The physical and chemical characteristics of service fluid, or occasionally even testing fluid, can cause valves to corrode as well. The corrosiveness of the fluid and external stress make the valves more prone to failure. Failures of valves, particularly check valves, raise safety concerns and result in unplanned process outages. To find early indications of wear and failure, which could lead to decreased efficiency, leaks, and fugitive emissions, manufacturing facilities employ a variety of valve inspection standards. Industrial valves require these examinations both during initial installation and over the course of their lifetime. Valve inspections are performed at pre-arranged intervals as part of standard maintenance procedures at the majority of plants. Maintenance supervisors can identify and replace valves with high leakage rates to increase their efficiency and, consequently, the overall effectiveness of the production processes. Regular valve inspections are an essential part of the maintenance process and adhere to industry-approved standards, such as API 598 and ISO 5208. Which valve inspection locations in a manufacturing facility are the most important?
1) Valve body
The valve body holds internal components and serves as the major pressure boundary, allowing the most fluid pressure to pass through. As fluid flow and velocity change at the valve sections, the resulting pressure acts on the valve body. Valve bodies are comprised of materials with special physical qualities that prevent them from early damage or rupture caused by fluid pressure. However, with time, they are prone to valve failure. Valve bodies also resist corrosion due to the chemical composition and viscosity of the service fluid. The shell, which is frequently subjected to a pressure test, expands and contracts repeatedly due to temperature variations during the procedure. Although the contraction or expansion is little, its long-term effects are significant. Valve body inspection offers important information about the valve's robustness and possible longevity. Cracks and fissures on the valve surface that are visible to the unaided eye are likely to result from fatigue brought on by fluid temperature and pressure. Advanced detection tools are necessary for other surface flaws. A chemical attack from the service fluid or a slow loss of protective coating could cause the valve's surface to corrode noticeably. Additionally, technicians can use non-destructive testing methods to confirm the valve's wall thicknesses and look for minute surface imperfections and cracks. Ultrasonic testing is the most widely used technique for detecting defects; eddy current and radiographic testing are additional inspection techniques.
2) Flanges, Gaskets and Fasteners
An essential component of testing valves, valve flanges join neighboring pipelines. They are specially designed to fit specific fluid applications. Detachable connections, such as threaded or bolted joints, and permanent techniques, like as welding, are used to unite the flanges to pipes. The torque of the fasteners used to join pipes and valves is precisely calibrated. It makes sure valves are securely fastened and avoids valve misalignment, which could obstruct flow or induce vibrations and interfere with certain pipe sections' ability to operate smoothly. Prioritizing flanges, gaskets, and fasteners is essential while performing a pressure test during valve inspection in a manufacturing facility. Leaks and fugitive emissions may result from faulty flanges, loose connections, or worn-out gaskets. Changes in fluid flow conditions can cause cracks to form in flanges. Among the techniques used to check these parts are:
Replacing worn-out gaskets right away is essential. Because they raise safety concerns, damaged gaskets are inappropriate for high-pressure fluid applications. Technicians should check the flange thickness, fastener hole sizes, end-to-end flange dimensions, and surface finish while replacing damaged valves.
3) Valve Discs, Seats and Seals
Fast-moving service fluids come into close touch with internal valve parts such as disks, shafts, and seats. Internal valve parts are designed to be durable and compatible with various media. Even when strict production standards are followed, valves lose their sealing effectiveness due to wear, erosion, and corrosion of seats, seals, and discs, including wire drawing. It may be challenging to identify internal valve damage; however, discs, seals, and seats can be inspected during a planned process or plant-wide stoppage. Condition-monitoring devices are used in automated operations to keep an eye on valve functioning. When underlying faults are revealed by changes in valve performance, production teams can arrange for a short shutdown so that maintenance technicians can undertake more examination and address the issue. At least once a year, internal valve components need to undergo thorough examinations. To make sure the seats and seals are in optimal operating condition, severe service valves and gas ball valves should undergo inspections more frequently. There are changeable and detachable mechanical parts in the valve trim. Any parts that show wear and tear need to be replaced right away. Verifying the disc connection points, return springs, and flow control mechanism thickness (ball, disc, or gate) is the best course of action. Non-metallic seals brittlely deteriorate with age, and some may even start to decay. The design of the valves affects how simple it is to replace these seals. Three-piece ball valves require less time and effort to change their seals than two-piece ones. Two detachable end caps and a middle segment make up 3-piece ball valves; removing the end caps makes it simple to reach the seals. When performing maintenance on a two-piece ball valve, technicians frequently have to take it out of the line, but with a three-piece design, the end caps can stay in place. The seals in the middle body part can be accessed in this manner by rotating or removing the valve body.
4) Valve Stem and Actuation Mechanisms
The chemical action of fluids also causes corrosion on the stem, which joins the actuator to internal valve components. Additionally, as it moves to open or close the fluid flow path, the packing and stem rub against one another, causing surface wear and tear. Actuator movements also result in compressive and torsional strains on the stem. Therefore, if valve stems are not routinely inspected, they may fail. Regular inspections are necessary for actuators, which supply the force needed to open and close valves. It's crucial to remember that an actuator that is not mounted correctly to a valve will cause the valve stem to deteriorate exponentially more quickly than one that is. Therefore, before installing your products, be sure they are being put together and tested by a reliable provider. The following are inspection points for valve stems:
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The type of actuator being utilized determines the level of examination for actuation mechanisms. Verify the insulation of electrical terminals, connectors, cables, and casings when examining electric actuators. Verify the external power supply's power ratings, motor cleanliness, and the maintenance of moving elements like bearings. Examine filters, fluid supply systems, and cylinders when working with hydraulic and pneumatic actuators.
Thorough Valve Testing to Guarantee System Integrity
In production settings, routine valve testing is crucial, with an emphasis on various types such as plug, control, and check valves. This crucial maintenance task entails a number of tests, each designed to evaluate particular valve conditions and overall performance.
Key Testing Procedures
The ability of valves to tolerate their operating pressures is ascertained by valve pressure testing. Tests of the valve seat make that the disc-to-seat interface is sufficiently tight to either stop valve leaks or permit a reasonable rate of leakage. Another crucial step is the valve shell test, which evaluates the valve's overall strength and integrity under predetermined pressure settings.
Specialized Valve Type Testing
Different valve types, including check valves, ball and globe valves, and others, call for particular, customized testing procedures. In order to operate in fluid systems, globe valves are tested for their capacity to regulate fluid flows. Check valve tests will guarantee that backflow is prevented, increasing the piping system's safety.
Advanced Safety Procedures and Valve Inspection Methods
Advanced valve inspection procedures, which take into consideration the complexities of valve operation and structure, are crucial for preserving the safety and functionality of industrial fluid systems.
How to Avoid Valve Failures
The prevention of valve failures is greatly aided by thorough inspection. This involves closely examining the state of the valve shell and the valve seat surfaces. Frequent inspections, especially of vital parts like valve discs and seats, aid in spotting wear or damage early on, such as corrosion or cracks.
Conclusion
In a manufacturing facility, normal maintenance tasks include valve inspection. To guarantee proper and timely maintenance of process valves, thorough asset management plans must be developed. In addition to extending valve durability and enabling continuous process continuity, timely valve inspection enables businesses to find and address underlying flaws. Additionally, it ensures the highest level of operating safety. Depending on the quantity of valves, the ease of access to valve chambers, and the complexity of the inspection jobs, valve inspection combines automated and manual inspection methods. Do you need help choosing the right valve for your manufacturing application?