Valve Test Benches: Something You Need to Know When Choosing It

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Valves are ubiquitous components in various industries, playing a crucial role in controlling the flow of fluids and gases. From regulating pressure in pipelines to managing water flow in irrigation systems, valve functionality directly impacts safety, efficiency, and overall system performance. To guarantee reliable operation, valves undergo rigorous testing procedures throughout their lifecycle, from manufacturing to maintenance. Valve test benches are specialized pieces of equipment designed to evaluate a valve’s performance against specific criteria. This article delves into the world of valve test benches, exploring different types, their applications, and factors to consider when choosing the right one.

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What is Valve Testing and How Important is it?

Valve testing is a crucial process that goes beyond simply checking if a valve opens and closes. It’s a comprehensive evaluation designed to guarantee a valve performs its designated function reliably and safely throughout its lifespan. These tests can be broadly categorized into three main areas:

• Functional Testing: This test focuses on the core mechanics of the valve. It measures the speed at which the valve opens and closes (opening/closing time). It also evaluates the distance the valve’s internal component travels during operation (stroke length). Additionally, functional testing assesses how well the valve regulates flow at various positions. This ensures the valve delivers the precise amount of fluid or gas required at different settings.
• Leakage Testing: Even the smallest amount of leakage from a closed valve can have serious consequences. Leakage testing meticulously measures the amount of fluid or gas that manages to bypass a closed valve. This identifies any potential weaknesses in the sealing mechanism, preventing compromised system integrity and safety hazards.
• Strength Testing: This test pushes the valve to its limits to ensure it can withstand the pressures it’s designed for. It involves applying both internal and external pressure loads to the valve body and monitoring for any signs of structural failure. Strength testing guarantees the valve maintains its structural integrity under real-world operating conditions, preventing potential ruptures or breakdowns.

The Importance  of Regular Valve Testing

By conducting these comprehensive tests regularly, valve testing offers a multitude of advantages:

• Enhanced Safety: Early detection of potential malfunctions or weaknesses within a valve helps prevent catastrophic failures. This proactive approach minimizes the risk of accidents and environmental damage that could occur due to valve malfunction.
• Improved Performance: Valve testing ensures valves operate precisely within the specified parameters they were designed for. This optimized performance leads to efficient system operation and minimizes energy consumption. Properly functioning valves contribute to smoother and more efficient overall system operation.
• Cost Savings:  Identifying valve issues early through testing allows for preventative maintenance. This proactive approach can save significant costs in the long run by preventing major repairs or unplanned system downtime. Early detection and correction of minor issues prevent them from escalating into costly problems later.
• Regulatory Compliance: Many industries have strict regulations mandating regular valve testing. These regulations aim to ensure adherence to safety and environmental standards. Regular testing helps companies comply with these regulations and avoid potential fines or penalties.

Types of Valve Test Benches

Choosing the appropriate valve test bench hinges on two key factors: the specific type and size of the valve being tested, and the desired test parameters. Here’s a detailed breakdown of three common categories of valve test benches:

1. General Valve Test Benches: Versatility for Everyday Testing Needs

General valve test benches are designed to accommodate a broad range of valve types and sizes, offering flexibility for routine testing procedures. These benches typically encompass the following key components:

• Clamping System: This secure mechanism holds the valve firmly in place during testing, ensuring a stable and leak-free environment for accurate measurements. The clamping system design varies depending on the valve size and connection type (flanged, threaded, etc.).
• Pressure Source: This component simulates the operating pressures the valve will encounter in its real-world application. General valve test benches can utilize various pressure sources, such as compressed air or gas cylinders, depending on the required pressure range.
• Sensors and Data Acquisition Modules: These electronic components play a crucial role in collecting and recording test data. Sensors measure pressure, flow rate, temperature, and other relevant parameters during testing. The data acquisition module then translates these sensor readings into usable data for analysis.

General valve test benches are suitable for conducting a variety of tests, including:

• Functional Testing: Verifying the valve opens, closes, and regulates flow according to specifications. This can involve measuring opening/closing speed, stroke length, and flow characteristics at different valve positions.
• Leakage Testing: Identifying and quantifying any leakage that occurs when the valve is closed. This helps ensure system integrity and prevent potential safety hazards or product contamination.
• Pressure Resistance Testing: Assessing the valve’s ability to withstand specified pressure loads without structural failure. This is crucial for valves used in high-pressure systems.

2. Hydraulic Valve Test Benches: Power and Precision for Demanding Applications

Hydraulic valve test benches utilize hydraulic systems to generate significantly higher pressure and flow rates compared to general benches. This added power makes them ideal for testing:

• High-Pressure Valves: These valves are commonly employed in demanding industrial settings like oil and gas pipelines, power plants, and heavy machinery. Hydraulic test benches can simulate the extreme pressures these valves encounter in real-world operation.
• Large and Heavy-Duty Valves: The robust clamping systems and high force capabilities of hydraulic benches make them suitable for testing large and heavy valves that may not be compatible with general benches.

Beyond the increased power, hydraulic systems offer several advantages:

• Precise Pressure Control: The inherent controllability of hydraulic systems allows for highly accurate pressure application during testing, ensuring reliable and repeatable results.
• Structural Integrity Testing: The high force generated by hydraulic systems enables testing the structural integrity of valves under extreme pressure loads. This is crucial for ensuring the valve can withstand potential pressure surges or malfunctions in the system.

3. Safety Valve Test Benches: Tailored for Critical Pressure Relief Components

Safety valve test benches are specialized tools designed specifically for testing pressure relief valves. These valves play a vital role in protecting pressure vessels, pipelines, and other equipment from catastrophic failure by automatically releasing excess pressure when it exceeds a predetermined threshold. Safety valve test benches simulate scenarios where pressure buildup occurs, and they measure the following critical parameters:

• Opening Pressure: This test verifies the pressure level at which the safety valve activates and begins to release pressure.
• Reseating Pressure: Once the pressure has dropped below the setpoint, the safety valve should automatically reseal to prevent unnecessary pressure loss. This test measures the pressure at which the valve reseals.
• Flow Capacity: This test assesses the valve’s ability to release excess pressure effectively. The flow capacity determines the maximum pressure relief capability of the safety valve.

By meticulously testing these parameters, safety valve test benches ensure these crucial components function correctly and can prevent catastrophic accidents in high-pressure systems.

Tips for Choosing the Right Valve Test Bench

Selecting the most suitable valve test bench requires a comprehensive analysis of several key factors to ensure accurate and safe testing procedures. Here’s a detailed breakdown of the crucial considerations when choosing a valve test bench:

1. Valve Type and Size Compatibility

• Valve Type Compatibility: The test bench must be designed to accommodate the specific type of valve being tested. This includes considerations like gate valves, ball valves, butterfly valves, or check valves. Each valve type may have unique connection methods, actuation mechanisms, and pressure ratings that require compatible features in the test bench.
• Size Constraints: The test bench’s clamping system and overall dimensions must be able to securely hold the valve throughout testing. Flange sizes, body diameters, and overall weight of the valve need to be compatible with the clamping system’s capabilities.
• Pressure Rating Match: The test bench’s maximum pressure generation capacity should exceed the valve’s rated pressure. This ensures the bench can simulate the full range of operating pressures the valve may encounter and accurately assess its performance limits.
• Flow Rate Capacity Alignment: The test bench’s flow rate capabilities should be sufficient to match the expected flow rates the valve will handle in real-world applications. This allows for testing the valve’s ability to regulate flow effectively under various operating conditions.

2. Pressure and Flow Requirements

• Pressure Simulation: The test bench needs to generate pressure levels that match or exceed the valve’s expected operating pressures. This ensures the test accurately reflects the stress the valve will experience during normal use. Insufficient pressure testing could lead to overlooking potential weaknesses that might only manifest under higher pressure loads.
• Flow Rate Matching: The test bench’s flow rate capabilities should be able to replicate the flow rates the valve will regulate in its actual application. This allows for evaluation of the valve’s flow control characteristics and ensures it can handle the intended flow volume without compromising pressure integrity.

3. Level of Automation and Data Acquisition

• Automation Level: The desired level of automation in the testing process needs to be considered. Some benches offer fully automated testing sequences, where the user simply selects the test parameters, and the bench performs the entire test autonomously. Other benches require manual operation of each test step. The choice between automation and manual operation depends on factors like test complexity, frequency of testing, and desired level of user control.
• Data Acquisition Capabilities: The test bench’s ability to collect and record data during testing is a crucial factor. Data acquisition systems typically record pressure, flow rate, temperature, and other relevant parameters throughout the test. This data can then be analyzed to identify potential issues, track valve performance over time, and generate reports for quality control purposes.

4. Safety Considerations

• Pressure Relief Systems: For testing high-pressure valves or safety valves, the test bench should be equipped with robust pressure relief systems. These systems automatically release excess pressure in case of malfunctions or equipment failures, safeguarding the operator and surrounding environment.
• Emergency Shut-Off Mechanisms: The test bench should also incorporate emergency shut-off mechanisms that allow the operator to immediately stop the test in case of unforeseen circumstances. This rapid response capability helps minimize risks associated with equipment failure or unexpected pressure surges.
• Material Compatibility: The test bench’s materials and construction should be compatible with the type of fluid or gas the valve is designed to handle. This ensures the test environment is safe and avoids potential chemical reactions or material degradation.

By carefully considering these factors, industries can select the most suitable valve test bench for their specific needs. Choosing the right equipment allows for accurate and reliable valve testing, ultimately contributing to the safe, efficient, and reliable operation of critical valve systems across various industries.

Conclusion

Valve test benches play a vital role in ensuring the reliable performance of valves across various industries. By simulating real-world operating conditions and evaluating critical parameters, these specialized pieces of equipment help guarantee the safety, efficiency, and longevity of valve systems. As technology advancements continue, valve test benches are likely to become even more sophisticated, incorporating features like advanced data analysis and remote monitoring capabilities. This will allow for more efficient and comprehensive valve testing, ultimately contributing to the development of even more reliable and robust valve systems for critical applications.

Overview of gate valves：

Gate valves are one of the most common types of valves in the isolation category. They can be found in every refinery, chemical plant, power station, and industrial production facility, and can be manufactured in sizes ranging from DN6 to . gate valves are chosen for the primary purpose of fluid shutoff. It is for this reason that gate valves are often referred to as "cut-off" or "blocking" valves.

Gate valves are generally used in the fully open or fully closed operation. When fully open, the pressure drop through the gate valve is very small; when fully closed, the pressure sealing performance is very good. Due to the fit of the gate and seat ring, there is almost no leakage when the gate valve is closed. However, in the case of very low back pressure (generally not less than 0.34 bar, 1 bar = 105 Pa), some leakage may occur.

Another advantage of gate valves is that they usually open and close very slowly, a feature that prevents fluid water hammer effects from damaging the piping system.

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The main limitation of gate valves is that they cannot be used in throttling conditions. When gate valves are used in dry throttling service, the fluid often has a high flow rate near the seat, which can cause erosion. Also in the partially open state, the gate will swing under the impact of the medium, which will cause damage to the seal. Usually, gate valves are more prone to seat and gate seal surface wear than globe valves, and the repair of such wear is difficult to be accomplished by means of grinding and polishing.

Because the structural characteristics of the gate valve are very suitable for large-scale devices, its application range is expanding, and to high temperature and high-pressure development. The maximum diameter of the gate valve has reached DN, in the ammonia plant has been a large number of high-pressure gate valve PN320, for oil and gas drilling wellhead gate valve working pressure up to 138MPa. manufacturing a high-temperature and high-pressure gate valve is the key to solving the problem of wedging the gate plate due to temperature changes, as well as ensuring its reliable sealing performance. To this end, the gate and seat sealing structure should be studied and improved. Resilient seats and resilient floating seats have begun to be applied to enable the gate valve to achieve inlet sealing, outlet sealing, or double sealing of import and export.

Composition of gate valve：

Gate valve, also called the gate valve, mainly consists of the valve body, bonnet, gate, stem, seat and seal packing, and other parts.

The gate valve is the opening and closing member (gate), driven by the valve stem, along the seat (sealing surface) to do a linear movement of the valve. Generally, the gate valve can not be used to regulate the flow, only a cut-off device can be used, either completely open or completely closed. Among the various types of valves, the gate valve is the most widely used one. It is suitable for both normal temperature and pressure conditions, as well as high and low temperature and high and low-pressure conditions, and can be applied to a variety of different media through the selection of different materials.

The advantages of the gate valve:

①Small fluid resistance. Gate valve body's internal media channel is straight, the media flow through the gate valve does not change its flow direction, so the fluid resistance is small.

② structure length (the distance between the two ends connected to the pipe) is small. As the gate is disc-shaped, is placed vertically in the body of the valve, and the globe valve flap (also disc-shaped) is placed parallel to the body of the valve, so compared with the globe valve, its structure length is smaller. Such as the PN16, and DN150 globe valve, the structure length of 480mm, while the same parameters of the gate valve structure length are only 350mm.

③ opening and closing less effort. When opening and closing the gate movement direction is perpendicular to the direction of media flow, while the shut-off valve flap is usually closed in the direction of movement and seated in the opposite direction of media flow, and therefore must overcome the force of the medium. Therefore, compared with the shut-off valve, the opening, and closing of the exposition valve is more labor-saving.

④ Media flow direction is not restricted. The medium can flow from both sides of the gate valve in any direction through the gate valve and can achieve the purpose of connection or cut off. Easy to install, suitable for the flow direction of the medium may change in the pipeline.

⑤ When fully open, the sealing surface is subject to minimal erosion of the working medium.

⑥The structure of the body is relatively simple, and the manufacturing process is good.

Disadvantages of the gate valve:

①Sealing surface is easy to produce abrasions. When opening and closing the gate and the valve seat in contact with the relative sliding between the two sealing surfaces, under the action of the medium thrust easy to produce abrasion, thus destroying the sealing performance, and affecting the service life.

② more parts, the structure is more complex, manufacturing and maintenance are more difficult, compared with the cost of the globe valve are higher.

③ shape size and opening height are larger, and the space required for installation is larger.

④Generally gate valves have two sealing pairs, which adds some difficulties to processing, grinding, and maintenance.

⑤ The operating stroke is large, and the opening and closing time is long. Since the gate needs to be completely lifted to the top of the seat channel when opening, and all the gate needs to fall down to block the seat channel when closing, so the opening and closing stroke of the gate is large, and the opening and closing time is long.

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