What is the function of the valve test?

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Valve Testing &#; Hydrostatic, Pneumatic, Shell, Seat, Fire&#;

The realization of safe and smooth operations of industrial processes is heavily reliant on valves performing their function with precision. Thus, valve testing ensures that these valves meet design specifications for the duration of their operational life.

Generally, valve testing simulates operating conditions in a controlled environment to ensure fit for service valves. However, testing also occurs periodically after installation in line with standard practices.

In this article, we will review common valve testing types and industry standards that offer guidelines for valve testing.

There are several types of testing to which a valve could undergo. The required test depends on the application, manufacturer standards, and customer specifications. The following sections examine common tests, an overview of their procedure, and industry guidelines.

General Pressure Testing

This test involves filling a valve body with a testing fluid, which is usually water with a corrosion inhibitor. Then, technicians apply pressure over a specific period of time. The time and level of pressure varies depending on factors including the valve material, valve size, and category of pressure test. But in most cases, the pressure level is higher than the operational/working pressure of the valve. Also, the procedure for the pressure test varies depending on the type of valve in question. Generally, pressure tests aim to ascertain the integrity of the valve shell, seat, and seal against leakages due to pressure. After carrying out a test, a valve will not be accepted if the following occurs:

• There is any distortion that disrupts the valve operation, due to the test.
• Visible leaks anywhere in the valve body/bonnet assembly.
• Leakage via static seals (packing) and gasketed joints, except where permitted by design the test standard.

Common industry guidelines for pressure testing valves can be found in ASME B16.34, API 598, MSS-SP-61, API 527, and ISO . Many tests are recorded on paper wheel charts or manually, although digital options are becoming more prevalent.

Valve Test Read-out Stand, Courtesy: Axcel TS

Hydrostatic vs Pneumatic Pressure Testing

Although water (hydrostatic) is the most common test medium in pressure testing, some conditions require pneumatic pressure testing of valves. For pneumatic testing, air or an inert gas such as nitrogen are the preferred media. Generally, in industry, hydrostatic testing is ideal for high-pressure applications where the equipment is not moisture sensitive.

In situations where moisture can damage certain equipment &#; usually via corrosion &#;  or alter the chemical balance in the system, pneumatic testing is recommended. Also, industry guidelines recommend the use of pneumatic testing for cryogenic and low temperature valves. This is because it is difficult to remove all water after the test. The presence of moisture in an operating system is highly discouraged. The table below highlights more of the differences between hydrostatic and pneumatic testing in line with standards and industry practices.

Hydrostatic TestingPneumatic TestingTypically, the system is pressurized to at least 1.5 times above the maximum operating pressure for shell testing, and 1.10 times for seat testing.Because it is used mostly for low-pressure applications, the system is usually pressurized to 10% above the maximum operating value or 100 psi max.The use of pressure-relieving devices is recommended. The use of pressure-relieving devices is mandatory.Requires extensive post-test clean-up to avoid damage to components or disruption to the system when operation begins.There is little or no need for cleaning after testing.Usually records low rates of equipment failure. It sees common equipment failure.The process is straight-forward and poses less danger. Thus, semi-skilled personnel can oversee it.Because of the dangers involved, an experienced operator supervises this process. For example, nitrogen leakage can gradually displace the air in the test lab and affect personnel. Also, the effects of overpressure are more catastrophic. Hydraulic Testing vs. Pneumatic Testing

Note: Testing above 100 psi gas pressure can be very dangerous due to the expansion properties of a gas.

When pressure testing a valve, there are key components that are given a closer look for the duration of the process. Three of these include the shell, seal, and seat.

Shell Testing

The valve shell refers to the main body of the device. Moreover, its testing in the industry is driven mostly by guidelines from API 598 and ASME B16.34. Typically, the valve is mounted on a test bench and partially opened. Then, the shell is pressurized, with ASME B16.34 recommending a minimum of 1.5 times the valve pressure rating at 100 &#; (38 &#;) for hydrostatic testing. While that of pneumatic seat testing is 1.1 times the maximum allowable pressure. Pneumatic testing is done to 80-100 psi. Also, both the API and ASME standards recommend varying test duration depending on the size of the valve being tested. The table below summarizes the test duration.

Valve Size (Inches)Test Duration (Seconds)&#; 2..5 &#; 6..0 &#; 12..0 &#;300Valve Size vs. Test Duration For Shell Test

In addition, the test water temperature should range between 41 &#; (5 &#;) and 122 &#; (50 &#;). And the pressure gauge used for measurements should have calibration ranging from not less than 1.5 times the test pressure, to not more than 4 times the test pressure. For a valve shell to pass the test, there shall be no visible leakage for the duration of the test.

A valve stem seal (packing) is also monitored during the shell test. For adjustable stem seals, the occurrence of leakage during the test is NOT a cause for rejection, as long as the manufacturer can demonstrate the seal&#;s capacity to retain at least the maximum allowable pressure of the valve without any visible leakage. Adjustments to the packing are allowed to eliminate leakage. For non-adjustable stem seals, no leakage is permitted during the shell test.

Seat Testing

Typically, the valve seat test is carried out after testing the valve shell. With the same API and ASME standards as with the shell test providing guidance. The recommended pressure is 110% of the maximum allowable pressure at 100 &#; (38 &#;), and the test time varies with size in accordance with ASME B16.34.

Valve Size (Inches)Test Duration (Seconds)&#; 2..5 &#; 8..0 &#; 18..0 &#;120Valve Size vs. Test Duration For Seat Test

The test duration recommendations from API 598 are similar to these, and it also states the allowable leakage rates from the seat.

Valve Size (Inches)Hydrostatic Leakage Rate (Drops Per Minute)Pneumatic Leakage Rate (Bubbles Per Minute)&#; 2..5 &#; 6..0 &#; 12.

For valve sizes greater than 14 inches, the hydrostatic test leakage rate should not exceed two drops per minute per inch. While the pneumatic test leakage rate should be less than four bubbles per minute per inch.

Fire Testing

One of the requirements of industrial valves is having reliable fire protection. This holds particularly true for sensitive applications such as oil and gas, refinery, and petrochemical industries. Moreover, valves in these industries must guarantee a reliable and safe shut-off in case of a fire incident.

In a fire test, a valve is pressurized and subject to high-temperature flames between &#; (750 &#;) and &#; ( &#;) for a period of thirty minutes. During this period, the heat intensity and the leakages &#; both internal and external &#; are monitored and measured. Also, after extinguishing the flames and allowing the valve to cool, the technician test its pressure-retaining capacity. All through the test, the leakage levels should be within acceptable limits for the valve to pass as being &#;fire-safe&#;. Some key things to note about fire testing include:

• Leakages from the piping to valve end connections are not part of the acceptance criteria.
• Technicians measure temperature measurement from at least two places. One is 1&#; (25 mm) from the upper stem packing box on the horizontal centerline, while the other measurement point is 1&#; below the valve.

Standards such as API 607, API 6FA, ISO , BS , and BS constitute industry guidelines for fire testing. On the basis of these guidelines, several companies set up their bespoke procedure for fire-safety valves. Of all the fire testing guidelines, API 607 and API 6FA are the most widely used. API 607 provides testing criteria for valves with non-metallic seating and quarter-turn valves. API 6FA provides the testing criteria for metal seated valves.

Note: Most metal-to-metal seated Gates, Globes, and Swing checks are NOT tested to API 607 due to their inherently Fire Safe Design. (There are no soft parts to melt during a fire.)

Fugitive Emissions Testing

A fugitive emissions test aims to assess the impact of gas or vapor leakage from a valve. Although this leakage can be from anywhere along the piping system, statistics show that approximately 60% of fugitive emissions stem from valves. This data highlights the importance of this test. In addition, the impact of these emissions has significant consequences including:

• Increase in the risk of fire and explosion.
• Economic losses due to leakage of the commodity.
• Long-term health risk to the workers and communities in close proximity.
• Environmental damage.

When carrying out fugitive emission tests, the most common test gases are helium and methane. The valve is pressurized with the test gas at varying temperatures. Then technicians monitor for leakages via the sniffing or vacuum method. International standards such as API 622, API 624, API 644, ISO -1, and ISO -2 all provide guidance on how to carry out this valve test. However, most organizations develop their specifications to ensure application suitability.

Cryogenic Testing

Cryogenic testing of valves is done for those operating at low temperatures or in cryogenic service. The test procedure involves placing the valve within an insulated tank, with liquid nitrogen at temperatures of down to -320 &#; (-196 &#;).

Then, helium pressurizes the valve to the operating pressure specified for its class. During the test, technicians closely monitor the temperature inside the valve and leakages. In the end, the valve is depressurized and warmed up until it attains ambient temperature. Thereafter, a detailed report summarizes the performance of the valve and whether leakages were within acceptable limits. There are several international standards that provide guidelines for cryogenic valve testing including ISO -1, ISO -2, EN , and BS .

In addition to the standards mentioned in the previous section, there are a host of standards that provide recommendations for different valve types and test procedures. The table below provides a list of these standards and the areas of testing they cover, for quick referencing.

Applicable StandardValve Type and Test Procedure API 598Valve inspection and test. Testing of cast iron gate, plug, check, and globe valves. Also, testing of steel gate, globe, check, ball, and butterfly valves. Cryogenic valves.API 527 and ASME PTC 25Pressure relief valves.API 6DTesting of pipeline valves.ASME B16.34Pressure seal valves and steal valves larger than NPS 24 inches. Flanged, threaded, and welded end of valves.MSS SP-80Bronze gate, globe, angle, and check valves.MSS SP-70, MSS SP-71, MSS SP-78 and MSS SP-85Testing of cast iron valves, flanged, and threaded ends.ISA S-75, ISO , and MSS SP61Hydrostatic testing of valves.FCI 70-2, ISA S-75Control valve testing.Standards for Valve Testing

In this post, we will explore the importance of control valve testing and inspection in ensuring optimal performance in industrial process control systems. By providing a comprehensive overview of the preparation, external and internal inspection, valve testing, and documentation involved in control valve maintenance, we aim to demonstrate the level of professionalism and expertise that valve distributors can offer to their customers. Our goal is to educate and inform industrial valve distributors on the best practices for maintaining control valves and ensuring reliable process control.

Our goal is to educate and inform industrial valve distributors on the best practices for maintaining control valves and ensuring reliable process control. Not only for butterfly valves, steel gate valves, cast iron plug valves, plug valves, and control valves, but also for cast iron plug valves, cast iron gate valves, angle valves, cast iron gate valves, pressure relief valves, cast iron check valves, resilient seated valves, steel valves, alloy valves, and ball valves.

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This post will provide valuable information and insights for those looking to enhance their understanding of control valve testing and inspection and its role in maximizing performance and reliability.

The importance of control valve testing and inspection

Control valves are critical components of any process control system, as they regulate the flow of fluids, gases, and other materials. Their performance is essential for maintaining efficient and safe operation of industrial processes, and any malfunction or failure can lead to production downtime, safety hazards, and increased costs.

Control Valve Inspection

To ensure optimal control valve performance, regular testing and inspection are necessary. The importance of control valve testing and inspection can be summarized as follows:

1. Safety: Control valves play a critical role in maintaining safety in process industries. Any malfunction in a control valve can result in a safety hazard, causing damage to equipment and endangering personnel. Regular testing and inspection can help identify potential safety issues and prevent accidents.
2. Performance: The performance of control valves can be affected by various factors such as wear and tear, corrosion, and the build-up of debris. Regular testing and inspection can detect any issues that may impact the performance of control valves, ensuring that they operate efficiently and as designed.
3. Efficiency: Control valves are essential for maintaining efficient operations in process industries. Any inefficiency can lead to increased energy consumption and production downtime. Regular testing and inspection can identify any issues that may impact the efficiency of control valves, allowing for timely maintenance and repairs.
4. Compliance: Process industries are subject to various regulations and standards, and control valves must meet the required standards. Regular testing and inspection can ensure that control valves comply with regulatory requirements and industry standards.
5. Cost savings: Regular testing and inspection can help identify potential issues with control valves early, allowing for timely maintenance and repairs. This can prevent costly production downtime, reduce maintenance costs, and extend the lifespan of control valves.

Control Valve Testing Standards

It&#;s important to choose control valves that meet the appropriate standards for your specific application to ensure optimal performance and reliability. Additionally, regular testing and inspection can help identify potential problems before they cause serious damage to the system.

Here are some of the most commonly used testing standards for control valves:

1. API 598: This is an American Petroleum Institute standard that covers valve inspection and testing.
2. ISO : This is an international standard that covers the testing of control valves.
3. MSS SP-61: This is a standard developed by the Manufacturer&#;s Standardization Society (MSS) that covers the testing of control valves.
4. NAMUR NE 107: This is a standard developed by the North American Instrument Manufacturers Users&#; Roundtable (NAMUR) that covers the interface between control valves and process control systems.

Control Valve Design Standards

The control valve design standards provide guidelines for the materials of construction, dimensions, connections, and performance requirements for control valves.

Here are some of the most commonly used design standards for control valves:

1. ISO Standard
   • This is an international standard that defines the dimensions and connection sizes for control valves.
   • It provides guidelines for the design of control valves, including the dimensions and connections of the valve body, bonnet, stem, and actuator.
2. API 6D Standard
   • This is an American Petroleum Institute standard that covers the design and manufacture of pipeline and pipeline valve components.
   • It provides guidelines for the design and manufacture of control valves, including the materials of construction, valve body and bonnet design, and actuator design.
3. ASME B16.34 Standard
   • This is an American Society of Mechanical Engineers standard that covers valve pressure-temperature ratings.
   • It provides guidelines for the design of control valves, including the pressure-temperature ratings, materials of construction, and valve body and bonnet design.
4. MSS SP-67 Standard
   • This is a standard developed by the Manufacturer&#;s Standardization Society (MSS) that covers the design of control valves.
   • It provides guidelines for the design of control valves, including the materials of construction, valve body and bonnet design, and actuator design.
5. NAMUR NE 107 Standard
   • This is a standard developed by the North American Instrument Manufacturers Users&#; Roundtable (NAMUR) that covers the interface between control valves and process control systems.
   • It provides guidelines for the design of control valves, including the communication between the valve and process control system, response time, and accuracy.

industrial valve manufacturing procedure

It&#;s important to follow a comprehensive testing procedure to ensure that control valves are functioning properly and provide accurate control of the process. By regularly testing control valves, you can identify potential problems before they cause serious damage to the system.

Here is a comprehensive guide for the control valve test procedure (you can also click here to download the pdf version):

I. Preparation:

• Gather all necessary tools and equipment, such as a multimeter, torque wrench, pressure gauge, and valve position indicator.

• Familiarity with the valve specifications, such as the pressure range, flow rate, and materials of each part.

• Review safety procedures and make sure that the system is properly isolated and depressurized before starting the testing.

Test Thickness For Casting Valve Body

II. External Inspection

• Check external inspection, including valve body, bonnet, stem, and actuator.

• Check the signs of damage or wear to look for during the inspection.

ultrasonic nondestructive testing

III. Internal Inspection

• Check the steps involved in internal inspection, including removal of the bonnet and inspection of internal components.

• Check the signs of damage or wear to look for during the inspection.

hydrostatic test&#;

• Close the valve and apply pressure to the system.

• Check for leaks in the body and bonnet using a pressure gauge or leak detection equipment.

• If a leak is detected, repair or replace the valve.

hydraulic test

V. Operational Characteristics Test

• Open the valve and measure the pressure drop across the valve.

• Measure the flow rate through the valve.

• Record the response time of the valve to a control signal.

• Compare the results to the specifications and make any necessary adjustments.

VI. Control Signal Test

• Apply a control signal to the valve and verify that it is functioning properly.

• Check the valve&#;s response to the control signal and make sure that the actuator is properly positioning the valve.

• If the control signal is not functioning properly, repair or replace the valve.

VII. Shutoff Capability Test

• Slowly close the valve and measure the pressure drop across the valve.

• Compare the results to the specifications and make sure that the valve is able to shut off completely.

VIII. Documentation

• Record the results of the testing in a logbook.
• Document any repairs or replacements that were made during the testing.
• Make note of any issues that need to be addressed in the future.

What is the difference between API 598 and ISO ?

What does API 598 mean?

API 598 is a standard developed by the American Petroleum Institute (API) that outlines the guidelines for the inspection and testing of valves. The purpose of this standard is to ensure that valves are functioning correctly and provide accurate control of the process. The standard covers various aspects of valve inspection and testing, including visual inspection, pressure testing, and functional testing.

• Visual Inspection: The first step of the valve inspection process is a visual inspection. This includes a thorough examination of the valve body, bonnet, stem, and actuator to identify any signs of damage, wear, or corrosion.

visual test (1)

• Pressure Testing: Pressure testing is an important aspect of valve testing to verify the valve&#;s ability to withstand the pressure required for its intended use. The valve is subjected to air or water pressure at a level of at least 1.5 times the maximum operating pressure of the valve. The test is performed to detect any leaks in the valve body or bonnet.

hydraulic test2

• Functional Testing: The functional testing aspect of API 598 is performed to verify the valve&#;s proper operation and control. This includes evaluating the valve&#;s response time, control signal, and shutoff capability. The goal of this test is to ensure that the valve is functioning correctly and providing accurate control of the process.

function test

It is crucial to follow the guidelines set forth in API 598 to ensure that valves are functioning correctly and providing accurate control of the process. The results of the inspection and testing should be documented and kept on file for future reference. By following the standard, valve manufacturers, distributors, and users can be confident that the valves they use meet the highest quality standards.

What does ISO Valve Test Standard mean?

ISO is an international standard that provides guidelines for the testing of control valves. The purpose of this standard is to ensure that control valves are functioning correctly and provide accurate control of the process. The standard covers various aspects of control valve testing, including performance testing, functional testing, and high-pressure testing.

• Performance Testing: Performance testing is an important aspect of control valve testing to verify the valve&#;s ability to perform its intended function. The test is performed to evaluate the valve&#;s flow characteristics, such as flow rate, pressure drop, and accuracy of control. The results of the performance testing are compared to the valve&#;s specifications to verify its compliance.

• Functional Testing: The functional testing aspect of ISO is performed to verify the valve&#;s proper operation and control. This includes evaluating the valve&#;s response time, control signal, and shutoff capability. The goal of this test is to ensure that the valve is functioning correctly and providing accurate control of the process.

• High-Pressure Testing: High-pressure testing is performed to verify the valve&#;s ability to withstand the pressure required for its intended use. The valve is subjected to a specified high pressure and held for a specified time to verify its ability to withstand the pressure without leaking.

Valves are tested to ensure that they are functioning properly and providing accurate control of the process.

The testing process typically includes a combination of visual inspection, pressure testing, and functional testing. During the visual inspection, the valve is examined for signs of damage, wear, or corrosion.

Pressure testing is performed to verify the valve&#;s ability to withstand the pressure required for its intended use.

Functional testing is performed to verify the valve&#;s proper operation and control, including evaluating the valve&#;s response time, control signal, and shutoff capability.

The results of the testing are documented and used to identify any necessary repairs or replacements to ensure optimal valve performance.

What are the API, ISO, MSS Codes and Standards for Valve Inspection and Testing

There are several codes and standards that outline the guidelines for valve inspection and testing, including:

1. American Petroleum Institute (API) Standards: API standards, such as API 598 for control valves and API 6D for pipeline valves, provide guidelines for the inspection and testing of valves. These standards cover aspects such as visual inspection, pressure testing, and functional testing.

2. International Organization for Standardization (ISO) Standards: ISO standards, such as ISO for control valves, provide international guidelines for the testing of valves. These standards cover aspects such as performance testing, functional testing, and high-pressure testing.

3. Manufacturers Standardization Society (MSS) Standards: MSS standards, such as MSS SP80 for bronze gate, globe, angle, and check valves, provide guidelines for the testing and inspection of specific types of valves. These standards cover aspects such as visual inspection, pressure testing, and functional testing.

Valve inspection is an important aspect of ensuring the safe and reliable operation of industrial valves. A thorough inspection of the valve can identify potential issues before they cause serious damage to the system and help to ensure the valve is functioning properly. This checklist provides a comprehensive overview of the items that should be considered when performing a valve inspection.

1. Physical Inspection: A visual inspection of the valve should be performed to check for any physical damage, corrosion, or other issues. The valve body, stem, and other components should be inspected for any signs of wear or damage.

2. Testing: The valve should be tested to verify its proper operation and control. This may include pressure testing, functional testing, and other types of tests as specified by the relevant standards.

3. Calibration: The valve should be calibrated to ensure that it is providing accurate control of the process. This may include adjusting the valve&#;s settings or using specialized equipment to calibrate the valve&#;s operation.

4. Documentation: The results of the valve inspection, testing, and calibration should be documented and kept on file for future reference. This documentation can be used to track the valve&#;s performance over time and to identify any potential issues that need to be addressed.

5. Maintenance: Any maintenance or repair work that is required as a result of the valve inspection should be performed in a timely manner. This may include replacing worn or damaged components, adjusting the valve&#;s settings, or performing other types of maintenance as needed.

1. Preparation:
   • TPI will review the valve specifications and requirements to ensure that the inspection is performed in accordance with the customer&#;s needs.
   • TPI will gather all necessary tools and equipment, such as a multimeter, torque wrench, pressure gauge, and valve position indicator.
   • TPI will review the safety procedures and make sure that the system is properly isolated and depressurized before starting the inspection.
2. Visual Inspection:
   • TPI will perform a visual inspection of the valve to identify any signs of damage, wear, or corrosion.
   • TPI will include a review of the valve body, bonnet, stem, and actuator.
   • TPI will document any issues identified during the visual inspection.
3. Pressure Testing:
   • TPI will perform a pressure test to verify the valve&#;s ability to withstand the pressure required for its intended use.
   • The valve will be subjected to air or water pressure at a level of at least 1.5 times the maximum operating pressure of the valve.
   • TPI will check for leaks in the valve body and bonnet using a pressure gauge or leak detection equipment.
   • TPI will document the results of the pressure test.
4. Functional Testing:
   • TPI will perform a functional test to verify the valve&#;s proper operation and control.
   • The test will include a review of the valve&#;s response time, control signal, and shutoff capability.
   • TPI will compare the results of the functional test to the valve&#;s specifications.
   • TPI will document the results of the functional test.
5. Documentation:
   • TPI will provide a detailed report of the inspection results, including any issues identified during the inspection.
   • The report will include recommendations for any repairs or replacements that may be necessary to bring the valve into compliance with the specifications.
   • TPI will provide a certificate of inspection, indicating that the valve has been inspected in accordance with the customer&#;s requirements.

This is a comprehensive guide to Third Party Inspection for valves. By having a third-party inspection company perform an inspection, valve brands, distributors, agents, EPCs, and end-users can be confident that the valves they purchase meet the highest quality standards.

china control valves factory

In conclusion, professional control valve testing and inspection are essential for maintaining optimal performance and safety in process industries. Regular testing and inspection can help identify potential issues early, prevent accidents, improve efficiency, and ensure compliance with regulatory requirements and industry standards. By investing in professional testing and inspection, companies can reduce maintenance costs, extend the lifespan of control valves, and minimize the risk of production downtime. Overall, control valve testing and inspection are critical components of any process control system, and companies should prioritize these activities to ensure the long-term success of their operations. Should you have any questions, welcome to contact THINKTANK for a free consultation.

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