Cryogenic valves are designed to operate effectively at extremely cold temperatures, making them indispensable in the petrochemical and aerospace industries where low-temperature fluid handling is necessary. The definition of cryogenic temperature varies depending on the industry, but generally speaking, cryogenic valves can operate efficiently between -40℉ (-40℃) and temperatures far below -320℉ (-196℃). This article will discuss the uses of cryogenic valves, their different types, the standards that apply to them, and the tests that ensure their reliability.
Cryogenic Valve Uses
Cryogenic valves are essential components for industrial facilities to harness the power of cryogenic temperatures for various unique applications. By utilizing these valves, businesses can benefit from improved product quality, reduced costs, and increased efficiency. Here are some of the critical applications that cryogenic valves can be used for:
- Liquefying gases such as oxygen, nitrogen, and argon
- Cooling and storing superconducting magnets in many scientific and industrial applications
- Storing and transferring liquid natural gas
- Cryogenic grinding of materials
- Separating components of gas mixtures
- Cooling electronics components
- Processing and storing biological samples
Cryogenic Valve Types
A range of cryogenic applications requires suitable valve types to ensure optimal performance. Selecting the correct valve type suited to the specific application is essential, as all cryogenic valves must provide a tight shut-off to protect against costly and potentially dangerous leakage. With the right valve type in place, cryogenic systems can ensure the safety and effectiveness of the application.
- Cryogenic Butterfly Valves
Cryogenic butterfly valves are an excellent choice for cryogenic applications. Their triple-offset design and metal-to-metal seal provide a bubble-tight shut-off with long-term integrity. They offer a quick opening and closing action, making them ideal for remote operation. Additionally, they deliver superior performance in extreme temperatures and are incredibly durable, making them a perfect choice for any cryogenic application.
- Cryogenic Globe Valves
Cryogenic globe valves offer superior performance and reliability in extreme temperatures. With a spherical shape and disc that rotates 90° to its body seat, these valves provide reliable long-term sealing. In addition, cryogenic globe valves are designed to resist erosion over extended periods, making them perfect for systems with high flow rates.
- Cryogenic Ball Valves
Cryogenic ball valves are ideal for applications requiring reliable sealing, low-pressure drops, and efficient flow characteristics. Their unique design incorporates a vapor space of sufficient height that allows for gasification below the gland, ensuring the gland packing maintains a temperature close to that of the surrounding environment, limiting thermal conduction between the interior and outside of the valve. Additionally, their robust construction minimizes wear concerns along the seals and ball, making them the preferred choice for unrestricted flow paths.
- Cryogenic Gate Valves
Cryogenic gate valves are an excellent choice for applications that require minimal pressure drop and desirable flow characteristics. The wedge-shaped gate allows for smooth and efficient operation but has a few limitations. Gate valves are more expensive and challenging to actuate than butterfly valves, making them less suitable for remote operation. Additionally, wear and tear can be an issue when the valves are operated frequently. On the upside, gate valves are less prone to seal failure due to cold flow than ball valves with Teflon seals.
Cryogenic Valve Standards
To ensure the highest quality of cryogenic valve services, most companies adhere to industry-standard engineering requirements such as MSS SP-134, BS 6364, ASME 16.34, and ISO 21011. These standards provide the necessary guidelines to ensure cryogenic valves’ safety, reliability, and performance. By adhering to these standards, companies are guaranteed to receive the best possible service for their cryogenic valve needs.
- MSS SP-134
The MSS SP-134 is the cryogenic valve code used in North America. It provides comprehensive requirements for material, design, dimensions, fabrication, pressure testing, and non-destructive examination of valves with body/bonnet extensions.
- BS 6364
BS 6364 has been developed as a British Standard for the design, manufacture and testing of valves for use in cryogenic applications. This standard ensures that these valves are manufactured and designed to the highest safety and quality standards, providing reliable and robust performance in extreme temperatures.
- ASME 16.34
ASME 16.34 is an essential standard that outlines significant specifications for valve parts, such as flanges, threading, welding ends, and more. This standard ensures the safety and reliability of valves by providing requirements for pressure testing, material selection, flange removal, and electrical continuity. Furthermore, it specifies the nominal pipe size and marking requirements for pipes.
- ISO 21011
ISO 21011 is an international standard that provides comprehensive guidance and requirements for designing, manufacturing, and testing valves for the operation of cryogenic fluids. This standard covers operations at ambient to extreme cryogenic temperatures, ensuring the safety and reliability of any valve used in these applications. Additionally, the specifications guide any necessary modifications to valves to operate cryogenic fluids. With this standard, engineers and manufacturers can ensure the highest safety, reliability, and performance levels when working with cryogenic fluids.
In addition to the standards related to cryogenic valve operation, other standards can be beneficial when working with these devices. These include:
- ISO 5208: Pressure testing of cryogenic valves
- ISO 10434: The cryogenic valves are bolted bonnet steel gates for petroleum, petrochemical and related industries
- ISO 11114-1:Compatibility of materials with gas contents for transportable gas cylinders and metal valves
- ISO 11114-2: Compatibility of transportable gas cylinder and non-metallic valve materials with gas contents
- ISO 15761: Metal gate, globe and check valves in steel up to size DN 100 for the oil and gas industry
- ISO 17292: Metal ball valves for petroleum, petrochemical, and allied industries
- ISO 21010: Cryogenic vessels and gas/materials compatibility
- ISO 21028-1and ISO 21028-2: Toughness requirements for materials in the low temperature range
- ISO 23208: Cleanliness of vessels for cryogenic service
Cryogenic Valves Testing
Testing cryogenic valves is a critical step to ensure they are working correctly. All valves undergo rigorous testing, and cryogenic valves are no exception. To ensure proper operation, the following tests should always be conducted when testing cryogenic valves:
- Shell Strength Test: Depending on the system’s working pressure and other characteristics, this could be a hydrostatic or pneumatic test. To ensure reliable performance, the test should be conducted to a level of 1.5 times the maximum working pressure of the system – as per industry guidelines.
- Shell and Seat Leak Test:To ensure a safe and secure environment, Shell and Seat Leak Tests are essential. Pressurize the system to 1.1 times the maximum working pressure for pneumatic tests. The pressure is raised to 1.3 times the maximum operating pressure for hydrostatic testing. This ensures that all components are thoroughly tested, and any leaks or deficiencies are detected and rectified.
- Cryogenic Prototype and Production Test: Ensure compliance with BS 6364 standards with rigorous cryogenic prototype and production testing. Experienced engineers will use the latest testing protocols and equipment to guarantee that your product meets the highest quality and performance standards.