What is Cryogenic Valve? Features and Applications

what is cryogenic valves?

A cryogenic valve is a type of valve designed for use in applications where temperatures are extremely low, typically below -200°C (-330°F). They can control the flow of liquefied natural gas (LNG), oxygen, nitrogen, and other cryogenically cooled gases. These valves feature unique construction materials and manufacturing methods, enabling them to withstand extreme temperatures and pressures in these applications. Cryogenic valves are commonly used in pipelines carrying LNG or industrial gases for storage, transportation or distribution. In addition, they may also be used on medical equipment such as MRI scanners or surgical lasers, which generate intense cold temperatures during operation.

What is Cryogenic Valve?

Cryogenic valves are required in piping and pipeline systems that handle liquid hydrogen, oxygen, helium, nitrogen, liquefied natural gas, or similar cold fluids. Cryogenics refers to materials and processes that operate below -1010 degrees Celsius (-2390F). As a result, cryogenic valves must be designed to withstand such low temperatures. The main distinction between cryogenic and standard valves is their ability to operate at such low temperatures while maintaining high pressures.

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Problems with Cryogenic Valves

The main problem with cryogenic valves is that any fluid leakage to the atmosphere through gaskets or gland seals degrades the valve’s performance and associated equipment. Furthermore, such leakage at the valve stem will cause localized icing, which may cause the valve-operating mechanism to seize. According to API 598, this is why cryogenic valves must be designed for high performance and zero leakage.

Cryogenic Valve Codes and Standards

The following codes and standards are used for cryogenic valves:

  • BS 6364
  • BS EN 12567
  • BS EN 1626
  • BS EN 12300
  • MSS SP-134
  • ISO 28921such

Cryogenic Valves Design Consideration

All cryogenic valves for liquid natural gas, methane, oxygen, ammonia, and other applications are custom-made. Cryogenic valves typically have long bonnets to keep the valve stem seals away from the cold source. This will serve two critical purposes:

  • The temperature of the valve stem seals will be relatively higher.
  • There will be enough space between the pipeline and the lever/handwheel that operates the valve to provide insulation.

Size and Pressure Rating of Cryogenic Valves

Cryogenic valves for industrial use are available in various sizes and pressure classes. Sizes typically range from 1/8 to 88 inches (3 mm to 2240 mm). Cryogenic valves have pressure ratings ranging from ultra-high vacuum pressure to 700 bar. These valves can operate at temperatures as low as -2540 C. (-4250F).

Materials for Cryogenic Valves

Aluminum, Monel, Brass, Bronze, Stainless Steel, Incoloy, Zirconium, and other common materials are used to construct cryogenic valves. The seal material is typically PTFE or graphite.

Valves Used in Cryogenic Applications

Typical cryogenic valves include specially designed globe, angle, gate, butterfly, and ball valves. As a result, selecting the appropriate type of cryogenic valve for the application is critical. In cryogenic service, there are no strict guidelines for valve type. However, there is a growing preference for the quarter-turn ball and triple-offset butterfly valves.

Ball Valves for Cryogenic Use

Double-seal ball valves are used in piping and pipeline systems for LPG, LNG, thermal fluids, liquid oxygen, and nitrogen applications. They are available in both reduced and full-bore configurations. Cryogenic ball valves include a vapour space of sufficient height to allow gasification beneath the gland. This keeps the gland packing close to room temperature.

As pipe sizes increase, the gate and globe valves become more difficult and expensive. That is why they are limited to smaller pipe sizes and applications that do not require remote operation.

Characteristics of Cryogenic Valves

  • Cryogenic valves should be lightweight because they are easier to cool from ambient to cryogenic temperatures.
  • Compared to heavier constructions, lighter cryogenic valves typically have lower conductivity, which aids in reducing heat influx.
  • For cryogenic piping connections, flange and welded configurations are commonly used. Welded valves, on the other hand, are superior.
  • Cryogenic valves should be assembled in a clean room, lubricant-free, or use cold service-compatible lubricants. Documented cleaning procedures must be collected when purchasing a cryogenic valve to verify and follow proper procedures during the assembly process.

Applications of Cryogenic Valves

Cryogenic valves are widely used in

  • Cryogenic valves are widely used in a variety of applications.
  • Plants for LNG liquefaction
  • Terminals for LNG
  • Systems for transporting LNG
  • Industry of food and beverages
  • Plants for air separation
  • Steel manufacturing plants
  • Laboratories for research
  • Petrochemical and chemical plants
  • Aviation storage facilities
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