Complete Guide to Cryogenic Ball Valve Maintenance

Cryogenic ball valves play an important role in fluid control at extremely low temperatures, and their stability and functionality are directly related to safety and equipment reliability. In order to ensure the best performance of cryogenic ball valves, proper maintenance and regular cleaning are essential. This article provides detailed maintenance guidelines for cryogenic ball valves, including preparation, cleaning, drying, assembly, and contamination prevention steps to help you effectively operate and maintain cryogenic ball valves and keep them in optimal condition.

Pressure Management in a Closed State

Pressurized fluid may still be present in the valve when the cryogenic ball valve is closed, so the pressure must be carefully managed.

Check Body Pressure

Even if the valve is closed, there may still be pressure inside. Before starting, be sure to check the actual pressure of the valve with the appropriate tool. Depending on the medium used and the system design, the pressure may vary, so familiarity with the operating parameters of the system is required.

Release Pressure

Before performing maintenance or cleaning, always open the valve and slowly release the internal pressure. A sudden release of pressure may cause a liquid or gas to squirt out, causing injury. It is recommended to use the gradual release method, and first open the valve gradually and observe the pressure change to ensure safe release.

Test Pressure Before Maintenance

Use pressure gauges to test the pressure of piping and valve systems to ensure that all pressures are within a safe range. This not only helps to identify potential stress issues, but also to detect equipment failures in advance.

Monitor Pressure Changes

Pay close attention to pressure changes during valve operation, especially when opening the valve for the first time. Pay attention to abnormal pressure fluctuations. If abnormal pressure fluctuations are found, stop the operation immediately and check.

Safety Measures

Always wear appropriate safety equipment, such as pressure gloves and goggles, to prevent accidental injury during pressure release. Also, maintain a safe distance around the pressure release area.

Preparation Before Maintenance

Before performing the overhaul, ensure that the pipe has been relieved of pressure and that the valve is open to ensure safety. To avoid accidental activation of the valve during maintenance, disconnect the power or air supply to ensure that the valve is in a safe condition. If the valve is equipped with an actuator, remove it from the mounting position before proceeding further. This will facilitate subsequent disassembly and maintenance.

Confirm Line Pressure

Check the Upstream and Downstream Pressure
Before removing the valve, check the pressure in the upstream and downstream pipelines. Check the pressure of each associated pipe with a pressure gauge to ensure that it has been reduced to a safe range to avoid accidents during disassembly.

Use a Pressure Gauge

Use a pressure gauge or other measuring tool to accurately measure the pressure in the pipeline, record the pressure value, and compare it with the normal safe value to confirm that the pressure has been completely released.

Check that There is no Pressure

Before removing the valve, ensure that there is no excess pressure in the pipes on both sides. This can be confirmed by releasing the pressure at both ends of the valve to ensure that the disassembly process is not affected by pressure.

Record and Mark

Record all the results of the stress test in detail, and record any abnormal conditions in the maintenance log for subsequent tracking and processing.

Precautions for Disassembly

Handle Parts Lightly

When disassembling, operate carefully to avoid damaging the sealing surface of parts, especially non-metallic parts. When removing the O-ring, special tools are recommended to ensure that it is intact.

Assembly of Flanged Connection

For flanged cryogenic ball valves, the bolts on the flange should be tightened symmally, gradually and evenly during assembly to ensure the integrity of sealing and stable connection. Ensure that the bolt is tightened evenly to avoid poor sealing or damage caused by local too tight.

Assembly of Welded Joints

In the assembly process of the cryogenic ball valve of the welded joint, the valve body needs to be properly cooled to avoid damage caused by excessive heat generated during welding. After the welding is complete, cool the part to be welded to room temperature before performing subsequent operations.

Cleaning Agent Selection and Use

The choice of cleaning agent should be matched with the rubber, plastic, metal parts and working media in the ball valve. For gaseous working medium, gasoline can be used to clean metal parts; Non-metallic parts should be cleaned with pure water or alcohol to ensure no damage to the parts.

Cleaning Method

For the individual parts that have been removed, the cleaning solution can be soaked and cleaned. The soaking time should be determined according to the degree of contamination, but long soaking should be avoided to avoid damage to the parts.
For metal parts that are not removed, you can wipe them with a clean cloth soaked in cleaning agent to ensure that all grease, dirt, glue and dust are removed. For areas that are difficult to clean, use a soft brush to scrub gently.

Drying and Assembly

The non-metal parts after cleaning should be removed from the cleaning agent immediately to prevent deterioration due to long-term immersion. For rubber or plastic parts, dry them with a lint-free cloth after cleaning to avoid moisture residue. The cleaning agent on the cleaning surface is fully volatilized and then assembled. If left for a long time, it may cause rust or dust contamination. For metal parts, it can be dried by compressed air. New parts should also be thoroughly cleaned before assembly to ensure that the surface is clean and free of foreign bodies. Gently wipe the new part with a clean cloth and appropriate cleaning agent to remove any protective oils or impurities that may be present.

Pollution Prevention

In the assembly process of cryogenic ball valve, strict measures must be taken to prevent pollution to ensure the normal operation of the valve and extend the service life. 

Ensure that the working environment for repair and assembly is clean and tidy to reduce dust, impurities and other sources of contamination. Use dedicated workstations and tools to keep the environment clean. When disassembling, pay attention to prevent metal debris from entering the valve interior. Use appropriate tools and clean cloth to ensure that the surface of the part is clean and to avoid metal debris during disassembly.

Before assembly, carefully inspect all parts to ensure that there is no grease, dust, welding slag or other foreign matter. Make sure the surface of the part is clean and free of any contaminants. During the cleaning and assembly process, take care to prevent any foreign objects from entering the valve interior. Ensure that all removed parts are thoroughly cleaned to avoid residue affecting valve performance.

Conclusion

By following the above maintenance and cleaning guidelines, you can effectively maintain the performance and safety of cryogenic ball valves. Regular maintenance not only extends the service life of the valve, but also ensures its reliability under extreme conditions. Ensure that every step is carefully executed to ensure that all components are clean and pollution-free, and careful operation is carried out during the assembly process to achieve the best operating effect of the cryogenic ball valve. This will greatly improve the efficiency of the equipment and reduce the risk of failure.