Valves in extreme cold: 3 criteria are decisive
Whether in Alaska, Norway or Russia: Industrial valves, such as those used in chemical plants or the oil industry, are exposed to extreme cold as low as -55°C in some regions. However, not all industrial valves are suitable for operation in extreme cold.
Avoid safety risk
Unsuitable industrial valves become a major safety risk for the entire plant in extremely cold conditions. To avoid this, you should focus on these three criteria when selecting your industrial valves:
The choice of materials
Only materials that guarantee safe and reliable operation even in extremely cold conditions may be used.
Example – Body material: While austenitic stainless steel has a sufficiently high resistance to low temperatures, other materials such as ferritic steel are unsuitable because they are slightly brittle under cold conditions. Combined with the high pressure that industrial valves are often exposed to, this can quickly lead to damage and leakage. It is also possible to use such steels at low temperatures, but in individual cases their suitability must be proven in a special process.
The design of the stem seal
Special care is required here to ensure leakage-free, bubble-tight sealing. It is precisely in this area that the material must have a particularly high load-bearing capacity because it must be resistant both to extreme cold and to process media. PTFE or graphite has proven to be the best material here. With graphite, however, the following must be observed: If graphite packs are stored in humid air, traces of moisture will accumulate interlaminarly.
If the “moist packing” is now exposed to a very low temperature of -55°C, the freezing moisture expands, which leads to an increase in packing compression and thus to an increased actuating torque.
Special coating in the area of the stem thread
Conventional valves lose their functionality at extremely low temperatures – they can no longer be opened and closed effortlessly. One of the reasons for this is the lubricant with which valves are normally fitted and which ensures a smooth operation under normal conditions. However, many lubricants are not suitable for use in extreme cold due to their temperature-dependent viscosity. The fatal consequence is that the valve “freezes”. “Freezing” of the valves can be very reliably prevented by using special low-temperature lubricants or a special coating in the area of the stem threads instead of the lubricant.
This special coating ensures dry lubrication, which ensures that the valve can move even in extreme cold.