Globe valves operating under low-temperature conditions, such as liquefied natural gas (LNG), liquid oxygen, liquid nitrogen, or liquid argon, face higher demands on materials, structure, and sealing performance. In low-temperature environments, metals can become brittle, sealing materials may contract, and the valve stem area can even experience freezing blockage. Therefore, standard globe valves cannot be used directly.
To ensure the safety and reliability of low-temperature media transport, globe valves must meet a series of specialized design requirements. This article summarizes the key design considerations for globe valves in low-temperature applications from a professional perspective, while providing accessible explanations to make the content both understandable and technically in-depth.
This is the most typical structural feature for low-temperature valves.
Low-temperature media can reach extremely low temperatures (e.g., -196°C). If the valve stem area is directly exposed to such cold, the packing may crack or lose elasticity. The purpose of the long bonnet design is to:
●Keep the valve stem and packing away from the low-temperature zone
●Maintain a higher temperature around the packing area to prevent freezing and sealing failure
The height of the long bonnet is usually determined based on operating conditions, media temperature, and the thickness of pipeline insulation.
In short, a long bonnet protects the valve’s sealing core from damage due to freezing.
Low temperatures can cause ordinary carbon steel to lose toughness and even fracture, making material selection critical:
●Stainless steel (e.g., 304, 316, 316L)
The most commonly used material for low-temperature applications, maintaining good toughness even at −196°C.
●Low-temperature carbon steel (LCC, LCB)
Suitable for moderately low temperatures (e.g., −46°C to −101°C), but not for extreme cryogenic conditions.
Materials must retain sufficient impact toughness and structural stability at the expected minimum operating temperature.
Low temperatures can cause packing materials to harden and shrink, resulting in:
●Reduced sealing force
●Increased risk of leakage
●Higher operating torque
To address this, the design should include:
●Use of flexible graphite, PTFE, or low-temperature-specific packing combinations
●Gland structures capable of compensating for contraction to maintain continuous sealing
●Some high-end cryogenic globe valves even employ spring-loaded packing to ensure constant sealing force
Metals contract at low temperatures, and different materials have different rates of contraction. Improper matching can lead to:
●Uneven stress on the valve seat
●Deformation of the sealing surface
●Incomplete closure or sticking
Therefore, the design must ensure:
●Compatibility of thermal expansion coefficients between the valve seat and disc materials
●Sealing surface hardness and toughness suitable for low-temperature impact
●Frequent use of fully forged stainless steel to ensure stability and reliable sealing performance
The surfaces of low-temperature valves are prone to frost or ice formation, which can lead to:
●Difficult operation
●Freezing that prevents rotation
●Accelerated surface corrosion
Solutions include:
●Anti-condensation design on external surfaces
●Provision for insulation layers on the exterior
●Positioning actuators or handwheels away from low-temperature zones
These measures are especially important in LNG facilities and other cryogenic chemical applications.
●Sufficient tensile strength
●High toughness to prevent brittle fracture
●Adequate surface hardness to minimize friction and wear
Commonly used materials include 304 and 316 series stainless steel or other low-temperature-certified alloys.
Whether manual handwheels or pneumatic/electric actuators, freeze prevention is essential:
●Manual valves: Extend the operating area to avoid freezing
●Pneumatic actuators: Implement anti-condensation measures
●Electric actuators: Add moisture and freeze protection
In low-temperature environments, any external mechanism seizing can result in valve loss of control.
Low-temperature conditions impose higher reliability requirements on globe valves. From materials and structure to sealing methods, designs must strictly comply with low-temperature standards. Standard globe valves cannot ensure safety under cryogenic conditions. Therefore, it is essential to select specialized cryogenic globe valves and verify that the manufacturer has proper low-temperature testing and certification capabilities.
Q1: Can a standard globe valve be used directly for low-temperature media?
No. Standard valve materials and structures are prone to brittle fracture, leakage, or failure under low-temperature conditions.
Q2: Is there a standard height for the long bonnet?
Typically, the height is determined based on media temperature, insulation thickness, and installation space, commonly ranging from 250 mm to 500 mm. However, the manufacturer should design it according to the actual operating conditions.
Q3: Must low-temperature globe valves be made of stainless steel?
In most cases, yes, because stainless steel maintains the best toughness at extremely low temperatures. For moderate low temperatures, low-temperature carbon steels such as LCB or LCC can also be used.
Q4: Do low-temperature valves require special testing?
Yes. Reputable manufacturers perform low-temperature performance testing (Cryogenic Test) to ensure reliable sealing and operation.
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