Stainless Steel Low-Temperature Gate Valve | -196°C Cryogenic

Our Stainless Steel Low-Temperature Gate Valve is a specialized cryogenic valve for -40~-196°C (custom -253°C) service, in stainless steel (304/316/316L/904L/Monel) with advanced cryogenic processing. Per API 600, ANSI B16.34, ASME B16.5, API 6D, GB/T 12234 for global interchangeability. Gate on-off control with low flow resistance, reliable cryogenic sealing, brittleness resistance. Cryogenic heat treatment/stress relief and extended bonnet/elastic wedge avoid brittleness and seal failure. Flange/thread/weld per ANSI B16.5. Class 150–900 / PN16–PN63, DN15–DN600, manual/electric/pneumatic/hydraulic. For LNG, cryogenic storage, refrigeration, aerospace, tested per API 598/GB 24925, zero leakage.

1. Superior Low-Temperature Adaptability: Specially designed for low-temperature (-40°C to -196°C) and ultra-low-temperature working conditions, with customizable configurations for service down to -253°C (liquid hydrogen). The valve body and all internal pressure-containing parts undergo cryogenic treatment (deep cooling below service temperature, typically in liquid nitrogen at -196°C) followed by stress relief processing, effectively avoiding low-temperature brittleness, dimensional instability, and post-installation shrinkage - ensuring structural integrity and sealing performance even at liquid nitrogen temperature. It reliably adapts to various low-temperature media including liquefied natural gas (LNG), liquid oxygen (LOX), liquid nitrogen (LIN), liquid argon (LAR), liquid carbon dioxide, and liquid hydrogen.

2. High-Quality Stainless Steel Material: Adopts high-grade austenitic stainless steel and corrosion-resistant alloy materials, including 304 (A182 F304), 316 (A182 F316), 316L (A182 F316L - low-carbon for welded cryogenic service), 904L (super-austenitic for highly corrosive cryogenic media), and Monel (nickel-copper alloy for seawater and special service). These materials have excellent corrosion resistance, oxidation resistance, and - critically - retained low-temperature toughness (no ductile-to-brittle transition, unlike carbon steel which becomes brittle below -40°C). All materials meet ASTM standards and are supplied with full MTR traceability, ensuring no rust, deformation, or damage under long-term low-temperature operation.

3. Reliable Cryogenic Sealing Performance: Adopts a special low-temperature sealing structure, matching low-temperature-resistant PTFE, flexible graphite, or metal-to-metal (Stellite hardfaced) sealing materials that withstand extreme low temperatures without aging, cracking, or loss of elasticity. The wedge-type elastic (flexible) gate design realizes self-tightening sealing, adapting to differential thermal contraction between body and gate under cryogenic temperature changes and reducing leakage caused by thermal contraction, achieving "zero leakage" in line with API 600 standards. All sealing materials are pre-tested for cryogenic compatibility to ensure performance at the rated minimum temperature.

4. Optimized Structural Design: The valve stem adopts an outside screw and yoke (OS&Y) design, allowing intuitive visual observation of the valve opening through the rising stem position; the valve stem is treated with an anti-friction and anti-corrosion coating to ensure smooth lifting even under low temperatures. A critical cryogenic feature is the extended bonnet (long neck), which distances the packing gland from the cold body cavity, keeping the stem and packing at a warmer temperature to prevent packing freezing, stem icing, and elasticity loss. The valve body and bonnet are connected by bolts (or welded for high-pressure models) to enhance overall strength and prevent cold-air leakage. Rolling bearings in the operating device make opening and closing light and labor-saving, even for large-diameter valves.

5. Strict Quality Control & Cryogenic Testing: Each valve undergoes strict cryogenic testing, pressure testing (shell strength test and seat seal test), and leakage testing in accordance with API 598 and cryogenic valve standards (GB/T 24925) before leaving the factory. The cryogenic leak test simulates the actual working environment - the valve is cooled to its rated service temperature (typically by liquid nitrogen immersion or cryogenic chamber) and tested for external leakage and seat tightness using helium mass spectrometry or the bubble method - ensuring that the valve can operate stably and reliably under actual low-temperature conditions with zero leakage. This is the most critical quality verification for cryogenic valves.

6. Flexible Operation & Installation: Supports multiple driving modes - manual (handwheel), electric (AC/DC with local/remote control and position feedback), pneumatic, and hydraulic - meeting the needs of manual operation for small valves and automatic/remote control for large valves or automated process systems. The flange connection conforms to ANSI B16.5 standards (RF or RTJ facing), with additional threaded (NPT, BSP) and welded (socket weld SW, butt weld BW) options available, providing strong universality, easy installation and disassembly, and convenient maintenance in global cryogenic piping systems.

The Stainless Steel Low-Temperature Gate Valve operates on the wedge gate principle, adapted for cryogenic service. OS&Y stem lifts elastic wedge: open, retracts for low-resistance flow; closing, wedge accommodates cryogenic contraction for tight sealing. Disc/seats use Stellite or low-temp PTFE/graphite, non-brittle to -196°C. Extended bonnet distances packing from cold body, keeping stem/packing warm to prevent freezing. Stainless/Monel body retains cryogenic toughness, with cryogenic treatment/stress relief. Joints use cryogenic gaskets. For on-off isolation only - not throttling.

LNG & Liquefied Gas Industry: LNG storage tanks, transportation pipelines, regasification stations, LNG terminals, and liquefied petroleum gas (LPG) facilities, used for cutting off and connecting liquefied natural gas and other cryogenic hydrocarbon media at approximately -162°C, ensuring safe and stable operation. The 316L/904L stainless construction and cryogenic testing make it the standard isolation valve for LNG import/export terminals, peak-shaving facilities, and small-scale LNG distribution, where zero leakage is essential for safety and emissions control.

Cryogenic Industrial Gas Storage & Transport: Liquid nitrogen (LIN, -196°C), liquid oxygen (LOX, -183°C), liquid argon (LAR, -186°C), and liquid carbon dioxide storage tanks, transportation tankers, and distribution pipelines, suitable for ultra-low-temperature media control in industrial gas plants and medical gas systems. The austenitic stainless body retains full toughness at these temperatures, and the extended bonnet prevents stem icing during repeated operation on fill lines and storage manifolds.

Refrigeration, Food & Cold Chain: Large-scale industrial refrigeration systems, cold storage warehouses, quick-freezing equipment, food freezing and processing lines, and district cooling, used to control refrigerants (Freon, ammonia, CO₂) and cooling water/brine under low-temperature conditions. The corrosion-resistant stainless construction and reliable cryogenic sealing ensure long maintenance-free operation in cold storage and food processing environments where hygiene and reliability are paramount.

Aerospace & New Energy: Aerospace engine test systems, rocket test stands, and cryogenic fuel (liquid hydrogen at -253°C, liquid oxygen at -183°C) storage and transportation systems, meeting high-precision and high-safety control requirements. Also used in new energy applications including hydrogen energy storage (liquid hydrogen), photovoltaic silicon wafer low-temperature processing, and lithium battery electrolyte low-temperature storage, adapting to the development needs of advanced energy and aerospace fields with custom -253°C configurations.

Chemical & Pharmaceutical Cryogenic: Low-temperature chemical reactions, cryogenic distillation and separation, gas liquefaction processes, and pharmaceutical freezing/lyophilization (freeze-drying) processes, suitable for corrosive low-temperature media such as low-temperature acids, alkalis, and organic solvents. The broad material selection (304, 316, 316L, 904L, Monel) and Stellite/PTFE sealing options ensure compatibility with aggressive cryogenic chemicals while maintaining zero leakage and product purity.

Every Stainless Steel Low-Temperature Gate Valve is manufactured and tested per API 600, ANSI B16.34, ASME B16.5, GB/T 12234, ISO 9001. Raw materials MTR-verified with cryogenic Charpy impact tests at -196°C for all stainless/Monel parts. Castings 100% RT/UT inspected. Pressure parts cryogenically treated and stress-relieved. Stem heat-treated, hardness verified. Sealing surfaces 100% cryogenically inspected. Extended bonnet verified. Valves get dimensional check, shell 1.5×, seat 1.1× per API 598, plus cryogenic leak test per GB/T 24925. Gaskets/packing verified. Actuators tested. Units ship with MTR, test certs, 18-month warranty, BV/SGS on request.

Q1: What makes a gate valve suitable for cryogenic / low-temperature service, and how is it different from an ordinary gate valve?

A: A cryogenic / low-temperature gate valve differs from an ordinary (ambient-temperature) gate valve in several critical design and manufacturing aspects that make it safe and reliable at temperatures below -40°C down to -196°C (or even -253°C for liquid hydrogen):

Material selection: Ordinary gate valves use carbon steel (WCB/A105), which undergoes a ductile-to-brittle transition at low temperatures (typically below -40°C to -46°C) and becomes susceptible to catastrophic brittle fracture. Cryogenic valves use austenitic stainless steel (304, 316, 316L, 904L) or nickel alloys (Monel, Hastelloy), which retain excellent toughness (no brittle transition) down to absolute zero. These materials are also more corrosion-resistant.

Cryogenic treatment: All pressure-containing parts are cryogenically treated - deep-cooled to below the minimum service temperature (typically -196°C in liquid nitrogen) and then slowly warmed - followed by stress relief. This stabilizes the material's microstructure, relieves residual stresses from welding and forming, and prevents dimensional shrinkage or distortion after installation, which would cause leakage or binding.

Extended bonnet (long neck): This is the most visible difference. The bonnet neck is extended significantly (typically 200–350 mm, depending on size and temperature rating) to distance the packing gland and stem from the cold body. This keeps the packing and stem at a temperature above freezing, preventing packing from becoming brittle, stem icing (frost/ice buildup on the stem that would damage packing and cause leakage), and loss of sealing. An ordinary short bonnet would allow the cold to reach the packing, causing failure.

Cryogenic sealing materials: PTFE, flexible graphite, and metal gaskets rated for cryogenic service are used instead of standard elastomers (NBR, EPDM) that would become brittle and crack at low temperatures. The elastic (flexible) wedge design accommodates differential thermal contraction.

Cryogenic testing: Every valve is leak-tested at its rated cryogenic temperature per GB/T 24925 (or equivalent), not just at ambient temperature - this verifies zero leakage under actual service conditions. An ordinary gate valve must NOT be used for cryogenic service, as it will suffer brittle fracture, packing failure, and leakage, creating serious safety hazards (especially with flammable cryogens like LNG and liquid hydrogen).

Q2: What is the extended bonnet (long neck) and why is it so important for cryogenic valves?

A: The extended bonnet (also called long-neck bonnet, cryogenic bonnet, or extended neck) is a defining feature of cryogenic valves. It is an elongated neck section between the valve body/bonnet flange and the packing gland / yoke, typically 200–350 mm long (the exact length depends on valve size, pressure class, and minimum service temperature - colder service requires a longer neck). Its purpose is thermal isolation of the packing area from the cryogenic fluid:

When the valve is in cryogenic service, the body and lower bonnet are at the cold process temperature (e.g., -196°C for liquid nitrogen). Without an extended neck, this cold would conduct up the stem and bonnet to the packing gland, causing: (1) the packing material (PTFE/graphite) to become brittle and lose elasticity, (2) moisture from the atmosphere to freeze on the exposed stem (icing), which damages the packing surface and causes external leakage when the valve is operated, (3) the stem itself to contract and potentially bind or seize.

The extended neck increases the thermal path length, so by the time cold conducts up to the packing gland, the temperature has risen significantly (typically to above 0°C, and often to near ambient) due to heat leak from the atmosphere along the neck and stem. This keeps the packing flexible, the stem free of ice, and the sealing reliable.

The extended bonnet also creates a "vapor barrier" or "gas seal" effect: as cryogenic liquid vaporizes in the bonnet cavity, the cold vapor fills the neck and provides an insulating column, while the top of the neck remains warm. Some designs include a vent or drain connection.

For very low temperatures (liquid hydrogen at -253°C) or large valves, the neck may be extended further, and some designs include a secondary seal or bellows at the top of the neck. The extended bonnet is not optional for cryogenic service - it is a fundamental safety and reliability requirement, and its length must be appropriate for the minimum design temperature. We calculate and specify the correct bonnet length per GB/T 24925 and API 600 for each application.

Q3: What temperature range can this valve handle, and what is "cryogenic treatment"?

A: Our Stainless Steel Low-Temperature Gate Valves cover a standard working temperature range of -196°C to -40°C, with customizable configurations for ultra-low temperature down to -253°C (liquid hydrogen service). The upper end is typically limited by the sealing material and application - these valves are designed for cold service, though the stainless body itself can withstand higher temperatures.

-40°C to -100°C: Common industrial refrigeration, cold storage, CO₂ service, some chemical processes. Standard 304/316 stainless with standard extended bonnet.

-100°C to -196°C: LNG (-162°C), liquid oxygen (-183°C), liquid nitrogen (-196°C), liquid argon (-186°C). Requires 316L/304 austenitic stainless, full cryogenic treatment, extended bonnet, and cryogenic leak test.

Below -196°C to -253°C: Liquid hydrogen (-253°C), liquid helium (-269°C, custom). Requires special materials (316L, aluminum, or special alloys), extended-length bonnet, and specialized cryogenic testing - available on custom order. Cryogenic treatment (cryo treatment / deep cryogenic treatment) is a manufacturing process in which the finished pressure-containing parts (body, bonnet, gate, stem) are slowly cooled to a temperature below the minimum service temperature (typically immersed in liquid nitrogen at -196°C, or colder for -253°C service), held at that temperature for a specified soak time (several hours), and then slowly warmed back to ambient temperature. This is followed by a stress-relief heat treatment. The purpose is: (1) Microstructure stabilization - in austenitic stainless steels, any retained austenite or metastable phases are transformed/stabilized, preventing phase transformation and dimensional change in service; (2) Stress relief - residual stresses from welding, casting, forging, and machining are relieved, preventing post-installation distortion; (3) Dimensional stability - the parts "shrink" to their stable cryogenic dimensions during treatment, so they do not shrink further when installed in cold service (which would cause flange leakage, stem binding, or seat misalignment); (4) Toughness verification - the treatment itself serves as a thermal cycle test. Without cryogenic treatment, a valve might seal at ambient temperature but leak or seize when cooled to service temperature due to differential shrinkage. Cryogenic treatment is mandatory for reliable cryogenic valve performance and is performed on every valve we supply.

Q4: What materials are available, and why use stainless steel instead of carbon steel for low-temperature service?

A: We offer the following body and trim materials for low-temperature service:

Body / Bonnet / Pressure-containing parts:

304 / A182 F304: General-purpose austenitic stainless, for non-corrosive cryogenic service (water, steam, general cryogens). Economy option.

316 / A182 F316: Molybdenum-bearing austenitic stainless, better pitting/corrosion resistance for marine and mildly corrosive cryogens.

316L / A182 F316L: Low-carbon 316 - the most common and recommended material for cryogenic service. The low carbon content prevents intergranular corrosion (sensitization) after welding, and it has excellent cryogenic toughness. Standard for LNG, LOX, LIN, LAR.

904L / A182 F904L: Super-austenitic stainless with high chromium, nickel, and molybdenum - for highly corrosive cryogenic media (acids, chlorides, special chemicals).

Monel (A494 / A182): Nickel-copper alloy - for seawater, hydrofluoric acid, and special corrosive cryogenic service; also used for oxygen service in some configurations.

Trim (Gate, Seat, Stem):

Gate/Seat: Stainless steel base with Stellite (CoCr) hardfacing (metal-to-metal sealing), or low-temperature-resistant PTFE / flexible graphite inserts (soft sealing).

Stem: 316, 316L, F6a (13Cr), Monel, Hastelloy - with anti-friction/anti-corrosion coating.

Sealing / Packing / Gaskets: Low-temperature PTFE, flexible graphite, metal gaskets (spiral-wound or ring type). Why not carbon steel? Carbon steel (WCB, A105, 25#) undergoes a ductile-to-brittle transition (DBTT) at low temperatures - above the transition temperature it is tough and ductile, but below it becomes brittle and can fracture catastrophically without warning (like glass). For standard carbon steel, the DBTT is typically around -40°C to -46°C (even lower for normalized/killed steel, but rarely below -100°C). At -196°C, carbon steel is extremely brittle and any impact, thermal shock, or stress concentration can cause sudden fracture - a catastrophic safety failure in cryogenic service, especially with flammable or asphyxiating cryogens. Austenitic stainless steels (304/316/316L) have a face-centered-cubic (FCC) crystal structure that does not undergo a ductile-to-brittle transition - they remain tough and ductile down to absolute zero (-273°C). This is why stainless steel (or nickel alloys) is mandatory for cryogenic valve bodies. Additionally, stainless steel offers better corrosion resistance for many cryogenic media (LNG, LOX, chemicals). For very large or low-cost applications above -100°C, low-temperature carbon steel (e.g., A350 LF2) can be used with proper impact testing, but for -196°C service, stainless steel is the standard.

Q5: How is the valve tested for cryogenic performance, and what standards apply?

A: Every Stainless Steel Low-Temperature Gate Valve undergoes a comprehensive test program, with the cryogenic leak test being the most critical and differentiating verification:

Material certification: All pressure-containing materials are supplied with MTR (Material Test Report) including chemical composition, mechanical properties, and - critically - low-temperature Charpy V-notch impact test results at or below the minimum service temperature (e.g., at -196°C), verifying that the material meets required impact energy (toughness) at cryogenic temperature.

NDE (Non-Destructive Examination): Castings undergo 100% visual inspection plus radiographic (RT) or ultrasonic (UT) examination per ASTM standards to detect internal defects. Welds are PT/MT/RT inspected as applicable.

Dimensional inspection: All critical dimensions (flange per ASME B16.5, face-to-face per API 600, extended bonnet length, stem travel) are verified.

Hydrostatic shell test: Shell pressure test at 1.5× rated pressure per API 598, verifying pressure-containing integrity.

Seat seal test: Seat tightness test at 1.1× rated pressure per API 598 (low-pressure air or high-pressure gas, as specified).

Cryogenic leak test (per GB/T 24925 - "Cryogenic valves" / equivalent to BS 6364 / MSS SP-134): This is the defining test. The fully assembled valve is installed in a cryogenic test rig, cooled to its rated minimum service temperature (typically by direct liquid nitrogen immersion, or by circulating cold cryogen through the valve for larger sizes), and held at temperature for thermal stabilization. It is then: (1) operated through several open-close cycles at cryogenic temperature to verify smooth operation and no stem binding; (2) tested for external leakage (body, bonnet joint, packing) using helium mass spectrometry (capable of detecting leak rates as low as 1×10⁻⁶ Pa·m³/s) or the bubble method (immersion in warm water, observing for bubbles); (3) tested for seat leakage (through the closed gate) at cryogenic temperature. Only valves passing zero external leakage and seat leakage within the specified limit are accepted.

Actuator testing: Electric/pneumatic/hydraulic actuators are functionally tested (torque, travel, limit switches) and verified for low-temperature rating if specified.

Standards: Design/manufacturing per API 600, ANSI B16.34, ASME B16.5, API 6D, GB/T 12234; testing per API 598 and GB/T 24925 (cryogenic). Optional third-party certification by BV, SGS, TÜV, and PED/CE / ASME U-Stamp available on request. Every valve ships with a serialized test dossier including MTR (with cryogenic impact data), cryogenic treatment record, hydrostatic test certificate, and cryogenic leak test report, providing full traceability and quality evidence for your project.

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