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Low-temperature and cryogenic ball valve stem seals require materials that remain flexible and resilient, avoiding brittleness at temperatures down to -196°C (-321°F) or lower. Virgin PTFE (Polytetrafluoroethylene), PCTFE/KEL-F (Polychlorotrifluoroethylene), and spring-energized seals are the standard, with extended bonnets used to protect the packing from direct cryogenic fluid exposure.
Key Low-Temperature Stem Seal Materials
- Virgin PTFE (Teflon): Highly popular for low temperatures because it remains flexible down to -425°F (-254°C). It offers low friction and chemical inertness, making it ideal for both static and dynamic sealing.
- PCTFE / KEL-F (PTFCE): Offers excellent performance down to -400°F (-240°C), recognized for high tensile strength, low thermal expansion, and near-zero moisture absorption.
- TFM (Modified PTFE): A second-generation PTFE providing superior stress recovery and reduced cold flow deformation, suitable for low temperatures (-100°F to 450°F range).
- Spring-Energized Seals: These combine a PTFE jacket with a metallic spring to provide consistent sealing force, allowing for compensation of thermal shrinkage and wear, ideal for cryogenic applications.
Design Considerations
- Extended Bonnet/Stem: Essential for cryogenic service to place the stem packing above the cryogenic liquid, creating a "gas column" that protects the seals from freezing.
- Live-Loaded Packing: Utilizes spring-loaded packing bolts to maintain constant compressive force, compensating for the contraction of materials during severe thermal cycling.
- Triple Barrier System: Often involves a primary seal, secondary PTFE/graphite packing, and a metal-to-metal backup to ensure security in critical applications.
Recommended Products
A 100% PTFE material described as conforming to packing glands, capable of handling cryogenic temperatures.
A pure PTFE packing that does not harden or adhere, effective for low-temperature applications.
Feature extended stems and bonnets, designed for temperatures down to -196°C.
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For optimal performance in low-temperature environments, selecting a PTFE-based seal with live-loading in an extended stem configuration is recommended.
What specific temperature range or media (e.g., LNG, LN2) are you sealing against?
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Web results
Low temperature Ball valve stem seal
JST-Seals
https://www.jst-seals.com › low-temperature-ball-valve-st...
JST-Seals
https://www.jst-seals.com › low-temperature-ball-valve-st...
OEM Low temperature Ball valve stem seal with reasonable price. More Low temperature Ball valve stem seal Solutions welcome to contact us!
Low Temperature and Cryogenic Ball Valves
ValveMan
https://valveman.com › content › specification-she...
ValveMan
https://valveman.com › content › specification-she...
PDF
Our Cryo extension bonnet is specially designed to reduce heat exchange between the fluid and the environment and to keep the packing chamber temperature to a ...Read more
4 pages
Ball Valves for Low Temperature services - KITZ Corporation
kitz.com
https://www.kitz.com › product › butterfly-ball › ball-v...
kitz.com
https://www.kitz.com › product › butterfly-ball › ball-v...
Compatible with low temperatures down to -104°C. Low Temperature Service Ball Valve has the extended bonnet for assured stem seal and freezing prevention.Read more
Low Temperature Trunnion Ball Valve
Eng-Tips
https://www.eng-tips.com › ... › Valve engineering
Eng-Tips
https://www.eng-tips.com › ... › Valve engineering
Nov 15, 2004 — The ice can cause the stem seals to be damaged, hence the suggestion to use a bonnet to keep the stem seals at or above zero Celsius and anyone ...Read more
Valve Sealing Performance in Low-Temperature Conditions
bossealvalves.com
https://www.bossealvalves.com › News
bossealvalves.com
https://www.bossealvalves.com › News
Nov 13, 2024 — For valves such as ball valves and butterfly valves that work at normal temperatures, metal-to-nonmetal seals are commonly used. Non-metallic ...Read more
Avoiding ball valves freezing during cryogenic filling
Reddit · r/rocketry
20+ comments · 10 years ago
Reddit · r/rocketry
20+ comments · 10 years ago
Either take it apart and examine how the seals and connections might lock at low temperature (which is honestly probably just thermal ...Read more
Stainless Steel 3-Piece 60 Series Low Temperature ...
Swagelok
https://products.swagelok.com › low-temperature-2-way-...
Swagelok
https://products.swagelok.com › low-temperature-2-way-...
Low-temp 2-way 60 Series ball valve, 1/2 in. Swagelok tube ends, 316 SS body, reinforced PTFE seats, lever handle, 2200 psig rating, swing-out design.
14-day returns
Understanding Ball Valve Sealing Principles and Mechanisms
cntopa.com
https://cntopa.com › Ball valve
cntopa.com
https://cntopa.com › Ball valve
Higher temperatures can cause certain materials to soften, potentially compromising the seal. Conversely, extremely low temperatures can make some seals brittle ...Read more
Proper Valve Stem Sealing Best Practices
isa.org
https://www.isa.org › intech-home › june-2022 › features
isa.org
https://www.isa.org › intech-home › june-2022 › features
Valve stem sealing is a critical component of valve specification for reducing product loss, increasing efficiency, and improving energy management.
Valve Seal Kit (316 on valve body) – 1/2
Blichmann Engineering
https://www.blichmannengineering.com › Shop
Blichmann Engineering
https://www.blichmannengineering.com › Shop
Valve Seal Kit (316 on valve body) – 1/2″ V-3E ball valve 2 ball seats, 2 stem packings, 1 thrust washer (used on newer NPT valves for fermentors) ...Read more
$5.99In stockFree delivery over $15030-day returns
Missing: Low ‎temperature