More about Ball Valve Seats
Polymer Ball Valve Seats
Our polymer ball valve seats aid in distributing the seating stress uniformly and is usually soft enough to conform to the shape of the ball so that a solid seal is achieved. Ball valve seats involve a collection of material requirements to work correctly. Essential properties include:
- low friction
- sufficient ductility to provide a reliable seal
- good stress recovery
- dimensional stability
- excellent wear resistance
- can be used in a wide variety of temperatures
Common Applications of Ball Valve Seats include:
- Air, gaseous and vapor systems
- Connecting instruments via instrument tubing
- Fluid Services
- High Temperature and High Pressure Applications
- Handle environments where high corrosion is an issue
High-Performance Ball Valve Seat Materials
However, when it comes to critical applications in aggressive environments, ball valve seat materials also need to be resistant to chemical attack, have stable properties even at extreme temperatures (which could include cryogenic or high temperatures), low water absorption, and a very low coefficient of thermal expansion. For applications that require sterilization (e.g., food and drug), ball valve seats need to be able to handle extended exposure to hot water, steam, or potentially caustic cleaning compounds.
Typical polymer materials used for ball valve seats include PTFE, PEEK, TFM, PCTFE, Acetal, Vespel and others. However, not all materials are suitable for ball valve seats that have to function in an aggressive environment reliably.
PTFE Ball Valve Seats
As a ball valve seat material, PTFE often rises to the top of the list because of its incredibly low friction and excellent chemical compatibility across a wide range of chemical types. It is available in several FDA-approved grades and is considered non-contaminating. PTFE can a wide range of temperatures from cryogenic all the way to 550°F and survive even with repeated exposure to steam and hot water.
Advantages:
- Exceptional chemical resistance
- Good resistant to heat and low temperatures
- Good electrical insulating power in hot and wet environments
- Good resistance to light, UV and weathering
- Low coefficient of friction
- Low water absorption
- Ductile
- FDA approved
PEEK Ball Valve Seats
PEEK has chemical resistance and low friction almost on the same order as PTFE, but can handle slightly higher temperatures ranging from -70°F to 550°F. This material is exceptionally well adapted to nuclear applications and those involving high temperatures and extreme loadings. PEEK is also quite flame retardant and is suitable for hot water and steam exposure.
Advantages:
- Also has excellent chemical resistance
- Low moisture absorption
- Good wear resistance
- Long lifespan
- Excellent heat distortion properties
- Good radiation resistance.
PCTFE Ball Valve Seats
PCTFE, or polychlorotrifluoroethylene, is a homopolymer of chlorotrifluoroethylene.
Advantages:
- Excellent thermal and chemical stability
- Low gas permeation
- Great low temperature resistance, up to -400°F.
- Extremely tough
- Low moisture absorption
TFM Ball Valve Seats
TFM is a specially formulated second-generation variant of PTFE. It is known for its low friction, good performance in high temperatures, and chemical resistance. TFM offers even better stress recovery than PTFE and has a denser molecular structure. Its working temperature range is -100°F to 450°F.
Advantages:
- Reduced cold flow
- Lower Porosity
- Lower void content
- Smoother surfaces
- Reduced deformation under load
- Improved permeability
Acetal Ball Valve Seats
Another common choice for ball valve seats in aggressive environments is acetal (sometimes known by one of its trademarked names, Delrin). Its temperature range is more limited at -70°F to 180°F, but it offers outstanding wear resistance and can handle pressure up to 5 ksi. It is a very rigid material with good toughness and dimensional stability and is resistant to cold flow.
Advantages:
- Strong and rigid
- Excellent mechanical stability
- Excellent creep resistance
- Low coefficient of friction
- Low water absorption
- FDA approved
Vespel Ball Valve Seats
Since it’s invention in 1965, Vespel polymide materials provide safe, reliable operations at temperatures ranging from cryogenic to extreme heat. Because of their low wear and low friction at high PV in lubricated or unlubricated environments, outstanding creep, strength and impact resistance, Vespel makes lighter weight part practical and sometimes better than other common materials such as metal.
Advantages
- Low creep
- Lightweight
- Chemical, electrical, wear and thermal resistant
- Works well under hard vacuum, radiation, and cryogenic conditions.