Ball valves are designed to control flow by rotating an internal ball within a housing. They’re often used for applications where there’s a need to regulate pressure, temperature, or flow rate.
A ball valve has two main parts: a body with a central opening and a ball that fits into the opening. As the ball rotates, it opens or closes the valve. In addition to the main parts, ball valves have different internal components that help them work in different environments. Standard ball valve components include:
- Chevron packings
- O-rings and backup rings
- Floating seats
Keep reading to learn more about these components.
Chevron packings are also called v packing or vee packing seals. These seals automatically react to changes in pressure. Multiple chevron seals are used together to form the overall seal. While these seals have a v-shape, they are shipped with a male and female adapter to provide a flat surface rather than the v-shape.
Chevron ball valve components work well at sealing fluid in centrifugal, static, and reciprocating environments. They are recommended to reduce pressure and avoid shrinkages in the presence of linear or rotary movement.
These seals are manufactured in virgin PTFE, modified PTFE, and glass or carbon-filled PTFE. While virgin seals are ideal for many conditions, filled compounds are recommended for most applications. Your provider will recommend the optimum PTFE compound.
O-Rings and Backup Rings
O-rings are a standard ball valve component. They are used whenever soft sealing is required to help prevent extrusion. The design of these seals allows them to be used in harsh conditions and with aggressive chemicals.
The o-rings found in ball valves are often used with backup rings. They can be made from neoprene, silicone rubber, polyurethane, and PTFE. The precise material will depend on the application and environment that the seal is employed.
Backup rings are circular sections, which may be cut or uncut, that help prevent the extrusion process. These are employed alongside o-rings or lip seals when couplings are not suitable.
A floating ball valve is one where the seat holds the ball in place while it floats around in the valve body. Pressure from the gas or liquid helps to push the ball against the downstream seat to form a tight seal.
Floating seats are used in several applications, such as oil and gas, cryogenic, heating, and pharmaceuticals. However, they are most commonly found in hydraulic systems. The type of polymeric material used in these seats depends on maximum pressure, working temperature, or the type of gas or fluid it regulates.
Like o-rings, inserts are in seats with soft sealing. This gasket can be manufactured from several different thermoplastic materials depending on its conditions.
For example, virgin PTFE seals are unsuitable for butadiene or styrene service. PEEK material is not resistant to nitric acid or sulphuric acid. However, filled PTFE works well in high temperatures and low pressures, while PCTFE is ideal for cryogenic applications.
Ball valve components help to ensure the valves seal correctly. Depending on the valve application, these components can include o-rings, backup rings, chevron packing, inserts, and floating seats.
Finding the appropriate seal inserts and materials can be challenging. Contact us today for help determining what best suits your application.