Butterfly valve parts

Below are the major components of a butterfly valve. Besides, there are smaller more common components such as the bushings, bearings, and fasteners that are part of most other valve constructions as well. Details on some of the components on the actuation end, such as the handle, lever, gearbox, and handwheel will be covered in the actuation section.

Valve Body
The valve body fits between the pipe flanges - the most common end connection types being flanged, double lug, and wafer types.
Disc
Attached to the valve body is the disc that functions as a gate that stops or throttles fluid flow; it can be considered equivalent to a gate in a gate valve, or a ball in a ball valve. The disc is typically bored to receive the stem, or shaft. There are many variations in disc design, orientation, and material in order to improve flow, sealing, and/or operating torque.
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Seat
Lining the internal valve body is a strong elastomer or metal anti-leak seal that secures the disc in place in the closed position in order to achieve complete shutoff. The 9881k series’ stainless steel weld filled and microfinished integral body seat ensures a corrosion and erosion resistant seat face. With this special type of seat design, it is possible to manufacture the valve drop tight according to EN12266 –A requirements.
Stem
The valve shaft, often also referred to as the stem, is the component that connects the disc to the actuation mechanism and transmits the torque through itself.
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Seals
Seals are present at multiple interfaces within the valve to either ensure a tight seal during operation or to isolate the process media from the valve’s internal components for a more flexible and cost-efficient design.

Sealing on seat face is ensured by a continuous T-profile resilient sealing ring which is held on the periphery of the disc by a retaining ring, preventing the sealing ring from rolling out. In the closed position, the sealing ring is pressed against the seat face, providing a tight seal on both the upstream and downstream ends. In the open position, the sealing ring is completely unstressed due to the double eccentric disc design.

By eliminating interaction between the process media and the stem/shaft, the multiple O-ring shaft sealing system ensures a maintenance-free sealing for the entire life span of the valve.

Butterfly valve parts