Butterfly valve parts name, butterfly valve components
Butterfly valves are fast acting (1/4 turn) rotary motion valves. This type of valve can be used to start, stop and regulate flow (throttle flow).
The butterfly valve has found widespread applications in many industries due to its low number of moving parts, low maintenance costs and simple design. This type of valve is particularly well suited to high flow, low pressure systems. As the butterfly valve has a large seating area, it is also able to seat well (seal tight) even when used within systems that have a large amount of suspended solids.
Industrial butterfly valves have very similar parts and function. While there are minor differences, the major components and their purpose are practically the same. A butterfly valve’s main components consist of stem, body, sealing arrangement, upper bearing, lower bearing, bonnet, actuator, seat and disc. The designs for each component varies depending on the materials used, the flow media, purpose and the likes.
Butterfly valve body
Butterfly valves generally have bodies that fit between two pipe flanges. The most common body designs are lug and wafer. The lug body has protruding lugs that provide bolt holes matching those in the pipe flange. A wafer body does not have protruding lugs. The wafer valve is sandwiched between the pipe flanges, and the flange bolts surround the body.
Each type of body has advantages, some of which are listed:
The wafer style is less expensive than a lug style.
Wafer designs do not transfer the weight of the piping system directly through the valve body.
A lug body allows dead-end service or removal of downstream piping.
Butterfly valve disk
The flow closure member of a butterfly valve is the disk. Many variations of the disk design have evolved relative to the orientation of the disk and stem in an attempt to improve flow, sealing and/or operating torque.
The disk is the equivalent of a plug in a plug valve, gate in a gate valve or a ball in a ball valve. Rotating the disk one-quarter turn or 90 Degrees opens and closes the butterfly valve.
Butterfly valve stem
The stem of the butterfly valve may be a one-piece shaft or a two-piece (split-stem) design.
The stem in most resilient seated designs is protected from the media, thus allowing an efficient selection of material with respect to cost and mechanical properties.
In high-performance designs, the stems are in contact with the media and, therefore, must be compatible, as well as provide the required strength for seating and unseating the disk from the seat.
Butterfly valve seat
The seat of a resilient-seat butterfly valve utilizes an interference fit between the disk edge and the seat to provide shutoff. The material of the seat can be made from many different elastomers or polymers. The seat may be bonded to the body or it may be pressed or locked in.
In high-performance butterfly valves, the shutoff may be provided by an interference-fit seat design or a line-energized seat design, where the pressure in the pipeline is used to increase the interference between the seat and disk edge. The most common seat material is polytetrafluoroethylene (PTFE) or reinforced PTFE (RTFE) because of the wider range of compatibility and temperature range.
Metal seats are also offered in high-performance butterfly valves. These metal seats allow a butterfly valve to be used in even higher temperatures to 1,000 Degrees F. Fire-safe designs are offered that provide the shutoff of a polymer seat valve before a fire, and the metal seal backup provides shutoff during and after a fire.
The above are the main components of the butterfly valve and their contribution to the function of the butterfly valve. Determine the environmental conditions of the butterfly valve and determine the selection of suitable material components for the butterfly valve.
VALTECCN has many years of experience in the production and sales of butterfly valves, processing and manufacturing of butterfly valve parts, and abundant spare parts in the warehouse. Welcome to consult and purchase.