Butterfly Valve End Connection Types
Butterfly valves have multiple options for end connection types, including wafer (flangeless), lug, double flanged and buttweld end. Some options allow for ease of maintenance, some are suited for dead-end service and some designs have weight and cost reduction implications compared to each other.
- Wafer butterfly valves are designed to be installed between flanges, with a short face-to-face dimension in relation to the pipeline diameter. These valves cannot be used for dead-end service, which requires additional isolation valves when shut down for maintenance. Wafer options are lighter and cheaper than lug style and often used in lower pressure applications.
- Lug butterfly valves are designed to be bolted to one or both flanges using fasteners threaded into lug protrusions on the valve body, with a short face-to-face dimension in relation to the pipeline diameter. These valves can also be used in dead-end service depending on seat design but may be de-rated and can be heavier than wafer style.
- Double flanged butterfly valves are designed with flanges on both ends of the body to secure the valve to mating flanges on the pipe with bolts or studs and nuts. They can be used in dead-end service; however, some valve types may be de-rated.
- Buttweld end butterfly valves are designed with bevels (weld preparation) on each face to match thickness and bevel on the pipe. The two ends are butted to the pipeline and welded, used in applications where dismantling is not common, or a potential leak path between flange bolting is a concern.
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