Butterfly valves have become a standard valve solution for controlling flow in a variety of industrial piping applications. Their low-profile, compact design allows installation into tight spaces where other valve types may not fit. Let’s explore the types of butterfly valves commonly used as well as characteristics to consider when selecting one.
GG-series valves like the ggg50 butterfly valve has standard wafer or lug body styles suitable for line sizes 1/2″ to 48″. The disc is connected to the valve stem via a stub or shaft depending on design. Bolted bonnet construction allows re-packing without dismantling. EPDM or PTFE seat materials provide tight shut-off against liquids and gases.
U-Type Butterfly Valves
U type butterfly valves have a U-shaped yoke that forms the top and bottom of the valve body along with a short sleeve section. This configuration eliminates cavities where solids could collect. U-style valves tend to have higher pressure ratings and bubble-tight shut-off compared to wafer types. They are a good choice for slurries, pastes or powders prone to settling.
Lug-Type Butterfly Valves
Similar to U-types but with extended lugs drilled and tapped instead of a short sleeve section. Lugs allow bolting between two flanges for maximum-strength installations subject to high differential pressures. Suitable for line pressures 300 PSI and above in applications like power plants, refineries or large pipelines.
LT butterfly valve is a specific type of lug-style butterfly valve:
- The LT butterfly valve has a lug-type body design.
- Due to its robust lug-style body, the LT butterfly valve has a higher pressure rating than wafer-style valves.
- LT valves require flanged connections between two pipe flanges.
- LT butterfly valves typically meet international standards like ANSI, DIN or JIS depending on the manufacturer.
Disc And Stem Connections
Most valves use either a stub shaft or threaded disc connection method to join the disc to the stem. Stub shaft connection provides strength and repairability by detaching the disc. Solid shaft designs offer higher torque transmission for severe service but are not as field-serviceable.
Seat And Disc Materials
Standard discs are made of polypropylene or stainless steel for corrosion resistance. Seats utilize resilient or metal-to-metal sealing for specific applications. Common seat elastomers include Buna-N, Viton, Teflon or Kalrez for chemical compatibility. Wafer valves typically use elastomer seats while high-pressure valves employ metal seats.
Maximum recommended velocity through a butterfly valve is around 25 feet/second depending on lining. Higher velocities would increase erosion risks to the disc edge and seat. Pressure limits vary per valve style and size – typically rubber-seated valves hold 150 PSI or less, while metal-seated types reach 300 PSI to 2500 PSI.
Industry-leading manufacturers provide top-quality butterfly valves in a variety of configurations. Top brands also supply automation, actuators, limit switches and controls to integrate valves into I/O systems for remote monitoring. Additional accessories include gear operators, gear-operated actuators or electric actuators for on-off service applications.
Butterfly valves offer an excellent economical flow control solution for many piping network applications. Selecting the right valve type, size, materials and construction for a given service delivers long-term performance and reliability.