Butterfly Valves | Lug Style | Wafer Style

Butterfly Valves:

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Used extensively in various industries, butterfly valves serve to isolate and regulate flow efficiently. The mechanism involves a disc that facilitates rapid shut off, similar to a ball valve. These valves are notably lightweight, which reduces the need for additional support. However, unlike ball valves, the disc remains in the flow stream, causing a pressure drop even when the valve is in the open position. Typically, the disc rotates a quarter turn to fully open the valve, but it can also be incrementally opened for throttling purposes.

TRUPPLY offers an extensive selection of butterfly valves.

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The construction of a butterfly valve consists of a disc that forms a seal against an elastomeric or metallic seal. The disc's rotation within the valve body restricts or allows fluid flow. Butterfly valves are praised for their versatility, applicable in both manual and process control, they effectively throttle on/off control of liquids or gases. Their compact size and cost-effectiveness make them a popular choice.

Butterfly valves typically operate with a quarter-turn action. Lever operators on these valves often feature a squeeze handle that disengages a pin from a gear-like rack. This pin assists in setting the desired disc position, enabling specific throttling. The valve can be secured in position using a thumb screw, which is particularly suitable for use on mud pumps in oil and gas drilling operations. The two predominant styles of butterfly valves are:

Wafer Type Butterfly Valve

Wafer type butterfly valves are designed to fit between two flanges, with bolts passing from one flange through to the other. This arrangement ensures the valve is held in place and sealed by the tension from the bolts. These valves are recognized for their low installation costs.

Lug Type Butterfly Valve

Lug type butterfly valves are typically used at the end of a pipeline, where there is no second flange to secure the bolts. Instead, lugs are cast into the valve body with tapped holes that correspond to the flange’s bolt pattern. Bolts are inserted through the flange holes and threaded into the lugs, as illustrated in the provided imagery.

For applications at the end of a line, the pressure rating of a butterfly valve is usually derated with a safety factor of two due to the absence of a companion flange to maintain assembly integrity. Some manufacturers may provide valves with full pressure ratings, so it's advisable to check the specific rating with the valve manufacturer before installation.

The most common types of butterfly valves come with elastomeric seals, which are effective for infrequent positioning and are usually best suited for on/off services. However, applications requiring frequent throttling of fluids should utilize metallic seals to minimize erosion risks associated with elastomers.

Butterfly valves present numerous advantages over alternative valve types, particularly in larger sizes. They are lightweight, save space, and are generally less expensive. Maintenance costs are also reduced due to fewer movable parts, and cavitation is minimized due to the lack of fluid traps.

This type of valve design is particularly suited for handling large volumes of liquids under low pressure and effectively managing slurries containing significant amounts of solids and particles. As a result, they are an ideal selection for mud pumps, which commonly contain lost circulation materials and various additives essential for drilling operations. The larger openings and simplicity of design help prevent the entrapment of such solids.

Think of the wafer style or lug style butterfly valves as pipe dampers. Flow control is facilitated by a disc that approximately matches the internal diameter of the piping system where the valve is installed. The disc rotates on either a horizontal or vertical axis, enabling fluid to seamlessly pass through.

Disk and Stem Design - Butterfly Valve

One of the key components of butterfly valves is the disc and stem assembly, which are designed as separate entities in both valve styles. The disc couples with the stem through precision machining. In one design, the disc is bored and secured to the stem using a bolt or pin. The alternative design features a bored disc with a stem that fits inside it, providing self-centering capability which can be beneficial for applications in corrosive environments.

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Q&A with a Valve Distributor

Recently, we conducted an interview with a valve distributor that specializes in smaller valves (up to 4") primarily serving the oil and gas sector. Below are highlights from this engaging session;

Speaker 1: These butterfly valves feature a ductile iron body, available in both wafer and lug styles, including a wafer option with alignment holes. The ductile iron body is designed for durability. The discs also come coated; we offer nickel-plated options with Buna-N seats and stainless steel options with Viton seats, as well as EPDM seats, correct?

Speaker 2: Exactly, Teflon is also an option. We provide different seats for these butterfly valves tailored to the applications our customers require. Recently, we have seen an uptick in clients dealing with acidic materials, prompting us to develop an epoxy-coated disc to withstand corrosive effects, along with specific seat materials like Viton or Teflon based on acid concentration. Our wafer-style butterfly valve includes a ductile iron disc and Buna-N seat, rated to 180 degrees. The lug style model features distinct notches for alignment with bolted flanges for ease of installation. The stainless steel variant, complete with a Viton seat, is rated up to 400 degrees Fahrenheit. Alignment holes, currently available in the 4-inch size, enhance operator convenience, particularly when working solo in the field.

Speaker 1: We offer these in sizes ranging from two to twelve inches, with new sizes unlocking soon, including three, four, six, and potentially eight inches.

Speaker 2: We are capable of custom manufacturing to fit your specifications; for example, we produced a set of 48-inch butterfly valves for an international buyer in Russia. Our service extends worldwide, with shipping available throughout the United States, enabling us to accommodate any custom request.

Speaker 3: What are the pressure ratings for these valves?

Speaker 2: The typical ratings are 200 class (200 lbs) or 150 lbs.

Speaker 3: Can these be used with water, oil, and gas?

Speaker 2: Definitely, they are suitable for various applications, including water and oil gas. For applications involving gas pockets or crude oil with H2S, we provide specific disc and seat recommendations based on operational requirements.

Speaker 1: It's crucial to customize the seat and disc depending on the application and conditions.

Speaker 2: All products from our factory undergo rigorous testing and come with the relevant documentation.

Our sanitary valves are engineered specifically for applications where cleanliness and sterility are critical. Whether you're handling food, pharmaceuticals, or sensitive chemicals, these valves are designed to maintain the purity of your products and minimize the risk of contamination.

Constructed from high-quality materials such as stainless steel, PTFE, and EPDM, all known for their resistance to corrosion, temperature extremes, and chemical compatibility. This ensures durability and longevity in demanding sanitary environments.

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