Wafer Vs Lug Butterfly Valves

Butterfly valves are quarter-turn valves used to control the flow of fluids in a wide variety of applications. Wafer and lug style butterfly valves are two common types, each with its own advantages and disadvantages. Choosing between them depends on factors such as cost, space limitations, pressure requirements, installation method, and piping configuration. Here's a detailed guide to help you make an informed decision:

1. Installation Method:

• Wafer Style: These valves are designed to be sandwiched between two flanges using bolts that go through the valve body and into the mating flanges. They do not have provisions for bolting directly to the pipe, which means they cannot be used for isolating services without additional support or double block-and-bleed systems.

• Lug Style: Lug-style butterfly valves feature integral lugs on the valve body, allowing them to be installed between two flanges using only two sets of bolts (four per valve). This design allows them to be installed without removing other sections of the pipeline, providing a more compact installation and enabling them to act as isolation valves. Furthermore, lug-type valves can be installed bidirectionally, meaning they can handle flow in either direction.

2. Piping Configuration:

If your system requires frequent disassembly for maintenance or replacement, wafer style valves may be more convenient since they're easier to remove from the line.

Lug style valves offer a dual-functionality where they can be installed inline and provide a shut-off in either direction, making them ideal for systems where isolation is necessary at multiple points along the line.

3. Pressure Requirements:

• Lug style valves typically have higher pressure ratings due to their sturdier construction and ability to withstand bi-directional pressures. They are often preferred in high-pressure applications or when positive shutoff is critical.

• Wafer style valves are generally suitable for lower pressure applications and systems where full isolation isn't required.

4. Space Constraints:

• Wafer style valves are thinner and take up less space between flanges, which makes them advantageous in tight spaces or where weight is a concern.

• Lug style valves are slightly bulkier but offer the advantage of not needing to install additional supports for isolation purposes.

5. Cost Considerations:

Generally, wafer style butterfly valves are less expensive than lug style valves due to their simpler design and fewer components.

However, if you need isolation capability without additional supports, the long-term savings in terms of maintenance and operation might justify the initial higher cost of lug style valves.

Fire-Safety Standards:

In some jurisdictions and certain applications, lug-style valves meet fire-safe standards because they can remain leak-tight even if one set of bolts fails in a fire situation.

In conclusion, choosing between wafer and lug butterfly valves largely depends on the specific demands of your application. Assessing your needs based on factors like pressure rating, flow direction, isolation requirements, available space, and budget will enable you to select the most appropriate valve type for your project.