Lug vs. Wafer Butterfly Valve: Know the Difference

Butterfly valves play a vital role in controlling the flow of various liquids and gases. Among the different types of butterfly valves, lug butterfly valves and wafer butterfly valves are two widely used options. Both valves have unique features and are suitable for specific applications. In this article, we will explore the differences between lug butterfly valves and wafer butterfly valves, which will help you make an informed decision when choosing a valve that suits your needs.

Lug VS. Wafer Butterfly Valve

Both wafer butterfly valves and lug butterfly valves refer to the connection types of butterfly valves. They have the same structural length and similar uses, but they are very different in design, installation, application, and cost.

  1. Design Difference

Lug butterfly valves are designed with threaded lugs at both ends of the valve body. These lugs are more conducive to fixing the valve.

In contrast, the wafer butterfly valve does not have any threaded inserts and is clamped between two flanges. Bolts pass through the pipe flange and the valve body to fix it, that is, it is designed to rely on the pressure of the flange of the pipe being squeezed by the bolts.

wafer vs lug butterfly valve
  1. Installation process.

Lug butterfly valves are suitable for situations where pipelines need regular maintenance or need to be frequently disassembled. Threaded inserts can be easily installed and removed without destroying the entire pipeline system. And the lug butterfly valve can be installed at the end of the pipe as a terminal valve.

In contrast, the wafer butterfly valve is more suitable for applications where space is limited to connect the two ends of the pipe, but it cannot be used as a terminal valve, otherwise it will fall off.

  1. Sealing mechanism.

The lug butterfly valve provides a tighter seal due to the threaded connection and safety bolts, ensuring leak-free operation and preventing fluid backflow.

In contrast, the wafer butterfly valve relies on the valve compression between the two flanges to achieve reliable sealing, so it needs to be installed completely aligned with the pipe to avoid misalignment and leakage.

  1. DN and PN

The wafer butterfly valve is usually DN600, and a single flange butterfly valve can be used for larger diameters. It is generally suitable for applications with pressure ≤PN16.

The lug butterfly valve has a larger diameter and can handle higher pressure levels, up to PN25, because the lug butterfly valve is more securely installed.

  1. Cost

Lug butterfly valves and wafer butterfly valves differ in cost-effectiveness. Wafer butterfly valves are generally more economical because they have a simpler design, simpler processing, and require less material. The lug ears of lug butterfly valves need to be threaded, so the processing process is more complicated.

In summary, although the purpose of lug butterfly valves and wafer butterfly valves is the same, both are to control fluid flow, they have significant differences in design, installation, sealing mechanism, DN, pressure rating and cost-effectiveness. The choice of these two valves depends on the specific requirements of the application. If regular maintenance or disassembly is required, the lug butterfly valve is the right choice. On the other hand, if space is limited and cost-effectiveness is critical, the wafer butterfly valve is a suitable choice. Understanding these differences will enable you to select the right butterfly valve for your needs and ensure efficient and reliable flow control.