Butterfly Valve Seats: How to Choose Between Hard, Soft, and Rubber Lined Options

Amongst the plethora of industrial valves, the wafer-style butterfly valve is renowned for its distinctive design and effective fluid control capabilities. Its unique lamellar design comprises a fixed disc mounted on a rotating axis, which rotates to completely block the passage when the valve is closed.When selecting a wafer-style butterfly valve, it is important to consider various factors, including the fluid type, pressure range, temperature range, and flange standard. 

Additionally, the selection of disc and seat materials should be determined based on the application and fluid medium. This valve provides reliable performance and an economical solution, whether in a new build project or as an upgrade to an existing system.

In the selection of wafer butterfly valves, we often consider hard rubber seat, soft back, and rubber lining. The most significant distinction between the three is the method of installation of the valve body and sealing material, which is reflected in the differing structural design of the valve body and the shape of the valve seat.

To illustrate this, we will consider the DN100 valve body as an example. 

What is the difference between butterfly valve seats?

Upon intuitive observation of the differences in valve bodies, it becomes evident that there are variations in the design of the valve seat. The valve seat is a removable component within the valve, designed to support the fully closed position of the valve plate and form a sealing ring. In general, the valve seat diameter is the maximum flow diameter of the valve.

The valve seat material of the butterfly valve is highly versatile, with a wide range of rubber and metal materials suitable for use as valve seat materials. Examples include EPDM, NBR, PTFE, VITON, STELLITE, and others.

Rubber Hard back seat

The hard back seat material is composed of rubber on the outside, wrapped around the hard back inside. Installation is typically performed using a professional valve assembly platform, which applies pressure to the valve seat during insertion into the valve body. This butterfly valve is the most common and cost-effective option on the market.

Rubber Soft back valve seat

The Rubber Soft back valve seat is composed of rubber alone, rendering it highly elastic and justifying its designation as a backless valve seat. Furthermore, the installation method is more convenient for workers to repair, replace, and disassemble at a later date. The butterfly valve has the advantage of facilitating the replacement of valve components. The product is currently experiencing high demand in the EU and US markets.

Rubber-lined (Vulcanized) butterfly valve

The rubber-lined butterfly valve comprises a rubber-lined seat that is attached to the valve body as a single unit. The product is manufactured in large quantities using sophisticated machinery. In comparison to traditional butterfly valves, this valve exhibits superior characteristics, including high temperature resistance, straightforward operation, minimal friction during opening and closing, optimal sealing performance, and an extended service life. The only disadvantage is that the seat component is not interchangeable.

Display of butterfly valve finished products

The following images demonstrate the appearance of different valve seats installed on the butterfly valve body. All images are of genuine products.

Concluding Remarks

In conclusion, each type of butterfly valve seat (hard, soft and rubber-lined) has its own unique advantages and applications. The selection of the appropriate valve seat can effectively enhance the performance and service life of the system. Union Valve is a leading supplier of butterfly valves, offering a comprehensive range of products and specifications. Should you require further information, we invite you to contact us at your earliest convenience.