Metal seated butterfly valve is that both sides of the seal are made of metal material or other hard materials. This seal has relatively poor sealing performance, but is resistant to high temperatures, abrasion and mechanical properties.

Metal seated is often combined of such as: steel + steel, steel + copper, steel + graphite, steel + alloy steel. The steel here may also be cast iron, cast steel, alloy steel or alloys for surfacing and spraying.

Soft seated butterfly valve means that the sides of the seal are made of metal material and the other side is elastic non-metallic material. This kind of sealing has good sealing performance, but it is not resistant to high temperature, easy to wear and has poor mechanical properties. For example: steel + rubber, steel + tetrafluoroethylene.

The soft seal seat is made of non-metallic material with certain strength, hardness and temperature resistance. It has good performance and can make zero leakage, but its service life and temperature adaptability are relatively poor. The metal seat is made of metal and the sealing performance is relatively poor. Soft seals do not meet process requirements for a portion of corrosive materials, a metal seat may can solve it. And the two seals can complement each other.
Differences between Metal seated & Soft seated butterfly valves mainly fall in

1, Structural difference
Soft-seated butterfly valves are mostly mid-line type, and hard seals are mostly single eccentric, double eccentric, and triple eccentric butterfly valves.

2, Temperature
The soft seal is used in a normal temperature environment. Hard seals can be used in low temperature, normal temperature, high temperature and other environments.

3, Pressure
Soft seal low pressure - normal pressure, Metal seat can also be used in medium and high pressure conditions.

4, Sealing performance
The soft seal and the triple eccentric Metal seated butterfly valve have better sealing performance. The eccentric butterfly valve can maintain a good seal under high pressure and high temperature environment.

In view of the above characteristics, the soft seated butterfly valve is suitable for two-way opening and closing and regulation of ventilation and dust removal pipelines, water treatment, light industry, petroleum, chemical industry and other industries. Hard-seated butterfly valves are often used for heating, gas supply, and gas, oil, acid and alkali environments.

With the wide use of butterfly valves, the features of convenient installation, convenient maintenance and simple structure have become more and more obvious. Electric soft sealing butterfly valves, pneumatic soft sealing butterfly valves, hard sealing butterfly valves, etc. have begun to replace electric gate valves and globe valves in more and more occasions.

Dervos is a leading valve manufacturer and provider of engineered products for different industries in China. If you’re looking for professional feasible solutions, check out our vast range of high-quality valves which covers gate valves, ball valves, butterfly valves, as well as other control valves and more.