The Difference Between Ball Valve’s Hard Seal And Soft Seal

1. Differences in structure and mechanism

Generally speaking, the hard seal of a ball valve refers to the seal between metal and metal, and the sealing sphere and valve seat are both metal. The soft seal means that the two contacting sealing surfaces can be used alone or all soft materials can be used.

2. Differences in sealing materials

Under normal circumstance, hard-sealed ball valves are precision machined by using valve seat materials to ensure the matching accuracy with the valve core (ball), generally stainless steel and copper. The soft seal means that the sealing material embedded on the valve seat is a non-metallic material. Because the soft sealing material has a certain elasticity, the processing accuracy requirements are lower than that of the hard sealing.

3. Differences in use conditions

In terms of use conditions, generally soft seals can reach a high level, while hard seals can be high or low according to requirements; hard seals can generally do high pressure, but soft seals cannot; soft seals the seal needs to be fireproof, because under high temperature, the material of the soft seal will leak, while the hard seal does not have this problem; the soft seal cannot be used in some situation due to the problem of the flowing medium (such as some corrosive media);

Hard-sealed valves are generally prices are higher than soft-sealed ones. As for manufacturing, there is little difference between the two, mainly the difference between the valve seat, the soft seal is non-metallic, and the hard seal is metal.

4. Differences in manufacturing standards

From a principle point of view, hard-sealed ball valves and soft-sealed ball valves are the same, but because it is a seal between metals, the hardness relationship between metals, as well as working conditions, should be considered medium, etc.

Hardening treatment is generally required, and continuous grinding between the ball and the valve seat is required to achieve sealing. The production cycle of hard-sealed ball valves is long, the processing is more complicated, and it is not easy to make hard-sealed ball valves well.

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