Difference Between Soft Seal and Hard Seal

1. Soft Seal
In addition to corrosion resistant lining valves, a general soft seal valve refers to nonmetallic material (Teflon/PTFE, rubber, etc.) which are used in either wedge/disc or seat. It has a better sealing performance than that of hard seal. But when pipeline installation and system cleaning, there might be sundries(welding slag, iron chip, etc.) left, which can easily scratch soft sealing surface. Time after time, leakage is increased and reliability of its seal is getting poorer. Therefore, choosing soft seal structure must consider the cleaning of medium and strictly wash the pipeline before putting into operation.

2. Hard Seal
On the contrary, hard seal valves are valves which have metallic material for sealing surface. Hard seal valve is a good choice for shut-off valve. Not only the sealing performance, but service life and reliability are considered when choosing this structure. Though it cannot have the zero leakage effect, it's more tough and durable in a solid circumstance. So it may be more economical from a long-term point.