Metal Seated Butterfly Valves

From: <bhanu>
Date: Tue May 15 2001 - 11:13:00 EDT

We want to procure metal seated butterfly valves for our water lines.

The seat leakage test pressure is 17.6 Kg/cm2.

The working pressures in the water line range from 10 kg/cm2 to 16 kg/cm2.

All the valve manufacturers have said that if we procure a metal seated BFV with a seat test pressure of 17.6 kg/cm2, the valve will work at 17.6 kg/cm2 but will leak at 10 kg/cm2. Therefore the valves would be leaking at working pressures, as 10 kg/cm2 to 16 kg/cm2 is our working pressure.

Is the argument right that metal seated BFV designed for a particular seat test pressure will leak at all lower pressures.

Please clarify on this argument.

Are there any codes which prohibit testing of seat leakages at lower pressures, other than the seat test pressure.

When we are pressurising a valve for seat leak test, is it ok if the valve leaks at lower pressures.

I would be glad for a early reply.

Bhanu

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