How to do the leak test of steam turbine valve? What are the criteria for judging its eligibility?

During the test, the main steam pressure is greater than 50% of the rated pressure, the back pressure of the condenser is less than 5kPa, and the steam turbine regulating valve or the main valve is operated separately;

After the valve is closed, the stable speed of the steam turbine is less than or equal to (pressure/rated pressure during test) × 1000r/min.

The purpose of steam turbine valve tightness test is to check whether the valve is tight and prevent the unit from overspeed when load rejection. Valve leak test is generally arranged before the turbine is connected to the grid.

Extended data:

Matters needing attention in steam turbine start-up and operation:

1, when the steam turbine is fully heated under normal conditions, no-load for a short time will not damage the unit. However, long-term low-load operation is not recommended.

2, after load rejection, the main generator with auxiliary load (auxiliary power) should not exceed a few minutes (3 minutes).

3. At all times, avoid steam flowing through the turbine during the static stage of the rotor.

4, when the rotor is stationary, should avoid air flowing through the gland device. Therefore, when there is no sealed steam in the steam turbine gland, do not start the vacuum pump or air extractor.

5. Under a certain degree of vacuum, don't make the inlet steam temperature of the intermediate pressure cylinder exceed the operation requirements, so as to avoid overheating of the low pressure part of the steam turbine.