1. The method for judging internal leakage of valves is: after the valve is closed for 4-6 hours, use an infrared temperature measuring instrument to measure the metal temperature 150mm downstream of the valve stem or valve body. If it is greater than 70℃, it is considered "internal leakage". This judgment method is applicable to most valves with internal leakage.
However, in actual work, we have encountered the following special situations:
(1) Due to the installation position of the pipeline, there is disturbed high-temperature steam before and after some valves, such as the drain valve or sewage valve connected to the pressurized drainage and drainage main pipe. Even if these valves are tight and leak-proof, their valve stem temperature will exceed 70℃.
(2) For the drain valve or sewage valve connected to the drainage and drainage main pipe in parallel, when the last valve position is close to the main pipe, as long as any branch valve in the pipeline leaks, the temperature of other valves will rise to more than 70℃, such as boiler sewage valve, superheated steam drain, etc.
2. If the operator confirms or suspects that the valve is leaking internally, the operator must notify the maintenance personnel to come to the site for confirmation. After confirming that it is leaking internally with the maintenance personnel, the defect can be registered. 3. If the operator and the maintenance personnel disagree on whether the valve is leaking internally, the inspection personnel of the Equipment Management Department should be notified to come to the site for judgment. The final judgment shall be based on the judgment of the supervisor of the General Department.
