[Q&A Question 064] 2016.06.23
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【Q&A Question 064】June 23, 2016: What are the key points in conducting a light-off inspection? The answer key will be available after responding; scoring is based on answering the key points. Flanges, valves, air-cooled plug valves, and equipment connections on high-pressure hydrogen pipelines.
It is commonly known as a dark-check; it involves turning off all nearby lighting at night for high-voltage live equipment, in order to inspect the live parts of such equipment for any signs of corona discharge or sparking. Especially between cables, breakdown discharge can occur easily, but it is difficult to detect under the illumination of external light sources; it can only be identified after the lights are turned off, which is why inspections should be carried out with the lights off.
It is mainly the high-temperature hydrogen-exposed areas, as hydrogen can catch fire on its own at high temperatures, producing a blue flame that can only be seen at night. The key points of inspection are the high-temperature flanges in the hydrogen system, especially the control valves and thermocouples in the reactor area, as well as all other high-temperature areas!
Mainly the hydrogen-related systems: hydrogenation compressors, reactors, high and low pressure separators, hydrogen production compressors, conversion furnaces, and various reactors
The key point when checking with the lights off is that all light sources inside the device are turned off.
Check the hydrogen system for leaks. Hydrogen leaks produce a faint blue light
Avoid interference from cold light sources such as on-site indicator lights