What are the issues regarding the inspection of pipes within the boiler area during internal boiler inspections?
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According to the requirements of the \"Rules for Periodic Inspection of Boilers,\" internal inspections require examination of the main steam pipes associated with the boilers. However, in our facility we have 3 boilers (two in operation and one as backup), and since all of these main steam pipes are connected to the steam header, when one boiler is shut down, the temperature of the main steam pipes cannot drop below around 130°C due to valve leaks, making it impossible to conduct inspections on them. Moreover, the valves on these pipes are welded, so it is not possible to install blind flanges to isolate them. What are some good ways to cool down the main steam pipeline for inspection?
Pipelines that need to be isolated must be equipped with blind flanges. There really isn’t much that can be done. It is impossible to work under pressure.
If nothing else works, stop all three units so that the temperature drops, and then inspect the main steam pipes on all three units together
Regarding the specific methods for online handling, considering opening holes under pressure and installing valve bypass lines to enable isolation could be an option； On the other hand, to prevent such situations from occurring, dual-valve control can be considered.