Issues regarding the acceptance criteria for steam purging
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The company recently carried out a steam purge, and I have some questions. Regarding the steam pipelines that enter the turbine, the forum mentions the requirements and acceptance criteria for testing. But for the steam pipelines that do not enter the turbine, is target shooting also required? But the people in the workshop said that if one doesn’t go inside the turbine, the requirements for purging are lower, but they didn’t explain how to determine whether it is satisfactory. I would like to ask, are there any other methods to determine whether such steam pipelines are qualified?
That means you can give it a gentle blow to blow out any large debris, and then use a drain to check that nothing obvious is left.
For ordinary steam pipelines, a piece of white cloth can be placed at the outlet; after purging is complete, check whether there are any impurities on it. This is how we do it.
The requirements for steam purging are quite strict, as debris entering the turbine can cause damage to its blades; therefore, it is generally necessary to verify the condition of those blades. Before purging, a 3-cm wide, smoothly polished copper sheet must be installed at the purge port (the appropriate size of copper sheet depends on the size of the purge port; if it’s too small, its effectiveness will be limited, while if it’s too large, it will interfere with the function of the purge port, resulting in poor purging performance and even causing the sheet to be blown away). After the purging is complete, check that there are no more than two to three visible particle marks per square centimeter on the blade.