Acid flushing corrosion removal

[corrosionman]

Hello, We have a heavy transformer enclosed in a mild steel case that has a cooling water jacket fed with fresh clean water. The unit is old and possibly has internal corrosion that might build up and block the narrow water passages.
Experimentally we acid flushed the jacket with Phosphoric acd and the filter contained lots of heavy sludge and a lot of small soft lumps of red/brown material. We have now washed it out again with hot clean water but are curious what we collected in the filter.
We did a web search on acid flushing but there is very conflicting opions, and its mostly about washing out engine blocks. Please has anyone any advice. Thanks in advance.
Corrosionman.

 

[EdStainless]

Acid flushing is used in many fields, with mixed results. As long as you have some tools in place it can work well.
0. Try hot water with surfactants first, don't use anything more aggressive than you need.
1. You need to know that your acid will not attack good metal, either use mild acid or add special inhibitors.
2. Have a way to tell when you have reached the end of cleaning. It is common to recirculate the solution and measure either pH or metals content.
3. Make sure that you can flush and neutralize so that there are not long term surprises.
4. Leak test when you are done. You may have removed corrosion products that were plugging leaks.

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