What are the causes of pitting on the water side of the boiler heat exchange tubes?
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Local scaling in the water side of the boiler’s heat exchange tubes occurred in several spots, with dimensions of 20X20X10. After mechanically removing the scaling from the tube walls, holes of 3-4 mm remained. I would like to know what caused this phenomenon and what methods can be used for testing it.
It could be oxygen corrosion, which occurs frequently in boilers. You can check the oxygen content in the water
It’s hard to say. If there aren’t major issues with the water and if it has been properly deoxygenated, I think it might be metal damage caused by excessive heat beneath the scale
It is underfilm corrosion; I forgot in which book I read about its corrosion mechanism.