Originally Posted by
machinist42
Filiform corrosion aka "filamentary corrosion" or "underfilm corrosion".
I politely beg to differ with the dire prognosis suggested previously, as I've generally found filiform corrosion to be readily checkable with an acid bath, I prefer phosphoric. though I suppose oxalic would work. In my experience filiform has been superficial. I'm not saying it can't erupt from within the tube, but I haven't seen that often. Mostly it's sweat spawned.
Also as you said it can be readily checkable, that's provided one is cognizant of it which many are not and that is what I think we are advocating here as two hadn't seen it before.
I also always like to learn all I can about new to me problems which always includes worst case scenario so it can be walked back from as necessary.
"'Plan for the worst, hope for the best"
