How many people have one of these sitting around the yard collecting rust and dirt? Somebody did. This is a heat exchanger. It is a carbon steel tube bundle that was left outside a little too long and required maintenance before it could be used again.
Who Are You Going to Call?
The first step was to clean the tube bundle. Sand blasting, they found, tore-up the tubes so a less abrasive solution was to try soda blasting to remove the loose rust.
Carbon steel is much harder and rusts slower, pitting less, than mild steel. Soda blasting will not clean mild steel as well as an abrasive media would because of this deep pitting. Since this bundle was made of carbon steel, we were able to clean this down to a suitable surface for re-coating. Soda blasting will also clean galvanized steel without damaging the zinc coating.
What's The Alternative?
Imagine wire brushing this by hand!