Student asks if EN is resistant to various acids

First of two simultaneous responses --

A. It depends on concentration, temperature, aeration and other factors (i.e., galvanic currents), etc. But basically EN will show some resistance to phosphoric (like 0.1 mm penetration per year at 85% conc., room temp) and sulfuric to some degree (0.4 mm /yr. at 65%, room temp). Not too much to hydrofluoric (probably measured in days ) and almost zero to nitric (0.1 mm in few hours).

Second of two simultaneous responses --

A. It is not that simple. It depends on the thickness of EN, the Phosphorous %, The heat treat state, The quality of the application. Then, for the acids, at what temperature, what other contaminants are also in the solution, the concentration, the solution flow or turbulence, oxygen levels, and probably several things that I left out. HF is so nasty that I would not use anything other than teflon to be in contact with it. I would not expect phosphoric to have an immediate or strong attack. Sulfuric will have a medium attack and nitric will have virtually an immediate attack.