What is the condition of storing H2So4 in miled steel tank?

Question

What is the condition of storing H2So4 in miled steel tank?

Answer 1

The H2SO4 must be concentrated (98-99%) and kept dry.

Don't wash the tank out with water.

The acid will absorb moisture from the atmosphere, so you must take steps to seal the take or keep moisture out.  Don't run steel vent pipes out of the tank, because moisture will crept back into the pipes (use PVC vent pipes).

Some small corrosion will occur (~1 mm/yr) and the acid will turn yellow from dissolved iron, unless you add anodic protection systems (see link).

Sulfuric acid in the 70%-100% range is considered concentrated, and as such, is an oxidizing acid.  Below 70% concentration it tends to act as a reducing acid.   The oxidizing or reducing behavior depends on the metal exposed.  If the sulfuric acid becomes reducing, rapid attack will occur with mild steel.