The rotary impingement tank cleaning machines combine pressure and flow to create high impact cleaning jets. Cleaning occurs at the point in which the concentrated stream impacts the surface. It is this impact and the tangential force that radiates from that point which blasts contaminants from the surface, scouring the tank interior. In conjunction with this impact, the tank washing system is engineered to rotate in a precise, repeatable and reliable, 360-degree pattern. This full-coverage, global indexing pattern ensures the entire tank interior is cleaned, every time. This combination of impact in a controlled indexing pattern results in an economic ideal, because impact is a one time investment; chemicals, temperature and time are continual, never-ending expenditures.