[unclebilly]

Use a diaphragm pump like Hugh suggested. We had something similar at the pilot plant at Tec Cominco 20 years ago for pumping concentrated HCl.

You may be able to get an iron control package to inhibit the acid attack on the lines - these are typically organic acids that coat the metal to passivity the surface temporarily. The acid eats the deposits, not your steel. We do this all the time in the oil patch - I could get you a simple and easily obtainable inhibitor if you want - pm me.