In investigating the effectiveness of using various plastics to protect the working parts of equipment, particularly screw and turbine mixing devices, or pump impellers, from corrosive wear, a unit for the sulfuric acid refining of benzene and toluene obtained in an oil shale pyrolysis unit in the "Slantsekhim" PO was selected as the pilot plant base. Tests of plastics were conducted* in turbine pumps whose impellers were analogous in form and size to turbine stirrers. The working media in the indicated assemblywere very characteristic from the point of view of aggressiveness, since various ones contained acid, alkali, crude benzene, and toluene. The toluene and benzene are not aggressive toward steel, but are aggressive toward plastics, since they dissoive them; the alkali and sulfuric acid are aggressive toward metals and toward plastics. The corrosivity of these media is intensified by the action of the turbinized stream of pumped liquids, which causes cavitatiozLal and corrosive-erosive breakdown of the impeller blades, as is confirmed by the results of tests of metallic specimens in spent alkali (sludge water) and the results of inspecting metallic pump impellers for pumping the same medium after operation for 750 h (Fig. i). The rate of the corrosive-erosive wear of the impeller blades is more than 20 times as great as the rate of wear of specimens fastened in the intake pipeline at the pump, and is more than 250 times as great as the rate of wear of specimens tested in the medium in the static state [i]. Probably the roughness of the blades, which increases with blade corrosion, leads to a change in the hydrodynamic characteristics of the stream, and to the appearance of cavitational and other mechanical actions.