CHEMICAL PICKLING AGENT FOR SURFACES OF THE CARBON STEEL AND LOW ALLOY STEEL COMPONENTS

摘要

The invention relates to a chemical agent for removing scale and dissolving corrosion products formed in water on the surfaces of the carbon steel and low alloy steel components. The chemical agent comprises citric acid, ferrous chloride, hydrochloric acid and an acid-corrosion inhibitor and acts best by recirculation at temperatures in the range of 80...100 degrees C, or at the boiling temperature under static conditions. A compact 3.0 mm-average - thickness layer of corrosion products consisting of magnetite (the greatest ratio), hematite and non-stoichiometric mixed oxides from samples collected from the pipes of the discarded components of hot water boilers used in the thermal power stations is removed by boiling for 15 hours in a solution of 0.2 M citric acid, 0.02 M ferrous chloride, 1 x 10 - 2 M hydrochloric acid and 0.8% acid corrosion film-forming inhibitor. The general corrosion rate of base steel is about 1 mg cm - 2 h - 1, without a localized attack visible by the optical microscope.