METHOD FOR THE PROTECTION AGAINST CORROSION OF A STEEL, PART MADE OF AUSTENITIC OR SEMI-AUSTENITIC STEEL DURING THE PRODUCTION OF SULFURIC ACID

摘要

1. A method for the protection against corrosion of at least one steel part of a device which is used in a plant for producing sulphuric acid, and in which the steel part gets in contact with concentrated sulphuric acid, characterized in that at a sulphuric acid concentration of 93 wt-% up to 100 wt-% and a temperature of 140°C up to the boiling point of the sulphuric acid, the steel part is made of austenitic or semi-austenitic steel which has a Cr content of 15 wt-% to 31 wt-% and an Ni content of 9 wt-% to 60 wt-%, and in which the ratio of the chemical elements (Cr + Si) (Ni + Mo) lies in the range from 0.9 to 1.25, and in which the steel part has an anodic corrosion protection, wherein an anode, a cathode arid a reference electrode are connected with a potentiostat which supplies an adjustable direct electric current, and wherein the cathode and the reference electrode are in contact with the sulphuric acid and the anode is in contact with the steel part.