MECHANISM OF STAINLESS-STEEL CORROSION IN COOKING MEDIA OF THE PAPER AND PULP INDUSTRY - GAS-VAPOR MEDIA

Mechanism of 10X17H13M2T steel corrosion in cooking cellulose pulp by sulfite and bisulfite methods is studied. A solution containing 1.2% M gO + H2O + x% SO2 (x varies from 3 to 7) was heated in a digester (T = 80 +/- 2 degrees C), and an effect of dissolved SO2 on the specimen c orrosion above the solution was studied; SO2 content and pH value of c ondensate were determined. A significant discrepancy between the measu red and calculated pH values is due to accumulation of 0.05 +/- 0.03 N H2SO4. The following solutions simulating condensate were studied ele ctrochemically in the bulk and under a drop: 0.05 N H2SO4 + x SO4 (x v aries from 0.01 to 1.0%) and (0.1 and 1.0%) SO2 + yH(2)SO(4) (y = 0.02 5, 0.05, and 0.1 N). The SO2 concentration ranges in the condensate (a nd the ranges of SO2 partial pressure in gas-vapor phase) are determin ed, in which the condensate corrosivity is reduced.