Localized corrosion in chlorine dioxide bleach media of paper industry

Chlorine and chlorine compounds have been in use since long for bleaching the brown colored pulp for producing bright paper. With the findings that these chemicals are responsible for producing carcenogenic compounds, the environmentally conscious paper industry is attempting to replace them. In this scenario, chlorine dioxide is finding wider acceptability. Indian mills have also introduced only recently chlorine dioxide as a bread stage, Recently conducted in-plant tests have shown excessive attack on stainless steel 316 L and 317 L. These in-plant tests motivated to perform laboratory tests on the above stainless steels along with more resistant duplex and super austenitic stainless steels. Long term localized corrosion tests were performed by exposing the coupons in chlorine dioxide solutions. Fitting, crevice corrosion and weld related attack have been evaluated. Attempt has I,een made to correlate the degree of attack with the chemical composition of the liquors and that of stainless steels.