Potentiostatic, potentiodynamic, and immersion tests were conducted on a range of alloys used in paper-machine service. It was found that thiosulfate contamination of white water can cause pitting in AISI 304 and CA-15 stainless steels (SS), and, by comparison, salts such as NaCl, Na2SO, and Al2(SO4)3 are much less corrosive. For sensitized AISI 304, thiosulfate levels in the range of 3 to 75 ppm cause pitting, 5 to 20 ppm S2O3= being particularly aggressive. Thiosulfate pitting occurred in the absence of chlorides when sulfate was present at SO4=:S2O3= molar ratios from 1.6 to 58. Compared to AISI 304, significantly greater resistance to thiosulfate pitting was found in AISI 316 and 317 L, Ferralium 255, and cast duplex SS, KCR-A171 and Alloy 75.

This content is only available as a PDF.
National Association of Corrosion Engineers
1985
You do not currently have access to this content.