August 21, 2019
Author: E. S. Beardwood. NACE Northern Region Symposium , November 1991, Toronto, Ontario, Canada
ABSTRACT: Calcium chloride brines used for deep ammonia refrigeration cooling equipment have long been known for their deleterious effects on the system’s metallurgy. Inorganic corrosion inhibiting packages (blends) have been available for the mitigation of the problem for many years. However, the most effective and wildly used, buffered chromate, has now come under environmental and work place hazard scrutiny. While it was expected that the closest inorganic corrosion inhibitor substitute, buffered nitrite, would provide similar performance, this was not found to be the case. The new All Organic blend approach provided carbon steel corrosion rate reductions of 99% , equivalent to 1600 mg/L (ppm) of buffered chromate and 450 mg/L (ppm) chromate with zinc and phosphonate blend. Copper and admiralty brass corrosion rates were in the 90% range compared to 60 – 70 % range for the chromate based programs. This was the first organic based brine corrosion inhibitor to be commercialized.