Case histories of using tin technology to control corrosion in water systems
Stannous chloride is an alternative corrosion control in aqueous systems. Stannous chloride’s effectiveness as a better corrosion inhibitor has been demonstrated in both municipal drinking water and industrial cooling water applications and its use has a reduced impact on rivers and streams.
Orthophosphate and other phosphate compounds are the most common treatments for reducing corrosion in municipal drinking water distribution systems as well as industrial cooling water systems. As a result, rivers and streams suffer because algae blooms occur due to over nutrification although phosphate use has helped preserve infrastructure. The alternative is stannous chloride, which is inorganic, so nutrients are not added to the water streams being treated or the wastewater discharge.
Stannous chloride has Generally Recognized as Safe (GRAS) status with the USDA. Maximum usage level is 1500 PPM as an antioxidant in canned tuna, it can also be used in canned asparagus at 20 PPM and 12.5 PPM in canned soda.
Since October 2000, AS-8150 (50% active SnCl2) has been added to the municipal drinking water of St. Paul, MN (Population 287,151) at a rate of 0.25 PPM to reduce the lead leaching rate. St. Paul has passed every round of Lead and Copper testing since treatment startup.
In February 2006, treatment with AS-8310 was initiated in the re-circulating cooling water system at the Park Central Office Complex in Denver, CO. Carbon steel and copper corrosion coupons were exposed to quantify corrosion occurring within the cooling system. Results have consistently shown corrosion rates of less than 1 Mil Per Year (MPY) on carbon steel and less than 0.2 MPY for copper. Note that AS-8310 includes a triazole for yellow metal protection.
Details of stannous chloride’s effectiveness in both St. Paul‘s municipal drinking water and Park Central’s industrial cooling water in Denver are included in the full body of this article.
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