Formulating a rust preventative spray for hot axles during cooldown

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I have a process in which spindles on Steel Axles are cooled down with a water spray. I currently have a product that I add to the water that does an alright job. I have noticed that triethanolamine is the main ingredient in many rust inhibitors. Can I add 99% triethanolamine directly to water and create an RP rinse? I am looking for the most cost effective method to cool down the parts and not create rust?

Brian Scott
Chemical Manager - Marysville, OH

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Sodium nitrite (NaNO2) or potassium nitrite (KNO2) is less expensive. More of a health hazard though, especially with spraying. Triethanolamine is mostly a pH buffer and an inhibitor of acid attack. Check your quenchant's MSDS; a minor ingredient such as a nitrite or an azole may be the actual corrosion inhibitor.

Triethanolamine also has the disadvantage of having a U.S. Department of Homeland Security Screening Threshold Quantity of 'Any Amount.' See this site's News post of June 26.

Check whether the cooling rate is important to properties of the part; don't alter a heat treatment detail without engineering approval.

Ken Vlach
- Goleta, California