August 20, 2019
Author: E. S. Beardwood. NACE Corrosion 2000, Paper No. 00649, NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas, 77084, USA. www.nace.org.
ABSTRACT: Many conventional chemically treated closed loop hydronic systems suffer from corrosion associated with oxygen. The failures have been addressed through the use of traditional chemicals, such as oxygen scavengers/metal passivators and thermal mechanical deaeration pretreatment. While these approaches have worked well for high temperature hot water heating under minimal make-up water conditions, the chemical eradication process eventually fails under high volume make-up conditions. The paper will discuss the conditions that lead to this type of corrosion, the corrective actions required and a field example of the corrective action outcome. An outline will be provided for corrosion inhibitor performance expectation. A number of “tell tale” signs or observations that can be made without extensive testing or exhaustive system study will also be provided in a trouble shooting table.