Situation:

An engineering firm had placed transformers at a substation located adjacent to a coastal wastewater treatment facility in Texas. In 2015, the substation began reporting issues with premature corrosion on radiators and fans.  Samples were taken of the corrosion and the engineering firm reached out to the wastewater treatment lab to understand the chemical processes used at the facility. Engineers learned that a chlorination process was used as well as diluted hydrochloric acid to assist in the breakdown of waste. Plus, pure oxygen was used to speed the process, leading to hydrogen sulfide gases. The combination of elements/chemicals, together with the C5 marine atmosphere featuring almost constant prevailing winds forced the customer to replace radiators. Fortunately, the replacement radiators were given a Heresite coating as a primer.

Results:

Three years later, the engineering firm returned to the site for another inspection. “We expected to see the same signs of anaerobic corrosion on this visit as well as an accelerated electrochemical corrosion that would be inherent to the process chemicals used next door and the saltwater in the air,” the firm’s report states. “However, although fans in use at the substation without the Heresite coating were showing signs of severe corrosion, replacement radiators that had Heresite coating as primer under powder coat showed no signs of secondary coating breech. Even though the powder coating is already breaking down in some areas, the Heresite phenolic undercoating is fully intact.” After inspection, the firm recommended cleaning and an application of protective paint to parts currently not coated with Heresite to slow down the corrosion process, but stated that the radiators with Heresite secondary coating, “can be painted for aesthetics however, the actual Heresite layer will not be breached by area corrosion.”