In their pursuit of coatings technology for protecting new concrete in headworks areas from biogenic sulfide corrosion, engineers at the wastewater treatment plant in Harvey, Louisiana arrived at a temperature-tolerant coating system from Tnemec. “And more than 20 years later, it’s evident that their choice was correct,” reported Tnemec coating consultant Eddie Borne. “Inspections of the plant in 2007 found almost no sign of deterioration or failure of any of the products that were used in 1987 during a major expansion of the facility.”
Surface preparation on all concrete surfaces exposed to biogenic sulfide corrosion involved dry-abrasive blast cleaning in accordance with SSPC-SP13/NACE No. 6, ICRI-CSP5. These surfaces were treated with Series 120-5003 Vinester F & S, a trowel-grade filler and surfacer used to fill voids and “bugholes” and reduce outgassing. Two coats of Series 120 Vinester, a novolac vinyl ester, were then spray-applied, providing protection against corrosive exposure, hydrogen sulfide (H2S) gases converting to sulfuric acid at the substrate if they can penetrate the liner, and temperature conditions that significantly contribute to the breakdown of concrete in headworks where raw sewage first enters the plant. “The higher the temperature, the quicker wastewater becomes septic,” Borne explained. “Vinester offers superior protection from these aggressive organic acids even under elevated temperatures.”
Exterior CMU walls were treated with Series 54-660 Masonry Filler, a polyamide epoxy, followed by a coat of Series 52 Tneme-Crete, a modified epoxy coat that protects against driving rain and freeze-thaw conditions. Coating performance was also required on interior concrete walls and containment areas in buildings where chemicals such as chlorine were stored in tanks. For these surfaces, Series 54-660 was applied as the primer, followed by two coats of Series 83 Ceramlon II, a ceramic-like modified aliphatic amine epoxy. Miscellaneous metal surfaces such as handrails, grating, piping and steel buildings were power-tool cleaned in accordance with SSPC-SP3, then coated with Series 530 Omnithane, a moisture-cured urethane primer containing micaceous iron oxide and aluminum. Spray and roller-applied, Omnithane was chosen for its excellent abrasion, moisture, chemical and corrosion resistance.
“The overall project required hundreds of gallons of Vinester and thousands of gallons of other coatings,” Borne added. “Vinester has performed exceptionally well, not only at the Harvey facility, but on headwork areas at other plants including almost all major cities in the Gulf Coast area.”
The city of Harvey is on the West Bank of the Mississippi River within the Greater New Orleans Metropolitan area.