New Coating Technology Helps Protect GAC Filtration Systems from Corrosion and Abrasion

By: Vicki Schauer
    

Chuck Bartunek, a representative for Enviroline, an International Paint Protective Coatings brand, introduced Fresno’s water municipality to a cost-effective, highly chemical-resistant, low-VOC alternative. “When I explained that Enviroline 230 is a fast-cure, 100% solids epoxy Novalac lining that can be applied in one application with virtually no maintenance required, it wasn’t hard for the City to calculate the significant cost and time savings it would bring to new construction and repair projects,” said Bartunek.

No Room For Error

As a trial, the City specified Enviroline 230 on a new GAC filtration project slated to support a new housing development. The three 10-foot diameter by 15-feet high GAC tanks were fabricated at Downey Welding in Downey, California, and then shipped to Goodwest Rubber Linings’ climate-controlled facility in Rancho Cucamonga, California for coating. More than 1,500 square-feet of steel would receive the Enviroline 230 lining.

The first step in the process was to prepare the tank interiors and exteriors. Working inside an enclosed blast booth, crews used steel grit to blast tank interiors to a NACE No. 1/SSPC-SP-5 white metal abrasive blast standard. The interiors were then vacuumed out to remove any remaining grit and contaminants. Crews wore blasting helmets, safety glasses, and leather garments to protect their upper bodies from steel grit overspray. The exterior tank surfaces were then blasted to a NACE No.2/SSPC-SP-10 near white standard. After surface preparation was completed, the tanks were moved into the facility’s spray booth.
 

The painters wore full-face organic cartridge respirators, chemical-resistant coveralls, and harnesses with lifelines, while the tanks were ventilated and grounded. One painter worked inside the tank, while another operated the Graco Xtreme plural component pump outside the tank. A third painter helped with the hoses and served as a manhole attendant.

Many solvent-based tank linings pose a high explosion risk; however the low-VOC, 100% solids Enviroline 230 thick-film lining posed no threat during installation, was easily applied in one coat at 30 to 50 mils, and allowed to cure at ambient temperature. The tank exteriors were coated with an alphatic polyurethane system.       

Goodwest’s President, Ryan Sears, said, “It would normally have taken up to three days to install the vinyl ester, using multiple coats and forced heat to evaporate solvents and meet the NSF-61 standard. The tank interiors were coated, cured, inspected and ready for service within 24-hours.”

Ed Darrimon, President of Bay Area Coating Consultants, was hired by the City to follow all surface preparation and lining operations including Holiday inspection of the tank interiors. Wearing a hard hat and safety glasses, Darrimon used an Elcometer model 236 high-voltage holiday detector to scan the lining for “holidays” or discontinuities that indicate a void in the lining’s surface. The process is straight-forward: Pinholes are clearly marked, and any amine blush is removed before repair. After the surface is de-glossed and abrated, the lining is re-applied by hand. Surfaces are then re-tested using the same process. In these tanks, only four or five pinholes were detected, mostly around welds and edges. After meeting the NACE SPO-188 standard, the tanks received a green light from Darrimon and were shipped to the Fresno housing site.

As the San Joaquin Valley continues to grow, Enviroline 230 will be working to help keep the area’s potable water supply safe. Fresno’s Water Division Engineer, Brock Buche, adds, “We’ve been very impressed at the quick turnaround on new GAC filtration construction and repair projects. Coating technology that can provide superior rust and corrosion protection, while saving time and money, is a valuable resource for every municipality.”


 

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