Owens Corning Asphalt Storage Tank Restoration
Owens Corning contracted with CommTank Inc. to provide a cleaning and repair report for a 15,000-gallon liquid asphalt aboveground storage tank. The tank is located in Brentwood, NH. The tank was cleaned out and prepared for inspection by CommTank. This summary documents the inspection and ensuing welding repair performed on the storage tank.
The liquid asphalt stored in this tank is liquefied by a heat transfer fluid system. The approach to successfully storing and handling liquid asphalt includes heating, safety and tank management. The heat exchange fluid that runs through coils on the tank bottom can be heated up to 550ºF. The asphalt on the tank bottom couldn’t be removed because the level was below the outlet flange. Ownings Corning has to guard against burns because of the elevated temperatures so CommTank’s crew could not enter the tank while the asphalt was in a liquid state. Instead we waited until the material cooled and used hydraulic chisels to remove the hardened asphalt. Tank interior surfaces were scraped down and cleared of liquid asphalt debris.
CommTank’s API 653 Inspector examined the cleaned tank and found the tank shell and interior surfaces including the ceiling, shell, roof, nozzles, and center roof support column to be in generally good condition. The tank exterior shell and roof surfaces were found to have wetted insulation in contact with the tank. This contact caused premature coatings failure and resulted in uniform corrosion. The tank bottom showed areas of severe corrosion and dime sized holes. The tank bottom plates were found to have areas of substantial metal loss.
Repairs to the tank bottom plating were a challenge due to the limited space between the heating coils and the tank floor. Our welder had to work within this tight spacing to grind and sand the metal, then weld new plates over the corroded areas.
Seam weld and plate repairs were performed to maintain the integrity of the tank. The chime on the exterior of the tank was seal repaired by preparing a steel profile proper for using a bonding agent, applying the bonding agent, and then recoating the surface of the chime.