Industrial Food Waste Digester Repair

Industrial Food Waste Digester Repair

CommTank was contracted by a food distribution center in Assonet, Massachusetts to perform an interior relining of their aboveground tank. The tank is used as a masher/pulper for food waste. The distribution center grinds up old fruit and vegetables, puts the mix in a digester, and recycles it. The resulting methane fuel is used to power the plant and the center gets a tax credit from the town.

Ultrasonic Thickness Testing (UTT) of the interior of the pulper, in the area of the expected patch plate weld repair, revealed that generally only 1/8” of steel remained. The metal thickness was insufficient to support the welding of a patch plate. CommTank’s inspector surmised that the acidic contents in the lower area of the digester eroded the steel over time.

CommTank ordered and delivered custom pre-rolled ¼” stainless steel sheets to the site. The internal configuration of the tank was measured and the plates were cut to size on site. Following OSHA confined space protocols; CommTank’s welder entered the tank. The plates were then loaded into the tank through the top access hatch. The stainless plates were tacked in place and welded onto the existing steel structure of the tank. This process was repeated until the entire course of the tank interior was covered with new stainless steel plates.

All work performed was inspected and reviewed by a trained, certified API-653 tank inspector. This tank is ready to be entered back into service.

Please see below photographs detailing the service.

New stainless steel section

Stainless steel is cut on the warehouse floor before being raised into the digester tank.

Digester tank support beams

CommTank staff lifts the steel support beams into place.

Welding the stainless plates

Welder tacks the support beams onto the wall of the digester tank.

Stainless steel plates welded onto the tank wall

Stainless steel plates have been tack welded to the digester tank wall.

Digester tank outer wall

A view of the digester tank exterior with the new stainless plates.

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