In early 2010 ECS received a contract to install (2) 72-foot tall stacks in Camden, New Jersey. Each stack was designed to meet air velocity requirements.

An alternative specification for two new towering exhaust stacks not only significantly reduced initial costs for the Camden County Municipal Authority. The durability and superior corrosion resistance of the stacks’ all-composite design will essentially eliminate maintenance costs at a Camden, New Jersey, wastewater facility for years to come.

The 96-inch diameter by 72-feet tall stacks were designed and manufactured by Composite and odor control specialists Engineered Composite Systems. ECS made the stacks and odor control system components with corrosion-resistant and fire-retardant Vipel K022 bisphenol A epoxy vinyl ester from AOC.

To meet the specification for freestanding stacks without guy lines, the Authority initially selected stacks made of steel. A thin inner liner of fiber-reinforced polymer (FRP) composite was to be added to protect the metal from corrosive exhausts. President Jeff Jones pointed out how all composite stacks could do the job better for less.

“We explained how with a bit of creativity, composites could be used to build stacks which would withstand the same forces that the steel stacks were designed for. In addition, the solid composite construction ensures superior corrosion resistance while providing a Class 1 fire rating throughout the entire structure – inside and out.

The stacks were manufactured by the filament winding process in which continuous fiberglass roving is encapsulated in the Vipel® resin. One design parameter that helped each composite stack meet the freestanding requirement was to manufacture the cylinder wall to be well over 1-inch (25.4- centimeter) thick.

Building a composite that thick can compromise laminate integrity because of excess exotherm, the heat generated when a composite resin cures into a structural solid. “Controlled exotherm was another benefit of using the AOC material, Jones pointed out. AOC’s Eric Stuck worked with us to develop a resin formulation that keeps exotherm down until the resin was fully cured.”