At the Ameren Missouri coal-power plant, the areas that are used to convey coal into furnaces, called tripper rooms, were fraught by a cloud covering. The facility owners at this plant needed to do something about it. Dust in a power plant is a fire hazard, after all, which meant that regular cleanup was required.
To find a better solution, the facility is moving to wash downs, but even that was having some issues. Leaks were starting to show — until now.
Solving the Leaks
Because the coal and dust weren’t going anywhere, the facility decided it needed to do something about the leaks. “Water would be dripping down in an area below the application area, but finding where it came from was not easy to determine because the water would sometimes run along a beam for a distance before dripping,” explained Will Strupp, project manager/estimator for Coatings Unlimited Inc. (CUI). To be on the safe side, the client contracted CUI to help with a more encompassing solution.
But first, they had to gain access. At approximately 100 feet (30.5 m) in the air, the rooms were far from the ground level where the larger equipment was stationed. The crew had to get their blast hoses and air lines up to the project area before they could start working. “It did prove quite challenging,” Strupp said. Luckily, they were able to use a freight elevator for any materials that had to be in the work area, such as the spray pumps. The larger equipment stayed on the ground, so the crew used walkie-talkies to communicate.
The crew, which averaged six people, started by abrasive blasting the approximately 15,000 square feet (1,393.6 m²) of uncoated steel. They used a fork truck to load all 3,000 lbs. (1,360.8 kg) of the abrasive super sacks into the 6-ton (5,443.1 kg) blast pot. “Abrasive blasting brought the steel back to a cleanliness level sufficient for the coating material to be applied,” said Strupp. For this step, they also used a 1300 CFM (36.8 m³/min.) compressor, two blast nozzles, and fans permanently affixed to the walls of the building “that helped remove dust for clarity while working,” Strupp continued.
While abrasive blasting, the crew wore air-fed hoods, long-sleeved shirts, and long pants. Although the clothes helped keep the crew members safe from the abrasive, they added another layer of safety concerns to the job: heat. Not only did this project take place during the summer months in Missouri when the plant was at its peak, but there were furnaces in the room below working on high demand. “I have much respect for these guys for not only performing difficult tasks, such as abrasive blasting but doing so in temperatures exceeding 120° F [48.9° C],” said Strupp. The substrate itself got up to 150° F (65.6° C) at times! Strupp explained, “This called for frequent breaks, which slowed production, but kept our men safe from heat stroke.” It also called for heat-stress training and the use of Clemco Industries Corp.’s Climate Control Cooling Vests.
With the substrate prepped, the crew was able to move onto the UrePrime 1305. They wore steel-toed boots, gloves, hardhats, safety glasses, and half-face respirators with 3M cartridges while they installed an average of 5 mils (127.0 microns) of the urethane primer using spray, brush, and roller techniques. All layers of the liquid-applied coating system were applied across the floor and about 6 inches (15.2 cm) up the walls.
Because the crew members had to work around the coal conveyors that ran almost the entire length of each room, they had to coordinate with the owner’s rep at the facility to have the conveyors turned off for short periods of time. When the conveyor belts were on, which was most of the time, the crew worked very carefully around the potentially dangerous equipment to prepare the equipment and substrate.
Time was crucial for the next step in the coating system. The crew applied an average of 90 mils (2,286.0 microns) using rented plural-component spray equipment: Graco’s NXT Xtreme 1:1 Reactor Skid with a Fusion gun. “We utilize daily toolbox talks and implement Jobsite Safety Analysis forms on all projects,” Strupp explained of the CUI crew, which also uses online resources for safety training.
“When utilizing a plural-component pump for application of coating materials, I would recommend having plenty of workers on hand for handling the hose lines and running the pump. Once the trigger is pulled, you can’t necessarily stop to make adjustments to anything; you must keep moving,” Strupp said. The crew applied this layer of the system by “flooding” areas where steel beams or holes came through the substrate. In areas with larger gaps, they used foam backer rods prior to applying the GeoTek 4950 polyurea. That helped keep the polyurea from flowing into the rooms below the work area and saved on material. “This solution for the owner’s problem came from Creative Polymers of St. Louis, Missouri, who wrote the specification and provided onsite technical support throughout the project,” Strupp explained.
On top of the polyurea, the crew applied a total of approximately 15 mils (381.0 microns) of 2505 polyurethane finish in two coats with Graco’s Bulldog/King 45:1 Pump, also used with the primer. Into the first coat of this epoxy material, they broadcast coal slag by hand to any areas that would have foot traffic.
The crew cleaned up excess slag with brooms, shovels, and compressed air. “CUI had a vecloader/industrial vacuum cleaner at ground level connected to an 8-inch [20.3 cm] plant pipe. The crew would shovel the spent abrasive into the pipe at the work level, and it would fall to ground level and be sucked through the vecloader into a 30-yard [27.4 m] Dumpster,” Strupp explained. The crew applied the second coat of 2505 polyurethane finish and tested the thickness.
Time to Test!
“Creative Polymers had to monitor the project extensively, providing the owner with inspections and sign offs due to the incredibly dusty conditions and potential inter-coat adhesion possibilities,” explained Jeff Jarboe of Creative Polymers.
Another test was used once the crew had pulled off the termination tape. The client hosed down the entire area and went back in to see if there was water dripping down below. “The water test worked well and exposed only a few areas that needed to be touched up,” Strupp said. A two-person crew from CUI plugged any areas with either caulking or the polyurea material. Once they cleaned out the pumps with solvent, they were able to put a full stop on the end of the month-long project.
According to Strupp, this was not only a success for the client but also for his crew. “The entire project team impressed me, as this was far from a routine application,” Strupp said. “One of the difficulties in such a large facility of this type is just that: the size of the facility,” explained Strupp. But the crew from Coatings Unlimited Inc. prevailed.