FGD STACK COATING AND REPAIRS

A FGD wet stack at a power plant was in need of a maintenance repair plan that would restore its longevity and exterior protective surface system. Industrial Access mobilized to clean the stack exterior and install a new protective coating. In addition, malfunctioning personnel and aviation warning lights were repaired according to regulations. Maintenance work is a regular but necessary procedure that makes sure the plant is safe and up to its standards.

A power generation plant in the southeastern United States contracted Industrial Access (IA) for a coating job on their FGD concrete wet stack of 490’ height and 51’ diameter. The operating conditions within and around a wet stack with flue-gas desulfurization process are very severe, with high level of corrosion on the concrete shell of the smokestack, especially at the top of the structure. Naturally, the concrete surfaces on the roof deck and the top section of the stack had worn down over time, and any remaining paint had lost its necessary qualities that protect the structure from its harsh environment. Industrial Access mobilized to replace the current deteriorating coating system with a fresh one for maximum resistance.

IA’s engineers and technicians are experts in providing rigging and unique access solutions for industrial work at height. For this project, IA chose the most efficient and economical solution to use a swing stage approach to stack exterior access. The crew set up parapet wall clamps and installed five swing stages that are mobile vertically across the working area of the stack.

In order to prepare the concrete shell for new coating, IA team thoroughly cleaned the 81’ top section of the stack windscreen. Hydroblasting method was utilized to remove dirt, loose material, and dust from the concrete exterior. Other power tool methods, such as circular grinding, sanding, and wire brushing, were used to remove any remaining paint, weak concrete, and protrusions. Once the surface preparation was complete, the crew applied a primer coat of Tnemec Series 113 and a topcoat of Tnemec Series 1081.

Similar treatment was administered to the roof deck as well. The deck floor and the parapet wall were washed and scrubbed to eliminate dirt and chipping paint. Vertical and horizontal cracks wider than 1/8” were grinded out to solid concrete and sealed using repair mortar, and smaller cracks were cleaned and sealed with a suitable silicone caulk. Any present holes were patched. Existing sealant between the roof slab and the parapet wall was cleaned out and a waterproof silicone material was injected to prevent leaking. Finally, roof deck walls and floors were coated with a primer of Tnemec Series 66HS and a topcoat of Tnemec Series 290.

The crew also performed troubleshooting on the AWL and personnel lighting systems on the top of the stack and identified areas in need of repair. Eventually, flash tubes and trigger transformer boards were replaced on two AWL units. Thirty fixtures and ten ballasts were replaced as well, and a new set of personnel lights was installed, thus concluding the lighting system repairs.

IA completed this project on time and within the given budget. The lighting repairs will ensure the plant is kept up to code and safety regulations, and the roof deck cracking repairs will help the stack maintain its full structural integrity. The high-performance Tnemec coating products IA used in this project will provide a non-fading, low-odor resistance to abrasion, chemicals, moisture, and stains, well-suited for exterior use. The coating job will protect the stack against harmful exposure to atmospheric conditions and preserve the structure’s longevity. This and similar regular maintenance repairs are necessary for every plant in order to meet regulations and to eliminate the potential of safety hazards as well as extensive future repairs.