FRP LINER BLISTER REPAIRS

A FRP smokestack had been experiencing a multitude of blisters forming on its FRP liner. These blisters were causing liner delamination and putting the liner at risk for more extensive damage. Industrial Access devised a repair strategy to address each of the blisters and patch the liner up to prevent further deterioration and to return the liner to an effective and safer operating condition.

A coal-fired power generation facility in the southeastern USA had been observing thousands of blisters forming and growing on the 490’-tall liner of their fiberglass reinforced plastic (FRP) stack. Industrial Access (IA) was contracted to perform an interior inspection to assess the condition and state of the liner and its defects. These blisters were filled with acidic moisture potentially caused by possible thermal overheating. The amount and severity of the blisters was varied across different elevations, and IA team was tasked with repairing the areas with the most delamination observed thus far.

To carry out the inspection, IA’s qualified, experienced technicians utilized rope access techniques to perform four drops down the stack interior to take visual documentation and Barcol Hardness readings. For the repairs, IA rigged multiple swing-stages to easily and efficiently access the full height of the stack liner and work at multiple problem areas simultaneously. This enabled the crew to fit the repairs into the limited outage schedule.

IA had identified liner elevations needing the most immediate attention with the most severe blistering. IA crew addressed the blisters one by one, starting with slicing them open, draining and drying. These open areas were then grinded down to solid base material and properly cleaned. The missing liner was rebuilt back to its original thickness using different layers of fiberglass mats, which were designed and coated appropriately for this purpose. The repair process was finished off with a coat of protective wax.

In addition, a few other repairs were performed per the client’s request. A previously observed deteriorated lifting lug plate was repaired by removing it, cleaning and prepping the area, and installing the plate back in place. IA also repaired the peeling edges of the top resin layer at the weld seams where sections of the liner have been spliced together. The peeling layer was grinded off and the weld seam was recoated with a waxing solution. Lastly, the coating of the false floor was fading, so IA crew recoated the area with a new layer of resin.

A total of 2,000 blisters were repaired, a full circumference spanning from the false floor to EL. 60’ and from EL. 175’ to 200’.  All of the liner repairs were completed successfully and on time, returning the stack to a safe and effective operating condition. Any smaller, sparser blistering that still remained will require regular monitoring to make sure that any damage is addressed before liner failure can occur. It is critical to catch any signs of liner defects early to prevent further damage to the structural integrity and operational safety of the liner.