CHIMNEY FRP LINER RELINE, SUPPORT RING REPLACEMENT & CONCRETE REPAIRS

A coal-fired power plant needed extensive repairs and reinforcement performed on their 404' chimney, including its concrete exterior shell, FRP liner, breeching duct, and mechanical systems. Industrial Access provided engineering, specialized access, and full-scope repair services to address structural, mechanical, and safety deficiencies throughout the structure, including FRP liner reline work, breeching duct cover plate replacement, and liner support ring, beam, and extension joint replacement. The complete repair program returned the unit to safe, reliable operation during a single extended outage.

A power generation facility in the southeastern USA operates a 404'-tall reinforced concrete chimney with a 400' FRP liner serving one of its coal-fired units. Following inspection, the facility identified a wide range of deficiencies throughout the structure requiring correction before the unit could be returned to full, safe service. These included severely corroded liner support members and support ring at the base of the liner elbow, a deteriorated stack expansion joint, a failing quenching system, and corroded breeching duct components.

The FRP chimney liner also showed signs of leakage, with staining visible on the exterior, and cracks, blisters, and other deterioration found in the laminate. Further spalling exterior concrete was identified, along with oxidized interior and exterior steel appurtenances and platform grating deficiencies. Industrial Access (IA) mobilized to perform a comprehensive repair scope to restore structural integrity and bring the chimney back into compliance.

To reach the full height of the chimney exterior, a combination of rope access techniques and swing stage access were utilized to perform the repairs on the concrete shell, breeching duct, and steel appurtenances. For the interior repairs, a custom work platform was assembled on-site and suspended from the top of the stack, giving technicians access to the full height of the interior liner, supplemented by rope access, swing stage, and scaffolding in select areas for other repairs. To safely replace the liner support ring, IA designed and installed a proprietary lifting system customized for the project to elevate and temporarily hold the elbow in place while the ring and support beams were removed and replaced.

IA began by addressing the structural repairs, reinforcing the corroded and buckled breeching duct support posts and beams by welding steel plating into place, then applying a corrosion-resistant coating. Deteriorated sections of exterior concrete were repaired throughout the chimney: damaged material and corroded reinforcement were removed, surfaces were prepped and primed, and repair mortar was applied to restore the shell. Breeching duct insulation was damaged and covered with vegetation, so the insulation was removed and replaced. Since the cover around the breeching duct opening was severely corroded, IA demolished it and replaced it with a newly fabricated, coated cover plate.

Throughout the interior and exterior, IA cleaned and coated oxidized steel appurtenances, including platform framing, access doors, guardrails, stay rods, ladder standoffs, and the liner support grillage. Damaged and corroded grating was replaced, and toe boarding was installed around remaining openings to eliminate falling hazards. A new rest platform was installed along the ladder to break up the long climb between the upper and lower interior platforms, and safety gates at every ladderway floor opening were replaced with new, self-closing, OSHA-compliant units. Additional miscellaneous repairs included replacing oxidizes conduit covers and missing flange bolts, and repairing non-functional AWL and personnel lighting.

On the mechanical side, IA replaced the severely corroded liner support beams at the base of the elbow and fully replaced the liner support ring. The new ring was fabricated in four sections, lifted into place, welded together in halves, and bolted and sealed around the liner, with all beams and the new ring coated in a two-part protective system to guard against acidic slurry exposure. IA also installed a new seal air fan and ductwork to restore proper stack ventilation, and replaced the aging, corroded expansion joint near the top of the FRP elbow. The quenching system was fully demolished and rebuilt, with a newly fabricated FRP header, stainless steel pipework, and nozzles installed and tested to confirm proper function.

For the liner itself, IA technicians media blasted and prepped damaged sections of the FRP from the breeching opening through the elbow and up to roughly 75' above, completing repairs across approximately 35% of the liner. Any non-conformities were ground out and tapered to blend with the surrounding laminate, then rebuilt with layers of strand-mat and stitch-mat, resin, and primer. Repaired sections were top-coated and post-cured, with Barcol hardness testing performed to confirm the repairs met required standards. Splice ring repairs were also completed at the designated elevations to tie the reline into the existing liner.

The full repair and reline scope was completed successfully, restoring structural integrity across the chimney's structural steel, concrete shell, and FRP liner while bringing safety features into full compliance. With critical mechanical systems replaced and reinforced, and roughly a third of the liner restored, the facility gained extended service life and improved reliability from the unit's chimney. IA regularly performs inspection and repair services for chimneys and stacks across the power generation industry, offering integrated engineering, access, and construction solutions for even the most complex structural repairs.