STEEL STACK REPAIR & GUNITE LINER REPLACEMENT

Power generation facility was operating a steel stack unit that was in need of liner replacement services. The existing gunite was severely deteriorated and signs of steel shell damage were present. Industrial Access delivered gunite liner system replacement and then easily adapted to the changing scope of work when additional urgent repairs were required. The damaged stack shell was repaired, and the stack was covered with a protective coating system to restore stack integrity and its defenses against the harsh environmental conditions.

A power generation facility in the Midwest was looking to get their 124’-tall corten steel exhaust stack repaired. Previous inspections reported the interior liner to be in poor condition, with large areas of gunite refractory missing, cracking, and crumbling. Stack exterior showed signs of steel degradation with numerous holes present. Industrial Access (IA) was contracted to replace the liner and perform any necessary repairs to ensure the stack can continue operating safely and effectively for years to come.

To perform these repairs, IA had to install an access door by cutting a hole near the base of the stack to allow access for the equipment required for the liner replacement procedure. The access panel was then reinstalled and the seal was welded towards the completion of the project. In addition, IA designed and installed a work platform below the stack inlet to provide a staging platform for and access to the swing stages. The crew utilized swing stages inside and outside of the stack to facilitate liner replacement and steel shell repairs. IA engineers and technicians are experts at providing unique access solutions at any given situation.

IA crew mobilized and rigged to begin the deteriorated gunite liner demolition. The entire refractory layer was broken loose from the stack walls and removed using pneumatic hammers, and the remaining debris was cleaned from the work platform at base at the end of each shift. Once the liner demolition was completed, over 100 holes were revealed on the steel stack shell. It was crucial to repair stack walls before installing a new liner system, so IA covered the holes by welding steel plates to the stack. The plate patching service was administered to both stack interior and exterior, including the doghouse. In addition, two full-circumferential steel stiffener rings were installed to address areas of thinning steel shell.

Once the stack surface was repaired and cleaned, every existing steel horn anchor was inspected to identify any in need of replacement. Anchors that were too oxidized or deformed were removed and replaced, and new steel horns were installed on any areas with anchors missing (particularly on the newly installed steel plates). IA then applied a coat of protective corrosion-resistant lining membrane to stack interior before a 2”-thick new gunite refractory liner was installed throughout the entire height of stack interior.

During this mobilization, the client approved a few additional urgent work items identified during the repairs. One of the items was an installation of a davit arm at the top of the stack to facilitate current and future access for stack repairs and maintenance. Lastly, IA performed a top-to-bottom washdown and application of a two-layer protective coating system across the entire exterior of the stack, including the doghouse, ladder, and cage.

The repair services were completed successfully and on time, ensuring the longevity of the structure and maximizing its operational efficiency. It is important to protect the steel shell of smokestacks from their harsh interior and exterior environment in order to preserve their structural integrity and safety. Performing regular inspections and timely maintenance on steel stacks and their liners will help identify signs of deterioration early and take preventive measures before extensive damage occurs.