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STEEL STACK EXTENSION AND RENOVATION

Power Generation

WORK PERFORMED

  • Removal of top section of stack and replacement with a new extension
  • Setup of a new platform and safety ladders
  • Demolition of existing refractory liner
  • Installation of a new interior protective membrane and gunite refractory liner system

SUMMARY

Industrial Access was contracted to perform elaborate renovation work on a steel stack. The crew installed an extension to the existing stack, relevant appurtenances, and a new gunite refractory system. Industrial Access utilized their multi-craft expertise and unique access solutions to enable safe and efficient approach to stack repair work.

TIME

3-4 weeks with inspection, preparation, and renovation

COST

Repair completed during a short scheduled outage window and within budget

SAFETY

Stack was rigged, cut, removed, and replaced without any safety incidents or recordables

CLIENT NEED

A power generation plant in the Midwest was required to extend the stack in accordance with the EPA guidelines, and Industrial Access (IA) was contracted for the job. Upon arrival, IA performed a stack condition assessment, inspecting the steel shell and the reinforced refractory of the 174’ stack. The team inspected the interior surface of the liner, observed extensive spalling, corrosion, and exposed wire mesh. Due to the amount of gunite found on the floor of the liner, it was determined that the stack needed to be cleaned and a new refractory system had to be installed.

ACCESS

Upon mobilization, IA addressed all safety training and orientation requirements. In order to perform the renovation, the team cut an access door to the interior of the stack. Rope techniques were utilized to install exterior knee-braces for temporary scaffolding on the exterior of the stack. Another temporary custom work platform was built inside the liner in order to enable secure demolition and extension of the stack. All access scaffoldings, ladders, and other safety devices were all in strict accordance with OSHA and SPRAT safety regulations.

SOLUTION

Once the mobilization was completed and the stack was shut down, IA began work by neutralizing and removing the existing lead coating around the stack splice area (overlap of steel plates). The stack was then rigged for access, and the existing gunite liner from the specified cut area was removed. The top section of the stack was torch-cut, lifted with a crane, and placed safely on grade. The crew properly prepped the cut edge on the existing stack for the welding of the new stack section. Using a crane, the extension was lifted, erected, and secured in place using internal and external full-circumference welds as indicated in the construction documents. A welding QC inspection was carried out. IA completed the exterior renovation by installing a new platform, ladders, access door, AWL system, and other appurtenances.

 

To perform the interior renovation, the crew first removed all of the existing concrete refractory in the original stack. They performed an interior sand blast cleaning to eliminate existing corrosion and prepared the stack interior surface to accept the new gunite refractory system. IA welded the new refractory “T” studs in a diamond shaped pattern on a 1’ centers for anchoring the gunite system. A No. 89 “Sauereisen High Temperature” impervious membrane was installed, approx. 1/8” thick. It resists acid, alkalis, and salts associated with flue gas environments and substrate movements from temperature changes and other causes. Finally, a 2”-thick coat of Sauereisen 35 acid resistant refractory cement was applied throughout the full height of the stack interior surface. This coating protects from high temperatures, thermal shock, abrasion, and chemical attack by mild acids or alkalis.

RESULTS

IA had successfully completed the renovation of the stack safely and on time, drastically improving the structure’s condition. The resulting height of the stack was 224’, an increase of 50’. The crew removed all of the debris from the area and disposed of the remains at an authorized dumpsite, leaving the area in “as found” or better condition. Industrial Access made additional non-scope observations on the existing oxidation and staining on the lower stack exterior and offered recommendations for future repair and maintenance work.

Renovation work on the interior and exterior of steel stack

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