BRICK CHIMNEY DRONE INSPECTION AND REPAIR

Brick chimneys operate in a wet, corrosive environment and require regular attention to ensure their structural safety and operational efficiency. Industrial Access was contracted to perform a drone inspection on a brick chimney, then carried out a recommended repair plan that included exterior mortar joint restoration and interior gunite flash coat application.

A hospital in New England was looking to do a general visual inspection of their 150’ brick chimney. Industrial Access (IA) sent a drone technician to perform an interior and exterior drone inspection. It is essential to survey these structures regularly due to the inevitable “wear and tear.” When changing fuel types or upgrading to more efficient boiler systems, it is common for the flue gas temperatures to drop and for the water content in the fuel source to increase. Since brick structures are highly permeable and vulnerable to moisture and temperature changes, this creates major issues that accelerate chimney deterioration, demanding for consistent inspection and maintenance care.

During the drone inspection, it was determined that the chimney exterior was in fair condition, with a number of minor defects noted, such as cracks in bricks as well as oxidation and efflorescence on brick and steel tension bands. The presence of the latter issues indicates that there’s a lot of moisture penetrating into the masonry and flowing back out at the mortar joints, and that the bands experience a coating failure as well as corrosion on their back side, which means there’s water flowing behind them too. It is critical to closely monitor such anomalies and apply repair solutions at the earliest convenience to prevent further damage.

Meanwhile, the interior of the chimney was determined to be in poor condition, with very large areas of severe mortar deterioration present. There was mortar missing down to over an inch from the original surface, leaving the remaining mortar softened and with compromised strength. This often happens due to acid attack from condensates of the flue gas. This observation demands for urgent corrective action without which the acid will continue reaching deeper into the joints and put the integrity and safety of the structure at risk. IA provided a recommended repair strategy to address the observed issues, and the client contracted IA to carry out the repairs.

Technicians at IA are experts in providing rigging and unique access solutions for industrial work at height. In this project, during work on the exterior, a fixed system scaffolding was installed around the 8’ diameter chimney to enable the repairs. In order to access the stack interior, IA’s engineers designed and built a temporary powered work platform. This platform provided access to the full height of the stack interior and maximized the crew’s work efficiency.

To start off the repairs on the exterior of the chimney, IA pressure-washed the structure and its appurtenances to remove any dirt and debris. Any loose deteriorated mortar was manually removed from the joints. Once the surface was prepped, the crew tuckpointed the mortar joints and filled any vertical cracks with refractory mortar. Then, the Lightning Protective System (LPS) replacement was performed, and new installed components were covered with lead to prevent corrosion. The entire height of the chimney’s exterior surface was waterproofed with a water repellent, while the tension bands were coated with a protective sealant, primer and top coat system for the necessary resistance against abrasion, moisture, corrosive fumes and chemicals. Lastly, IA tightened and realigned the steel cap at the top of the chimney.

To prepare for the interior repairs, the crew first pressure-washed the interior to clean off loose buildup and surface contaminants. Then, a 1” thick gunite flash coat was applied throughout the 95’ height of the chimney. This will help to seal the interior surface of voids and cracks and protect the structure from high temperatures and corrosive flue gas effects.

All of the repairs were completed successfully and on time. Restorative work on the chimney exterior in addition to the new interior gunite liner system will ensure the longevity of the structure and maximize its operational efficiency. Since brick chimneys are especially susceptible to water damage, it is critical to inspect these structures regularly to prevent extensive – and expensive – future repairs. IA uses innovative, cost-effective solutions to help facilities maintain, restore and upgrade their existing brick industrial chimneys and smokestacks.