As reinforced concrete cooling towers age, their harsh operating environments can lead to deterioration and structural distress. Both mechanical and natural-draft cooling towers present unique conditions inherent to their type of construction and exposure conditions. With time, process and environmental exposure conditions render the towers susceptible to corrosion of embedded steel reinforcing, concrete cracking and spalling, and in cold climates freeze-thaw deterioration. Operational cycling and construction defects can accelerate deterioration. Condition assessment of cooling tower structures is essential to identify safety and structural concerns, determine the root cause of distress, and plan maintenance needs. Condition assessments typically involve visual inspections and various nondestructive testing techniques. Depending on observed conditions, concrete core sampling and laboratory testing are used to characterize materials quality and durability. Structural analysis may be required to evaluate structural capacity. Condition assessments are typically conducted during short-duration outages. Depending on the elements to be surveyed, man lifts, suspended swing stages, or fixed scaffolding are used to provide up-close access. Condition assessment of cooling towers is a key component of an overall facility maintenance program. Case studies will be presented to illustrate condition assessment methods and results. Information from the assessments provides the knowledge necessary to monitor structural conditions, plan maintenance, and when necessary prioritize repairs to maximize the service life of cooling towers.
10-23: Structural Condition Assessment of Concrete Cooling Towers
Kevin Michols and Leandro Etcheverry, Wiss, Janney, Elstner