In-service Water Tank Testing
Aboveground storage tanks dedicated to water storage are used most often for fire protection and potable water. Water tanks for fire protection are used in numerous applications including fire sprinkler systems supply, water source for firefighting, to create a fire perimeter, and as a source of water at fire departments to fill up trucks. Potable water storage tanks have many applications in commercial and residential circumstances. Water tank inspections are generally conducted in accordance with National Fire Protection Association (NFPA) – 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems and American Water Works Association (AWWA) M42 Steel Water Storage Tanks. Compared to aboveground storage tank inspections of petroleum product tanks, water tank inspection is typically less complex and expensive since the water is not a hazardous material, non-flammable, and clear. Water clarity allows for excellent in-service tank testing with remotely operated vehicles (ROVs) that provide high quality video of the tank internal coating, shell, and nozzle conditions. However, precautions must be made that any ROV used for water tank inspection does not contaminate the water. Well defined rigorous sanitation processes must be applied to all tools entering the tank before water tank inspections. These guidelines are outlined in AWWA C652 – Disinfection of Water Storage Facilities. This article discusses some of the in-service water tank inspection guideline and the non-destructive testing (NDT) technology to support water tank testing.