Wind gusts up to 200 km/h can damage or even rip tanks out of the ground, causing huge financial losses and putting many lives at risk.
In order to avoid wind-related incidents, tank manufacturers should consider, in the structural calculations, the information concerning isopleths referred to in the standard NBR-6123 – Wind Loads on Buildings, the company says.
“However, this standard is from 1988 and, since then, there have been several changes on wind isopleths in Brazil,” says Gerson Vieira, Engineering Manager at Tecniplas.
That is why, according to Vieira, tank suppliers should obtain all the information prior to the beginning of the project.
“Sometimes, the region is not subject to such intense wind loads, but the tank will be installed in a high and fairly open area, a common situation in supplies for condominiums,” he says. “In other cases, wind gusts may be constant, but the equipment will remain inside a shed. For this reason, it’s vital to have all the information in hand before starting the works.”
Once the risk identification phase has been completed, Tecniplas designs the tanks subject to wind loads by adding reinforcement areas, which protects them against external pressures and avoids dents that can damage their structure. The most challenging scenario occurs when the tank is empty, as the liquid exerts a counter force and helps to reduce the damage caused by wind gusts.
Another key area is the support and anchoring design of the tank. The installer must correctly calculate the construction base and duly fix the anchor bolts, so that the wind will not rip the tank out of the ground.
Tecniplas has completed a number of projects that experience high wind loads, including those to sanitation companies Companhia Catarinense de Água e Saneamento (CASAN) and Companhia de Saneamento Básico de São Paulo (SABESP).
“For SABESP, for example, we produced tanks that were installed near the city of Ibiúna, in an area of difficult access and strongly affected by winds,” Vieira reports. “The region is so complex that the tanks were taken by helicopter. We also built 26 m high columns installed in Ceará, a project that also contemplated the study of wind loads.”