26 March 2010
26 March 2010
Tecniplas has recently introduced an oblation system for tanks into Brazil, to allow the transportation of large-diameter composite cooling towers, water treatment plants and reservoirs.
“Due to the impossibility to transport our tanks, they were forced to have the diameter limited to 7 meters. With the oblation, we started producing reservoirs of up to 15 meters, which are able to store 2,500 m³”, said engineer Giocondo Rossi.
The new technology presented by Tecniplas allows the sections of the tanks to be flattened, gaining a form similar to a figure of eight. A reservoir of 15 metres in diameter measures 5 metres after being flattened, the appropriate size for the Brazilian road transportation standards. At the installation site, sections are resized and manually rolled over each other. “The oblation system is able to reduce transport time from 90 to 10 days. Depending on the tank’s diameter, it could also allow the transportation of two or three rings in the same cart. That leads to a considerable gain in logistics”.
The tanks are manufactured at Tecniplas' plant, located in Cabreúva, São Paulo, through a vertical filament winding process. In order to be deformed, the sections must be made with resins that have a high elongation to break. “Thus, the tanks accept the oblation and return to its original shape without any mechanical damage”, said Rossi. Ashland was selected to provide the resin for two of Tecniplas’ projects involving oblation: four tanks measuring 6 to 8 meters of diameter for Alunorte and one of 13 meters for Braskem. “The oblation system of tanks is rare and requires special resin features. In addition to the high elongation, which prevents the formation of cracks during the oblation process, it must have a great connection with fibreglass, so that it generates the thinnest structural wall as possible”, according to Alexandre Jorge, business development manager of Ashland.
In both cases the vinyl ester resin Derakane Momentum 411-350 was used, because of its high chemical resistance and elongation at break of approximately 5.5 to 6.0%. “We have dozens of similar cases in North America in which the resin was applied with great success. That is why we decided to suggest it for this new application in Brazil”, explained Jorge.
Replacement of Steel
According to Tecniplas’ director, oblation allows composite materials to compete in a segment where steel currently prevails. “Large reservoirs, especially those focused on the storage of water, are usually made of steel coated with rubber. The problem is that leaks from corrosion are common, which does not occur when tanks are made of composites”.
Throughout 2010, Rossi believes that Tecniplas will provide three to five flattened tanks. “The acceptance has been very positive and, for this reason, I'm sure we have just opened up a new market for composites in Brazil”, he adds.