Sauereisen Restores Acid Drying Towers

Two-year Inspection Reveals Excellent Results

In 2002, a metals refinery on the outskirts of Lima, Peru faced a major problem within their vertically integrated operation. A drying tower located in their sulfuric acid plant sprung a series of leaks.

The leaks became apparent with sulfuric acid on the outside of the structure and surrounding area. The source of the problem was a failed Teflon lining in the interior of the tank. Acid had penetrated the damaged Teflon and reached the underlying metallic surface where corrosion rates accelerated.

Unfortunately, the prospect of emptying the tank to repair it internally was problematic for several reasons. Downtime was the primary issue. An alternate idea was to install a metallic jacket around the tank to hold back further leakage. Such a solution would be sacrificial, however, since the corrosive action would eventually cause the problem to recur.

Sauereisen Inc. of Pittsburgh, PA proposed a more permanent solution - polymer concrete, comprised of potassium silicate, to be used in place of the metal jacket. Sauereisen's Acidproof Concrete No. 54-Structural Grade was selected based on its resistance to highly concentrated acids. No. 54-SG may be specified for environments up to 1400oF that include full concentrations of virtually all acids except hydrofluoric. Under the most challenging conditions, the polymer concrete cures quickly enough to permit full chemical exposure within 48 hours.

The polymer concrete jacket was designed at a thickness of two inches around the tower. The steel substrate was sandblasted to obtain a suitable bonding profile. After erecting forms, the contractor poured the polymer concrete into place. The forms were removed the next day and the tower returned to service soon after. In all, the project was completed within a timeframe and budget that the owner hadn't imagined possible at the outset.

To aid in future inspections, the exposed surface of No. 54-SG was painted purple. Two years later, the drying tower remains in service without acid leaks. The exterior surface of the polymer concrete jacket continues to hold up to the outside elements, too.

SOURCE: Sauereisen, Inc.