Agenda Packets - 1985/08/05 - Laserfiche WebLink

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April 17, 1984 Subject: Steel Water Siorage Tank Exterior Coating Cold Weather I'op-Off Gentlemen: This past year a large part of the Central u. S. got a 30 - 40 degree below temperature shock in late December 1983. Some newly painted water towers suffered what we have been calling "cold weather pop -off". The finish paint and prior coatings tend to delaminate from the steel substrate. It can, however, break away from a layer of previous primer or aluminum finish. In the winter of 1981-82, we had a cold spell similar to what we had in December of 1983. We knew of seven tanks in our area that had popped paint within three days. Of that seven, five had l Tnemec coating; two Tneme-Closs, two Spra-Sat, and one Endura- j Shield. All the tanks had two things in common; all had been repainted within two years and all had 10 plus mils of paint. Of the five tanks we are aware of, they were repaired the following way. One tank at Devils Lake was touched up on the pop -off areas. No reoccurrence has taken place this winter. A tank at Mcorhead was so bad it had to be completely repainted. It was sandblasted and recoated. A tank here in the Twin Cities was touched up. A very few areas popped off again this year, but not as serious as the first time. The other two tanks that had Tnemec finishes were in the south part of the State and as far as I know, a touch-up cured the problem the first time with no reoccurrence this winter. In the winter of 1983-84, there were a number of reported pop - offs in Iowa and a few in Minnesota. In all of the pop -off problems this year that we have been able to investigate, we find the same set of conditions prevail; excessive mil thickness along with recent recoat of the tank. There were two tanks this year that failed through a previous aluminum coating. ATTACHMENT N1 - PAGE 1 kling & associates 0 9142 davenport it. n.e. • minnespolis, minnesota 55434 9 (612) 786.8555