The Case of the Sliding Lining
From JPCL, December 2011
More items for
Quality Control
| by Richard A. Burgess, KTA-Tator, Inc. |
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In this month's F-Files, the application of a liner to the interior of a demineralized water storage tank was stopped mid-way through the process because of dramatic defects in the applied film. An independent assessment was conducted to determine why the liner material exhibited runs, sags, fingering, and "sliding" separation during installation....
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Tagged categories:
Coating failure;
Epoxy amine;
Runs, sags, curtains or "sliding";
Steel;
Tank interiors;
Water Tanks
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Comment from Keith Holdsworth, (1/17/2012, 10:24 AM)
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This will be experienced more and more as regulations force VOC content lower in coating materials. A substrate temperature of 48 degrees is low and severly hinders build charateristics during application. In the older solvent based products the solvent evaporation rates assisted in build characteristics while evaporating from the coating material during application. Hence various specific blends for certain linings. In this instance a job site heater large enough to maintaine a steel substrate temperature to the entire tank at a minimum 65 to 75 degrees and controlled mixing and storage area to maintain the coating materials at the higher end of the recommended storage temperature would have prevented most of this. The "fingers" which were mentioned is an indication they were dealing with inadequate pressures at the spray tip and heavier than normal viscosities. The running and sliding is an indication of material beyond its pot life or more likely due to low substrate temperatures. The article doesn't mention pump ratio or flow rates nor does it mention tip sizes utilized during the spray operation.
Based on the critical nature of the lining to the plant operations I would have recommended the entire shell and floor have the previous lining removed and replaced competently.
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Comment from Steve Stroud, (1/18/2012, 11:22 AM)
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Every painter, that applies exotic coating, should read this article. Often, in the field, specific manufacture instructions are viewed as being trivial, over cautious or just "rhetoric" to cover the manufacturers behind. This article serves to remind us of the consequence of less than a "professional" approach to our craft.
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Comment from Doyle Menard, (1/19/2012, 10:14 AM)
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It's seams to me that a lot of this problem could had a been solved up front, if 3rd party inspection had been involed during the started of the project.
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