ABSTRACT:

Coating manufacturers go to great lengths to formulate, test, and develop improved coating materials which are capable of handling the ever increasing demands of the industrial market place and are at the same time user-friendly. Product data sheets, label instructions, and supplementary application guides are all part of a measured program to ensure that coatings are properly applied, and that the end user is completely satisfied with the long term performance of the coating system. This paper relates several case history examples of how, despite good intentions by all of the involved parties, things go wrong on industrial coating projects.

INTRODUCTION:

Representatives for coating manufacturers are in a unique position in that the “customer” includes everyone involved with a project. People make mistakes, and on industrial coatings projects this can include mistakes made by the owner, the engineer, the inspector, the contractor, and the manufacturer. When problems on a coatings project arise, it is incumbent upon the coating representative to treat each party responsibly and fairly, as everyone is the customer to them. The following case histories detail a few examples of problem projects, and how each situation was resolved. Many of these case histories invoke what has been described as the “more on” theory. This is the belief that you can fix a bad situation on a coating project simply by covering it up…, moron.

DISCUSSION:

Mis-proportioning of Plural Component Epoxy A 74,000 bbl riveted, floating roof tank at a refinery was to be lined using a three coat system consisting of two coats of a plural component “seam sealing” epoxy, followed by a solvent based, thin film, white epoxy polyamide topcoat. This was a common system in use by the refinery at the time. There had been years of good experience on a large number of riveted tanks. The seam sealing epoxy was a 100% volume solids, solvent less, high build material which was specified to “seal” rivets and seams. This coating was designed to be applied by heated, plural component spray equipment in a 2-1 ratio of base to converter. To ensure that the material was properly proportioned, the product consisted of a white base and a dark blue converter. Once mixed by proportioning pump at the proper 2-1 ratio, the applied coating would be a pale blue color. By designing the product in this way, it would be easy for the applicator to know, while spraying, if the material was properly mixed. That is, of course, if the person holding the spray gun knew that it was supposed to be pale blue. Soon after the job was completed, the coating manufacturer was called in to investigate a rather strange complaint. After the thin film white epoxy topcoat had been applied, there were areas in the tank above the floating roof where when the coating was pressed, as if to take a dry film thickness reading, the coating felt soft and a dark blue, resinous “goo” would seep out from under the white top coat.

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