The repair of damaged coated steel surfaces is a difficult and time-consuming task. Many of these difficulties stem from the repair methods used and many asset owners take these repairs for granted.

They opt to use sub-standard repair methods such as chipping or mechanical power-tooling due to accessibility and perceived time, material, labor and equipment savings.

These sub-standard methods only partially remove corrosion products and damaged coatings which in turn, eventually results in premature failure to the touch-up coatings that were applied over these repair areas. Consequently, this results in the process having to be repeated again and again.

When the initial coating system was applied over the original surfaces, abrasive blasting would be the most preferred method and these substrates would be cleaned to White (Class Sa 3) or Near-White (Class 2½). If spot repairs are necessary, it is important that corrosion products in the coating breaks must be completely removed and the pit is corrosion free.

It is also very important that the damaged coating be removed to the point where it is solid, intact and tightly adhered to the surface. Otherwise, failure will continue to occur at the same spot.

It is therefore essential that the coating be tapered from the corrosion repair area out to the solid adhered area creating a featheredge at the junction between the steel and the old coating. This transition zone is not only necessary for a proper repair but also provides a much better appearance since there are no jagged rough edges to give the appearance of a patch job.

Therefore, Spot Abrasive blasting is the ideal repair method to address these concerns as it can effectively clean the corroded areas to the highest-class standards and create the interface between the blasted area and old coating edge.
 

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