3 Coating Failures To Watch For

men with hard hats on

The state of your protective coatings is an indicator of possible future repairs for your bulk gas storage tanks. 

When applied correctly, protective coatings can increase the longevity of steel assets by protecting them from corrosion damage. Most business owners or plant operators want to avoid those costly, totally preventative repairs. To avoid, corrosion damage, you must be able to identify when there is a protective coating failure.

Here are 5 coating failures to watch for during your next equipment survey:

Loss of Adhesion

Loss of adhesion presents itself when the paint system does not adhere correctly to the base surface. You can tell if a coating does not adhere correctly through a pull-off test. If left untreated, the paint will flake off, revealing the unprotected base. The steel is now vulnerable to environmental concerns like corrosion. Loss of adhesion occurs when any of these factors are present: 
  1. Surface contamination
  2. Unsuitable primer or primer application
  3. Exceeding the overcoating time
To repair a coating failure like this, the painting contractor must remove the failed coating through sanding & repaint with the appropriate painting system.
loss of adhesion example

picture courtesy of corrosionpedia.com

Chalking

example of chalking coating failure

picture courtesy of corrosionpedia.com

Chalking occurs over time when coatings are exposed to weathering and ultraviolet light. A good test to see if this is occurring to your tank is to simply rub your hand against the surface of the tank. If a powdery layer is left on your fingers, the coating is chalking. To prevent this from happening, a top coat must be chosen that is resistant to ultraviolet light. If this is happening to your bulk gas storage tank, it is time for a new coat of paint.

Blooming

Blooming is best described as a loss of gloss or dulling of the paint color. It is caused by paint not having enough time to cure before low temperatures hit. This coating failure can be easily avoided by the painting contractor by avoiding painting during rain or cold weather. If the coating has bloomed, a repaint must be issued. CRYOGENIC TANK old logo

Cracking

Cracking or “alligatoring” happens when the steel surface shrinks faster than the body of the paint film. This can happen when a topcoat is applied before the undercoat has dried. Cracking can also refer to “alligatoring” because the texture of the failure is similar to the skin of an alligator.
craking coating failure

picture courtesy of corrosionpedia.com

The cracks can just penetrate to the undercoat in some cases but in more severe situations the cracks can go all the way down to the substrate. To prevent this from happening, the painting contractor should avoid applying the coating at high temperatures, avoid excessive film thickness, and use the correct coating specification. If the coating has cracked, a new coating system must be applied.

Bridging

Bridging is the result of poor coating application. This coating failure happens when cracks or corners are not covered correctly. Gaps in application introduce a weak point for the coating, which can cause premature corrosion issues. Protective coatings should be brushed into corners and over welds.
example of bridging coating failure

picture courtesy of corrosionpedia.com

Just the tip of the iceberg

There are many ways that protective coatings can fail, but these 5 failures give you a good introduction to what you should be looking out for on your assets. If you would like to learn more about coating failures, please review this coating failure guide from corrosionpedia.com.  Keep an eye out for these coating failures to minimize damage to your equipment from corrosion issues.  Have some bulk gas storage tanks that need a new protective coating, reach out to us here.