Coating Failures and Their Consequences
To better understand why coatings fail and the devastating consequences, we must describe coating failures and some of the most common types.
This blog will describe a coating failure and the two main effects.
- One – safety concerns, employee injuries, and public safety
- Two – the cost to our economy, or expenses caused by the corrosion
What is a Coating failure?
Protective coatings aim to prevent environmental disasters and catastrophic failures by protecting structures from deterioration and corrosion. This deterioration is primarily caused by premature coating failure or the absence of a protective coating.
Such a failure occurs when the bond between the surface and coats has disappeared or has been reduced over time. This creates a scenario when protective coating cannot fulfill its primary function leaving the substrate exposed to corrosion or deterioration.
An example of such a failure is:
- Failure to cure – results from not adding the cure to the base, adding the wrong cure, or not adding the correct amount of cure during mixing.(NACE, CIP lvl 1)
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- An internal chemical problem with the coating material sent from the coating manufacturer
- Environmental issues, too cold, too hot, too humid
- Wrong thinner or contaminated thinner
- Adhesion failure – this is a defect due to loss of adhesion between coating layers or the substrate caused by:
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- Contamination on the surface to which the coating was applied
- Wrong surface preparation specified
- Failure to inspect surface preparation
- Insufficient surface preparation
- Exceeding topcoat window
- Application of incompatible coatings
- Applying a coating to a glossy surface
- The repair depends on the extent of the failure:
- For small areas, remove, clean, feather edge, and replace.
- In large areas, the coating will have to be completely removed and replaced (NACE, CIP lvl 1)
- Failure on welds and Edges –a common source of in-service coating failure is rust that starts at a sharp edge or rough spattered weld seam. The fundamental reason is that coatings will pull away from a sharp edge.This is because coatings are applied to the surface wet. As they dry, the solvent is released, and the coating shrinks. When this happens on edges, welds, or spatter, it leaves a thin coating film at the peak or top of the anomaly causing premature failure. Furthermore, applying a coating by spray or roller will cause the coating to bridge over a slight depression in the substrate. The small depression holds oxygen and eventually water, and a corrosion cell will form, causing rust. (NACE, CIP lvl1).
Safety Consequence
The goal of protective coatings is to protect systems from corrosion, which can severely impact public safety over a long period. Corrosion affects public safety by:
- Public infrastructure such Bridges, Highways, Rail, Amusement Parks
- Utility Structures Water Treatment Plant, Storage Tanks,
- Pipeline structure Oil & Gas, Underground & pipeline structures
Any damage to such a structure will have a massive impact on public safety. In addition, structures damaged by corrosion pose a direct like;
- Bridges and buildings that must support extreme weight and load. Otherwise, it cost human lives and money. In addition, it reduced bridge integrity due to concrete deterioration or steel corrosion, decreasing overall bridge strength.
- Leaking of toxic gases or fluids into the environment harms people and wildlife.
- Contaminated products in food and beverage industry due to corrosion of metal parts.
- Sinking vessels, crashed planes, broken equipment, to name a few
Cost Consequences
Safety is not the only problem of a coating failure; economic impact is another area of concern. It is no secret that ignoring an issue such as corrosion can be expensive at the time, but how expensive can it be?
According to NACE, “In 2016 it was estimated that the cost of corrosion reached 2.5 trillion US$.”
In Canada, the cost is estimated at 63$ Billion CAD annually for corrosion-related deterioration and failures of national assets, according to AMPP.
Repairing and repainting rusted steel is usually far more expensive than the initial cost of protecting a surface against corrosion. The intended service life of a corrosion protection system represents the engineered economic value by protecting an asset. (NACE, CIP lvl 1) The initial cost to prepare the surface properly is outweighed by the extended service life of properly installed coating systems. Therefore, it is generally a good idea to be proactive rather than reactive when it comes to protecting your assets.
This is what consequences look like:
- Repainting and repairs
- Downtime and inability to generate revenue
- Cost of material
- Cost of work
- Expenses due to potential lawsuits
- The effort required to prepare the steel substrate properly increases the cost of fabrication
Expensive downtime of repairs and recoating can be minimized, resulting in maximized asset utilization over its intended service life and more significant revenue generation.
It is estimated that there is an opportunity to save 25 to 30% of that cost by using “optimum corrosion control practices, according to AMPP.
Summary
Finally, the protective coatings industry is an essential part of our economy, which plays a crucial role in protecting structural integrity against corrosion. One of the most common reasons corrosion occurs is due to coating failure.
Coating failure can have a massive impact on our safety since most of these structures we rely on are all around us: our bridges, highways, water treatment plants, and many others.
It can also harm our economy, with nearly 63$ billion in expenses annually.
This is why coating inspectors recommend considering corrosion prevention during the early stages.
REFERENCES
- A & A COATINGS. (2018, January 21). What are the dangers of corrosion?: A&A Thermal Spray Coatings. A&A Coatings. Retrieved January 25, 2022, from https://www.thermalspray.com/what-are-the-dangers-of-corrosion/
- AMPP. (2021, June 17). AMPP News. Corrosion Study Reveals $63 Billion Annual Cost to Canadian Taxpayers. Retrieved January 25, 2022, from https://www.ampp.org/blogs/webmasternaceorg/2021/06/17/corrosion-study-reveals-63-billion-annual-cost-to
- Corrosionpedia, C. (2018, November 5). What is a coating failure? – definition from Corrosionpedia. Corrosionpedia. Retrieved January 25, 2022, from https://www.corrosionpedia.com/definition/1414/coating-failure#:~:text=Coating%20failure%20is%20the%20reduction,does%20not%20provide%20other%20functions.
- NACE. (n.d.). Economic impact. impact.nace.org. Retrieved January 25, 2022, from http://impact.nace.org/economic-impact.aspx#:~:text=2%2D2).-,The%20global%20cost%20of%20corrosion%20is%20estimated%20to%20be%20US,individual%20safety%20or%20environmental%20consequences.
