Industrial exterior coatings: Anti-corrosion best practice

The holy grail for all our commercial and industrial clients is endurable, long-lasting performance, especially for exterior structures. Storage tanks and silos, bridges, grain elevators, refineries, and power plants are just a few examples of structures that must endure the daily abuse of weather on top of operational wear and tear.

Yet endurance is only one factor when judging coating performance—cost and safety are two additional considerations.

Painters USA vice president Paul Cook discusses all these factors in an article published in Tank Storage Magazine, “the world’s largest circulation magazine dedicated exclusively to corrosion prevention and control” published monthly by NACE International, now the Association for Materials Protection and Performance or AMPP.

Painters USA VP and NACE-certified inspectors Paul Cook contributed to Tank Storage Magazine, February/March 2021 issue, in the article “A Cost- and Safety-Conscious Approach to Coating Tank Exteriors.”

Following is a summary of his key points, with a link to a PDF version of the entire article at the end.

1. Give tank coatings greater consideration

Paul says that coating work is a small part of the planning and budgeting of tank maintenance that facility management and tank teams address. But as he states in the article,

Giving coating work careful consideration reaps outsized returns.

He advises facility and terminal managers to boost tank protection and maximize their budgets by using best practices to spot issues that are still small and not yet obvious before they become something bigger and more destructive. 

According to Paul, surveys and testing are a key step toward getting the most protective, long-lasting surface coatings. He gives an example of a facility manager who invited a certified NACE Institute inspector to his facility for a tank sandblasting and coating project. The inspector noticed a few flaking spots that were almost imperceptible and inquired if the tank had ever been inspected via ultrasonic testing. This procedure uses a device that measures high-frequency ultrasonic waves to measure metal thickness and loss due to corrosion and other imperfections. 

Ultrasonic testing is usually part of a procedure called a Holiday Test, and it’s not called a holiday test because it takes place between Thanksgiving and Christmas. In the coating industry, a holiday is the term that describes any discontinuity, including pinholes, sagging, cissing, and cratering. 

According to Paul, certified coating professionals recommend surveys and tests before doing any industrial cleaning and surface prep projects, especially those that involve abrasive blasting.

2. Involve a certified corrosion expert

Coating professionals with certified inspection credentials from NACE (now AMPP) have a trained eye developed through formal coating instruction and experience. You can ask any contractors you are vetting for tank work about their NACE / AMPP certifications or include in your RFP as another valuable decision point. 

3. Realize one size can't fit all, even within the same organization

The same company may have industrial tanks located in different locations with widely different service environments. According to Paul, even one large facility with hundreds of tanks can have many variations. He mentions characteristics like tanks located directly below a flight path of commercial aircraft, which may experience settling of spent (and corrosive) jet hydrocarbons. In facilities that cover a large area, Paul advises maintenance  professionals to assess their environment in many different ways, with possible different schedules for cleaning and coating tank exteriors.  

4. Develop accurate coating job specifications

Coating contractors cannot deliver maximum coating performance without detailed and accurate job specifications. These specifications guide them to the best products and methods, and as Paul states in his article, they help tank and facility managers save time and money in the long run. 

Details also ensure the safest environment, not only for people but for physical property. Paul gives examples of tanks located near a parking lot with employee vehicles or a tank farm’s control room filled with computers. which could be compromised or damaged from abrasive cleaning fallout.

Tank facility managers and owners don’t always consider these details, which can lead contractors to specify the wrong coating system or application methods.

5. Don't neglect quality assurance

Since quality can be highly subjective, it’s important to measure it based on data and specific requirements. Quality assurance, or QA, means quality that can be qualified.

As Paul mentions:

There must be a specified blast profile left behind, so the new coating will properly adhere to the tank’s surface.

Ensuring this profile happens requires a blast profile measurement that can be performed with a ‘profile tape,’ or a newer electronic gauge to record the millimeter thickness as verification. Paul says that quality contractors also record daily conditions and QA measurements to meet project specifications.

Companies with large storage tank facilities must consider many factors, including local zoning requirements, applicable government regulations, business owner needs and perspectives, and more. 

Coatings and coating application may seem to be a small part of the picture, but their role is actually quite big. As Paul states, 

A company’s profits and the safety of its workers, equipment and cargo depend on it.

For those of you with access to this publication, look for “A Cost- and Safety-Conscious Approach to Coating Tank Exteriors” in Tank Storage Magazine, February/March 2021, Volume 17, Issue 01. For those without access, download the article (PDF).

We invite you to contact us if you would like to discuss your industrial tank facilities.

Meanwhile, learn more about Painters USA training and certifications