Selecting the right coating – the basic questions

Industrial coating decision tree

If one coating could do everything, coating selection would be limited to color and gloss choices and specification writing would be relatively simple. Since that magic coating does not yet exist, we are left with hundreds of possible choices.

Many popular coatings can perform multiple functions. But real-world situations often demand more specific performance requirements. Effective coating selection should be based on the demands of the project, such as performance, application, budget and other requirements.

There are some basic questions that the specifier, engineer or owner need to answer to narrow the choices and find the best option.

4 questions to ask when selecting an industrial coating

Questions to ask when selecting an industrial coating

What is being coated and why?

The answer to this question indicates the scope of the project and the expectations of the owner. It may sound basic, but answers can be surprisingly deceptive.

The reason for coating something like a vessel could simply be the company CEO is going to visit it next month. Appearance then means everything and no one is really interested in the benefits of a 25-year corrosion resistant coating system.

What exposure will the item see?

This is perhaps the real “meat and potatoes” question that tells us what environmental conditions the application will regularly face. There are many parts to this question which include:

  1. Is the item exposed to the weather or wet interior environments like food process areas?
  2. Are there any elevated temperature conditions?
  3. Are there any harsh chemical fumes or potential chemical spills?
  4. Will the coating be covered by insulation?
  5. Will there be any thermal cycling/shock?
  6. How frequent will the coating be cleaned and with what chemicals?
  7. Will the coating experience any abrasion? What type (cutting or small particulate)?
  8. What is the existing condition of the substrate (new steel, contaminated steel, rusted steel, old coatings)?
  9. What is the condition of existing coatings?

How, when and where will the item be painted?

Answering this question will define the logistics of the painting project — whether applied at the shop, in the field or at an operating plant.

The coating may need to withstand early rain exposure or cold temperature cure. Certain coating systems will handle shop application better than others and will likely involve less shipping damage.

If spraying the coating is not possible due to issues like overspray problems, a brushed or rolled coating must be selected. If the speed of completion of the project is critical, fast dry/cure products will be preferable.

In many operating plants, open abrasive blasting may not be possible, so products with surface tolerant properties must be selected. And while these products are technologically advanced, those that require higher degrees of cleanliness are preferred for longer service lives.

What are the owner’s expectation in terms of service life?

At face value, one would think that the answer should be “as long as possible,” but this is not always the case, especially with limited budgets.

In the earlier case where the CEO was to visit the plant, giving the vessel a fresh look could be done rather inexpensively using a coating system with a minimal design life, especially if the vessel is to be dismantled in five years.

On the other hand, it would make sense to select a long-term service life system for an elevated water tank with a design life of 90 years, especially if it has the local high school mascot painted on it. But the longer service life systems will cost more in surface preparation and application.

Don’t guess, be certain

In the end, it is best to discuss your coating needs with a coating professional who will walk you through the basic analysis outlined here and match the right coating system for your specific set of circumstances and expectations of service life.


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