coating inspection

“Do it once, do it right” with a coating inspection

Problems can arise during the pre-treatment, application and curing phases of a coating job. Coating jobs that at first seem perfect can begin to fail. There are so many variables in any coating application, from the environment to the material itself, that getting a perfect job is a highly skilled task. This is why we need the coating inspection: we need trained and certified professionals on board at every step, testing and guiding the coating process, as well as making sure the coating job is maintained. Do it once, do it right; the cost of repairing a badly executed coating can be many times the cost to paint it in the first place.

Coating inspection begins with coating survey and specification

A coating inspection is carried out by a certified coating inspector who is familiar with all the aspects that contribute to optimal performance of a coating, and the specific standards each coating should individually meet. The coating inspection process starts with inspecting the substrate and the environment, which becomes part of a coating specification. A coating specification is an important document: it should provide clear and precise instructions to the contractor on what is to be done and how it is to be done in order to ensure optimal performance. Some manufacturers actually provide specification services, so that every step of the process is overseen by someone who knows the coating products inside out.

The coating survey

conducting coating inspection on coated steel pipe

Inspecting the surface and environment is a standard part of coating inspection.

First of all you have a facility, infrastructure, asset or machinery that requires coating, or a coating job that needs refurbishing or evaluating. You want assurance that the job will, at every step, be of only the highest quality. Therefore, your coating inspection procedure starts with a site condition survey, which forms a foundation for the coating specification. This condition survey will answer questions such as:

  • What is the substrate, and what is its condition?
  • Is there previous coating, and is it damaged?
  • Is there deterioration, such as rust or peeling?
  • To what degree is there damage, does it require starting again?
  • Are there any environmental issues which need to be taken into account?

Any problems that might be found, or maintenance required, need to be dealt with.

Writing the specification

Is your coating specification clear and comprehensive, making sure there are no misunderstandings between engineers, applicators, contractors, and managers? The specification needs to clearly describe the owner’s expectations for their project, aesthetically and structurally. It must also include a description of the substrate and the environment the coating will be applied in. A well-written specification contains as much detail as is required to make these expectations clear, in plain unambiguous terms. It is a template, and thus needs to be as accurate as possible for the finished product to turn out as planned. 

A standard coating inspection consists of 6 steps

Once the specification has been written, the application process must be monitored from beginning to end; from surface preparation to final colour and gloss. This process generally consists of six standard steps:

  1. Inspecting the surface preparation and pre-treatment
    The most fundamental phase of a coating inspection. A well-prepared surface is the foundation of a successful coating. The aspects to inspect include surface cleanness and roughness. There are coating inspectors who specialise in assessing surface preparation such as sand blasting.
  2. Assessing climate conditions
    Environmental factors such as climate must be assessed to prevent the air, surface temperature, or humidity affecting the curing and adhesion of the coating. The specification should define the optimal application conditions.
  3. Measuring film thickness (before and after curing)
    It is important to inspect the film thickness of powder coatings and liquid coatings before the coating cures so that and deviation from the specification can be detected and repaired before curing. The dry film thickness is measured to make absolutely sure the film thickness is in accordance the optimal performance of the coating.
  4. Observing  the curing rate
    The coating must be cured to the degree defined in the specification; if the coating is not cured enough the surface lacks hardness, making the finished coating layer more vulnerable to hazards such as abrasion and chemicals.
  5. Checking for sufficient adhesion
    The current methods of testing adhesion are all destructive, so the test is usually conducted on a sample substrate. It is crucial that the sample has undergone the exact same treatments under the exact same conditions as the real substrate.
  6. Evaluating the colour and gloss of the cured film
    The colour of a coating needs to match the specification, but also be consistent across the whole surface. Gloss level is also measured, and checked for deviation.

Regular coating inspections to check compliance to specification

Even though the coating is in place, the need for coating inspections has not disappeared. Maintenance inspections are conducted to confirm that the coating continues to meet the expectations set in the specification. If damage is detected, a failure analysis must be conducted to discover the reason for the coating failure, repair the coatings and prevent further damage.

Maintenance

Is the coating conforming to the expectations outlined in the specification? An examination of all coatings needs to be carried out, to check that properties such as thickness, corrosion and fire damage all conform to the specification. Corrosion costs the US nearly $500 billion  a year in replacing and repairing damaged assets, so having a regular coating inspection can catch the problem before it goes too far.

Failure analysis

It happens. Coating projects fail, damage happens, or corrosion wins. In this case, the coating inspection has one goal – to find the culprit. Like a detective, they will gather and analyze information about the coating, its environment, its usage, its application process and thus uncover the reason behind the failure. Once found, they outline the best way to deal with the issue and how to prevent it recurring in the future.


Coating inspection courses and certifications: NACE and SSPC

While there are a couple of programs available for coating inspection and application training, the NACE certification remains the most reliable. NACE International is the Worldwide Corrosion Authority. ASTM and ISO (International Organisation for Standardization) are the international bodies which produce the standards that guide the coating industry.

NACE Certification

The NACE Coating Inspector Program (CIP) has been setting the standard for inspections in the protective coatings industry for over 30 years. The CIP is an international certification program that produces the highest caliber of paint inspectors. These come in Level 1, 2, and 3, with 3 being the highest. NACE also publishes a book outlining the use of coating inspection instruments.

SSPC PCI Certification

SSPC is the Society for Protective Coatings, and they run training and certification programs and bridging courses for coating inspectors. The PCI is the Protective Coatings Inspector program, and like the NACE certification there are 3 levels, which level 3 being the highest qualification.

Coating inspection instruments

The instrumentation is a vital part of a coating inspection and there are many options, including coating inspection kits, to ensure that readings and calculations are done correctly. A coating inspection kit includes the following instruments:

  • a thickness gauge
  • a hygrometer (for testing humidity)
  • a dew point calculator
  • a thermometer with surface probe
  • a wet film gauge

Inspection instrumentation manufacturers such a BYK also sell their instruments, if required as part of your coating management plan. If you would like more information about how to purchase coating inspection instruments, contact our experts by using the “request a quote” button.

Coating inspection companies in the US

Many companies operating in the US offer coating inspection services. The following are a small sample. NACE also has a handy tool on their website for finding a certified professional in your area. If you would like more information about the right company for you, please contact us!

CompanyServicesCertification
US CoatingsOn-site survey with site-specific asset evaluation and recommendations. Specification consulting. OEM customized solutions.NACE
Bureau VeritasOn-site survey. Analysis of conditions, application methods, systems, and quality. Visual inspection of coatings.NACE
The Merrick Group IncOn-site survey. Ensure coating specification and quality adherence and application.NACE
CorrproOn-site survey. Ensure adherence to quality and specification. Project management. Failure analysis.NACE
SGSOn-site survey. Technical specifications and periodic quality controls. Failure analysis.NACE
Amerisafe ServicesCoating specifications. On-site survey. Management of coating projects.NACE

 


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