PAINTSQUARE BLOG

In my previous post, I introduced my concerns about the role of coating condition surveys in keeping offshore workers safe and keeping offshore assets secure. Last week's blog addressed some of the planning that should go into coating condition surveys, as well as the qualifications that a surveyor should possess and the role he or she should play.

In this, the second in this two-part series, we'll take a look at standards that will play a role in many coating condition surveys, and the process itself.

On Visual Standards

A great deal of the coating condition survey is visual in nature, and for this reason, various standards exist for evaluating the extent of corrosion and coating failure. These standards should be used extensively by the coating condition surveyor. It is critical that the use of visual standards, and the type of visual standards to be used, be established at the pre-survey discussions or pre-planning stage.

All images: © iStock.com / mikeuk

Coating condition surveys play an important role in keeping offshore workers safe and keeping offshore assets secure.

One such visual standard that is commonly used is the SSPC-VIS2: Standard Method of Evaluating Degree of Rusting on Painted Steel Surfaces (also ASTM D 610).

This standard is regularly used for rust evaluation, and it includes reference color photographs and corresponding black-and-white images that depict the percentage of rusting both in general and pinpoint rusting types.

A table is also included to compare against other rust grade scales, such as the ISO and European grades.

Along with the ASTM D610, ASTM has a number of standards that can be used by the coating surveyor:

• ASTM D660 – Degree of checking;
• ASTM D661 – Degree of cracking;
• ASTM D662 – Degree of erosion;
• ASTM D714 – Degree of blistering; and
• ASTM D772 – Degree of flaking.

There are clearly a great number of standards available to the surveyor, and the standards to be used for the coating condition survey should be clarified at the pre-planning stage.

While the SSPC and ASTM standards for evaluation are often specified for coating condition surveys in North America, outside of the United States, the international standards are used more frequently. EN ISO 4628 deals with the evaluation of degradation of paint coatings and designation of intensity, quantity and size of common types of defects.

The document, which contains text and black-and-white illustrations, only has six parts:

• Part 1 – General principles and rating scheme;
• Part 2 – Designation of degree of blistering;
• Part 3 – Designation of degree of rusting;
• Part 4 – Designation of degree of cracking;
• Part 5 – Designation of degree of flaking; and
• Part 6 – Designation of degree of chalking.

The coating surveyor can compile a comprehensive report based on the information that the above standards offer, which is comprehensive and technical guidance to the coating condition surveyor to use once in the field.

The Survey Itself

As we are starting to ascertain, there is a great deal of information to be gathered and taken into account in order to execute an efficient and successful coating condition survey, with much pre-planning and many critical points to consider. Once all of the above factors are established, it should be time to move on to the actual coating condition survey.

Typically, a full coating condition survey usually takes the form of non-destructive testing with a high focus on visual assessment for degradation and deterioration of the protective coating, which is to be assessed and compared to the evaluation standards listed above.

The coating condition survey needs to be thoroughly planned, implemented and executed with a pre-determined scope of work that is thoroughly understood by the coating surveyor.

Dry film thickness readings are often required, in addition to a full pictorial reference catalog of the area/equipment being surveyed. However, there is often a requirement to carry out destructive testing, which may include any of the following tests:

• Adhesion testing;
• DFT assessment using the Paint Inspection Gauge (PIG);
• Solvent rub testing; and
• Sampling (taking paint flakes for laboratory analysis).

The coating surveyor should also detail at minimum the following items within the coating condition survey report, including the location, zone or area:

• Condition of substrate (i.e., factors like contaminated surfaces—grease, oil, etc.—that make the coating survey difficult);
• Rust evaluation;
• Coating assessment or breakdown;
• Any evident rust staining?;
• Loss of gloss retention;
• Adhesion;
• DFT;
• Metal (section) loss or pitting;
• Missing sections (steel, bolts, nuts etc.);
• Access problems and issues;
• Environmental constraints and issues;
• Coating failures, flaking, blistering, runs, sags, cracking, etc.;
• Discussion on gathered data;
• Recommendation on future works;
• Proposed coating systems and methods of surface preparation; and
• Health and safety issues with conducting future work in line with recommendations

There is clearly a great deal of comprehensive pre-planning and coating engineering required in order to implement and execute a successful strategic coating condition survey, and there is an abundance of factors and issues which need to be taken into consideration. It is not a case of simply turning up with a notepad and a camera: The coating condition survey needs to be thoroughly planned, implemented and executed with a pre-determined scope of work that is thoroughly understood by the coating surveyor.

The author would like to thank Brendan Fitzsimons for his technical help and assistance with this piece.

ABOUT THE THE BLOGGER Lee Wilson Lee Wilson, CEng, FICorr, is a NACE Level 3-certified CIP Instructor, NACE Corrosion Specialist, NACE Protective Coating Specialist and Senior Corrosion Technologist, as well as an ICorr Level 3 Painting Inspector and Level 2 Insulation Inspector. The author of the best-selling Paint Inspector’s Field Guide, Lee was named one of JPCL Top Thinkers: The Clive Hare Honors in 2012. Contact Lee. SEE ALL CONTENT FROM THIS CONTRIBUTOR