Long-Term Coatings Lab Testing Data Analysis for Service Life Correlations and Evaluation of New Testing Methods

Project ID: 23014
Principal Investigator: Bobbi Jo Merten
Research Topic: Repair and Maintenance
Funded Fiscal Years: 2023 and 2024
Keywords: None

Research Question

This research evaluates the following two questions:

1) How can modern data analytics provide useful data mining of coatings laboratory data sets spanning 10-30 years to identify statistically significant correlations to field performance, i.e., service life prediction?

2) Are there new testing approaches or sensors that should be incorporated in routine laboratory coating evaluations that will improve screening and service life prediction?

Question 1 will be answered through a coordinated effort to analyze the large coatings testing datasets at USACE and Reclamation laboratories. These includes a 6-month testing suite and long-term immersion tank testing. The 6-month testing approach determines coating performance via immersion, accelerated weathering, electrochemical, and physical testing methods. The long-term immersion tank testing is a novel resource, given that provides several decades of natural degradation. The team will determine appropriate destructive or non-destructive testing to apply to these materials.

Question 2 will be answered by reviewing the literature for potential new test methods to add to the existing testing suite. Several team members are industry experts with experience researching coating service life prediction. This will provide an advantaged starting point for developing a short list of potential test methods to evaluate, whether altogether new or improvements upon existing methods. USACE is initiating a research effort to evaluate IDEs and will provide these sensors for evaluation under this proposed research. Researchers also bring prior experience in demonstrating the effect of increased water temperature during immersion testing. As previously stated, the testing results from Question 2 will be added to the dataset for Question 1 and analysis re-run to determine if any of the new tests provide strong predictors of coating performance.

Need and Benefit

Need: This research is needed to improve laboratory coating evaluation and to expedite the evaluation of new coatings for use on Reclamation structures, specifically for the new coatings needed to replace Reclamation's historically used coatings. Coatings require occasional removal and replacement to provide the long-term corrosion protection needed to maintain reliable hydropower production and water delivery. Without the highest quality coatings and good maintenance practices, the structures experience corrosion or pitting that can only be repaired with costly replacements or weld repairs. These repairs were recently incurred on projects, adding approximately $1 million to the contract cost.

The coal tar enamel originally applied as linings on Reclamation pipes provided approximately 50-80 years of service but are no longer used do to environmental and safety concerns. Similarly, solution vinyl coatings provide 40-50 years, and a replacement is sought due to the high volume of volatile organic compounds (VOCs), i.e., solvents, required during coating application.

Urgency: This research is needed now because Reclamation is facing a total relining cost approaching $0.5 billion for its 6.6 million square feet of interior penstock surfaces alone, based on a typical contracted cost of $50 per square foot. This cost and the recoating cost for the remaining inventory of steel gates, outlet works, and similar structures is anticipated to be incurred over the next 30 years. At least eighteen Reclamation facilities currently have incomplete recommendations in Power Review Information Systems (PRIS) for coating repair or relining at an estimated cost of more than $8 million.

The coatings currently used as replacements are estimated to provide 20-30 years of service, greatly increasing the frequency of this recoating investment. More specifically, Reclamation's first total coating replacement projects were initiated in the last two decades and many facilities have yet to begin incurring this high-cost and high-risk construction maintenance activity.

Benefits: Enhancing laboratory testing methods to expedite new coating development and evaluation will result in longer service lifetimes and greatly reduced annual recoating investment across Reclamation. Therefore, replacement coating sooner will increase reliability, reduce costs, and improve safety by reducing the frequency of this high-risk maintenance activity.

This research combines the expertise of several water management agencies and commercial coating manufacturers to help address the issue of poor correlation between laboratory testing and field performance. The knowledge gained from this research will help all parties to better serve their organizational missions to provide the best coatings possible for corrosion protection on steel structures.

Impacts: The immediate impact of this research is enhanced understanding of the results of coatings laboratory tests, including guidance for translating results to expected field performance, where predictive nature exists. The future impact of this research is more efficient research and development of new coating systems, including those needed to protect Reclamation's infrastructure from corrosion. If the anticipated cost to Reclamation for protecting steels structures during a 30-year lifecycle far exceeds $0.5 billion, accurately identifying coatings to that will yield even 5 or 10 additional years of service life will provide a quick and substantial return on the research investment.

Contributing Partners

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Research Products

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Last Updated: 6/22/20