Polyurea-based coating chemical resistance

Polyurea-based coating for chemical resistance

9:54 AM, 6th March 2017
Rhino Linings HiChem 11-70 Monolithic Secondary Containment Barrier for a Large Texas Anodizing Plant.
This new facility would serve as a major regional hub for many of their coating services including hot dip galvanizing, E-coat, anodizing and powder coating.

Problem

Valmont Industries, a leading producer of centre pivot and linear irrigation systems for large-scale agriculture as well as infrastructure and industrial products, was moving into a brand-new facility in Brenham, Texas. This new facility would serve as a major regional hub for many of their coating services including hot dip galvanising, E-coat, anodising and powder coating. Just a few weeks before their new facility was due to open, the company was faced with environmental concerns over the potential containment of harsh chemicals in their sub-grade concrete anodising bay.

The process of anodising produces two environmentally dangerous chemicals: sulphuric acid and aluminium hydroxide. Both of these chemicals are strictly regulated by the Environmental Protection Agency (EPA) and companies are expected to take great care in preventing their introduction into groundwater. Since both of these chemicals are highly corrosive, the possibility that they may degrade and escape their primary containment had to be considered. Though concrete was an optimal choice for the durable structure of their anodising bay, a protective coating was required to prevent leeching through the porous material.

Valmont Industries contacted Global Coat, an authorised Rhino Linings® applicator based in Baytown, Texas, to advise a long-term containment solution that would protect the concrete bay and surrounding environment from chemical damage and seepage. The protective coating solution also needed to provide a rapid return to service so that other contractors completing the facility could remain on schedule.

Global Coat proposed Rhino Linings HiChem™ 11-70, a 100% solid, zero-VOC polyurea-based lining. HiChem 11-70 is Rhino Linings Corporation’s most chemical resistant product to date, it boasts a high tensile strength and it has a dense, impermeable chemical structure. It can be quickly applied with plural component spray equipment and fully cures in less than 24 hours. HiChem 11-70 is often used to create a seamless primary and secondary containment lining.

In addition to HiChem, Global Coat recommended that Rhino Extreme™ HP 11-50 be applied over the facility floors to protect against the daily wear and tear of foot and light vehicle traffic. Rhino Extreme HP 11-50 is a pure polyurea industrial lining with high chemical and corrosion resistance, superior hardness and elongation, high tensile strength and excellent tear and abrasion resistance. The proposed product applications were ideal for Valmont Industries’ needs and Global Coat was awarded the contract for both the anodising bay and the facility floors.

The brand-new 9,000-square-foot concrete anodising bay did not have a barrier preventing moisture intrusion from the ground below. Because of the nature of concrete, the natural moisture in the ground was bound to establish capillaries that would siphon water from the ground through the concrete. If the potential moisture issue was not addressed prior to installation of Rhino Linings coatings, the applicator would risk delamination and failure of the final coating. In an effort to prevent water intrusion,

Global Coat used a moisture meter to test moisture levels over the entire substrate. Any areas that registered with 5 percent or more vapour were treated by penetrating the substrate to check for detectable water and then filled with an injection of epoxy or foam depending on the severity. Areas that registered under 5 percent vapour were addressed with a coat of Rhino Linings Moisture Guard, a water-based densifier and moisture vapour blocker that create a permanent integral barrier and greatly reduce the permeability of concrete.

To create a smooth surface for ease of clean up and maintenance, Global Coat filled “bug-holes” or imperfections. They then proceeded to abrasively remove laitance and create a rough profile that would encourage adhesion of the primer and coatings. Instead of using concrete grinder, which creates excess dust and debris, Global Coat blast tracked the entire application area. Blast track surfacing is a dust free procedure that uses no chemicals or water.

This preparation choice was important for this application as debris and dust would have affected the progress of the other contracted crews working in the facility and water would have delayed the final application, as the substrate would need to dry prior to coating.

The prepared surface was then segmented into smaller, workable sections and each section was primed with 3 to 4 mils of Rhino 1500 Primer, a waterborne epoxy primer that has a unique “lacquer dry” cure that allows it to be recoated quickly.

Though Rhino 1500 Primer dries quickly (60-90 minutes) it has a long working time (2-3 hours). The longer working time allowed the applicator to mix larger batches as well as roll and blend the primer into each segment before moving to the next section. The biggest timing challenge came with the application of both final coatings. Because Valmont Industries was adamant to open the facility on schedule in order to meet production demands, a number of crews were working side by- side in the same space.

For the spray application to proceed, proper personal protection equipment was required to be worn Global Coat needed to coordinate with contracted painters and welders working overhead to ensure they were able to step away from their work when it was time to spray-apply the coatings.

Once the primer had cured to tacky, and with minimal delays clearing out other crews, the applicator applied between 60- 80 mils of HiChem to the floors and walls in each section to establish a monolithic secondary containment barrier in the anodising bay. Global Coat then quickly transitioned to the Rhino Extreme HP 11-50 floor application. This substrate was also segmented and the chemical coating was applied at 60-80 mils.

Results

The three-man Rhino Linings applicator crew worked diligently over eight days to complete both projects with minimal interruptions to the other crews. The facility opened right on schedule with a chemical-resistant secondary containment coating for their new anodising bay, as well as a protective coating for high trafficked areas of the plant. Valmont Industries was pleased with the long-term, durable and chemical-resistant Rhino Linings coating solution that ensures their new facility is compliant and protected for many years to come.

© Coatings Special by Chemical Today Magazine


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