Polymeric Coating Protects Dispersant Vessel Used for Offshore Spills

Oil spills can be an ecological disaster, and are challenging to mitigate. To complicate it further, nearly 20% of current rigs are located in regions where the temperatures can often be below freezing. To address spills or leaks, specialty companies are hired to apply oil dispersant chemicals onto the spill, encapsulating the oil particles and breaking slicks into very small particles which are more easily absorbed into the sea without further damaging the ecosystem. 

Carried underneath a helicopter while in operation, the underslung oil dispersant vessel needed to withstand sub-zero temperatures of -25°C and protect the vessel from corrosion from saltwater and other damage. There were also weight considerations that had to be accounted for since the vessel would be airborne. The conventional insulation and finishing technologies used by the client weren’t holding up, so they turned to Belzona (Miami, Fla.).

In cooperation with licensed Belzona contractor, Grade2, Belzona recommended using Belzona 5871, applied in multiple layers. Belzona 5871 is a two-component, polymeric, solvent-free system that provides a thermal insulation barrier, corrosion protection and thermal and sub-zero “cool-to-touch” properties.

Designed for application to metal pipework, ducting and other industrial equipment, Belzona 5871 is thermally insulating and provides protection against contact-burn injuries, eliminates corrosion, condensation and anti-icing, improving safety and durability. The product expands upon application and produces a lightweight, closed-cell foam that is typically used to reduce the surface temperature of where it’s applied, but in this case, was used to insulate the tank. It is tested to ASTM B117 salt spray corrosion resistance tests for up to 4500 hours, along with other corrosion resistance tests.

After much consideration, Belzona 5871 was applied in three layers for maximum insulation and corrosion protection, for a total of 9mm dry film thickness (DFT). For added protection, the client elected to overcoat with an acrylic emulsion membrane, Belzona 3211 Lagseal, for added waterproofing, UV and fire protection. Lagseal is a water-based acrylic emulsion membrane that incorporates a polymer-bonded gladd reinforcing sheet to provide seamless insulation. It meets ASTM E84 standards and provides protection from water ingress while allowing trapped moisture from the insulation to evaporate. And it doesn’t support the growth of bacteria or algae. Orange pigment was added at a ratio of ≤5% for high visibility. 

The products were applied to the tank after careful surface preparation to ensure good adhesion to the stainless steel vessel. The substrate was grit blasted to achieve the standard minimum specification of ≥ 75μm, Sa 2.5 cleanliness vacuumed and clean degreased.

Once the surface was prepared, the Belzona was applied via a pneumatic cartridge spray gun, speeding up the application and keeping within the parameters required at ambient temperature. The product was applied at approximately 1mm wet film thickness, which expanded to 3mm DFT when cured. Within the product’s overcoat window, two more layers were applied for extra corrosion protection. The Lagseal mixed with the orange pigment was applied by roller as the final topcoat. When completed, the finish added just ≤ 10mm thickness onto the vessel dimensions which met the client’s needs and was more effective than traditional cladding.

Belzona’s representative, Marc Docherty, said that they aren’t sure what the total lifespan of the vessel is expected to be, or the coating. “This is a new design and an experiment for this type of work. However, the lifespan would be considerable but isn’t yet quantifiable since it’s a new concept.”

After one year in service, the solution has been effective and enabled the client to protect the vessel in its extreme operating conditions. Belzona is now considering other applications where this product can be used to offer similar benefits to its customers.