Innovative Corrosion Protection and Thermal Insulation Solution for Oil Dispersant Vessel

A Client who deals with environmental spills was faced with a unique problem when insulating its underslung oil dispersal vessel. The vessel would need to be carried underneath a helicopter over sub-zero temperature conditions to decontaminate the water after potential oil spills. Due to the vessel’s requirements, the insulation material needed to fit very particular specifications.

Belzona insulates and protects the oil dispersal vessel in extreme conditions
Belzona insulates and protects the oil dispersal vessel in extreme conditions

Specification of Belzona 5871 and Belzona 3211 (Lagseal)

The job specifications required the insulation material to withstand -25°C (-13°F) temperatures without allowing the dispersant within the vessel to freeze, as well as protecting the vessel against corrosion and damage.

When the Client considered insulation methods, conventional means proved to be technically not suitable for the operating conditions due to weight restrictions and the potential effects of salt water ingress through standard insulation cladding joints and seams. Also, the proximity of the vessel to salt water in cold temperatures would expose the seams to sea water spray which could cause the insulation to become damp, resulting in corrosion under insulation (CUI) problems; a vessel not being adequately sealed leaves the system vulnerable to corrosion.

Belzona and its licensed Contractor, Grade2, jointly recommended the use of corrosion protection system, Belzona 5871, applied in three layers for maximum insulation and corrosion protection, of a total of 9mm dry film thickness (DFT). This would provide an effective, solvent-free, thermal barrier, while also eliminating condensation, contact damage, anti-icing issues, waterlogging and corrosion. Belzona 5871 is a uniquely placed thermal barrier coating able to also provide long term corrosion protection having been thoroughly tested to ASTM B117 (Salt Spray) for 4500 hours, among other corrosion resistance tests.

The Client chose to overcoat the insulation with acrylic emulsion membrane, Belzona 3211 (Lagseal), for additional waterproofing, UV and fire protection. They also mixed in orange pigment at a ratio of ≤ 5% for high visibility in its working environment, as Belzona was able to adapt to the Client’s needs.

Simple and Precise Application

The products were applied in a controlled factory environment in the North of England, 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.

The vessel after grit blasting to prepare surface

Once the surface preparation was finished, Belzona 5871 was decanted into Belzona-issued cartridges and used in conjunction with a pneumatic cartridge spray gun. This sped up the application, keeping within the working life at ambient temperature. The product was spray applied at approximately 1mm wet film thickness (WFT), which expanded to 3mm DFT once cured. Within the overcoat window, a further two coats were applied, giving a final DFT ≥ 9mm. This was necessary due to the extreme conditions in which the vessel needed to operate.

Belzona 5871 was able to adhere very well to the vessel shell, giving a uniform DFT across all geometries, ensuring an effective corrosion barrier at the recommended ≥ 9mm total DFT. The Belzona 3211 (Lagseal), mixed with safety orange pigment, was applied by roller, as a final topcoat.

The application of the products added just ≤ 10mm thickness onto the vessel dimensions, ensuring that the Client’s weight and protection specifications were met far more effectively than would have been possible using traditional cladding.

Belzona protects against corrosion under insulation
The vessel was coated with three layers of Belzona 5871
The total DFT after three coats was just 9mm

Successful Application Represents Future Insulation Potential

Belzona’s solution has performed extremely well in tests over its first year in service, which shows the effectiveness of the products. The polymer technology enabled the Client to protect the vessel against the extreme conditions in which it operates, while also meeting specifications such as weight and thickness. Belzona proved more effective than traditional cladding, and the successful application demonstrates the potential for its use across multiple industries.

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