Solution To

Certain grades of oil that contain sulphur emit corrosive, sour gas vapors that destroy the internal surfaces of Aboveground Storage Tank (AST) roofs and their support structures above the product layer. Aggressive pitting and crevice corrosion create holes in the tank tops that cause unsafe operating conditions and environmental problems. Internal tank coatings decrease surface corrosion but have proven to be ineffective in preventing dangerous pitting and crevice corrosion – especially in the interstitial spaces between the roof and support structures.

Product Information
NTIC has developed the Zerust® ReCAST-R solution to protect the interior surface of AST roofs, consisting of dispensers that deliver the proprietary inhibitor formulations into the vapor space between the surface of the product and tank roof. The Zerust inhibitor forms a protective layer that prevents corrosion in highly-aggressive environments (H2S, SO2, etc). Zerust ReCAST-R solution can be implemented to extend the service life of a single tank roof to 25 years and beyond. Each system is tailored to the client’s requirements, depending on specific environmental conditions, product stored, tank diameter, and can be applied on both new and existing roofs.

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The VCI Dispensers are installed atop the AST roofs.
Zerust ReCAST-R VCI Dispenser
Zerust inhibitor molecules form a layer, protecting the interior surface of AST roofs.

Successes
Below are photos of the Zerust ReCAST-R dispensers, installed atop a 25-meter diameter aboveground storage tank:

The Zerust ReCAST-R system has been successfully deployed in aggressive internal corrosion environments as illustrated by the key parameters below:

recast-r-installation_1recast-r-installation_2
Critical Parameter Range in Field Applications Range in Laboratory Tests
Ambient Temperature, °C 22-40 20-55
Inside Tank Temperatures, °C 22-55 20-55
Relative Humidity, % 90-100 60-100
H2S, ppm 20-50 1,000-4,600
SO2, ppm >20 500-3,600

Contact us to learn how Zerust can help you manage your corrosion problems.