ABSTRACT

Availability and accessibility to clean water for industrial applications such as hydrostatic pressure testing of pipelines, vessels, and plumbing distribution systems has been a challenging task especially when the job sites are in remote locations. These circumstances have forced the use of contaminated water containing for example, large amounts of chloride. Hydrostatic testing of metallic equipment is an important method for quality control of parts, after production and during use. When contaminated water is used in these tests, corrosion of the metallic components of the system, during and after testing become a major concern, therefore, application of inhibiting system is required. Vapor-phase corrosion inhibitors (VCI), can be added to water in small concentrations to prevent corrosion during testing, or wet storage and after testing. These inhibitors are to prevent corrosion of metallic components in three phases, within the solution, at the water line, and above the water line.

Three commercially available corrosion inhibitors (USDA Biobased) were evaluated in this study to optimize the best combination of inhibitors to minimize the corrosion of these multi-metallic components system. Laboratory studies are presented in this paper, showed the effectiveness of VCI products in both fresh and salt water applications. Results confirmed the effectiveness of VCI products in various water chemistries including fresh and salt water. Average corrosion rate dropped from ~10 mpy for salt solution to less than 1-1.6 mpy when various inhibitors was added. However, the effectiveness of these inhibitors is remarkable in the fresh water (less than 0.4 mpy). Exposure of the steel samples to these inhibitors did not show any loss in mechanical properties. Both strength and ductility of the low carbon steel samples was maintained. Adsorption energy for these inhibitors was about -21,520 to -24,970 J/mol, indicating a strong physisorption mechanism.

Application of an inhibitor in any water system requires compliance with the Clean Water Act and the National Pollutant Discharge Elimination System (NPDES). These three investigated corrosion inhibitors investigated were water-based, bio-based, environmentally friendly, and can be effective replacements for toxic nitrite, chromate or hydrazine base inhibitors and satisfy all the required environmental compliance.

This content is only available via PDF.
You can access this article if you purchase or spend a download.