Vapor Corrosion Inhibitors in Hydrotesting and Wet Storage Applications

Hydro-testing or hydrostatic testing of metallic equipment such as vessels, piping, valves etc. is an important method for quality control of parts, after production and during use.  When water is used in these tests, corrosion of the metal, during and after testing is a concern. Vapor-phase corrosion inhibitors (VCI), when added to water in small concentrations are able to prevent corrosion during testing, and during wet storage  after testing.  
            The mechanism of amino-carboxylate based vapor-phase corrosion inhibitors is to prevent corrosion of metals in three phases: within the solution, at the water line, and above the water line.  VCI-based compounds prevent corrosion in the areas which are not reachable with other corrosion inhibitors. .Genrally NPDES permits exclude heavy metals, oils and products outside of pH range 5-11.  These requirements are in compliance with VCI makeup.  Lab studies and examples of use on various pieces of industrial equipment will be presented in this paper to show effectiveness of VCI products in both fresh and salt water applications.
Key Words: Hydro-testing, corrosion, vapor-phase corrosion Inhibitors