Abstract
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, during wet storage and 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. As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. Generally NPDES permits exclude heavy metals, oils, and products outside of pH range 5-11. VCI makeup is in compliance with these requirements. 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.
