Development of New Corrosion Inhibitor to Prevent Black Powder Formation Using Quartz Crystal Microbalance Technique

Black powder formation is an oxidative corrosion process that over time can cause operational problems as the solids collect within the system.  There is a net weight gain within the system as molecular oxygen becomes incorporated as part of the solid materials. A novel quartz crystal microbalance (QCM) test apparatus has been developed to determine the effectiveness of various corrosion inhibitors to prevent black powder formation in sales gas pipelines. The QCM measures minute changes in frequency of a quartz crystal with weight gain/loss.  For our test apparatus, the QCM crystal was coated with iron where small increases in mass due to oxidation of the iron layer are recorded as a drop in frequency. Using the Sauerbrey equation, the drop in frequency observed during corrosion testing can be converted to a corrosion rate.  Several inhibitor chemistries were tested using the QCM apparatus.  In this study it was found that a new oil soluble corrosion inhibitor is the most effective for preventing black powder formation.