Modifications to the copper strip corrosion test for the measurement of sulfur related corrosion
The copper strip corrosion test (CSCT) is used to measure the corrosivity of sulfur compounds in hydrocarbon fluids. The CSCT is performed by immersing a strip of cleaned, polished copper in a hydrocarbon fluid at a specified temperature for a predetermined time, then 'rating' the strip against a standard. In this work, instead of using the usual large, oblong strips designed to measure 30 mL fluid samples, we used small circular Cu 'coupons' as an alternative method for carrying out CSCTs on microscale samples of fluid. The motivations for reducing the scale include: applicability to small samples, ability to archive the small and inexpensive coupons, reduced waste, and potential for automated analysis using autosampler vials as reaction vessels. Moreover, the symmetric circular geometry facilitates the analysis of the images with mathematical color spaces. Mixtures of n decane:n tetradecane with varying concentrations of H2S (from a distillation column) were used as a source of microscale samples of corrosive fluid to demonstrate the viability of the smaller scale CSCT. Additional experimental details concerning the lighting conditions and digital photography of the coupons, measurement of corrosion using color space, and quantification of the sulfur content of the distillate are also described. +Contribution of the US Government; not subject to copyright in the USA.