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C H E M I C A L T R E AT M E N T FIguRE 1 detailed description of the apparatus has been provided in previous work.4-5 In this work, we have used the QCM apparatus for measuring the effect of chemicals on the water condensation rate and the iron corrosion rate. The water condensation rate in the absence and presence of various chemicals was determined using a gold-coated quartz crystal placed in the vessel. The vessel is purged with nitrogen until the vessel reaches a dew point temperature of –30 °C to remove water from the system. The vessel is then pressurized and kept at a temperature of 30 °C until a stable baseline frequency is attained. At this stage, 250 µL of solution (with or without CI) are injected in the vessel. The frequency of the quartz crystal is monitored for 30 min, and the crystal temperature is then lowered to 5 °C to induce condensation. As condensation occurs, the frequency of the quartz crystal is reduced. When a stable condensation layer develops, the crystal is heated to 30 °C to remove the layer of condensation. If the frequency is essentially the same as the frequency before the condensation, this indicates the changes in mass were due to condensation. An iron-flm deposited quartz crystal is used to measure the corrosion of iron and the effects of chemicals on the corrosion of iron. The iron-coated quartz crystal is placed in the vessel. As condensation occurs, the frequency of the quartz crystal is reduced. When a stable condensation layer develops, the crystal is heated to 30 °C to remove the layer of water condensation. At this point, the vessel is pressurized with 100 psi CO2. The crystal temperature is then cooled to 5 °C to induce condensation. As water condensation and corrosion occurs, the frequency of the quartz crystal is reduced. The crystal is maintained at 5 °C for several hours to enable corrosion to occur. The crystal is then heated to 30 °C to remove NACE International, Vol. 52, No. 5 the water condensation layer. At this stage, the frequency changes of the QCM are due to corrosion and the formation of a corrosion product layer. Linear Polarization Resistance Corrosion Test In addition to the QCM studies, the standard corrosion tests were performed at atmospheric pressure using CO2 at 48.9 °C using a linear polarization resis- QCM setup. tance (LPR) technique. The tests were carried out in a 50% light hydrocarelastomers was evaluated in 14-day imbon-50% synthetic brine mixture. mersion tests. The tests involved the Material and Environmental placement of previously weighed coupons Compatibility of each plastic or elastomer in the formuThe compatibility of the proprietary lation and maintaining the temperature CI formulation with different metals was at 60 °C. The samples were then weighed evaluated in 14-day immersion tests that after exposure following the percent followed NACE Standard TM0169- weight change procedures provided in 2000.6 The tests involved the placement the NACE standard.6 of previously weighed coupons of each metal in the formulation and maintaining Results and Discussion the temperature at 60 °C. The corrosion Calibration of Iron Film rate was measured by weight loss. The mass of iron deposited on goldThe compatibility of the proprietary formulation with different plastics and coated QCM is determined from the FIguRE 2 Frequency changes vs. time for an iron-coated quartz crystal with a condensed water flm in a 100-psi CO2 atmosphere. May 2013 MATERIALS PERFORMANCE 57