Ethane feeder pipeline corrosion rate prediction analysis

Abstract

Carbon dioxide CO2 is one of the major gases of concern in ethane feeder pipeline since it presence will induce corrosion which then damage the pipeline. The purpose of this study is to determine the corrosion rate using NORSOK M-506 commercial software prior to comparing corrosion rate with international standard, identify optimum level to control corrosion rate, and analyse the relationship of moisture content towards H2CO3 impact and its pH level for variety of CO2 concentration, temperature, pH and moisture content in the ethane feeder pipeline. Evaluation impact was done for CO2, temperature and pH value using average value and is categorised as moderate between 0.025 to 0.12 mm/year as per an International Standard – National Association of Corrosion Engineer (NACE). Corrosion rate for CO2 is 0.055 mm/year while for temperature and pH are 0.054 mm/year and 0.055 mm/year respectively. Based on the average corrosion rate of 0.05 mm/year, the simulation results produce the optimum corrosion control level when CO2 concentration is 1.40 mole percent at temperature of 21.5 °C and pH of 4.7. Since NORSOK M-506 software has the limitation of pH coverage within 3.5 – 6.5, moisture effect is analysed using chemistry equation approach. It was found that the concentration of H2CO3 increases with moisture content. More H2CO3 formation in pipeline will definitely promote a more serious internal corrosion.