Abstract

Abstract CO2 corrosion often becomes a problem with respect to material selection for natural gas gathering pipelines and compressorstations. With the aim of finding a method to prevent such CO2 corrosion, the authors have made investiations on the effects of CO2 partial pressure, temperature, chloride content and flowrate on carbon steel, 410, CA 15 and Type 18Cr - 2Mo steels, using a corrosion loop test unit. Comparative studies on the data thus obtained (Laboratory Data) and actual corrosion monitoring data relating to existing gas gathering systems and actually measured wall thicknesses of existing pipes after long-term operation (Field Data) have indicated practical agreement between them. The authors would also discuss actual uses of 410, CA 15 and Type 18Cr - 2Mo steels as corrosion-resistant materials in severe CO2 corrosion environments - that is high temperatures and high CO2 partial pressures. In general these materials are difficult to weld. However, as a result of reviewing and adjusting welding conditions such as the selection of welding rods and thermal control, the authors have successfully welded thousands of weld points on such materials without encountering any specific problems. The authors would finally discuss actual uses of clad plates and clad pipes of Type 18Cr - 2Mo in severe corrosive environments.