Offshore pipelines are exposed to a series of challenges due to the harsh nature of their operating environments. These challenges include but are not limited to fatigue, metrological conditions (action of environmental forces), slugging, corrosion, etc. This study considers corrosion affecting the inner section of offshore pipelines. Internal corrosion is the gradual reduction of pipe wall thickness due to the chemical reaction between the component of the fluid flowing through the pipe and the microstructure of the pipe. The study employed a computational-based empirical approach to predict system reliability. The approach was tested with an API XL X52 pipeline. A parametric study investigated the effects of CO2 and water content on pipeline reliability. Increasing the %mole composition of CO2 from 1 to 2.5 and 3.5% resulted in an increase in reliability from 33.39 to 38.73%, 13.95 to 16.43%, and 10.2 to 12.12%, respectively. Similarly, higher water content improved the reliability from 13.43 to 15.77% at 5% mole, 13.95 to 16.43% at 10% mole, and 14.48 to 17.08% at 15% mole. The study offers a safety-based integrity management tool for steel pipelines under corrosion defects.