Internal Corrosion Predictive Modeling (ICPM) and Solids Deposition Predictive Modeling (SDPM) Using In-house Corrosion Model Software for a 30” X 44.15-Mile Natural Gas Pipeline

Abstract The NACE SP0110-2018 WG-ICDA Standard Practice was applied for internal corrosion predictive modeling of a 30” X 44.15-mile natural gas pipeline using the Broadsword in-house software. Operational data for 25 Meter stations over 5 years were collected daily and averaged seasonally. A null point at mile 739.05 was identified where gas flows west through Station 1 and east through Station 2. ICPM results showed stable temperature and pressure profiles along the pipeline, with corrosion rates <1mpy and wall loss <2%. The average wall loss (%) as calculated from the ILI data was 1.2%, and the average wall loss predicted by the in-house software was 1.6%. Predominant corrosion products were Fe3O4 and FeCO3, indicating air-contaminated gas streams and CO2 corrosion at low rates. Solids deposition modeling revealed maximum accumulation in the first 60,000 ft due to low gas velocity. Cumulative corrosion product weight and volume were high upstream and decreased towards Station 2, highlighting susceptibility to localized corrosion with brine water contamination. Enhanced monitoring during low gas flow periods is recommended to prevent operational upsets leading to free water dropout. Regular water analysis on free water and pigging debris samples is crucial due to observed chloride content correlation with pitting corrosion frequency.