A predictive flow model was used to identify specific locations where internal corrosion is likely to occur in an aging gas gathering system. The model integrates the effects of a fully compositional, mechanistic pipeline simulation model combined with digital elevation profile data to determine specific locations and severity of identified stagnant water hold-up locations. The work was completed for 17 high-pressure line segments (230 cumulative kilometres) and 96 low-pressure collection laterals (650 cumulative kilometres) covering a region of approximately 14,500 square kilometres. Conventional corrosion rate models1 suggest a very low unmitigated corrosion rate of 0.15 mm/year (6.0 MPY),
however, an overall integrity assessment was warranted given that the majority of the gathering system has been operating for approximately 40 years without an internal corrosion mitigation program in place. The results of the evaluation were used to develop a focused inspection and corrosion mitigation plan for the most highly susceptible pipeline segments identified within the study.