Effect of Corrosion Growth Rate Estimated from Consecutive Assessments on Response to In-Line Inspection Anomaly Predictions

摘要

Executing an appropriate response to conditions affecting pipeline integrity, as predicted by in-line inspection tools, can be affected by the rate of growth for time dependent threats such as metal loss due to corrosion. Corrosion growth rates can be estimated from predictive models considering the known corrosion mechanisms. Corrosion rates can also be determined from measurements of metal coupons exposed to the corrosive environment or from comparisons of pipe wall measurements over time. In-Line Inspection (ILI) assessments have been used by industry to provide wall loss measurements for corrosion growth rate determination with estimates developed from single ILI assessments based on pipeline age or comparison of wall loss measurements from consecutive ILI assessments using the approaches of feature list positional matching, box or full signal matching. This paper presents a case study comparison of corrosion growth rate results obtained from a gas transmission pipeline using the currently available industry procedures and the implications of each within the context of response strategies to ILI predictions.