This paper presents the Root Cause Analysis (RCA) of severe accelerated top side external corrosion of a pipeline within a casing. The pipe was exposed as part of an integrity excavation to investigate fast-growing external corrosion features identified through successive In-Line Inspection (ILI). Upon excavation, the external corrosion morphology was atypical and concentrated along a narrow 1 to 2-inch-wide band at the top of the pipe over the distance of several joints. This paper presents summary information from the ILI along with cathodic protection results, Non-Destructive Examination (NDE) results, and laboratory testing performed as part of a causal investigation. After eliminating the most likely mechanisms of accelerated external corrosion, a rather unusual corrosion scenario was identified. This case study of severe and rapid external corrosion within a casing should be of interest to operators of pipelines where operating temperatures are increasing.

Subject
Abrasive blasting, Carrier pipes, Pipe surfaces, Water, Piping, Annulus, Condensation, Pipelines, Inspection, Metal loss, Joints, Corrosion products, External corrosion
Keywords:
External Corrosion, Casing, Pipeline, Root Cause Analysis
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2025
Association for Materials Protection and Performance (AMPP)
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