Failure analysis and root cause analysis (RCA) of corroded pipelines and piping system components can provide operators with valuable information to help prevent future failures while optimizing mitigation costs. If a corroded pipe sample is not handled or preserved properly because of inadequate planning, the ability to diagnose the corrosion mechanism(s) is lost. Using some basic steps for preparation and investigation, operators can determine the applicable corrosion mechanism(s) causing the corrosion and implement or adjust the measures taken to mitigate the corrosion. Collecting multiple lines of evidence about chemical and microbiological conditions, corrosion products, and operating parameters is essential. Further, with the increasing use of molecular microbiological methods (MMM), the role of microorganisms can be determined with greater certainty than has been possible in the past. Targeting mitigation measures to only the applicable corrosion mechanism(s) can support mitigation cost optimization, such as by applying only the correct chemical treatments rather than an all-encompassing "security blanket" approach.
Forensic corrosion engineering (FCE) is a practice that seeks to understand the contributing causes and underlying mechanisms of corrosion damage and apply this knowledge to mitigate risk resulting from corrosion threats. FCE focuses on the physical and circumstantial evidence associated with materials degradation or failures resulting from corrosion. The objectives of FCE include characterizing the basic electrochemical mechanisms of the corrosion damage, identifying the environmental factors that supported the corrosion mechanism, and proposing effective means of mitigating corrosion for similar facilities or equipment.1
The first phase of the investigation involves determination of the immediate cause. For a pipeline internal or external corrosion failure, the "immediate" (or direct) cause of the failure relates to the findings of a metallurgical laboratory analysis performed on the removed pipe section or component. The laboratory analysis is used to determine the damage mechanism that caused the leak or failure.
