Corrosion of pipe, both from the inside/out and from the outside/in, has been a generic
problem that literally “comes with the territory”. Many techniques exist for locating leaks in
pipelines, which are applied in industry with varying levels of success. Once located, proper
failure analysis and diagnosis of the root cause for the corrosion that resulted in failure of the
pipe is a key element for the successful mitigation and prevention of recurrence. This involves
a deliberate and programmed approach to investigate all possible causes, comprehensive
gathering of field data, and performance of necessary laboratory analyses in order to reach an
informed and scientifically justified conclusion.
Mechanisms that are known to be associated with localized pipeline corrosion include pitting
corrosion, crevice corrosion, microbiologically influenced corrosion (MIC), galvanic corrosion,
flow assisted corrosion, and stray current corrosion. These corrosion mechanisms can occur
from the inside/out or from the outside/in and may occur at various stages of the deterioration
and/or in combination with each other. Once the root cause has been identified, mitigation and
prevention techniques and procedures should be based on the outcome of such an analysis. A
particular mitigation method, which has proven to be successful in one instance, may not be
successful in other circumstances. Every installation has some unique features in terms of
environment and possible contributing factors to corrosion, which should be taken into
consideration during failure analysis and subsequent identification of mitigation techniques and
prevention methodologies. This paper will provide a description of the key elements of such a
programmed and integrated failure analysis and diagnosis approach. Case studies of field
experience with pipe failures are utilized to illustrate various aspects of this approach, including
general and localized corrosion and microbiologically influenced corrosion.
Key words: pipeline corrosion, leak detection, internal pipe inspection, pin hole leaks