Author(s): D.P. Riemer & M.E. Orazem
External corrosion is commonly mitigated by coating the structure with a high
resistance film and by employing cathodic protection (CP) to protect regions that
are inadequately coated or where the coating has degraded.
Defects in the coating
are termed holidays, and such holidays can expose bare steel.
The objective of this
paper is to explore the state-of-the-art in computer models for cathodic protection.
The emphasis is placed here on mitigation of corrosion of underground pipelines,
but the concepts, models, and techniques described are sufficiently general to be
applied to mitigation of corrosion of any structure.
Since the beginning of the 20th century, petroleum products and natural gas have
been transported over long distances by buried steel pipelines.
Over 1.3 million
miles of buried steel main-line pipe are used to transport natural gas within the
United States .
An additional 170,000 miles of pipeline are used to transport
crude oil and refined petroleum products .
The limited availability of right-of-way corridors requires that new pipelines be
located next to existing pipelines.
Placement of pipelines in close proximity introduces
the potential for interference between systems providing cathodic protection
to the respective pipelines.
In addition, the modern use of coatings, introduced to
lower the current requirement for cathodic protection of pipelines, introduces as
well the potential for localized failure of pipes at discrete coating defects.
of the performance of cathodic protection systems under these conditions
Size: 614 kb
Paper DOI: 10.2495/1-85312-889-9/09
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