Simon, Philip D., Executive Vice-President, Operations Norton Corrosion Limited, Inc. United States of America
This paper presents test data, evaluation and recommendations resulting from an investigate cathodic protection and coating integrity survey of a twenty year old, onshore crude oil pipeline. The pipeline discussed is 20 inches (508 mm) in diameter, 233 kilometers long and originates at a pumping facility in an inland oil field. The pipeline runs through pumping facility in an inland oil field. The pipeline runs through mountainous terrain, low lying marshland and terminates at a twin 16 inch submarine crossing. The pipeline is located in Southern Kalimantan, Indonesia and is p art of the Pertamina Unit IV installation.
The field testing was performed by Norton Corrosion Limited (NCL) during the months of March ad April, 1983 and was done concurrently with river crossing profile work by Sterling Energy and Resource Technologies, Limited. The purpose of the survey was to determine the condition of the pipeline and the condition and effectiveness of existing corrosion control pipeline and the condition and effectiveness of existing corrosion control measures. The pipeline had experienced an increasing number of leaks in recent years and it was necessary to know the physical condition of the line and what could be done to extend its useful life. The present and future integrity of the pipeline was critical to the clients' planning in that this particular line is the only onshore connection between the field and new refinery which was nearing completion.
The corrosion of metals is an electrochemical process. That is to say, it is a chemical reaction which involves the transfer of electrons. Metal is lost at the anode (oxidation reaction) and atomic hydrogen is produced at the cathode (reduction reaction). A corrosion cell is a system in which a cathode and an anode are electrically connected and submerged in a common electrolyte. When this oxidation-reduction reaction occurs, a DC electrical current will flow with metal lost at the anode.
This system is called a corrosion cell. A corrosion cell will be formed when the following conditions are met:
There must be a cathode and an anode with a difference in electromotive force (driving voltage).
The anode and cathode must be electrically connected by a metallic path.
The anode and cathode must be immersed in a common (the same)electrolyte.
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