Control & Monitoring Petroleum Pipelines Corrosion

Abstract

Corrosion is the deterioration of the metal as a result of its reaction with the surrounding environment. The corrosion in the pipelines that carry petroleum products is considered as the main problem facing petroleum products pipelines which is as a result of its reaction with environment that include soil, its salts and water. The corrosion resulting from this reaction is called external corrosion which is more dangerous, there fore it will be considered more than internal corrosion that occur between pipe internal surface and petroleum product compounds. The present study aimed to investigate the effect of different environments and different kinds of soil through which pipeline buried extends from Shagara (Khartoum) to Port Sudan, and it is also aimed at the detection of the effectiveness of coating and cathodic protection system that it has followed. Also in this study chemical analysis has been done to examine the sorts of soil surrounding the pipeline and its chemical properties. These properties include soluble salts, degree of acidity, soil resistivity and relative humidity, and have followed the pipe inspection that has been carried out by Pipeline Integrity Inspection Company (PII) 2002-2003, and on the view of study it can be evaluated. Through this study the obtained results show that the soil in Khartoum, Shendi and Atabara areas is non corrosive because of the low soluble salts and also its corrosion resistance is very high, and is dry most of year months, moreover it is an alkaline soil. The inspection results indicate that the corrosion is spreading extensively in those areas because cathodic protection is poor. On the other hand corrosion is very weak in Port-Sudan area, although the soil in this area has a very low soil resistivity, very high insoluble salts, and high relative humidity but cathodic protection is extensively used in this area. So the study accessed that most corrosion occur under the tape, that means corrosion is not as a result of coating defect surrounding the pipe which indicate that corrosion is not connected to the circumstance surrounding the pipe, but it may be as a result of the poor protection due to the less number of the cathodic protection stations, or defects in the type of pipes material that is was made of, manufacturing process, or coating process methods. A worthy study and searching should be carried for this phenomenon. The study also recommended some methods used on control and monitoring of pipeline corrosion.