Corrosion, diagnosis and repair of the pipelines. Case of the Algerian OB24' oil pipeline.

摘要

The oil pipeline OB1/24" is the first pipeline built in Algeria (length 660 km, 55 years old), intended for the transport of the crude oil and condensate starting from Haoud El-Hamra, towards the marine Terminal of Bejaia. The initial capacity of transport is 17,8 million tons per annum, (the equivalent of a flow of 2540 m~3/h), has transported, since its start-up in 1959, more: 530 Million tons of the crude oil and condensate. The buried steel pipelines are subject to corrosion, and to the damage of the equipment, whose consequence, after a certain period of operation, is a metal loss affecting their resistance (decrease of the Maximal Operating Pressure). The corrosion phenomena are known not only by their economic significance, but also by their complexity. A leak of oil can result, in addition to the loss of product, the losses due the stops operating and the repair costs. To this add the risk of fires, pollution, with potentially grave consequences: The oil pipeline OBI, in spite of the reliability and the system effectiveness of cathode protection and the coating applied from the start of exploitation, the effect of the ground aggressiveness added to the degradation of the coating (tiredness and breakdown), have caused a corrosion that is distributed over the entire length of the pipeline. This effect can be noticed by the appearance and multiplication of leaks at the places where the thickness is weak, and the pressure is significant. The aim of this paper is to show, through the presentation of a pipeline exploited during 55 years: 1. On the one hand the effects on the pipeline metal of the ground aggressiveness and the petroleum products, in spite of the reliability and the quality of the applied protection systems. 2. On the other hand, the importance of the inspection by the intelligent tool to the determination of the new maximum operating pressure and, consequently, its rational exploitation and its period repair.