Abstract
Failures resulting from intensly localized external corrosion of ADCO's buried pipes were minimized by the application of suitable protective coating supplemented by continuous cathodic protection. These protective measures generally proved effective for the total circumference, including the underside in a large number of pipelines built and operated by ADCO since 1965.
The lines were not internally coated. Internal corrosion caused by the accumulation of water in the pipeline due to the low velocities of the crude proved more difficult to control. The lines are, however regularly pigged to remove the water as far as possible.
Preventive maintenance is generally accepted as the most efficient means of protecting and ensuring safe operation of engineering structures over a significant period of time. As a result of a number of major oil leaks it was decided to investigate the use of an instrumented pig to provide information on the condition of the pipelines, both internally and externally, prior to any incipient corrosion becoming critical, and without interupting the pipelines operations.
This paper summarizes ADCO's experience on the successful work carried out using an instrumented pig to identify areas of corrosion in the 124 mile (199.5 km) long main oil line (MOL). It reviews the preparations necessary for such operations, the results obtained and indicates the potential savings which are possible using this technique. It also highlights recommendations for the future application of these devices in ADCO's operation, in particular its use as a preventive maintenance aid.
