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SCCS - Informa on on Cathodic Protection of Steel and Concrete Pipelines Page 1 of 1 CATHODIC PROTECTION APPLICATIONS PIPELINES '') Copyright 1999 'CS Pty Ltd Steel pipelines are susceptible to corrosion and whilst the presence of a coating will reduce the amount of corrosion incurred, only the application of cathodic protection will guarantee that corrosion will be completely controlled. Impressed current is more economical for longer pipelines in open country where many miles of pipeline may be protected from a single groundbed. The pipeline must be electrically continuous which is automatically provided for welded steel pipelines but provision for bonding across joints must be made for rubber ring or flange jointed pipes. A groundbed typically consists of a number of silicon iron anodes laid in a trench of special carbonaceous backfill at a distance of approx. 100 - 150m from the pipeline. Current is supplied by a transformer rectifier unit which may be either pole or plinth mounted. Sacrificial anodes are economically adopted where short lengths of well coated pipelines are to be protected. They are also useful for protecting pipelines in built -up areas where there would be no room for an impressed current groundbed or where there would be a high possibility of interference on other buried structures due to stray currents. Packaged magnesium anodes are usually installed via a test post that indicates the location and also enables potential and current measurements to be taken. Test/marker posts are normally installed at least every 1 km apart and at corrosion 'hot spots' to enable the potential of the pipeline to be monitored and interference effects to be checked. Monitoring systems usually include buried reference electrodes. Coupon monitoring and electrical resistance probes are highly recommended for assurance of complete protection. In the vacinity of high voltage power lines induced currents and power surges could create hazards for both the pipeline and personnel. Remote monitoring systems should be considered for lines in remote areas or critical pipes as fast response times and reduced maintenance costs are possible. Further information can be obtained by e- mailing SCCS Pipeline Divison. Solomon Corrosion Control Services Pty Ltd - www.sokoccom.00 - Ph: +613 9563 8665 To help service you better, please contact the webmaster if there are any problems associated with this page. ttp://www.solcor.com.au/diyis.ons/pipeline/app._pme.html 09/20/2002