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Copyright © 2000, MCB UP Limited
Remote CP monitoring
Keywords BAC Corrosion Control, Pipelines, Corrosion monitoring
As part of its ongoing programme of work to reduce water leakage, Northumbrian Water has awarded BAC Corrosion Control Ltd, Telford, a £300,000, 15-month contract to carry out a pipeline audit, ongoing rehabilitation and a cathodic protection programme for all its large diameter steel trunk mains.
Part of the work will involve linking corrosion protection systems into existing telemetry facilities to provide remote monitoring of pipe condition. This is believed to be the first time remote monitoring of corrosion protection systems has been used in the UK water industry.
Northumbrian Water, whose territory extends from Berwick in the north down to North Yorkshire and from the coast across to the Pennines, is surveying all of its major steel trunk mains. Pipes from 12in. up to 40in. diameter are involved and existing impressed current cathodic protection systems are being upgraded by BAC to modern standards. The steel mains being surveyed are part of Northumbrian Water's total of 350km of large diameter trunk mains.
As well as upgrading existing ICCP systems, BAC's remit is to investigate steel mains that have no cathodic protection and prepare a prioritised programme of works based on corrosion protection viability. The ultimate aim is to have all the major lines protected cathodically, routes mapped and integrity managed to indicate problem areas. Remote monitoring will reduce the subsequent field work involved. Impressed current cathodic protection systems employ inert (non-galvanic) anodes with an external source of DC power to impress a current from anode to cathode through the soil. Voltages are applied to overcome soil resistance to give an impressed current a spread of protection from 2km on a poorly-coated pipe up to 50km or more for well-wrapped pipe under cross-country conditions.
Anodes are commonly used in groups in a low-resistance backfill called a groundbed. ICCP systems are seldom used in urban areas due to the risk of interference, typically from other buried structures, but are considered to be the most efficient cathodic protection systems for long-distance cross-country lines.
Details available from: BAC Corrosion Control. Tel: +44 (0) 1952 290321.