MERLIN CP Monitor
Pipeline operators must confirm that pipelines and other buried metal structures such as tanks and vessels, are protected cathodically against corrosion. This can be done in various ways: In impressed current systems• By taking pipe-to-soil potential measurements at test posts along the pipe (usually sited at road, rail and river crossings and at field/property boundaries and other rights of way). • By checking sleeves, critical bonds and isolation joints to make sure that the integrity of the pipeline is maintained. In galvanic systems • By checking the supply of current from the sacrificial anode to the structure it is protecting Although not usually taken as frequently as at the rectifier, measurements at CP test points are only spot checks. Again, they only indicate problems well after they have occurred and have no alarm capability. By contrast, MERLIN CP Monitors provide an immediate indication of CP levels at the important points in the pipeline network. In a well maintained CP system all points should be tested periodically but "key posts" should be monitored more intensively.