Electrical continuity of CP system

One thing is often overlooked in the Cathodic protection design is  electrical continuity of the pipeline cathodic protection system. Similar to the function of electrical isolation, the current continuity is a key to make sure the current flow to wherever it designates to. This is not only for CP current, but also for induced AC current, telluric current and lightning current. The electrical continuity is particular important to nonwelded pipeline to allow sufficient CP current passing through. This is also critical to lightning protection of the pipeline and its CP equipment. Nonwelded parts, such as flange, coupling, spool piece etc, are not considered as reliable electrical conduction path for lightning strikes. This can be mitigated by the installation of permanent bonds over high resistance flanges/couplings, using cables and approved attachment methods.The continuity of nonwelded pipelines should be checked, e.g., by carrying out overlapping potential measurements.

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