Currents and cathodic protection

It may be desirable to electrically isolate a cathodically protected structure from all other metallic structures, such as connecting lines, pump stations, terminals, etc. If the installation is not isolated, these connections also will be cathodically protected, and current requirements frequently will be excessive. Electrical insulation of pipelines and other structures is accomplished by dielectric isolation. Small lines may be insulated by insulating couplings or unions. If feasible, insulated flanges should be assembled and electrically tested with an ohmmeter before being connected into a line. 

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