Measures in different metal installations

In some gas stations, in order to keep the fuel clean, all filters, components and parts are made of stainless steel and aluminum alloy. The electrostatic potential of these materials is different from that of ordinary carbon steel. Cathodic protection of different materials in devices made of different metals is possible only when the protective potential ranges of various materials overlap with each other. If there is no overlap, an insulating joint must be installed. If the protection current density difference is very large, this provision is also appropriate, even necessary. If the various materials are separated by insulating joints, but they are connected to the same protection system, these insulating joints must use a bipolar circuit to avoid bimetallic corrosion when the protection system is turned off. Furthermore, different protection currents should be regulated by variable resistors.