1.1 This standard prescribes the minimum mandatory requirements governing the design of cathodic protection (CP) systems for onshore metallic well casings. Commentary Notes: The cathodic protection requirements for offshore well casings are beyond the scope of this Standard. Cathodic protection as addressed in this Standard provides corrosion mitigation for the external side of the well casing only. It does not provide corrosion protection for the internal surface of the well casing. 1.2 Onshore oil, gas, water injection, and water supply well casings with a predicted life expectancy greater than five years shall be provided with impressed current cathodic protection (ICCP) if: a) The well casing is installed through a corrosive formation, or b) The well casing is not installed through a corrosive formation but has a permanent buried metallic flow-line. In this situation, sufficient ICCP shall be provided to maintain the flow-line at an acceptable protection level without electrical isolation of the well casing from the flow-line Commentary Note: Cathodic protection systems compliant with the above requirements may be dedicated or shared ICCP systems, i.e. more than one well per CP system. 1.3 A metallic well casing that is not installed through a corrosive formation and does not have a permanent flow-line, does NOT require cathodic protection. However, if a foreign impressed current anode bed is within 500 meters of this type of well, electrical bonding shall be implemented to minimize the probability of downhole interference. 1.4 A metallic well casing installed within a metallic or non-metallic cellar shall be provided with a galvanic anode installed inside the wellhead cellar if: a) The cellar is backfilled, and b) The casing has NOT been coated with Fusion Bonded Epoxy (FBE), to a depth below the base of the cellar