Corrosion control of electrical cables used in cathodic protection

Abstract

This invention resides in corrosion control of electrical cables associated with cathodic protection systems. In the preferred embodiment the cable is in the form of passive metals chosen for electrolysis-corrosion-resistance, including titanium, tantalum, niobium, zirconium, nickel, or alloys thereof. Small diameters may be used to make the cable flexible. The wires may be bare or enclosed insulator materials for easy handling. The invention which is applicable to the “impressed current” and “sacrificial anode” methods, is particularly advantageous in situations where the cable/structure is embedded deep in soil or concrete, and cannot be easily repaired or replaced if any damage occurs.

I claim: 
     
         1 . In a cathodic protection system having an anode, the improvement comprising:
 a passive metal electrical interconnection to the anode.   
     
     
         2 . The improvement of  claim 1 , wherein the passive metal includes titanium, tantalum, niobium, zirconium, nickel, or alloys thereof. 
     
     
         3 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection is coated with a mixed-metal oxide. 
     
     
         4 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection includes one or more wires, each with a diameter of 3 mm or less. 
     
     
         5 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection includes a plurality of wires, each with a diameter of 1 mm or less. 
     
     
         6 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection includes a plurality of thin strips. 
     
     
         7 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection is bare metal or insulated. 
     
     
         8 . The improvement of  claim 1 , wherein the passive metal passive metal electrical interconnection comprises one or more passive-metal-clad copper wires. 
     
     
         9 . A cathodic protection system, comprising:
 a structure acting as a cathode to be protected from corrosion;   a sacrificial anode in electrical communication with the structure; and   passive metal electrical interconnection to the anode, the cathode, or both the anode or cathode.   
     
     
         10 . The cathodic protection system of  claim 9 , wherein the anode is connected directly to the cathode in a passive “sacrificial anode” configuration. 
     
     
         11 . The cathodic protection system of  claim 9 , further including an external DC electrical power source to provide current between the anode and cathode in an “impressed current” configuration. 
     
     
         12 . The improvement of  claim 9 , wherein the passive metal includes titanium, tantalum, niobium, zirconium, nickel, or alloys thereof. 
     
     
         13 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection is coated with a mixed-metal oxide. 
     
     
         14 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection includes one or more wires, each with a diameter of 3 mm or less. 
     
     
         15 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection includes a plurality of wires, each with a diameter of 1 mm or less. 
     
     
         16 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection includes a plurality of thin strips. 
     
     
         17 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection is bare metal or insulated. 
     
     
         18 . The improvement of  claim 9 , wherein the passive metal passive metal electrical interconnection comprises one or more passive-metal-clad copper wires.