Apparatus for Cathodic Protection System Using an Impressed Current Anode and a Sacrificial Anode

Abstract

Cathodic protection of steel in concrete is provided by locating an anode assembly including both a sacrificial anode and an impressed current anode in contact with the concrete and providing an impressed current from a power supply to the anode. The impressed current anode forms a perforated sleeve surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material between. The system can be used without the power supply in sacrificial mode or when the power supply is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.

1 . An anode apparatus for cathodically protecting a metal section in an ionically conductive material, the anode apparatus comprising:
 a sacrificial anode of a material which is less noble than the metal section;   an impressed current anode;   the sacrificial anode and the impressed current anode comprising components of the anode apparatus so that, when the components of the anode apparatus are located in contact with the ionically conductive material, each of the sacrificial anode and the impressed current anode is in ionically conductive communication with the other and with the metal section;   the impressed current anode and the sacrificial anode being electrically separated to prevent electrical communication therebetween;   a first electrical connector arranged for connection to the sacrificial anode;   and a second electrical connector arranged for connection to the impressed current anode.   
     
     
         2 . The anode apparatus according to  claim 1  including a DC power supply with positive and negative terminals. 
     
     
         3 . The anode apparatus according to  claim 2  including switchable connectors for connection to the positive and negative terminals of the power supply, to the first and second electrical connectors and to the metal section. 
     
     
         4 . The anode apparatus according to  claim 1  wherein the impressed current anode is perforated so to allow passage of ionic current to pass through the impressed current anode. 
     
     
         5 . The anode apparatus according to  claim 1  wherein the sacrificial anode forms a rod and the impressed current anode forms a sleeve surrounding the rod. 
     
     
         6 . The anode apparatus according to  claim 1  wherein the impressed current anode and the sacrificial anode comprise side by side plates. 
     
     
         7 . The anode apparatus according to  claim 1  wherein there is provided an ionically conductive filler material adjacent to the sacrificial anode. 
     
     
         8 . The anode apparatus according to  claim 7  wherein the ionically conductive filler material is different from said ionically conductive material. 
     
     
         9 . The anode apparatus according to  claim 7  wherein the ionically conductive filler material contains at least one activator to ensure continued corrosion of the sacrificial anode. 
     
     
         10 . The anode apparatus according to  claim 7  wherein the ionically conductive filler material has a pH sufficiently high for corrosion of the sacrificial anode to occur and for passive film formation on the sacrificial anode to be avoided. 
     
     
         11 . The anode apparatus according to  claim 1  wherein there is provided a plurality of sacrificial anodes and wherein the impressed current anode is separate from said sacrificial anodes. 
     
     
         12 . The anode apparatus according to  claim 1  wherein there is provided a plurality of impressed current anodes and wherein the sacrificial anode is separate from said impressed current anodes. 
     
     
         13 . The anode apparatus according to  claim 1  wherein the impressed current anode is arranged to be mounted in or on the covering material temporarily. 
     
     
         14 . The anode apparatus according to  claim 1  wherein the impressed current anode is arranged to be mounted on a surface of the covering material to provide current through the surface of the ionically conductive material. 
     
     
         16 . The anode apparatus according to  claim 1  wherein the impressed current anode is arranged to be mounted and operated temporarily for re-charging of the sacrificial anode 
     
     
         17 . The anode apparatus according to  claim 1  wherein the metal section is steel and the ionically conductive material is concrete or mortar. 
     
     
         18 . The anode apparatus according to  claim 1  wherein there is provided a porous or deformable material to absorb corrosion products from the sacrificial anode. 
     
     
         19 . The anode apparatus according to  claim 1  provided as a preassembled unit. 
     
     
         20 . The anode apparatus according to  claim 19  wherein the anode apparatus including a DC power supply which is provided as a preassembled unit. 
     
     
         21 . The anode apparatus according to  claim 19  wherein the DC power supply is a photovoltaic cell or battery so as to provide an intermittent DC power supply. 
     
     
         22 . An anode apparatus for use in cathodically protecting a metal section in an ionically conductive material, the apparatus comprising:
 a sacrificial anode of a material which is less noble than the metal section arranged for engagement with the ionically conductive material;   and a second anode arranged for engagement with the ionically conductive material;   the sacrificial anode and the second anode being arranged such that when the second anode is connected to a DC power supply the sacrificial anode is charged or re-charged with ions of the sacrificial anode material.   
     
     
         23 . The anode apparatus according to  claim 22  wherein the apparatus includes a DC power supply with positive and negative terminals. 
     
     
         24 . The anode apparatus according to  claim 22  wherein the second anode is perforated so to allow passage of ionic current to pass through the impressed current anode. 
     
     
         25 . The anode apparatus according to  claim 22  wherein the sacrificial anode forms a rod and the second anode forms a sleeve surrounding the rod. 
     
     
         26 . The anode apparatus according to  claim 22  wherein the second anode and the sacrificial anode comprise side by side plates. 
     
     
         27 . The anode apparatus according to  claim 22  wherein there is provided an ionically conductive filler material adjacent to the sacrificial anode. 
     
     
         28 . The anode apparatus according to  claim 22  wherein the impressed current anode is arranged to be mounted in or on the covering material temporarily. 
     
     
         29 . The anode apparatus according to  claim 22  wherein the impressed current anode is arranged to be mounted on a surface of the covering material to provide current through the surface of the ionically conductive material. 
     
     
         30 . The anode apparatus according to  claim 22  wherein the metal section is steel and the ionically conductive material is concrete or mortar. 
     
     
         31 . The anode apparatus according to  claim 22  provided as a preassembled unit. 
     
     
         32 . The anode apparatus according to  claim 31  wherein the anode apparatus including a DC power supply which is provided as a preassembled unit.