Use of focused accelerated corrosion for metal decommissioning

Abstract

The present invention is directed to a method of using accelerated corrosion to remove metallic assets.

What is claimed is: 
     
         1 . A method for removal of unwanted materials from the surface of a metallic asset by controlled uniform corrosion of a focused area of the metallic asset. 
     
     
         2 . The method of  claim 1  wherein the metallic asset is employed as a sacrificial anode and coupled with a cathode assembly of lower redox potential than the asset comprising a non-conductive permeable spacer the cathode and the anode and an electricity conducting fluid that is used to complete the circuit between the anode and cathode. 
     
     
         3 . The method of  claim 2  wherein the focused area of corrosion is accelerated to affect 0.1 mm thickness corrosion in one minute or less. 
     
     
         4 . The method of  claim 3  wherein the accelerating corrosion comprises a) increasing the conducting fluid circulation rate and/or temperature through the cathode assembly, b) adjusting the power and/or adjusting the spacing between the cathode and the anode, and/or c) changing the type of non-conductive permeable spacer. 
     
     
         5 . The method of  claim 4  wherein the power is sourced by a DC power supply wherein the amount of power per square meter will be higher than in an impressed system and the power delivered will be dependent upon a number of brush heads employed to the focused area. 
     
     
         6 . The method of  claim 5  wherein the brush heads are magnetized and moveable. 
     
     
         7 . The method of  claim 6  wherein the power supply consists of 70 amps per 6 cm squared, 10 up to 50 Watts per cm squared. 
     
     
         8 . The method of  claim 7  wherein the power is adjusted in bursts to corrode the metal section in intervals with subsequent scrubbing of the corroded area. 
     
     
         9 . The method of  claim 4  wherein the temperature of the conducting fluid delivered is increased up to about 60° C. 
     
     
         10 . The method of  claim 4  wherein the 0.1-1 amp/cm2 is applied is applied through the cathode at a given distance from the asset's surface for a period of time sufficient to achieve corrosion.