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.

Description

FIELD OF THE INVENTION[0001]This invention relates to a method of accelerated controlled uniform corrosion of a focused area of a metallic asset.BACKGROUND OF THE INVENTION[0002]Decommissioning metallic assets that have been impacted with naturally occurring hazardous materials which may include mercury, arsenic, lead and other contaminants have been traditionally costly to clean. These materials are often found embedded within the surface scale or corrosion layer. Standard industry practice to remove these materials can be achieved physically or chemically. The physical approach uses high pressure water jets to detach the surface scale or corrosion from the asset. This process typically generates a significant amount of wastewater and makes slow progress. The chemical approach commonly uses acidic chemistries that dissolved the inorganic scale or corrosion material. As a result, this process generates a large volume of acidic waste. U.S. Ser. No. 10 / 181,706 describes a method to re...

AI Technical Summary

Benefits of technology

[0004]An embodiment of the invention is controlled uniform corrosion on a focused area of a metallic asset to remove unwanted materials from the asset's surface. The metallic asset is used as a sacrificial anode and coupled with a cathode assembly of lower redox potential than the asset. A non-conductive permeable spacer, and an electrolytic conducting fluid (e.g., seawater, water containing a corrosion enhancing agent, etc.) are used to complete the circuit between the anode and cathode. A preferred embodiment is an accelerated corrosion on the metal area of up to 0.1 mm thickness in one minute or less.

Problems solved by technology

Decommissioning metallic assets that have been impacted with naturally occurring hazardous materials which may include mercury, arsenic, lead and other contaminants have been traditionally costly to clean.

This process typically generates a significant amount of wastewater and makes slow progress.

As a result, this process generates a large volume of acidic waste.

Decommissioning of Subsea Pipelines can be prohibitively expensive if pipeline removal is required.

If removal of these types of pipelines and facilities is necessary, then the presence of impregnated metals and other impurities can add significant costs to the removal and disposal.

Subsea pipelines can be flushed and pigged to remove internal hydrocarbons; however, this process will not remove contaminants impregnated into the metal.

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