Pulp and Paper Research Institute of Canada

Andrew Garner

Laurent H Laliberte

Douglas L Singbeil

A monitor assembly is provided herein for monitoring the effectiveness of anodic protection of a carbon steel vessel containing a corrosive liquor, e.g. pulp digesters. The monitor has two identical carbon steel coupons mounted on a mount rod, one coupon being in electrical connection with the anodically protected vessel, the other being out of electrical connection with such vessel. A reference electrode is mounted on the same mount rod in such a way that the reference electrode, but not the mount rod, is wetted by the liquid contents of the carbon steel vessel. In this novel combination of elements, the mount rod, the metal components of a sealing gland and a metal spacer disc are made of any metal with sufficient mechanical and chemical stability to withstand the corrosive environment of the liquid contents of the carbon steel vessel and the mechanical stress. An electrically non-conductive sleeve and electrically non-conductive spacer elements are formed of any electrically non-conductive material having sufficient mechanical and chemical stability to withstand the corrosive environment of the liquid contents of the carbon steel vessel and the mechanical stress. The reference electrode is formed from any metal which provides a stable potential when exposed to the liquid contents of the carbon steel vessel.

Monitor assembly for monitoring anodic corrosion protection of carbon

A method is provided herein for the electrochemical corrosion protection of a partly submersed, rotating, stainless steel drum in a vat containing a corrosive, oxidizing, chloride-containing bleach liquor. The method comprises the step of impressing a protection potential to the stainless steel drum at a predetermined voltage in the range of -600 to +400 mV.sub.Ag/AgCl. This predetermined voltage is sufficiently low to draw the stainless steel into a passive corrosion protection zone. However, that voltage is not sufficiently low to draw the stainless steel into a zone of uniform corrosion. Specific means for the placement of the anode in the vat are also provided.

Electrochemical corrosion protection of stainless steel bleach plant

A monitor assembly for monitoring the effectiveness of a method and apparatus for electrochemical crevice corrosion protection by electrochemical potential control of a stainless steel vessel containing a corrosive washing solution, e.g. bleach plant washer equipment used in the pulp industry.

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Pointe Claire, Canada

Andrew Garner