A system comprises a cathodic protection system having an anode and configured to protect a protected structure from corrosion. The system comprises a monitoring circuit operatively coupled to the cathodic protection system. The monitoring circuit comprises an electrical-to-optical transducer. The electrical-to-optical transducer is configured to generate a light signal in response to electrical current flowing between the protected structure and the anode of the cathodic protection system, the protected structure and a reference electrode, or the reference electrode and the anode.

A system comprises a cathodic protection system having an anode and configured to protect a protected structure from corrosion. The system comprises a monitoring circuit operatively coupled to the cathodic protection system. The monitoring circuit comprises an electrical-to-optical transducer. The electrical-to-optical transducer is configured to generate a light signal in response to electrical current flowing between the protected structure and the anode of the cathodic protection system, the protected structure and a reference electrode, or the reference electrode and the anode.

An anode assembly is disclosed for use in a cathodic protection system. The anode assembly includes an elongated housing, an electrical cable, an anode, and electrically conductive backfill. The housing has a leading end and a trailing end through which the electrical cable extends. The anode is located within the housing and is in the form of a plurality of electrically conductive segments which are spaced apart from each other and which are electrically connected to the electrical cable at respective electrically conductive joints. The backfill surrounds the anode and cable within the housing.

An anode assembly is disclosed for use in a cathodic protection system. The anode assembly includes an elongated housing, an electrical cable, an anode, and electrically conductive backfill. The housing has a leading end and a trailing end through which the electrical cable extends. The anode is located within the housing and is in the form of a plurality of electrically conductive segments which are spaced apart from each other and which are electrically connected to the electrical cable at respective electrically conductive joints. The backfill surrounds the anode and cable within the housing.

A marine cathodic protection system configured to protect a metal structure exposed to seawater from corrosion. The system includes a first anode provided on or adjacent the protected metal structure at a first position. The first anode is exposed to seawater, is electrically insulated from the protected metal structure, and is formed of a metal having a greater negative potential than the protected metal. The system further includes a second anode provided on or adjacent the protected metal structure at a second position. The second anode is electrically connected to the first anode. The first position is preferably substantially submerged in said seawater such that the protected metal and the first anode cooperate to define a seawater battery configured to apply an electrical current to the second anode, the second anode thus being an impressed current anode.

A marine cathodic protection system configured to protect a metal structure exposed to seawater from corrosion. The system includes a first anode provided on or adjacent the protected metal structure at a first position. The first anode is exposed to seawater, is electrically insulated from the protected metal structure, and is formed of a metal having a greater negative potential than the protected metal. The system further includes a second anode provided on or adjacent the protected metal structure at a second position. The second anode is electrically connected to the first anode. The first position is preferably substantially submerged in said seawater such that the protected metal and the first anode cooperate to define a seawater battery configured to apply an electrical current to the second anode, the second anode thus being an impressed current anode.

A method and apparatus is described that uses a device that presents a surface of a dielectric material to a flowing or circulating fluid that results in charge being created at a boundary layer of the dielectric where it contacts the fluid by ion exchange and charging of compounds, for example insoluble dielectric particles such as colloids, and using at least one control impedance to control an impressed current in the fluid caused by the fluid flowing through the device and to cause suspended particles in the fluid to be charged, whereby the charge of the suspended particles is then neutralised causing coagulation of the particles as suspended insoluble particles.

A cathodic protection system is provided for a subterranean well casing having an enclosed upper section of the well casing being substantially shielded by a cellar from an impressed-current cathodic protection circuit passing through earth media. The impressed-current cathodic protection circuit is provided to protect an unenclosed lower section of the well casing. To protect the enclosed upper section of the well casing, a supplemental cathodic protection circuit is provided. The supplemental cathodic protection circuit is a galvanic anode cathodic protection circuit comprising the enclosed upper section of the well casing and one or more bracelet galvanic anodes being circumferentially mounted to the enclosed upper section. The enclosed upper section of the well casing and the one or more bracelet galvanic anodes are substantially surrounded by a cellar backfill, and the galvanic anode cathodic protection circuit is equally effective throughout a broad range of non-homogeneity within the cellar backfill.

A cathodic protection system is provided for a subterranean well casing having an enclosed upper section of the well casing being substantially shielded by a cellar from an impressed-current cathodic protection circuit passing through earth media. The impressed-current cathodic protection circuit is provided to protect an unenclosed lower section of the well casing. To protect the enclosed upper section of the well casing, a supplemental cathodic protection circuit is provided. The supplemental cathodic protection circuit is a galvanic anode cathodic protection circuit comprising the enclosed upper section of the well casing and one or more bracelet galvanic anodes being circumferentially mounted to the enclosed upper section. The enclosed upper section of the well casing and the one or more bracelet galvanic anodes are substantially surrounded by a cellar backfill, and the galvanic anode cathodic protection circuit is equally effective throughout a broad range of non-homogeneity within the cellar backfill.

An assembly of parts has a first metal part having a first surface having a corrosion resistant surface treatment and a second surface being free of corrosion resistant surface treatment, a second metal part having a third surface having a corrosion resistant surface treatment and a fourth surface being free of corrosion resistant surface treatment. The second metal part defines a recess that defines the fourth surface. The first and third surfaces are in contact. A conductive member is disposed at least in part in the recess and is in contact with the second and fourth surfaces. A sealing member disposed in the recess around the conductive member. A sacrificial anode is mounted and conductively connected to one of the first and second metal parts.