The metal tank portion of an electric water heater is protected against corrosion utilizing a corrosion protection system that detects a voltage potential between the sheath portion of a tank water-immersed electric heating element and the tank. In one embodiment of the corrosion protection system the sensed sheath/tank potential is utilized to enable a user of the water heater to accurately gauge the necessity of replacing a sacrificial anode extending into the tank. In another corrosion protection system, the sensed sheath/tank potential is utilized to provide impressed current cathodic protection of the tank and also to prevent dry firing of the electric water heater.

A marine ICCP system includes an electrical circuit comprising a primary and a secondary circuit. The primary circuit comprises a first electrode connected to a positive terminal of a power source to act as an active anode; and a second electrode connected to a negative terminal of the power source. The secondary circuit comprises a passive electrode normally disconnected from the electrical circuit and arranged to act as back-up protection, wherein the second electrode connectable to the passive electrode. The passive electrode is arranged to be connected to the power source if a detected output voltage in the primary circuit reaches a maximum value and if a determined polarization potential for the cathode is insufficient. The control unit is operable to control the output voltage supplied to the primary and secondary circuits separately in order to supply an individual output voltage to each circuit.

The invention relates to an arrangement for measuring salinity in water, which arrangement is part of an impressed current cathodic protection system having an electrical circuit comprising a source of electrical power (310); at least one first electrode (315) connected to a positive pole of the power source (310); at least one second electrode (317) connected to a negative pole of the power source (310); a voltage sensor (341); a current sensor (342); and a control unit (313). The control unit is arranged to initiate a measurement sequence at predetermined intervals, wherein the control unit is arranged to connect at least one first electrode (315) to the negative pole of the power source (310) to act as a cathode; connect at least one passive electrode (326) to the positive pole of the power source (310) to act as an active anode; register the output voltage; register the current; determine the circuit resistance using the output voltage and the current; and calculate the resistivity of the electrolyte based on the determined circuit resistance and at least one stored electrode property value, which resistivity is inversely proportional to the salinity. The invention further relates to a vessel provided with such a measuring arrangement and a method for its operation.

An intelligent system is provided for monitoring a subsea structure and delivering appropriate cathodic protection to desired areas of the subsea structure. According to an embodiment, the technique involves monitoring a cathodic protection potential level at an important location or locations of the subsea structure. Based on the data acquired via monitoring, a controller is able to apply voltage levels to the subsea structure so as to attain and modulate a desired cathodic protection level, e.g. a cathodic protection level within a range of about −800 mV to −950 mV (SCE). Consequently, undesirable overprotection and under protection are avoided and the subsea structure is adequately protected from corrosion while reducing undesirable production of hydrogen.

A corrosion resistant article including an aluminum substrate and a corrosion-inhibiting cerium based corrosion inhibitor corrosion inhibiting additive on the aluminum substrate, the corrosion inhibiting additive comprising an anodic corrosion inhibitor and a cathodic corrosion inhibitor, the anodic corrosion inhibitor greater than 25 wt % of the total inhibitor.

The metal tank portion of an electric water heater is protected against corrosion utilizing a corrosion protection system that detects a voltage potential between the sheath portion of a tank water-immersed electric heating element and the tank. In one embodiment of the corrosion protection system the sensed sheath/tank potential is utilized to enable a user of the water heater to accurately gauge the necessity of replacing a sacrificial anode extending into the tank. In another corrosion protection system, the sensed sheath/tank potential is utilized to provide impressed current cathodic protection of the tank and also to prevent dry firing of the electric water heater.

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 molten salt reactor comprising a reactor vessel and a molten salt contained within the reactor vessel. There is a corrosion reduction unit configured to process the molten salt to maintain an oxidation reduction ratio, (E(o)/E(r)), in the molten salt at a substantially constant level, wherein E(o) is an element (E) at a higher oxidation state (o) and E(r) is the element (E) at a lower oxidation state (r).

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 portable unit is arranged to measure a value for polarized potential in a corrosion protection system comprising a protected structure, an anode and a reference electrode, which portable unit is connectable to the protected structure and to the reference electrode. The portable unit is arranged toperform voltage measurements to detect and monitor an instant-off sequence, wherein the corrosion protection system is turned off for a predetermined time period during normal operation. If an instant-off sequence is detected, then a voltage measurement is performed to measure a voltage signal representing a direct current potential curve for the corrosion protection system during the instant-off sequence. A step response detected in the voltage signal during an initial IR drop and a subsequent voltage decay are analysed. An initial value for the voltage signal at the time of the step response is determined and displayed as a value for polarized potential.