Abstract: Disclosed are processes for removing carbon steel components of a subsea oilfield facility in a subsea environment by accelerating the corrosion of the carbon steel components in the surrounding seawater, by a passive and/or active impressed current method. In the passive method, the facility is connected to a cathodic metal of greater electrical potential, such as copper. In order to cause the maximum and uniform corrosion, it is preferred that a wire of the chosen cathodic metal be extended along the facility and through pipelines. In the active impressed current method, an external DC electrical supply is used to apply an electrical potential difference between the steel components of the facility and the cathodic metal.

Abstract: Various embodiments associated with signal conversion while underwater are described. A source can transmit an alternating current signal with a relatively high frequency over a relatively long distance. The alternating current signal with the relatively high frequency can be converted to an alternating current signal with a relatively low frequency. An example of this conversion can be done by converting the alternating current signal with the relatively high frequency into a direct current signal. The direct current signal can then be converted into the alternating current signal with the relatively low frequency. The alternating current signal with the relatively low frequency can be transmitted from a transmission coil to a pick-up coil. After reception by the pick-up coil the alternating current signal with the relatively low frequency can be processed, such as processed to determine a direction of the source of the alternating current signal with the relatively high frequency.

Abstract: A control system for a two-wire power and communication system is described herein. A gateway connects to an irrigation controller and at least two wires that are further connected to a plurality of decoders. The gateway includes an H-bridge circuit that creates an alternating potential at the same potential or lower than the nearby ground. In this respect, when one of the at least two communication wires are damaged, little or no wire corrosion will occur.

Abstract: A method for corrosion protection in a marine construction including a plurality of metal elements and at least one reference electrode at least partly immerged in water, the metal elements including an anode and a metal part, the anode being provided for corrosion protection of the metal part includes measuring an electric potential of the metal part with the reference electrode as a ground reference. At least one of the metal elements and at least one of the at least one reference electrode are connected to a DC electrical power outlet so as to allow an electrical regeneration current through an electrical circuit including the at least one of the metal elements, the at least one of the at least one reference electrode and the electrolyte so that the reference electrode is anodized.

Abstract: A control system for a two-wire power and communication system is described herein. A gateway connects to an irrigation controller and at least two wires that are further connected to a plurality of decoders. The gateway includes an H-bridge circuit that creates an alternating potential at the same potential or lower than the nearby ground. In this respect, when one of the at least two communication wires are damaged, little or no wire corrosion will occur.

Abstract: An input terminal is electrically connected to a contact point. An anti-corrosion current supplying section is operable to supply an anti-corrosion current to the contact point through the input terminal so as to remove corrosion in the contact point. A series resistor is electrically interposed between the input terminal of the signal processing circuit and the contact point. The anti-corrosion current is supplied to the contact point through the series resistor.

Abstract: A galvanic ground isolator adapter protects against galvanic corrosion on a boat when a boat power system is connected to a shore power system. A ground isolation assembly in the ground connection between the two system grounds prevents current from passing between the two system grounds when the voltage difference between the two is low. When the voltage difference exceeds a preset value, the ground connection is established. The adapter is entirely contained within a rigid housing with a male plug at one end and a female socket at the other end. In this form it can be simply connected to a power cord that is normally used in connecting the shore and boat power systems. It may be provided with a locking mechanism that prevents it being removed once it is attached. It may be supplied with a sonic alarm to indicate when current is flowing in the ground connection.

Abstract: A ceramic conductor is supported by an electrically insulative support member for attachment directly to a marine propulsion drive and for use as either an anode or electrode in a corrosion prevention system. The ceramic conductor is received within a depression formed in a surface of the electrically insulative support member and the exposed surface of the ceramic conductor can be offset from or coplanar with an exposed surface of the electrically insulative support member. The ceramic conductor can comprise oxides of iridium, tantalum and titanium that are formed as a coating on a titanium substrate.

Abstract: The present invention generally provides a method for prevention of corrosion in a metal object by inducing a surface current over the entire surface of the metal object. The surface current can be induced by direct or indirect application of electrical waveforms having AC components generated from a circuit. The metal body and the negative terminal of a source of DC voltage (battery) are grounded. The positive terminal of the source of DC voltage is connected to the electronic circuit that imparts electrical waveforms of low voltage DC to the conductive terminal connected to the metal body. Alternate methods of inducing surface currents include direct capacitor discharge through the metal body, or movement of an electromagnetic field over the metal body, or by generating an RF signal attached to a transmitting antenna such that the transmitted signal is received by the metal body.

Abstract: A method for inhibiting galvanic corrosion of marine propulsion components impresses an electronic current into the protected component and causes the protected component to act as a cathode in a galvanic circuit which comprises a conductor, such as a ground wire connected between the protected component and an electrical conductor which is external to the marine vessel on which the protective component is attached. The electrical conductor can be a ground wire of an electrical power cable connected between the marine vessel and the shore ground. The sea bed is caused to act as an anode in the galvanic circuit, with varying voltage potentials existing within the water between the sea bed and the protected component. The system can be a closed loop control circuit using a voltage sensed by an electrode, or an open loop circuit that provides current pulses based on empirical data.

Abstract: Method and apparatus for alternately providing positive and negative direct current voltages to a single twisted pair includes a power source configured to provide a first signal and a second signal, the first and second signals having different polarities, a controller configured to provide a control signal in accordance with a predetermined timing signal, and a voltage alternating switch circuit having first and second output terminals, the voltage alternating switch circuit coupled to the power source configured to receive the first and second signals, the voltage alternating switch circuit further coupled to the controller configured to receive the control signal, and in accordance thereto, providing first and second signals alternately to first and second output terminals, such that the adverse corrosive effect of positive voltage line powering is minimized.

Abstract: A parking meter includes a vault and mounting plate inside the vault. The plate and vault have contacting metal surfaces such that corrosion tends to occur in a region at and in the vicinity of the contacting metal surfaces in response to electrolysis induced electric current having a tendency to flow between the contacting metal surfaces. A spider attachment bolt passing through openings in a base of the vault is threaded to a bore in the mounting plate and a spider having legs engaging the interior wall of a hollow pole connecting the vault to a concrete structure in the ground so the vault is secured to the pole. A metal structure electrically and mechanically connected to the region and inserted into the earth in the vicinity of the parking meter shunts to the earth the current having a tendency to flow between the contacting metal surfaces.

Abstract: An apparatus for prevention of corrosion in metal objects uses a pad having a conductive facing, a dielectric substrate and an adhesive, attached to a metal body being protected from corrosion. The metal body and the negative terminal of a source of DC voltage (battery) are grounded. The positive terminal of the source of DC voltage is connected to electronic circuitry that imparts pulses of low voltage DC to the conductive facing of the pad. These pulses of electrical current inhibit the oxidation of the metal object by providing a source of electrons to the oxidizing chemicals in contact with the metal. The electronic circuitry includes a reverse voltage protector to prevent the application of reverse source voltage. The circuitry also includes a power conditioner to supply a constant DC voltage to a microprocessor. The microprocessor generates pulses of DC signals that are amplified by a pulse amplifier and imparted to the conductive facing of the pad.

Abstract: A galvanic isolator to protect against galvanic corrosion of a submersible metal marine drive. The galvanic isolator is positioned between shore ground and boat ground to prevent the flow of destructive galvanic currents between the shore ground and the boat ground, while maintaining the safety function of neutral ground. The galvanic isolator of the invention includes a blocking element positioned between the boat ground and the shore ground that can be switched between an open and a closed state by a trigger circuit. The trigger circuit closes the blocking element when the voltage difference between the boat ground and the shore ground exceeds a threshold value, such as 1.4 volts. During operation of the galvanic isolator during the high fault current situation, power is dissipated only by the blocking element, rather than by the combination of the blocking element and the trigger device.

Abstract: A system and method for testing and monitoring the operation of a galvanic isolator. The galvanic isolator is positioned between shore ground and boat ground to prevent the flow of destructive galvanic currents between the shore ground and the boat ground. The monitoring system transmits a test current through the galvanic isolator at specific time intervals to test the effectiveness of the galvanic isolator. The monitoring system includes a first counter that outputs an enabling signal after a desired period of time. The enabling signal allows a test current to flow through the galvanic isolator for a brief period of time determined by a second counter. As the test current flows through the galvanic isolator, a current sensing circuit measures the test current and activates an alarm if the test current flowing through the galvanic isolator falls outside a predetermined range. In this manner, the monitoring system of the invention monitors and periodically tests a galvanic isolator.

Abstract: An automatic system uses sacrificial galvanic anodes to to provide a controlled and optimum amount of cathodic protection against galvanic corrosion on submerged metal parts. Intermittently pulsed control circuitry enables an electro-mechanical servo system to control a resistive element interposed between the sacrificial anodes and the electrically bonded underwater parts. In an active mode of operation a current is applied directly to the anodes to quickly establish the proper level of correction which is maintained during the passive mode. Incremental corrections are made over a period of time to provide stabilization of the protection and to conserve power. A visual indication of the amount of protection is available at all times. Circuitry and indicating devices are included which facilitate location and correction of potentially harmful stray currents and to prevent loss of sacrificial anodes to nearby marine structures.

Abstract: In a metallic pipeline (1) disposed in the ground, alternating voltages may be induced from adjacent transmission lines and cause corrosion. To reduce the risk of corrosion, an alternating current (i.sub.1) is caused by means of a compensating device (PD) to flow through the line and to cause a voltage drop which counteracts the induced voltages. A measuring conductor (2) provides a signal (u.sub.s) which is a measure of the induced voltage. This signal controls the amplitude and phase position of an alternating voltage (u.sub.1) which is generated by an a.c. source which is connected to feed points (A, B) on the line and which causes an alternating current (i.sub.1)) to flow through the line. (FIG.

Abstract: In a metallic pipeline (1) disposed in the ground, voltages may be induced from adjacent transmission lines and cause corrosion. To reduce the risk of corrosion, voltages are induced in the pipeline with the aid of a transformer (8), which voltages counteract the induced voltages. A measuring conductor (2) provides a signal which is a measure of the induced voltage. In a suitable way, this signal controls the amplitude and phase position of a voltage (U.sub.1) which is generated by a converter coupling (7) and is applied to the primary winding of the transformer (8). (FIG.

Abstract: An electric circuit substrate apparatus having a micro-processor for a control of a device is comprised of a substrate, an electric circuit arranged on the substrate and including a rectifier, an electrolysis condenser, a detecting device for detecting the voltage of a current outputted from the electrolysis condenser and the micro-processor which is set to stop the control of the device upon receipt of a signal from the detecting device, and an enclosing device for immersing therein the substrate and the electric circuit, except for a portion of electrolysis condenser, in order that the immersed elements are interrupted from the ambient air.

Abstract: This invention primarily relates to an electrical anticorrosion device for a marine propulsion arrangement. More particularly, the invention relates to a cathodic protection arrangement which is suitable for use with an inboard/outboard propulsion unit. According to the invention, an anode and a reference electrode are housed within a housing unit which is mounted upon a propulsion unit mounting bracket. The two electrodes are arranged so that each is essentially equidistant from a point located approximately midway across the lateral width of an outboard drive unit, which unit is secured to the mounting bracket, when the unit is positioned for driving the associated watercraft in a generally forward direction. The electrode housing further serves as a low speed/idle exhaust gas device which breaks up exhaust gas bubbles which otherwise might cause loud and objectionable noise.

Abstract: A power module for a cathodic protection system is provided having a switch-mode power circuit and a synchronous switch assembly. The method of the invention comprises rectifying an alternating utility power signal with a power transformer and switch assembly. The switch assembly is controlled by a phase control circuit to provide a selective controlled phase delay to provide a 0-100% range power signal to the load selectively operable in a constant current, constant voltage or off-potential manner.

Abstract: There is disclosed a cathodic protection system current control apparatus incorporating an IR compensator circuit wherein the electric potential between a reference cell such as a copper-sulfate half-cell and the wall of a tank or other structure being corrosion protected is measured in such a way that nearly all of the potential due to IR voltage drop through the electrolyte is compensated for and eliminated leaving only a voltage measurement representing the true electrolytic potential at the cathodically protected object. This true electrolytic potential is utilized to act as a control input for a conventional current controller to maintain the desired electrolytic potential by changing the current passing through the electrolyte. The compensator circuit includes a rectifier device and a capacitor charged by a constant current source, and thus has a much longer response time for rising voltage values than it does for falling voltage values.

Abstract: A method and device for automatic surveillance of electrochemical protection on submersible metal structures. The difference in electric potential between the steel structure and at least one electrode, in contact with the ambient water, is detected with a supply of electric alternating current, via the steel structure and a parallel, insulated conductor. The detected values are transmitted to a central monitoring unit recording said values, via said steel structure and said conductor, as a pulse coded signal, superposed upon the supply current, which acts as a system clock.

Abstract: A method for detecting the polarized potential of a buried pipe which is cathodically protected by rectified alternating current impressed upon the pipe. Each rectified protection current is periodically pulsed to an off state for a precise pulse duration and pulse period which are integral multiples of the period of the alternating current. The potential between the pipe and a reference electrode at the test site is sampled and analyzed to detect the polarized potential. It is analyzed to find the area under the portion of the waveform during which no off pulses are present and to use that area to detect the on potential. The area within the off pulses, after reactive spikes are eliminated, is substracted from the on potential area to determine the IR drop potential. The IR drop potential is then subtracted from the on potential and the difference is displayed as the polarized potential.

Abstract: An effective process of preventing the oxidation of metal objects by capacitive coupling is disclosed. An electric current is impressed into the metal object by treating the metal object as the negative plate of a capacitor. This is achieved by a capacitive coupling between the metal object, a dielectric material and a positive plate. Pulses of direct current are provided to the positive plate. The metal object has a common ground with the means for providing the pulses.

Abstract: A replaceable deep anode system for the cathodic protection of underground metallic structures is disclosed. The system includes an anode casing received in a drilled hole. The casing has an electrically non-conductive upper portion and a substantially incorrodible electrically conductive lower portion preferably comprising a steel piping having a coating of a conductive polymer. A selectively insertable anode is received in the casing contiguous to the lower portion to define an active anode area. Electrically conductive material received in the casing adjacent the anode and about the casing lower portion provides a primarily electronic current path from the anode to the drilled hole wall. The casing provides an integral anode housing for selective removal and resupply of anodes as may be needed over a period of time. The conductive polymer preferably comprises a polymer concrete including conductive carbon elements.

Abstract: Method, system and apparatus for carrying out the cathodic protection of structures wherein evaluation of true current and true voltages at the counter electrode is carried out by an integration procedure which is timed in conjunction with the cross-over times of the originating a.c. input to the power source. The system also may employ an IR drop free potential measurement of a variety employing a reference electrode and a control which periodically turns off the fluctuating current drive to the working electrode for purposes of carrying out potential measurement from the reference electrode. To improve performance of the system, as well as the true current measuring features, difference networks are used to develop the difference between the signals of one channel, i.e. ground, and the parallel channel, i.e. positive, leading to the working and reference electrodes. With the arrangement, spurious noise phenomena are cancelled.

Abstract: An apparatus for liquid-jet recording having heat-generating means and means for jetting a liquid utilizing an energy generated by the heat-generating means comprises an electrode provided in contact with the liquid in impart a potential to the liquid lower than the potential used to generate heat.

Abstract: A control system (17) for cathodically protecting an outboard drive unit (11) from corrosion includes an anode (12) and a reference electrode (13) mounted on the drive unit (11). Current supplied to the anode is controlled by a transistor (20), which in turn is controlled by an amplifier (25). The amplifier is biased to maintain a relatively constant potential on the drive unit (11) when operated in either fresh or salt water.

Abstract: An electrode apparatus (15) is provided for mounting an anode (17) and reference electrode (19) of a cathodic protection system on an outboard drive unit (10). The apparatus includes an insulating housing (20) on which the anode (17) and reference electrode (19) are mounted and a copper shield (30) mounted between the anode (17) and electrode (19) to allow them to be mounted in close proximity to each other. The shield (30) is electrically connected to the device to be protected and serves to match the electrical field potential at the reference electrode (19) to that of a point on the outboard drive unit (10) remote from the housing (20).

Abstract: An electronic circuit for measuring the IR drop free potential of a cathodically protected structure includes a shunting transistor which is periodically pulsed on to shunt or electrically connect the output lines of a rectifier to force the voltage and current delivered to a structure being cathodically protected to zero. The reference cell potential is measured during this zero or sampling time and a minimum value detected by a detector circuit which holds the value until changed in successive sampling periods. The minimum reference cell potential is then compared to a voltage corresponding to a desired reference cell potential and the difference used to generate a firing voltage for SCRs in the rectifier and thereby control its output to achieve the desired level of cathodic protection.

Abstract: A marine cathodic protection system maintains a submerged portion of a marine drive unit at a selected potential to reduce or eliminate corrosion thereto. An anode is energized to maintain the drive unit at a preselected constant potential in response to the sensed potential at a closely located reference electrode during normal operations. Excessive current to the anode is sensed to provide a maximum current limitation. An integrated circuit employs a highly regulated voltage source to establish precise control of the anode energization.

Abstract: A clamp apparatus is provided for use in securing cathodic protection, single anodes, double anodes, riser clamps and the like to the offshore drilling platforms and the like in a marine environment. The apparatus provides a U-shaped channel for fitting against the surface of, for example, the platform leg with a first section extending angularly out from the wall portion of the channel, and a second section extending out from the second wall of the channel. A chain bolt connector is inserted into a provided hole in the first plate section with the chain wrapped around the leg of the drilling platform and end chain links then inserted into a keyhole in the second plate extension and locked in by a movable plate. The nut bolt is then tightened to secure the apparatus against the leg of a platform. A set screw makes contact with the platform leg to complete the cathodic protection circuit.

Abstract: A corrosion detector for use in detecting corrosion currents in the form of AC and DC leakage currents which occur in a marina. The detector monitors AC power and ground lines or other conductive lines interconnected between boats in a marina and includes a transducer to detect leakage currents which occur in the boats connected to the power lines. The detector provides either an alarm signal or displays the damage rate and location to indicate corrosion currents in one or more of the boats in a harbor.

Abstract: The sensor system senses a drop in the flow of impressed cathodic protection current to a minimum threshold level. A potential difference is developed which is a sample of the cathodic protection current. A comparator receives the sample potential difference and normally produces an output control signal which drops to substantially zero when the cathodic protection current drops to a predetermined threshold level. A relay responsive to the control signal then switches a signaling device to its signaling condition. A standby battery is also coupled to the signaling device through the relay. In the event of any failure in the sensor system or in the primary source of power energizing the sensor system, the standby battery becomes connected to the signaling device to cause it to change to its signaling condition.

Abstract: A method of providing a secure, long-lasting electrical connection between the concentric neutral wires of a Underground Residential Distribution (URD) cable and a sacrificial anode. The invention provides for the prevention of corrosion of the neutral wires of the URD cable. The method comprises: securing a mold around the URD cable and the concentric neutral wires over the area of contact with the anode connecting wire; pouring a low-melt alloy into the mold to surround the URD cable so as to contact at least 50% of the surface area of each of the neutral wires and the anode connecting wire in the area of contact; and cooling the low-melt alloy to form a solid casting around the concentric neutral wires and the area of contact with the anode connecting wire, whereby a secure, long-lasting electrical connection is provided between the neutral wires and the anode.

Abstract: A parallel galvano-electrolytic current path is provided to conduct a current comprising (i) a portion of the interfering current and (ii) currents arising due to varying degrees of polarization of metal surfaces. The current is measured and a variable resistor inserted in the galvanic path is reduced in value until zero current flows through the parallel galvano-electrolytic current path in the direction of the electrolytic portion of said galvano-electrolytic path. Also disclosed is a circuit for applying said method.

Abstract: Method and apparatus for determining the true cathode polarization potential or reference voltage for any corrosion protection system and which determination may be visually indicated, used as a feedback for automatic control of the corrosion protection system or both.

Abstract: An impressed current cathodic protection apparatus has an electromechanically actuated variable transformer providing a variable output voltage and shunt-connected current monitors to monitor the impressed current and to vary the transformer turns ratio to maintain the impressed current within a predetermined range of values.

Abstract: Fence fabric formed of a multiplicity of entwining electrically conductive metal wire cores each coated with a heat disintegrable electrical insulation is rendered susceptible to grounding by disposing each of said metal cores in contact with at least one electrically conductive ground element. To produce this product, one or more of the foregoing conductive elements is placed in permanent contact with each coated wire of the fence fabric and sufficient current passed through said conductive element to disintegrate the insulation coating and provide an electrically conductive path between the metal core of each of said wires and said electrical conductor.

Abstract: Metallic structures located in an electrolyte, such as soil or water, for example, tend to corrode. In order to prevent metal loss from the structure due to corrosion, a D.C. current flow is created in the metal structure. This current flow causes a hydrogen ion film to form on the structure which insulates it from the electrolyte. The direct current is supplied to the metal structure by a combination of a solar array and storage batteries. During peak solar activity, the solar array both charges the batteries and supplies current to the metal structure. When the batteries are fully charged, the batteries are disconnected and the entire solar array output is applied to the metal structure. If solar activity decreases below a predetermined level, the batteries are switched back into the circuit to maintain current flow at a predetermined minimum level.

Abstract: A terminal box used with underground electrical conductors is formed of opposed channels and a top cap with depending sidewalls. Air is permitted to flow to the interior of the housing via a filter beneath the cap, this filter being resistant to the passage of dust, water, blowing snow and insects. A weathertight seal is provided between the opposed channels by a resilient sealing strip and overlapping vertical marginal portions; and, upward access by animals and ground moisture to the interior of the housing is deterred by a continuous barrier sheet which extends transversely across the housing and is sealed thereto.Corrosion damage to the housing is minimized by connecting it electrically to a buried plate formed of a metal which is anodic in the EMF series with respect to the housing metal. Grass fire and lawnmower-impact damage is reduced by surrounding the terminal box at ground level by a vegetation-inhibiting sheet.

Abstract: A marine ground isolator for selectively completing the current path through a ground connection. The herein illustrated embodiment includes a switch circuit connected in series between two portions of the ground connection and arranged so as to complete the current path therethrough only in response to an applied control signal; and means for monitoring the potential between the two portions of the ground connection and for applying the control signal to the switch circuit only when the absolute magnitude of the dc potential exceeds a first value or when the ac potential exceeds a second value.

Abstract: A system for the underground distribution of electrical power is provided and includes an electrical cable construction particularly adapted for use underground; and, the cable construction has a central conductor, a tubular insulator system for the conductor, a dual-purpose sacrificial anode supported by the insulator system and extending along substantially the full length of such insulator system, and a concentric neutral conductor supported by the insulator system and engaging the anode at a plurality of points therealong, with the dual-purpose sacrificial anode protecting the concentric neutral conductor against galvanic and soil corrosion as well as reducing AC corrosion of the concentric neutral conductor by providing additional surface area for the dissipation of currents leaving the neutral conductor.

Abstract: A method and apparatus for remotely measuring the cathodic protection level on a cathodically protected structure. The method uses a remote apparatus to measure the cathodic protection level and convert it to a related acoustic signal that is transmitted via the structure or surrounding media to a conveniently located receiving location.

Abstract: A cathodic protection, anticorrosive circuit comprises a diode connection of a transistor or a Schotkky diode interconnected between a buried structure to be protected and a galvanic anode or the like so that even when the difference in potential between them is relatively low, an effective forward or anticorrosion current may flow while positively preventing the reverse current which causes the corrosion of the buried structure.

Abstract: A cathodic protection system monitor is coupled to an impressed current cathodic protection circuit used for corrosion protection of a submerged marine drive. The cathodic protection circuit includes one or more anodes and a reference electrode mounted below the water line and connected to an automatic controller for supplying an anode current which is regulated in order to maintain a predetermined reference potential on the protected structure. A switch selectively connects a light emitting diode (LED) lamp or other light source between the controller output and ground so that the controller current may, when tested, be used to operate the light source in order to confirm that power is available to the anode.