US3242064A - Cathodic protection system - Google Patents

Cathodic protection system Download PDF

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Publication number
US3242064A
US3242064A US85008A US8500861A US3242064A US 3242064 A US3242064 A US 3242064A US 85008 A US85008 A US 85008A US 8500861 A US8500861 A US 8500861A US 3242064 A US3242064 A US 3242064A
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Prior art keywords
transistor
cell
current
cathodic protection
voltage
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Expired - Lifetime
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US85008A
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English (en)
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Paul B Byrne
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BASF Catalysts LLC
Engelhard Industries Inc
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Engelhard Industries Inc
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Priority to NL136909D priority Critical patent/NL136909C/xx
Priority to NL261794D priority patent/NL261794A/xx
Priority to US85008A priority patent/US3242064A/en
Application filed by Engelhard Industries Inc filed Critical Engelhard Industries Inc
Priority to DK87361AA priority patent/DK112841B/da
Priority to GB7183/61A priority patent/GB957467A/en
Priority to FR854104A priority patent/FR1292235A/fr
Priority to DE19611446395 priority patent/DE1446395B2/de
Application granted granted Critical
Publication of US3242064A publication Critical patent/US3242064A/en
Assigned to ENGELHARD CORPORATION reassignment ENGELHARD CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PHIBRO CORPORATION, A CORP. OF DE
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/04—Controlling or regulating desired parameters

Definitions

  • This invention relates to corrosion reduction systems in which t-he direct current supplied to the ⁇ surface to be protected, such as the h-ull of a ship, is automatically varied in accordance with the protective conditions on the hull, as monitored by a sensin-g half-cell.
  • a principal object of the present invention is the provision of a cathodic protection system, especially suitable for use in connection with small boats, which is simple and inexpensive, and wh-ich has a power output directly controlled by the sensing half-cell signals.
  • Another object of the invention is the protection of aluminum surfaces, eg. small boat hulls, by cathodic protection techniques.
  • a further object of the invention is to increase the throwing power of cathodic protection systems.
  • the foregoing objects may be achieved by the use of a cathodic protection system in which unidirectional pulses are supplied to the anodes, with the ratio of the pulse duration to the ytime between pulses applied to the anode being controlled in dependence on cathodic protection conditions by ⁇ means of a signal obtained from a sensing .half-cell.
  • an oscillator m-ay be employed for supplying pulses to the anode ⁇ or anodes.
  • the current level of each pulse may be substantially constant, since the .total current supplied to the anode and to the surface to be protected is the ⁇ sum of pulse durations during any given period of time.
  • the ratio of the pulse duration to the time between pulses therefore directly .controls the total protective current supplied.
  • This ratio when maintaining constant ⁇ the length ⁇ of pulse duration, depends on the frequency of pulses or the time between pulses, as exemplified by one of the embodiments described below. Alternatively, the frequency tions prevail.
  • duration ⁇ of pulses may be varied in order to control the total current output.
  • the system which constitutes a closed-loop system, may be designed to exhibit high response speed and sensitivity suflicient tection.
  • a mean frequency corresponds to optimum conditions, and is maintained as long a optimum condi-
  • the cath-odio protection system in accordance with the embodirnent under consideration is driven to a degree of over-sensitivity at which overshooting, generally considered objectionable, must necessarily occur so that" J constantly extremely small, and therefore harmless, changes between overand underprotection are impressed on the surface to be protected, with the changes appearing as oscillations at a frequency determined by cathodic protection condit-ions, or requirements.
  • the pulses may be of substantially constant current level, and their periodici-ty is increased or decreased to provide more or less cathodic protection in accordance with signals from the sensing half-cell.
  • periodicity is used herein to define the frequency of pulses having equal length in time.
  • frequency indicating only the number of pulses, regardless of their length, would not adequately include the necessary second magnitude -involved which is the duration of the pulses.
  • the same ratio of pulse duration to the time between pulses may be obtained at any desired frequency and, then, the total current delivered would be the same. Controlling only the frequency would, consequently, not necessarily result in a control of the total output current supplied during a given time.
  • a transistor having emitter and base control electrodes is employed as a preamplifier.
  • Automatic regulation of the cathodic protection action is initiated at a predetermined level in accordance with a preset adjustable voltage level.
  • a sensing half-cell is connected to one of the control electrodes of the transistor, while the reference voltage level is supplied to the other control electrode of the transistor.
  • a pulse circuit is connected to supply metered increments of unidirectional current to the anode or anodes of the system. The periodicity of the pulse circuit is determined by the conduction level of the input transistor. Accordingly, when cathodic protection conditions change, e.g. on the hull in the case of ship protection, the frequency of current pulses increases or decreases to provide a proper increase or decrease in total current supplied to the surface of the hull during any given period of time, thereby restoring optimum cathodic protection conditions.
  • a direct current protection system includes an electrode, a sensing cell, circuitry for supplying unidirectional pulses to the electrode, and additional circuitry responsive to signals from the sensing cell for changing the ratio of pulse length to the period between pulses.
  • the frequency of the pulses is adjusted.
  • an aluminum water craft is provided with a cathodic protection anode or anodes and a sensing half-cell.
  • circuitry is provided for applying current of one polarity to the anode, and also for controlling the total current applied to the anode in accordance with the potential sensed at the half-cell.
  • the input electrodes of a transistor amplifier are connected between the sensing half-cell and a reference voutage source in an electrical corrosion prevention system, and circuit arrangements are provided for varying the unidirectional current applied to the protective electrode in accordance with the output of the transistor amplifier.
  • the system in accordance with the present invention, has the advantage of accurately following the cathodic protection conditions on the surface of the hull, whether these conditions are a result of changes in conductivity of the water or of changes in speed of the craft, or other factors.
  • tests indicate that the throwing power of the system is significantly increased by the use of unidirectional pulses preferably at a steady level, as compared with either continuous current output or current interrupted at a constant frequency with the current level being adjusted in dependence on the sensing half-cell signals, as it is the case with systems used heretofore.
  • FIGURE 1 is a circuit diagram of a cathodic protection system in accordance with the present invention and using an oscillator;
  • FIGURE 2 is a plot which is useful in understanding the mode of operation of the circuit of FIGURE 1;
  • FIGURE 3 is a block diagram illustrating a cathodic protection system of high sensitivity and adapted to oscillate, under the action of naturally or normally occurring changes in cathodic protection conditions;
  • FIGURE 4 is a detailed circuit diagram of a cathodic protection system in accordance with FIGURE 3.
  • the principal components of the circuit include a sensing halfcell 12, an anode 14 and a source of direct current (not shown) coupled to the power lead 16.
  • the anode has a platinum surface or is otherwise of electrochemically inert material.
  • the remainder of the circuit of FIGURE 1 is designed to apply pulses of current from lead 16 to the anode 14. These pulses are unidirectional of constant duration, and vary in frequency in accordance with signals from half-cell 12 indicating the level of cathodic protection on the hull18.
  • the electrical circuit includes five transistors, 21 through 25.
  • the first two transistors 21 and 22 are preamplifier transistors; the second two transistors 23 and 24 form an oscillation circuit; and the last transistor 25 is the output or power transistor. It may be noted that transistors 21 and 23 are npn type transistors, while transistors 22, 24 and 25 are pnp type transistors.
  • Proper biasing potentials for operation of the transistors are provided by the various resistors included in the circuitry.
  • the circuit resistors include resistors 28 and 30 in the circuit of meter 31.
  • Resistor 32 is connected in series with the cell 12 at the input to the base of transistor 21 and is sufficiently large to prevent burn out of transistor 21 if resistor 32 is inadvertantly connected to the voltage supply.
  • a potentiometer 34 is connected in the emitter circuit of transistor 21. This voltage assumes the role of a bucking voltage in circuit opposition to the voltage developed by the sensing half-cell 12.
  • the silicon diode 36 provides an 0.7 volt drop (at 10 milliamperes) across the potentiometer 34.
  • a Zener diode could also be used, in place of diode 36.
  • a number of resistors 38, 40, 42, 44 and 46 are connected from the 12 volt input lead 16 to various points in the circuitry of transistors 21 through 25 to supply the proper operating potentials.
  • Resistor 48 is connected between the emitter of transistor 22 and the base of transistor 23.
  • resistor 50 is connected between the collector of transistor 23 and the base of transistor 24.
  • a resistor 52 and a capacitor 54 are connected between the base of transistor 23 and the collector of transistor 24.
  • Resistor 56 is connected from the collector of transistor 24 to ground.
  • Capacitor 60 in the input circuit to transistor 21 forms, with resistor 32, a lowpass filter to prevent high frequency transients from affecting transistor 21 by shunting them to ground.
  • resistor 32 With reference to the cathodic protection anode 14, it may be spaced from the hull 18 by a suitable insulating layer 62. The insulation 62 may extend around the anode 14 to,
  • the boat owner would initially set the potentiometer 34 to a predetermined meter reading as shown on meter 31 with the switch arm 64 contacting terminal 66.
  • This desired potential is a known function of the sensing half-cell material and the surface to be protected.
  • the desired reading on the meter 31 is 400 millivolts. Accordingly, this voltage level is set on the variable resistor 34.
  • steel has a galvanic potential in sea water of about 0.60 volt or 600 millivolts with respect to a saturated calomel halfcell, or a standard silver-silver chloride cell.
  • Aluminum has an activity of about -750 millivolts with respect to a calomel half-cell. This gives an initial difference of 150 millivolts.
  • the protective hydrogen film on the surface to be protected increases the negative potential by 250 millivolts. The total desired reading on the meter is therefore 400 millivolts.
  • the oscillator including transistors 23 and 24 starts oscillating at a high rate as soon as the circuit is turned on and continues to oscillate rapidly as cathodic protection builds up on the hull.
  • Standard pulses are applied through transistor 25 to the anode 14. The frequency of these pulses varies in accordance with cathodic protection conditions. When the level of protection is high, pulses are only applied to the anode 14 infrequently, and the pulse repetition rate is low. Initially, however, when there is no protective film built up on the hull of the ship, a high rate of oscillation is maintained, thus providing maximum current to the anode 14.
  • the maximum rate of oscillation is approximately 300 pulses per second. This rate ranges down to about pulses per second as the lowest rate available with the circuit of FIGURE 1.
  • normal cathodic protection needs under constant operating conditions for even the smallest boat will be greater than 10 pulses per second. With minor circuit changes other frequencies could readily be obtained.
  • transistor 24 is in the energized state.
  • Transistor 23 is also energized to supply drive to the base of transistor 24.
  • the base of the npn transistor 23 must be positive with respect to its emitter for it to conduct.
  • capacitor 54 charges up, reducing the base drive to transistor 23.
  • the base drive to transistor 24 is also reduced, and the collector current of this transistor 24 is decreased.
  • the reduction of current ow through transistor 24 reduces the voltage across resistor 56 and provides a cumulative effect.
  • Transistors 23 and 24 then cutoff.
  • the time required for the discharge of capacitor 54 to a level where transistors 23 and 24 are reactivated is determined by the discharge path through resistors 48 and 52 and voltage on capacitor 58.
  • Transistor 22 controls the voltage across capacitor 58. If the voltage across capacitor 58 is high (when maximum power output is desired) transistors 21 and 22 are off. Under these conditions, capacitor 54 discharges quickly, the potential at the base of transistor 23 rises rapidly, and the off time is short. The resulting high pulse repetition rate through transistor 25 gives maximum power to the cathodic protection anode 14. Under the maximum pulse repetition rate conditions of 300 pulses per second, the specific circuit of FIGURE 1 has an off time which is about equal to the on time. Thus, the ratio of the pulse duration to the time between pulses is changed in accordance with the sensed input signals from the sensing half-cell 12.
  • the graph of FIGURE 2 represents a plot of the relative current supplied to anode 14 plotted against the departure of the half-cell 12 from the preset voltage on potentiometer 34. Assuming, for example, that the optimum voltage which is desired at sensing cell 12 is 400 millivolts, resistor 34 is initially set to give a 400 millivolt reading on meter 31. Initially, the sensing half-cell will have a much lower reading as no protective lm will have ⁇ built up on the hull. This corresponds to the portion 72 of the plot of FIGURE 2. As a protective film builds up on the hull, the voltage level of the sensing half-cell 12 builds up and the current applied to anode 14 is reduced, This situation corresponds to the section 74 of the curve of FIGURE 2.
  • an average operating point 76 will be reached, at which the voltage supplied by the sensing half-cell 12 will be equal to the voltage preset on resistor 34, when compared by switching meter 31 from terminal 66 to terminal 68.
  • the voltage at sensing half-cell 12 will exceed the preset voltage and the current applied to the anode 14 must be reduced.
  • the resistor 28 differs from resistor 30. This difference is provided in order to equalize the meter readings when optimum conditions are obtained.
  • the resistor 30 is different from resistor 28 by 6,000 ohms to compensate for the 0.1 volt drop across the input base and emitter electrodes of transistor 21. With this difference in resistance, the meter readings appear to be exactly the same when the system is at the desired operating point as shown at point 76 in FIGURE 2.
  • the use of the transistor 21 as the first preamplifier stage has a number of advantages. First, it is substantially free from drift, and will always conduct at the same level with the same difference in potential across the input base and emitter electrodes. It is unaffected by the vibration characteristic of shipboard installations. In addition, it has a low input impedance when back biased, and requires no biasing circuitry, in addition to the adjustable voltage which is preset on potentiometer 34.
  • the term throwing power is used to designate the maximum distance from each anode at which the potential impressed at a given total current output is still sufficient to ensure satisfactory protection.
  • the throwing power increases with the applied voltage and, since current is applied by the system of this invention in increments separated by off-periods, it will be apparent that a higher voltage level is associated with the current pulses supplied as compared to a continuous current supply operating at the same average current. In other words, an increased throwing power is achieved under otherwise identical conditions when using protective current supplied as pulses, interrupted by off-periods.
  • the cathodic protection system shown is designed to exhibit high response speed and sufficient sensitivity to oscillate under normal operating circumstances between the conditions termed above underprotection and overprotection,
  • the closed-loop system oscillates as a whole with it natural frequency which depends on the naturally occurring cathodic protection conditions on the surface to be protected, such as a hull.
  • most closed-loop systems when deviating from optimum conditions, perform in a manner generally referred to as hunting, as a phenomenon necessary to reach optimum conditions at which the otherwise useless and objectionable hunting performance comes to a stop.
  • that of the present invention is designed to continuously oscillate under any conditions, which includes optimum or balance conditions, in such a manner that oscillations of the system as a whole occur at a frequency of at least 1 per second, preferably 20 to 200 per second.
  • This result may be achieved by the inclusion of at least one amplication stage driving the sensitivity of the system to a degree at which overshooting occurs under any circumstances, including optimum conditions.
  • the system of FIGURES 3 and 4 is at no time in balance but, due to the intentionally induced overshooting, the system oscillates even under continuing optimum conditions.
  • the protective anode current is a pulsating current, with the ratio of the pulse duration to the time between pulses being a function of the signal voltage of the sensing half-cell, and the frequency being dependent on naturally occurring changes in cathodic protection conditions, such as the hull polarization and the speed of the ship, in the case of ship protection.
  • the hull or other surface to be protected is designated by reference numeral 80.
  • a signal voltage is developed which is representative of cathodic protection conditions on the hull, as illustrated by the graph 84 with a high at 86 and a low at 88.
  • the sensing circuit so described includes a bucking or reference voltage derived from a potentiometer 90.
  • the sensing half-cell voltage and the reference voltage are compared by a first transistor of the amplification stage designated in FIGURE 3 by the symbol 92.
  • the graph following the amplifier 92 at its right-hand side illustrates the shape of an amplified signal 94 which appears at this stage with reversed polarity.
  • the following stage 96 is a conventional component frequently referred to as a Schmitt Trigger for translating the signal into the shape of distinct pulses designated 98 in the corresponding graph.
  • the signal is applied to a driver transistor 100 (graph 102) which, in turn, actuates the power transistor 104 performing as a protective current switch in the output circuit branch connecting a power supply 106 with the anode or anodes 108.
  • the output or protective anode current represented in graph 110, is in opposite phase with respect to that of the driver output, graph 102. Therefore, it is in phase with the original signal 84 obtained from the sensing helf-cell. Since the higher level of a signal indicates overprotection, the corresponding phase of the output is that with the output transistor 104 being cut-off, so that no protective current is supplied to the anode 108.
  • FIGURE 4 is a detailed circuit diagram of the system schematically shown in FIGURE 3 and described in the foregoing paragraph. Identical components are designated by the same reference numerals.
  • Transistor 112 which also constitutes one component of the amplifier 92 of FIGURE 3, compares the reference half-cell voltage with a voltage set on potentiometer 90.
  • the voltage across the potentiometer 90 is regulated by means of the diode 114.
  • the difference between the desired hull potential, set on potentiometer 90, and the voltage generated by the reference half-cell 82 is amplified by transistors 112 and 116. This amplified voltage appears across resistor 118 and is applied to the base of transistor 120. When this voltage exceeds a predetermined value, in practice approximately 5 volts, transistor 120 will conduct and transistor 122 will be cut-off to asume its non-conductive state, due to the coupling between them, known as a Schmitt Trigger and designated 96 in the block diagram of FIGURE 3.
  • transistor 122 starts to conduct. Consequently, the voltage across resistor 124 increases to cause transistor 120 to cut-off. While transistor 122 is conducting, current can pass from the base of the driver transistor 100. This causes the voltage appearing across resistor 126 to be nearly equal to the voltage appearing at the positive terminal 128 of the power supply 106, generally a l2 volt battery on small boats. Therefore, no current can pass from the base of current switch transistor 130, and no current is supplied to the anode or anodes 108.
  • transistor 112 draws less current
  • tran ⁇ sistor 116 draws more current
  • the voltage developed across resistor 118 and at the base of transistor 120 increases. This causes transistor 120 to become conductive, and transistors 122 and 100 assume their nonconductive states. Now current can Ipass from the base of power switch transistor 130 through resistor 126, and current to the anode or anodes 108 is available.
  • transistor 112 conducts more current, transistor 116 conducts less current, and the voltages across resistor 118 and at the base of transistor 120 decreases.
  • Transistors 120 and 122 are cut-off and transistor 100 becomes conductive. No current can pass from the base of output switch transistor 130, since it is at a larger positive voltage than the emitter. When such conditions prevail, the voltage drop across transistor 100 may be 0.2 volt, while the drop across the rectifier 132, used to provide a voltage drop at the emitter of transistor ⁇ 130, is 0.5 volt. As a result, no protective current is supplied to the anodes 108.
  • Rectifier 132 affords, additionally, temperature stability at transistor 130 for the off or non-conducting state.
  • Another rectifier, 134, and capacitor 136 are used to filter the voltage derived from power supply 106.
  • the remaining resistors, 140 ⁇ 158 and capacitors 160 and 162 are used for providing proper potentials at different points of the circuits, and for forming filters, respectively.
  • the meter 164 is continuously connectedto read the sensing half-cell voltage, and is used to set the reference voltage on potentiometer 90.
  • Power Supply 106 12 volt battery.
  • a system for cathodic protection of a surface comprising an anode insulated from the surface, a source of electric power, a transistor connected to the source of power and t-o the anode to pass current to the anode in the form of pulses as the transistor is intermittently switched between its conductive and non-conductive states, a sensing half-cell insulated from said surface, and electric circuit means connected between the sensing half-cell and the transistor to switch the transistor to its conductive state and to vary the ratio of the duration of the pulses to the time between in proportion to the response of the half-cell when the negative potential of said surface decreases to a first predetermined level relative to the potential of the sensing half-cell and to switch the transistor to its non-conductive state when the negative potential of the surface increases to a second predetermined level relative to the potential of the half-cell, the negative potential of said second level being greater that the negative potential of said first level.
  • a system for cathodic protection of a surface comprising an anode insulated from the surface, a source of electric power, a rst PNP transistor having its emitter connected to the source of current and its collector connected to the anode to pass current to the anode in the form of pulses, a sensing half-cell insulated from said surface, a first NPN transistor having its collector connected to the source of current and its base connected to the sensing half-cell to become conductive in response to a difference in electric potential between the sensing half-cell and said surface when the potential on the surface exceeds a desired level, and circuit means between the first NPN transistor and the base of the first PNP transistor to energize the PNP transistor to its conductive state and to vary the ratio of the duration of the pulses to the time between in proportion to the response of the half-cell when the conductive level of the first NPN transistor falls below a first predetermined level and to switch the first PNP transistor to its non-conductive state when the conductive level of the first NPN transistor exceeds a second
  • said circuit means comprises a second NPN transistor having its base connected to the source of power and to the collector of the first NPN transistor, said second NPN transistor having its collector connected to the source of power and its emitter connected to ground through a rst resistor, a third NPN transistor having its collector connected to the source of power and its base connected to the emitter of the second NPN transistor between said emitter and said rst resistor, a fourth NPN transistor having its collector connected to the source of power and its emitter connected to ground through to a second resistor, the third NPN transistor having its emitter connected to the emitter of the fourth NPN transistor between the emitter of the fourth NPN transistor and the second resistor, a capacitor and a third resistor connected in parallel between the collector of the third NPN transistor and the base of the fourth NPN transistor, and a second PNP transistor havings its base connected through a fourth resistor to the collector of the fourth NPN transistor, said second PNP transistor having its emitter connected t0 the source of power and
  • a system according to claim 2 in which a potentiometer is connected between the emitter of the rst NPN transistor and the source of power to apply a voltage through the sensing half-cell in opposition to the voltage produced through it by a difference in potential between the half-cell and said surface.
US85008A 1960-02-29 1961-01-26 Cathodic protection system Expired - Lifetime US3242064A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL136909D NL136909C (xx) 1960-02-29
NL261794D NL261794A (xx) 1960-02-29
US85008A US3242064A (en) 1960-02-29 1961-01-26 Cathodic protection system
GB7183/61A GB957467A (en) 1960-02-29 1961-02-27 Cathodic protection system
DK87361AA DK112841B (da) 1960-02-29 1961-02-27 Anlæg til katodisk korrosionsbeskyttelse af metaloverflader.
FR854104A FR1292235A (fr) 1960-02-29 1961-02-28 Système de protection cathodique
DE19611446395 DE1446395B2 (de) 1960-02-29 1961-02-28 Vorrichtung zum kathodischen Schutz einer Fläche

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1159360A 1960-02-29 1960-02-29
US85008A US3242064A (en) 1960-02-29 1961-01-26 Cathodic protection system

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US3242064A true US3242064A (en) 1966-03-22

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US85008A Expired - Lifetime US3242064A (en) 1960-02-29 1961-01-26 Cathodic protection system

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US (1) US3242064A (xx)
DE (1) DE1446395B2 (xx)
DK (1) DK112841B (xx)
GB (1) GB957467A (xx)
NL (2) NL136909C (xx)

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330751A (en) * 1963-05-20 1967-07-11 Lockheed Aircraft Corp Cathodic protection circuit including diode means
US3350288A (en) * 1963-04-27 1967-10-31 Almar-Naess Almar Method for corrosion protection
US3360452A (en) * 1964-02-24 1967-12-26 Nee & Mcnulty Inc Cathodic protection system
US3362900A (en) * 1962-10-17 1968-01-09 Hull Protectors Inc System for cathodically protecting a structure
US3373100A (en) * 1964-05-22 1968-03-12 Rubelmann Haydn Precontrol salinity compensator for automatic cathodic protection system
US3374162A (en) * 1962-08-21 1968-03-19 Rubelmann Haydn Control unit for automatic cathodic protection
US3424665A (en) * 1965-10-22 1969-01-28 Harco Corp Cathodic protection system
US3442779A (en) * 1964-07-27 1969-05-06 Canadian Ind Anodic protection of metals
US3493485A (en) * 1967-10-25 1970-02-03 Cornell Aeronautical Labor Inc Apparatus for determining dissolved oxygen concentration of biological fluids
US3622489A (en) * 1968-09-25 1971-11-23 Institutual De Cercetari Si Pr Cathodic protection system
US3674662A (en) * 1970-11-10 1972-07-04 Shell Oil Co Cathodic protection of closely spaced oil well casings
US3953742A (en) * 1974-07-17 1976-04-27 Brunswick Corporation Cathodic protection monitoring apparatus for marine propulsion device
US4085009A (en) * 1976-07-28 1978-04-18 Technicon Instruments Corporation Methods for determination of enzyme reactions
US4440611A (en) * 1981-12-09 1984-04-03 The Texas A & M University System Cathodic electrochemical process for preventing or retarding microbial and calcareous fouling
US4510030A (en) * 1982-12-21 1985-04-09 Nippon Light Metal Company Limited Method for cathodic protection of aluminum material
US4767512A (en) * 1986-12-03 1988-08-30 George Cowatch Process and apparatus for preventing oxidation of metal by capactive coupling
US4795537A (en) * 1987-04-10 1989-01-03 H.P.G. Research Ltd. Electrical conditioning system for electrodes in an electrolysis cell
US4828665A (en) * 1986-01-10 1989-05-09 Mccready David F Cathodic protection system using carbosil anodes
US4950372A (en) * 1986-01-10 1990-08-21 Mccready David F Cathodic protection system using carbosil anodes
US5102514A (en) * 1986-01-10 1992-04-07 Rust Evader Corporation Cathodic protection system using carbosil anodes
US5139634A (en) * 1989-05-22 1992-08-18 Colorado Interstate Gas Company Method of use of dual bed cathodic protection system with automatic controls
DE4118831A1 (de) * 1991-06-07 1992-12-10 Corrobesch Vertriebsgesellscha Verfahren zur verhinderung eines bewuchses von stahlwasserbauwerken und schiffen
US5338417A (en) * 1990-08-08 1994-08-16 Vereinigte Aluminium-Werke Aktiengesellschaft Cathodic corrosion protection for an aluminum-containing substrate
US5407549A (en) * 1993-10-29 1995-04-18 Camp; Warren J. Electronic corrosion protection system
USH1644H (en) * 1990-08-13 1997-05-06 The United States Of America As Represented By The Secretary Of The Navy Method and apparatus for providing continuous cathodic protection by solar power
US6046515A (en) * 1997-04-25 2000-04-04 Lewis; Michael E. Process and apparatus for preventing oxidation of metal
US6365034B1 (en) 1997-05-07 2002-04-02 Polymer Alloys Llc High throughput electrochemical test for measuring corrosion resistance
US20020088720A1 (en) * 1997-04-25 2002-07-11 Red Swan, Inc. Process and apparatus for preventing oxidation of metal
EP1241280A1 (fr) * 2001-03-12 2002-09-18 Cebelcor A.S.B.L. Procédé et installation pour la protection cathodique d'une structure métallique
US20040211677A1 (en) * 1997-04-25 2004-10-28 Lewis Michael E. Method for inhibiting corrosion of metal
US20070025898A1 (en) * 2005-07-29 2007-02-01 Manuel Marquez Salvatierra Anticorrosive treatment for shaving blades
EP1777322A1 (en) * 2005-10-18 2007-04-25 Technische Universiteit Delft Apparatus for cathodic protection of steel reinforced concrete structures and method
US8118983B1 (en) 2010-01-15 2012-02-21 Brunswick Corporation System for inhibiting corrosion of submerged components in a marine propulsion system
CN103014721A (zh) * 2012-12-06 2013-04-03 青岛雅合科技发展有限公司 智能多路恒电位仪及其工作方法
WO2014081339A1 (ru) 2012-11-23 2014-05-30 Sulimin Yuriy Vladimirovich Станция защиты от коррозии импульсным током
US20150218712A1 (en) * 2012-10-11 2015-08-06 Ecospec Global Technology Pte Ltd System and method for providing corrosion protection of metallic structure using time varying electromagnetic wave

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2021519A (en) * 1933-12-12 1935-11-19 Polin Inc Corrosion preventative
GB657392A (en) * 1949-02-17 1951-09-19 Charles Antoine Hajosi Electrical method for protecting metal surfaces from corrosion and formation of incrustations
US2659850A (en) * 1950-03-14 1953-11-17 Leeds & Northrup Co Motor control system and the like
US2752308A (en) * 1952-08-18 1956-06-26 Smith Corp A O Cathodically protected water storage tank with safety shutoff
US2759887A (en) * 1951-01-24 1956-08-21 John A Miles Cathodic protection regulator
US2832734A (en) * 1952-02-14 1958-04-29 Leeds & Northrup Co Coulometric systems
US2912635A (en) * 1956-11-01 1959-11-10 Ford Motor Co Electrical regulator device for generators
US2932783A (en) * 1958-08-01 1960-04-12 Motorola Inc Voltage regulated power supply
US2939824A (en) * 1957-07-26 1960-06-07 Kaiser Aluminium Chem Corp Method and apparatus for the production of aluminum
US2962651A (en) * 1959-07-13 1960-11-29 Dressen Barnes Corp Transistorized voltage regulator
US2982714A (en) * 1958-05-09 1961-05-02 Rolland C Sabins Electrolytic system
US3127337A (en) * 1958-12-01 1964-03-31 Anodic passivation system

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2021519A (en) * 1933-12-12 1935-11-19 Polin Inc Corrosion preventative
GB657392A (en) * 1949-02-17 1951-09-19 Charles Antoine Hajosi Electrical method for protecting metal surfaces from corrosion and formation of incrustations
US2659850A (en) * 1950-03-14 1953-11-17 Leeds & Northrup Co Motor control system and the like
US2759887A (en) * 1951-01-24 1956-08-21 John A Miles Cathodic protection regulator
US2832734A (en) * 1952-02-14 1958-04-29 Leeds & Northrup Co Coulometric systems
US2752308A (en) * 1952-08-18 1956-06-26 Smith Corp A O Cathodically protected water storage tank with safety shutoff
US2912635A (en) * 1956-11-01 1959-11-10 Ford Motor Co Electrical regulator device for generators
US2939824A (en) * 1957-07-26 1960-06-07 Kaiser Aluminium Chem Corp Method and apparatus for the production of aluminum
US2982714A (en) * 1958-05-09 1961-05-02 Rolland C Sabins Electrolytic system
US2932783A (en) * 1958-08-01 1960-04-12 Motorola Inc Voltage regulated power supply
US3127337A (en) * 1958-12-01 1964-03-31 Anodic passivation system
US2962651A (en) * 1959-07-13 1960-11-29 Dressen Barnes Corp Transistorized voltage regulator

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3374162A (en) * 1962-08-21 1968-03-19 Rubelmann Haydn Control unit for automatic cathodic protection
US3362900A (en) * 1962-10-17 1968-01-09 Hull Protectors Inc System for cathodically protecting a structure
US3350288A (en) * 1963-04-27 1967-10-31 Almar-Naess Almar Method for corrosion protection
US3330751A (en) * 1963-05-20 1967-07-11 Lockheed Aircraft Corp Cathodic protection circuit including diode means
US3360452A (en) * 1964-02-24 1967-12-26 Nee & Mcnulty Inc Cathodic protection system
US3373100A (en) * 1964-05-22 1968-03-12 Rubelmann Haydn Precontrol salinity compensator for automatic cathodic protection system
US3442779A (en) * 1964-07-27 1969-05-06 Canadian Ind Anodic protection of metals
US3424665A (en) * 1965-10-22 1969-01-28 Harco Corp Cathodic protection system
US3493485A (en) * 1967-10-25 1970-02-03 Cornell Aeronautical Labor Inc Apparatus for determining dissolved oxygen concentration of biological fluids
US3622489A (en) * 1968-09-25 1971-11-23 Institutual De Cercetari Si Pr Cathodic protection system
US3674662A (en) * 1970-11-10 1972-07-04 Shell Oil Co Cathodic protection of closely spaced oil well casings
US3953742A (en) * 1974-07-17 1976-04-27 Brunswick Corporation Cathodic protection monitoring apparatus for marine propulsion device
US4085009A (en) * 1976-07-28 1978-04-18 Technicon Instruments Corporation Methods for determination of enzyme reactions
US4440611A (en) * 1981-12-09 1984-04-03 The Texas A & M University System Cathodic electrochemical process for preventing or retarding microbial and calcareous fouling
US4510030A (en) * 1982-12-21 1985-04-09 Nippon Light Metal Company Limited Method for cathodic protection of aluminum material
US4828665A (en) * 1986-01-10 1989-05-09 Mccready David F Cathodic protection system using carbosil anodes
US4950372A (en) * 1986-01-10 1990-08-21 Mccready David F Cathodic protection system using carbosil anodes
US5102514A (en) * 1986-01-10 1992-04-07 Rust Evader Corporation Cathodic protection system using carbosil anodes
US4767512A (en) * 1986-12-03 1988-08-30 George Cowatch Process and apparatus for preventing oxidation of metal by capactive coupling
US4795537A (en) * 1987-04-10 1989-01-03 H.P.G. Research Ltd. Electrical conditioning system for electrodes in an electrolysis cell
US5139634A (en) * 1989-05-22 1992-08-18 Colorado Interstate Gas Company Method of use of dual bed cathodic protection system with automatic controls
US5338417A (en) * 1990-08-08 1994-08-16 Vereinigte Aluminium-Werke Aktiengesellschaft Cathodic corrosion protection for an aluminum-containing substrate
USH1644H (en) * 1990-08-13 1997-05-06 The United States Of America As Represented By The Secretary Of The Navy Method and apparatus for providing continuous cathodic protection by solar power
DE4118831A1 (de) * 1991-06-07 1992-12-10 Corrobesch Vertriebsgesellscha Verfahren zur verhinderung eines bewuchses von stahlwasserbauwerken und schiffen
US5407549A (en) * 1993-10-29 1995-04-18 Camp; Warren J. Electronic corrosion protection system
US7198706B2 (en) 1997-04-25 2007-04-03 Canadian Auto Preservation Inc. Method for inhibiting corrosion of metal
US6046515A (en) * 1997-04-25 2000-04-04 Lewis; Michael E. Process and apparatus for preventing oxidation of metal
US20020088720A1 (en) * 1997-04-25 2002-07-11 Red Swan, Inc. Process and apparatus for preventing oxidation of metal
US20040211677A1 (en) * 1997-04-25 2004-10-28 Lewis Michael E. Method for inhibiting corrosion of metal
US6875336B2 (en) * 1997-04-25 2005-04-05 Canadian Auto Preservation, Inc. Process and apparatus for preventing oxidation of metal
US6365034B1 (en) 1997-05-07 2002-04-02 Polymer Alloys Llc High throughput electrochemical test for measuring corrosion resistance
EP1241280A1 (fr) * 2001-03-12 2002-09-18 Cebelcor A.S.B.L. Procédé et installation pour la protection cathodique d'une structure métallique
EP1598445A2 (en) 2004-05-17 2005-11-23 Canadian Auto Preservation Inc. Method for inhibiting corrosion of metal
US20070025898A1 (en) * 2005-07-29 2007-02-01 Manuel Marquez Salvatierra Anticorrosive treatment for shaving blades
US7540945B2 (en) 2005-07-29 2009-06-02 Marquez Salvatierra Manuel Antonio Anticorrosive treatment for shaving blades
EP1777322A1 (en) * 2005-10-18 2007-04-25 Technische Universiteit Delft Apparatus for cathodic protection of steel reinforced concrete structures and method
US8118983B1 (en) 2010-01-15 2012-02-21 Brunswick Corporation System for inhibiting corrosion of submerged components in a marine propulsion system
US20150218712A1 (en) * 2012-10-11 2015-08-06 Ecospec Global Technology Pte Ltd System and method for providing corrosion protection of metallic structure using time varying electromagnetic wave
US10494723B2 (en) * 2012-10-11 2019-12-03 Sembcorp Marine Repairs & Upgrades Pte. Ltd. System and method for providing corrosion protection of metallic structure using time varying electromagnetic wave
WO2014081339A1 (ru) 2012-11-23 2014-05-30 Sulimin Yuriy Vladimirovich Станция защиты от коррозии импульсным током
CN103014721A (zh) * 2012-12-06 2013-04-03 青岛雅合科技发展有限公司 智能多路恒电位仪及其工作方法
CN103014721B (zh) * 2012-12-06 2014-12-10 青岛雅合科技发展有限公司 智能多路恒电位仪及其工作方法

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DE1446395B2 (de) 1970-06-18
DE1446395A1 (de) 1969-03-27
DK112841B (da) 1969-01-20
NL261794A (xx)
NL136909C (xx)
GB957467A (en) 1964-05-06

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