US3769521A - Impressed current cathodic protection system - Google Patents

Impressed current cathodic protection system Download PDF

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Publication number
US3769521A
US3769521A US00295403A US3769521DA US3769521A US 3769521 A US3769521 A US 3769521A US 00295403 A US00295403 A US 00295403A US 3769521D A US3769521D A US 3769521DA US 3769521 A US3769521 A US 3769521A
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Prior art keywords
supporting member
anode
power supply
underwater
transmitting
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US00295403A
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English (en)
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J Caldwell
G Sump
R Benedict
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ExxonMobil Upstream Research Co
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Exxon Production Research Co
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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

  • An impressed current cathodic protection system for a [21] Appl. No.: 295,403 marine structure includes an elongated supporting I member which can be lowered into position adjacent [52] U S CL 307/95 61/54 166/0 5 g the underwater structure to be protected, an underwa- 175/5 204/l'96' ter power supply mounted in the supporting member [51] lm.
  • This invention provides an improved impressed current cathodic protection system which alleviates many of the problems associated with systems available in the past and facilitates the use of cathodic protectiaon for off-shore platforms and other marine structures.
  • the improved system of the invention includes an elongated supporting member which can be lowered into position adjacent the structural members to be protected and later retrieved as necessary, an underwater power supply mounted on the supporting member for converting high voltage alternating current from a surfacemounted source to low voltage direct current, one or more low deterioration rate anodes mounted on the supporting member near the structural members which are to be protected, a potential controller for regulating the level of protection provided, and a reference cell for monitoring the system.
  • the supporting member employed in the improved system will preferably comprise an elongated string of pipe or conduit which can be lowered into position from the waters surface through guides on the structural members and connected to the structure near the lower end of the member.
  • the pipe or conduit may be metallic, in which case it will serve as the negative conductor between the power supply and the structure, or may be made of nonconducting material and provided with an internal conductor to ground. If a metallic pipe or conduit is used, the anodes employed will normally be mounted on dielectric shields carried on the outer surface of the pipe. These shields may be dispensed with if a conduit of nonconducting material is employed. Arms may be attached to the pipe of conduit for supporting the anodes if desired. In lieu of such a pipe or conduit, the protection system may be mounted on an insulated cable which can be pulled downwardly into position on the structure and returned to the surface when necessary.
  • the underwater power supply employed in the system of the invention will normally comprise a transformer and rectifier for converting high voltage alternating current to low voltage direct current.
  • An automatic potential controller including a magnetic amplifier, silicon controlled rectifiers, and the like may also be included or instead may be installed above the waters surface.
  • the power supply will normally be enclosed in a suitable housing incorporated in the retrievable pipe string, conduit or cable system at a point near the anodes. Two or more power supply units may be provided in each retrievable system if desired.
  • Provisions may be made for pulsing either the high voltage alternating current or the low voltage output from the rectifier.
  • Reference cell monitors used to establish the required potential and regulate the controller are provided on the supporting member and may also be located on the marine structure itself. Manual controls and instrumentation are located on the deck of the structure or at an equally accessible surface location.
  • the anodes employed in the retrievable system will preferably be low deterioration rate anodes such as platinum over tantalum, platinum over niobium, platinum over titanium, platinum studded lead, or the like. As indicated earlier, these are mounted on the supporting member or on arms extending therefrom and are connected to the potential controller through leads extending within the supporting member.
  • the system of the invention has numerous advantages over impressed current cathodic protection systems available in the past.
  • the use of an elongated pipe or similar supporting member and an underwater power supply as described above permits the transmission of low voltage, high amperage direct current to the anodes with negligible power losses and without the heavy conductors required in earlier systems; provides significantly better cooling of the transformer, rectifier, and automatic potential controller and thus makes possible the use of lighter, more compact units; makes it possible to vary the level of the anodes with respect to the submerged structure; results in savings in deck space and reduces platform structural requirements; provides greater safety because the power supply and most of the associated leads are underwater'where danger of fire or damage due' to lightning is minimized; eliminates or greatly reduces radio frequency interference; provides greater'reliability because of the shorter direct current power leads; permits the use of long life dielectric shields mounted directly on the supporting member; makes possible periodic maintenance and repair without'the' use of divers; and provides a system which is fully compatible with existing off-shore equipment and petroleum industry practices.
  • FIG. I in the drawing is a schematic representation of an offshore platform provided with the improved impressed current cathodic protection system of the invention
  • FIG. 2 is an enlarged longitudinal cross-section illustrating the system of FIG. 1 in greater detail
  • FIG. 3 is a schematic electrical diagram illustrating the system of the invention.
  • Y I FIG. 4 is a fragmentary longitudinal cross-section through the supporting member in an embodiment of the invention using a metallic supporting member;
  • FIG. 5 is a fragmentary longitudinal cross-section through the non-metallic supporting member of an alternate embodiment of the invention.
  • FIG. 6 illustrates the use of arms attached to the supporting member for positioning the anodes employed in accordance with the invention
  • FIG. '7 is a fragmentary view of another embodiment of the invention in which the apparatus is supported by means of a cable or similar member;
  • FIG. 8 illustrates still another embodiment for the protection of an underwater separator or similar device.
  • FIG. I in the drawing is a schematic representation of an offshore platform provided with the improved impressed current cathodic protection system of the invention.
  • the platform depicted in FIG. 1 includes an open framework I 1 of tubular steel members extending from the bottom 12 of a body of water 13 to a platform 14 located a distance of 50 feet or more above the surface of the water 15.
  • the upper deck of the platform is provided with a shelter 16 for the housing of personnel and equipment, with a derrick 17 for use in well operations, and with other conventional items of equipment.
  • The, layout of the deck and the equipment provided thereon will depend in large part upon the particular purpose for which the platform is intended.
  • the facilities provided will normally include risers extending upwardly along the platform structure to production facilities located on the deck, equipment for use in well maintenance and workover operations, offloading facilities, and the like.
  • the invention is not restricted to the particular type of platform shown and may be employed with a variety of different structures, including offshore drilling and production platforms of the monopod type, buoyant tower structures which are hinged near the bottom to permit limited'lateral movement in response to waves and currents, seadrome type structures held in place by three or more parallel members hinged near the ocean floor, offshore storage facilities, marine radar stations, semisubmersible drilling barges, underwater pumping and separator stations, and the like.
  • the cathodic protection system employed on the offshore structure of FIG. 1 includes an elongated supporting member 20 which is secured nearv its upper end to platform 14 and extends downwardly through guides 21, 22, 23, 24, 25, 26 and 27 on the platform framework to a receptacle located within a guide funnel 28 near the base of the platform.
  • the supporting member 20 will normally comprise a string of steel pipe or tubing between about 2 and about 9 inches in diameter but in some cases may be made of hard plastic or other dielectric material.
  • the string of pipe or conduit be made up of threaded sections about 30 feet in length to facilitate its disassembly when withdrawal of the system to the surface becomes necessary, although welded or bolted connections can be used in lieu of threaded joints if desired.
  • the guide members 21 through 27 through which the pipe string extends are funnel-shaped members mounted at appropriate points on horizontal members of the platform and are of sufficient diameter to pass enlarged sections of the string.
  • the lower end of member 20 normally contains a plug or other fluid-tight closure to prevent the entry of water and the escape of oil or other fluid from within the member and will be provided with threads, detents orother means for holding the lower end in place within the receptacle in guide funnel 28.
  • member 20 is made of a dielectric material, an electrical connection to ground may be provided by extending a ground conductor through the closure so that it makes contact with the structure within the receptacle.
  • the location of supporting member 20 and the associated guide members will depend in part upon the configuration of platform framework 11 and the electrical characteristics of the cathodic protection system.
  • the anodes employed in the system are normally capable of providing effective protection over relatively large areas. On large structures, however, a plurality of supporting members spaced at selected intervals may be used to insure adequate protection for the entire structure.
  • the system depicted in F IG.' 1 includes a second supporting member which is essentially identical to supporting member 20 and will therefore not be described in detail.
  • Supporting member 20 in the apparatus of FIG. 1 serves as a conduit through which the electrical leads of the cathodic protection system extend between the deck of the platform and the underwater components.
  • These components may include an underwater power supply containing a transformer and rectifier for converting high voltage alternating current produced by a generator on the platform deck into low voltage direct current, an automatic potential controller for regulating the amount of current delivered by the system, one or more anodes upon which the delivered current is impressed, and one or more reference cells for monitoring and controlling the automatic potential controller.
  • the power supply 30 will normally be enclosed in a cylindrical housing 31 which is connected into the supporting pipe string 20 at an intermediate point along its length.
  • the automatic potential controller may be located in the same housing or, if desired, may be positioned at the surface or placed in a separate housing positioned a short distance away from housing 31.
  • the entire pipe string assembly be made up of threaded pipe secitons which have sufficient mechanical strength to resist wind, wave, and current forces and to withstand impact by ice and flotsarn in both the tidal splash zone above the waters surface and the submerged zone beneath the surface. Longitudinal ribs may be provided to increase the strength of the string if necessary.
  • the lowering of the supporting member into position, the locking of the member in place by threading the lower end 32 containing closure 33 into the receptacle in funnel 25, the unlocking of the pipe string, and its retrieval can all be accomplished with conventional hoisting equipment and tools normally available on offshore platforms for use in oil field drilling and production operations.
  • the use of such a pipe string also provides an effective negative return from the platform structure by draining current at the threaded connection at the bottom of the string and at the top where the pipe string is supported on the platform deck.
  • the underwater power supply employed for purposes of the invention is shown in greater detail in FIG. 3.
  • the power supply depicted is a saturable reactor type system which includes saturable reactors 40, 41 and 412 connected in series with the three input lines 43, a4, and 45 from a 440 to 460 volt, 60 cycle three-phase alternator located on the platform, a step-down transformer having a delta-connected primary 46 which is connected to the three saturable reactors and two low voltage secondary windings 47 and 48, a three-phase double-Wye silicon rectifier assembly comprising rectifiers 511, 52, 53, 54, 55 and 56 connected to the secondary windings of the transformer, and leads extending from the rectifier assembly through suitable fuses, circuit breakers, or other protective devices 57 and 58 to the anode leads 59 and 60.
  • the step-down transformer reduces the high voltage alternating current to a voltage level between about 3 and about 50 volts and the rectifiers in turn convert this to low voltage direct current.
  • the control windings 6E, 62 and 63 of the saturable reactors energized by the atuomatic potential controller 64 as will be pointed out in greater detail hereafter, serve to regulate the input to the primary winding of the step-down transformer and thus regulate the amount of current which is delivered through the rectifiers tothe anodes 65 and 66 of the cathodic protection system.
  • Saturable reactor type power supplies useful for purposes of the invention are available from a variety of different commerical sources and will therefore be familiar to those skilled in the art.
  • saturable reactor type power supply is normally preferred but that other systems may also be employed. These include silicon-controlled rectifiers, servo-controlled variable transformers, servooperated variable reactance devices, thyristers and the like. Other voltage levels and frequencies may also be employed.
  • the location of the saturable reactor type or other power supply described above in housing 30 on supporting member 20 permits substantial reductions in the size and weight of the power supply because of the better cooling obtained.
  • Heat transfer through the housing wall to the surrounding sea water will normally be significantly better than could be obtained with a unit mounted on the platform deck.
  • a light hydrocarbon oil, a silicone fluid, a transformer oil, or the like will normally be maintained within supporting member 20 and the housing surrounding the power supply in order to further improve heat transfer and maintain high operating efficiencies.
  • the smaller size and lower weight of the power supply unit reduces the platform structural requirements from a loading and lateral wave force standpoint. More importantly, the use of a submerged power supply eliminates the necessity for devoting a substantial portion of the platform deck to housing the power supply.
  • the automatic potential controller 64 in the apparatus of FIGS. 1 through 3 monitors the level of protection of the submerged portion of the platform by means of one or more reference cells 70 and provides a signal to the saturable reactor control windings for adjusting the amount of current fed to anodes 65 and 66 so that the desired level can be maintained.
  • the reference cells employed will normally contain silver-silver chloride, zinc, or other suitable electrodes of conventional design. Each such cell is mounted on the exposed structure, preferably at a point where the degree of protection afforded by the cathodic protection system can be expected to be low and preferably a substantial distance from the nearest anode.
  • the silver-silver chloride electrode normally consists of a silver screen coated with silver chloride and welded about a silver rod.
  • This electrode is mounted in a shock-resistant plastic tube
  • This current is also conducted through a second conductor 71 in supporting member 20 to the automatic potential controller 64.
  • the controller can either be located at the surface as shown in FIGS; 2 and 3 or mounted in underwater housing 3H.
  • the system of the invention is not restricted to the use of a silver-silver chloride electrode and may employ other commercially available reference electrodes which will produce potential differences which can be used to monitor operation of the system.
  • the automatic potential controller 64 preferably includes a high gain differential direct current amplifier '75 which operates on two input signals, the potential difference between the reference electrode 70 and the platform structure ll and a control voltage from controller power supply 76 and potentiometer 77 representing the desired potential difference between the electrode and the structure.
  • the difference between these two input voltages is amplified by the controller and used to regulate the output voltage fed to the control windings till, 62 and 63 of the saturable reactor power supply 31.
  • This regulation' is accomplished by means of a silicon controlled rectifier output bridge 78 which acts as a switch to pass a portion of an alternating current powerline voltage from input leads 79 and 80 to the control windings.
  • the rectifiers in the bridge circuit are turned on for a very short period of time during each cycle of the alternating current in response to pulses from a pulse control circuitsll.
  • the pulse control circuit pulses the silicon controlled rectifiers at the end of each cycle of the alternating current so that no output voltage is conducted to the saturable reactor control windings 6H, 62 and 63.
  • the timing of the pulses is advanced toward the beginning of each cycle of the alternating current so that more power flows through the silicon controlled rectifiers to the control windings of the saturable reactor power supply.
  • the rectifiers -turn themsevles off automatically at the end of each cycle of the alternating current.
  • the output voltage fed to the saturable reactor windings will thus range between zero and about 100 volts direct current, depending upon the potential difference between the electrode in reference cell 70 and the structure 11 and the desired potential difference.
  • the controller will normally also include a provision for manual control by shutting off the differential amplifier output by means of switch 82 and substituting an adjustable voltage from potentiometer 83, which can be controlled from the surface.
  • the differential amplifier may be provided with automatic gain control to permit changes in the sensitivity of the controller to differences between the two inputs to the differential amplifier.
  • control systems suitable for impressed current cathodic protection systems are available commercially and can be readily adapted for purposes of the invention by one skilled in the art.
  • the controller shown is located at the surface, it is often advantageous, as pointed out above, to position both the controller and power supply beneath the water to further reduce the danger of fire due to electrical malfunctioning of the equipment or lighting, shorten the required length of direct current power leads and thus give greater reliability, lower powerlosses and improve safety, and eliminate or reduce radio frequency interference, particularly where high frequency power or pulsed DC power is used.
  • the anodes employed for purposes of the invention will preferably be low deterioration anodes of the platinum over titanium, platinum over niobium, or platinum over tantalum type. These anode materials last for long periods and normally permit the use of relatively small anodes at high current densities. They are therefore particulary useful in the retrievable cathodic protection system disclosed herein. Other types of anodes may also be employed, however. Although other configurations can also be used, anodes mounted directly on the supporting member 20 are normally preferred.
  • FIG. 4 in the drawing illustrates one embodiment of the invention utilizing such an anode.
  • Supporting pipe 20 in this particular embodiment is a string of 2% inch diameter steel pipe extending downwardly into the water between the structural members of the platform.
  • a dielectric shield '85 which serves to isolate the anode from the supporting member and promote uniform distribution of the protective current about the anode.
  • This dielectric shield may be made of coal tar epoxy resin, phenolic epoxy resin, fiberglass reinforced polyester resin, polyurethane, polyvinylchloride, neoprene rubber, or the like.
  • the material selected may be applied to the pipe section by conventional techniques involving the use of baking, flame sprays, fluidized beds, or the like.
  • a precast section of polyvinylchloride pipe or similar material can be inserted over the supporting member and held in place mechanically.
  • Polyvinylchloride pipe may be used in conjunction with a primer of coal tar epoxy resin or a similar dielectric material.
  • the metallic anode 86 preferably comprises a plurality of longitudinal tantalum strips, or rods, each covered with a thin layer of platinum on the order of from about 0.00005 to about 0.005 inch in thickness. These strips are interconnected and will normally be mounted so that the outer surfaces of the platinum coated metal are slightly recessed with respect to the surface of the dielectric material at each end of the anode and are thus protected against damage as the supporting member is raised and lowered.
  • Conductor 87 extends through an opening in the wall of supporting member 20 and dielectric sleeve to the backside ofthe tantalum base metal of one or more of the strips.
  • a rubber or plastic plug 88 surrounds the end of the insulated conductor to prevent contact with the wall of the supporting member and preclude the leakage of oil or other fluid from within the supporting member.
  • the anodes may be mounted at or near joints in the supporting member to facilitate assembly of the apparatus.
  • FIG. 5 in the drawing illustrates an alternate embodiment of the apparatus in which a dielectric supporting member 90 of polyvinyl chloride, glass reinforced polyester, or similar material is employed in place of the metallic supporting member referred to earlier.
  • a dielectric supporting member 90 of polyvinyl chloride, glass reinforced polyester, or similar material is employed in place of the metallic supporting member referred to earlier.
  • Anode 91 comprises a platinum coated rod or wire of titanium or the like which extends through openings in the supporting member to form a plurality of anode surfaces extending parallel to the longitudinal axis of the supporting member. The openings in the supporting member through which the anode passes are sealed to prevent fluid leakage.
  • Conductor 92 is connected to one end of the anode and extends to the underwater power supply.
  • Rings '94 and 95 on the outer surface of the supporting member near the ends of the anode extend outwardly beyond the anode surfaces to protect them against damage.
  • the anode can be recessed in shallow slots or grooves extending parallel to the longitudinal axis of the supporting member in the outer surface thereof.
  • the dimensions and configuration of the anodes will depend in part upon the area to be protected by each anode, the current densities to be used, and other factors. in general, however, it is normally preferred that the anodes be from about 2 to about feet in length and that, if a metallic supporting member is used, the dielectric sleeve extend about 10 feet or more above and below the ends of the anode. This isolates the anode from the supporting member and helps insure substantially uniform protection over a relatively large area surrounding the anode.
  • FIG. 6 in the drawing illustrates schematically an arrangement in which a metallic supporting member 100 extends downwardly in the water below the deck of the platform and arms 161 of polyvinylchloride or a similar dielectric material are hinged to the supporting member by means of brackets 1112 and hinge pins 103. Each arms swings upwardly about the hinge pin as the assembly is lowered through the guide members on the platform and is held in the extended position after it is passed through the guide members by a shear pin 104.
  • the metallic anode 1115 is mounted on the outer end of the arm 10 feet or more from the supporting member.
  • the assembly When it becomes necessary to retrieve the apparatus, the assembly can be pulled upwardly through the guide members with sufficient force to cause the shear pins to fail and permit the arms to move downwardly into positions parallel to the supporting member.
  • the shear pins can be easily replaced before the assembly is to be lowered bacl: into position.
  • F16. i in the drawing depicts still another embodiment in which the lower end of the supporting member 1111 is connected to a cable 111 which extends about a sheave 112 or similar member near the base of the platform and passes upwardly to a winch or reel 113 on the platform deck 114.
  • the upper end of the supporting member 11% is connected to a cable 115 by means of which it is held in tension.
  • the supporting member may be of either metallic or dielectric material and is provided with reference cells 116 and 117 and anodes 118 and 119 on its outer surface.
  • the electronic components of the apparatus are housed in capsule 120 at an intermediate point on the supporting member. Power is supplied from the surface through cable 121. Guide members on the platform structure which help stabilize the assembly and prevent lateral movement are not shown in the drawing. This type of installation facilitates adjustment of the vertical position of the anodes and permits rapid withdrawal of the equipment to the surface if necessary.
  • FIG. 8 of the drawing The use of the system of the invention for the cathodic protection of an underwater oil-gas separator or similar totally submerged installation is illustrated in FIG. 8 of the drawing.
  • the installation shown includes a separator vessel 130 which is mounted on supports 131 and 132 and provided with an input line 133 and output lines 134 and 135. Valves, remote control apparatus and other features which will normally be provided but have nothing to do with the cathodic protection system have been omitted in order to simplify the drawing.
  • the protection system employed includes an elongated, generally cylindrical supporting member 138 from which a line or cable 139 extends upwardly to a float or buoy 140 at the waters surface. This buoy serves to-mark the location of the apparatus and facilitate retrieval of the supporting member but is not essential.
  • the upper end of the member may be fitted with a spearhead or other device which can be engaged by a retrieving tool lowered from the surface when retrieval becomes necessary.
  • the supporting member is provided with anodes 141 and 142, reference cell 143, and an underwater power supply and automatic potential controller housed in an enlarged lower section 144. All of these components may be similar to those described earlier in connection with other embodiments of the invention.
  • An upper guide funnel 145 is mounted on the side of separator vessel 130 for guiding the supporting memberinto the desired position adjacent the vessel.
  • the lower end of enlarged section 144 seats in a receptacle located within lower guide member 146 to provide electrical connections between the supporting member and multiconductor electrical cable 147.
  • the connecting device be an inductance type connector containing windings similar to those in a transformer. This premits the transmission of alternating current or pulsed direct current from the cable into the supporting member without direct electrical connections.
  • Such connectors have been described in the literature and will therefore be familiar to those skilled in the art.
  • Cable 147 extends to an offshore platform or shore station equipped with alternators or the like for providing the required electrical energy to the system.
  • the alternating current used to energize the automatic potential controller and underwater power supply in supporting member 138 can be transmitted through the cable over long distances without significant powerlosses.
  • An impressed current cathodic protection system for a marine structure which comprises a supporting member that can be lowered in the water into position adjacent said structure and later retrieved, an underwater power supply on said supporting member for converting an applied alternating current to low voltage direct current, at least one anode on said supporting member, means'for transmitting direct current from said underwater power supply to said anode, and means for transmitting alternating current from a remote source to said underwater power supply.
  • Apparatus as defined by claim 1 incluidng a potential controller for regulating the direct current voltage applied to said anode, at least one reference cell for monitoring the potential difference between said anode and said structure, and means for transmitting a signal from said reference cell to said potential controller.
  • said potential controller comprises a differential amplifier and a silicon controlled rectifier output bridge.
  • said underwater power supply comprises a saturable reactor.
  • said means for transmitting alternating current to said underwater power supply comprises a submerged electrical cable extending to an electrical connector located near the lower end of said supporting member.
  • said means for transmitting alternating current to said underwater power supply comprises an electrical cable which extends downwardly in said supporting member from a power source located on said marine structure above the waters surface.
  • An impressed current cathodic protection system for a marine structure having a platform located above the waters surface and metallic structural members extending downwardly below the surface which comprises an elongated tubular supporting member of sufficient lengthto extend downwardly from said platform to a point adjacent said structural members, an underwater power supply mounted in said supporting member at an intermediate point therein for converting alternating current to low voltage direct current, means for transmitting alternating current from a power source on said platform to said underwater power supply, at least one anode mounted on said supporting member, means in' said supporting member for transmitting direct current from said underwater power supply to said anode, an automatic potential controller for regulating the direct current voltage applied to said anode, a reference cell for monitoring the'potential difference between said anode and said structural members, and means for transmitting a signal from said reference cell to said automatic potential controller.
  • conduit comprises plastic pipe and said anode is mounted on the outer surface of said pipe.
  • conduit comprises a string of metallic pipe and a dielectric shield is positioned between said anode and the surface of said pipe.
  • An impressed current cathodic protection system for an underwater installation which comprises a supporting member provided with means for lowering said member into position adjacent said installation and later retrieving said member, an underwater power supply mounted in said supporting member for converting alternating current to low voltage direct current, at least one anode mounted on said supporting member, means in said supporting member for transmitting direct current from said underwater power supply to said anode, and means for transmitting high voltage alternating current from an underwater cable to said underwater power supply in said supporting member.
  • Apparatus as defined by claim 17 including a potential controller for regulating the direct current voltage applied to said anode, at least one reference cell for monitoring the potential difference between said anode and said underwater installation, and means for transmitting a signal'from said reference cell to said potential controller.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Prevention Of Electric Corrosion (AREA)
US00295403A 1972-10-05 1972-10-05 Impressed current cathodic protection system Expired - Lifetime US3769521A (en)

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US4170532A (en) * 1978-04-11 1979-10-09 C. E. Equipment, Inc. Deep well platinized anode carrier for cathodic protection system
US4211625A (en) * 1978-09-11 1980-07-08 Borg-Warner Corporation Impressed current cathodic protection system for submersible downhole pumping assembly
US4219807A (en) * 1978-04-17 1980-08-26 Cathodic Protection Services, Inc. Sensor system for an impressed cathodic protection circuit
US4280124A (en) * 1978-10-12 1981-07-21 Wuertele James W Corrosion detector
US4322633A (en) * 1979-07-19 1982-03-30 Brunswick Corporation Marine cathodic protection system
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US4484838A (en) * 1982-04-09 1984-11-27 Shell Oil Company Method and apparatus for installing anodes at underwater locations on offshore platforms
US4506485A (en) * 1983-04-12 1985-03-26 State Of California, Department Of Transportation Process for inhibiting corrosion of metal embedded in concrete and a reinforced concrete construction
US4609307A (en) * 1984-11-05 1986-09-02 Exxon Production Research Co. Anode pod system for offshore structures and method of installation
US4690587A (en) * 1985-10-21 1987-09-01 Texaco Inc. Corrosion detection for marine structure
US5814982A (en) * 1997-07-02 1998-09-29 Cc Technologies Systems, Inc. Coupon test station for monitoring the effectiveness of cathodic protection
US6276455B1 (en) * 1997-09-25 2001-08-21 Shell Offshore Inc. Subsea gas separation system and method for offshore drilling
US6837311B1 (en) * 1999-08-24 2005-01-04 Aker Riser Systems As Hybrid riser configuration
US20080105562A1 (en) * 2006-11-07 2008-05-08 Marine Project Management, Inc. Systems and methods for underwater impressed current cathodic protection
GB2474084A (en) * 2009-10-13 2011-04-06 Aish Technologies Ltd Impressed current cathodic protection (ICCP)
US20120152559A1 (en) * 2010-12-21 2012-06-21 Vetco Gray Inc. System and Method for Cathodic Protection of a Subsea Well-Assembly
US20130320664A1 (en) * 2010-10-27 2013-12-05 Roxar Flow Measurement As Connector
US20150002092A1 (en) * 2012-04-11 2015-01-01 Ihi Corporation Underwater power supply system
CN105039999A (zh) * 2015-08-20 2015-11-11 南方电网科学研究院有限责任公司 一种实现对直流输电接地极交替阴极保护的控制方法
US9803887B2 (en) 2013-06-24 2017-10-31 Rheem Manufacturing Company Cathodic corrosion and dry fire protection apparatus and methods for electric water heaters
US10309019B2 (en) * 2017-08-01 2019-06-04 Frank Seth Gaunce Corrosion protection methods for the protection of the national infrastructure of copper/iron, copper, lead/iron potable water distribution systems and the national iron-based infrastructure
CN113814145A (zh) * 2021-09-07 2021-12-21 长江三峡通航管理局 船闸人字门金属结构防腐处理工艺
CN114023500A (zh) * 2021-10-28 2022-02-08 大连理工大学 用于浮式平台的网状辅助阳极以及参比电极复合电缆装置
CN114875413A (zh) * 2022-05-18 2022-08-09 唐彪 可调节保护电位的船体外加电流阴极保护装置及方法
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US4164257A (en) * 1977-12-15 1979-08-14 Atlantic Richfield Company Internal protection of well casing
US4170532A (en) * 1978-04-11 1979-10-09 C. E. Equipment, Inc. Deep well platinized anode carrier for cathodic protection system
US4219807A (en) * 1978-04-17 1980-08-26 Cathodic Protection Services, Inc. Sensor system for an impressed cathodic protection circuit
US4211625A (en) * 1978-09-11 1980-07-08 Borg-Warner Corporation Impressed current cathodic protection system for submersible downhole pumping assembly
US4280124A (en) * 1978-10-12 1981-07-21 Wuertele James W Corrosion detector
US4322633A (en) * 1979-07-19 1982-03-30 Brunswick Corporation Marine cathodic protection system
US4415293A (en) * 1982-04-05 1983-11-15 Shell Oil Company Offshore platform free of marine growth and method of reducing platform loading and overturn
US4484838A (en) * 1982-04-09 1984-11-27 Shell Oil Company Method and apparatus for installing anodes at underwater locations on offshore platforms
US4506485A (en) * 1983-04-12 1985-03-26 State Of California, Department Of Transportation Process for inhibiting corrosion of metal embedded in concrete and a reinforced concrete construction
US4609307A (en) * 1984-11-05 1986-09-02 Exxon Production Research Co. Anode pod system for offshore structures and method of installation
US4690587A (en) * 1985-10-21 1987-09-01 Texaco Inc. Corrosion detection for marine structure
US5814982A (en) * 1997-07-02 1998-09-29 Cc Technologies Systems, Inc. Coupon test station for monitoring the effectiveness of cathodic protection
US6276455B1 (en) * 1997-09-25 2001-08-21 Shell Offshore Inc. Subsea gas separation system and method for offshore drilling
US6837311B1 (en) * 1999-08-24 2005-01-04 Aker Riser Systems As Hybrid riser configuration
US20080105562A1 (en) * 2006-11-07 2008-05-08 Marine Project Management, Inc. Systems and methods for underwater impressed current cathodic protection
GB2474084A (en) * 2009-10-13 2011-04-06 Aish Technologies Ltd Impressed current cathodic protection (ICCP)
US20130320664A1 (en) * 2010-10-27 2013-12-05 Roxar Flow Measurement As Connector
US20120152559A1 (en) * 2010-12-21 2012-06-21 Vetco Gray Inc. System and Method for Cathodic Protection of a Subsea Well-Assembly
US8607878B2 (en) * 2010-12-21 2013-12-17 Vetco Gray Inc. System and method for cathodic protection of a subsea well-assembly
US20150002092A1 (en) * 2012-04-11 2015-01-01 Ihi Corporation Underwater power supply system
US9467005B2 (en) * 2012-04-11 2016-10-11 Ihi Corporation Underwater power supply system
US11698209B2 (en) 2013-06-24 2023-07-11 Rheem Manufacturing Company Cathodic corrosion and dry fire protection apparatus and methods for electric water heaters
US9803887B2 (en) 2013-06-24 2017-10-31 Rheem Manufacturing Company Cathodic corrosion and dry fire protection apparatus and methods for electric water heaters
US10837673B2 (en) 2013-06-24 2020-11-17 Rheem Manufacturing Company Cathodic corrosion and dry fire protection apparatus and methods for electric water heaters
CN105039999A (zh) * 2015-08-20 2015-11-11 南方电网科学研究院有限责任公司 一种实现对直流输电接地极交替阴极保护的控制方法
CN105039999B (zh) * 2015-08-20 2018-03-16 南方电网科学研究院有限责任公司 一种实现对直流输电接地极交替阴极保护的控制方法
US10309019B2 (en) * 2017-08-01 2019-06-04 Frank Seth Gaunce Corrosion protection methods for the protection of the national infrastructure of copper/iron, copper, lead/iron potable water distribution systems and the national iron-based infrastructure
US11634822B2 (en) * 2017-09-15 2023-04-25 Onesubsea Ip Uk Limited Systems and methods for providing monitored and controlled cathodic protection potential
CN113814145A (zh) * 2021-09-07 2021-12-21 长江三峡通航管理局 船闸人字门金属结构防腐处理工艺
CN114023500A (zh) * 2021-10-28 2022-02-08 大连理工大学 用于浮式平台的网状辅助阳极以及参比电极复合电缆装置
CN114023500B (zh) * 2021-10-28 2022-07-26 大连理工大学 用于浮式平台的网状辅助阳极以及参比电极复合电缆装置
CN114875413A (zh) * 2022-05-18 2022-08-09 唐彪 可调节保护电位的船体外加电流阴极保护装置及方法
CN114875413B (zh) * 2022-05-18 2024-01-09 唐彪 可调节保护电位的船体外加电流阴极保护装置及方法

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GB1418557A (en) 1975-12-24
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NO134494C (ru) 1976-10-20
AU5817373A (en) 1975-01-23

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