US2855358A - Galvanic anode - Google Patents

Galvanic anode Download PDF

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US2855358A
US2855358A US485373A US48537355A US2855358A US 2855358 A US2855358 A US 2855358A US 485373 A US485373 A US 485373A US 48537355 A US48537355 A US 48537355A US 2855358 A US2855358 A US 2855358A
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anode
anodes
coating
current
coated
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Douglas Burke
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Dow Chemical Co
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Dow Chemical Co
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Priority to US485373A priority Critical patent/US2855358A/en
Priority to GB1295/56A priority patent/GB803864A/en
Priority to DED22233A priority patent/DE1258704B/de
Priority to FR1146077D priority patent/FR1146077A/fr
Priority to US657446A priority patent/US2882213A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
    • C02F1/481—Treatment of water, waste water, or sewage with magnetic or electric fields using permanent magnets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B59/00—Hull protection specially adapted for vessels; Cleaning devices specially adapted for vessels
    • B63B59/04—Preventing hull fouling
    • 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
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/10—Electrodes characterised by the structure
    • 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
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/18—Means for supporting electrodes
    • 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
    • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
    • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
    • C23F2213/31—Immersed structures, e.g. submarine structures

Definitions

  • This invention relates to the cathodic protection of metals and particularly to improved consumable anodes for use in cathodic protection systems.
  • Cathodic protection systems are Well known in which a metal immersed in an electrolyte is protected from corrosion by means of a sacrificial or consumable anode which is immersed in the electrolyte and is electrically connected to the (cathodic) metal which is to be protected.
  • Sacrificial or consumable anodes comprise a metal which is anodic to the metal urface to be protected and some means, such as a metal core strap, rod or cable to attach the anode to the surface to be protected.
  • some means such as a metal core strap, rod or cable to attach the anode to the surface to be protected.
  • the cathodic protection of pipe lines, ship hulls, metal sea walls, and water tanks are examples of uses made of sacrificial anodes, such as magnesium anodes, for example.
  • sacrificial anodes such as magnesium anodes
  • the expense of replacing anode represents a substantial part of the cost of the protective system.
  • the anodes may be replaced conveniently only at infrequent intervals, such as when the ship is in dry dock.
  • Resistance elements have been used in series with the electrical circuit between the anode and the cathodic surface to limit the current flow therebetween. Resistance elements give only a partial answer to the problem of extending anode life, however. Anodes are consumed as .a result of chemical attack as Well as by current flow, and the resistance element does not affect the rate of chemical attack. -Thus, anode circuits including a resistance element operate at a lower efliciency (measured in ampere hours per'p-ound of anode) than do anodes which are operated in systems not having series resistance elements included therein.
  • Anode eificiency is but one criterion by which an anode is judged.
  • Another indication of the worth of a galvanic anode is its throwing power or, stated differently, the cathodic area in which the anode provides adequate cathodic protection.
  • the throwing power of anodes which are mounted close to the cathodic surface is quite limited since much of the current from the anode is used to protect areas of the cathodic sur- "ice face which are closely adjacent to the anode. Thus, the close-in areas are over-protected (by excessive current) and remote areas are inadequately protected. Resistor anodes, while limiting the total current, do not change the proportional distribution of the available current.
  • anode consumption often follows a pattern such that the magnesium anode body (for example) becomes loosened from its mounting means or core while the body weight is still a significant percentage of the anode Weight when installed.
  • the anodic metal is wasted which remains after the electrical contact between the core or anode mounting means and the anode body is broken or becomes a high resistance contact.
  • the labor cost for mounting anodes often represents a substantial part of the cost of the cathodic protection system, since men having several basic skills, such as welders, boiler makers, and painters may be used in mounting the anodes on a ship hull, for example.
  • An anode which requires workers having only a single skill or trade to mount would therefore result in a saving in the cost of the cathodic protection system.
  • a cathodically protected water heater in which the magnesium anode rod is inserted from either the top or the bottom of the tank is an example of an anode use in which the anode is subject to the above diificulty.
  • a principal object of this invention is to provide an improved galvanic anode which has a longer useful life per unit weight of anode material.
  • Another object of this invention is to provide an improved galvanic anode having improved current distribution to the cathode.
  • a further object of this invention is to provide an improved galvanic anode structure which needs no separate insulating means to separate the anode from the cathodic surface.
  • Another object of this invention is to provide an improved galvanic anode structure having means for selectively controlling the rate of anode consumption in various parts of the anode body.
  • a galvanic anode comprising a consumable body portion and core means by which electrical connection between the anode and a cathode surface may be made, the anode being enclosed in an insulating covering or casing.
  • the casing is provided with a plurality of apertures in at least one surface thereof.
  • Fig. 1 is a planview of a plastic coated anode in accordance with the invention.
  • Fig. 2 is a side elevational view of the anode shown in Fig. 1; i
  • Fig. 3 is a sectional view taken along the lines 33 of Fig. 1; i
  • Fig. 4 is a fragmentary sectional view, on an enlarged scale, showing the plastic coating extending over the mounting strap;
  • Fig. 5 is a sectional view taken along the lines 33 of. Fig. 1 and showing the anode consumption pattern after partial consumption of the anode shown in Fig. 1;
  • Fig. 6 illustrates an anode of the type shown in Fig. l as mounted on the side of a ship hull;
  • Fig. 7 is an elevational view of a plastic coated anode in accordance with the invention which is especially adapted for use with small metal-hulled craft and which requires no underwater connection to the hull of the craft;
  • Fig. 8 illustrates an anode in accordance with this invention which is adapted for use in water heaters or like uses
  • Fig. 9 illustrates a cable-cored coated anode in accordance with the invention.
  • Fig. 10 is a graph showing output current as a function of. exposed anode area
  • Fig. 11 is a graph showing the percent of total anode current at various distances from the anode under initial operating conditions
  • Fig. 12 is a graph showing current density versus distance from anode for three types of anodes under initial operating conditions
  • Fig. 13 is a graph showing the current distribution (under initial conditions) of a perforated anode in accordance with this invention and a bare anode restricted with a resistor when the total current outputs of each anode. are equal, and
  • Fig. 14 is a graph showing current density versus distance from the anode for a bare anode and a coated and perforated anode under conditions of continued operation (i. e., after 24-30 hours of operation).
  • a galvanic anode indicated generally by the numeral 20 and comprising a consumable body 22, made of magnesium, for example, and having a metal core 24 (such as steel) embedded in the magnesium and bonded thereto and extending therefrom as a mounting strap 24a.
  • the anode is encased in a plastic cover 26 which fits closely about the anode body 22 and mounting straps 24a.
  • the top of the plastic cover 26 contains a plurality of apertures 28 which are illustrated as being round although apertures of other configurations may be used. It should be noted that no apertures 28 appear in that part of the plastic coating which lies directly above the cores 24.
  • the plastic cover 26 extends along at least a part of the mounting straps 24a.
  • the mounting straps 24a usually contain a plurality of bores 30 which serve two purposes.
  • the bores 30 in the straps provide a convenient means by which the anode 20 may be bolted to a supporting structure.
  • the plastic cover 26 which extends on each side of the straps 24a flows through atleast one of the bores 30, causing the plastic on opposite sides of the strap to be bonded to itself. Such bonding of the cover 26 lessens the likelihood that the plastic cover 24 will tear off the mounting straps 24a and thence tear off the anode body 22.
  • the plastic cover 26 may entirely cover the mounting straps 24a, but may be cut back to the desired point when the anode 20 is to be mounted.
  • the plastic cover 26 is a dispersion resin coating of dispersion grade polyvinyl chloride resin or, vinyl chloride copolymer resins plus plasticizer and stabilizer. Such anode coatings are electrically insulating and are physically tough. A coating thickness of /8 inch has been found to be sufficient for most applications.
  • a specific coating formulation which may be used comprises:
  • polyvinyl chloride plastisol .4 which is an organo-tin chemical sold by the Metal and Thermit Co. of New York, N. Y.
  • the plasticizer used is one which is relatively ineffective at room temperatures. However, when an anode which is heated to 350 to 400 F., for example, is dipped into the dispersion, the heat increases the activity of the plasticizer and a resinous coating is formed on the hot surface of the anode.
  • a coating may be applied by hot dipping an anode into an ethyl cellulose gel lacquer.
  • the anode may be coated with neoprene which has an advantage in that such a coating would be relatively immune to attack by light hydrocarbons.
  • neoprene coated galvanic anodes are well adapted for use in cathodically protecting gasoline tanks or compartments in tank ships.
  • dip coated anodes in accordance with this invention often contain a groove 31 in their top surface 32 which is disposed about A" from the peripheral edge of the anode body.
  • the groove 31 is about /8" wide and about /s deep.
  • the coating or cover 26 is applied by dipping (or spraying, painting, etc.) the groove 31 becomes filled with a rib 33 of the coating material.
  • the rib 3.3 of coating which extends into the groove 31 lengthens the ion path through the electrolyte to the upper edge of the anode body 22.
  • the peripheral surface portion of the body tends to remain as a shell to keep the plastic cover 26 tightly in place over the anode body 22.
  • the result is a neater anode which has more resistance to tearing of the cover 26 from the anode body 22 than does a partly consumed anode in which the sides of the anode body 22 are consumed and the cover becomes loose.
  • FIG. 5 One of the advantages of anodes made in accordance with this invention is illustrated in Fig. 5.
  • the surface 32 of the anode which lies below the apertures is primarily consumed, leaving relatively untouched the anode surface under that part of the cover 26 where there are no apertures 28. While the entire upper surface of the anode body 22 will eventually be consumed, the surface area under the apertures 28 in the cover 26 will be eaten away the fastest.
  • the result is that the magnesium anode body 22 will remain firmly bonded to the cores 24 even though the distance between the surface 32 and the bottom 34 of the anode on either side of the cores 24 is less than the space between the core 24 and the bottom surface 34 of the anode.
  • anode 20 of the above type almost the entire body weight of the anode gives useful cathodic protection.
  • Fig. 6 illustrates an anode 20 of the type shown in Fig. 1 as attached to a ships hull 36.
  • the anode is attached by welding the ends of the mounting straps as at 38 to the hull. Because anodes made in accordance with this invention require no additional insulation device or electrical control to separate them electrically from the cathodic surface, the cost of the anode installation, particularly the labor cost, is materially reduced as compared with the cost of installing a bare anode.
  • the current output of the anode 20 may be controlled by regulating the number and size of the apertures, thus controlling the flow of current from the surface of the anode 20.
  • the top surface of the anode is conveniently used for this purpose. It is also known that the current output of various parts of the anode surface may be controlled by the size and number of apertures 28 above the various parts of the anode surface.
  • depolarized conditions are those in which the anode and cathode are each at their natural potential while uncoupled in sea water.
  • polarized conditions as the term is used herein, the anode is at its natural potential while the cathode is at a potential which is a function of both the current density and the length of time the current from the anode has been flowing to the cathode.
  • the graph shown in Fig. shows the relationship between the anode current (in milliamperes) and the exposed anode surface area (measured in square inches of opening in the cover 26) for different types of anodes.
  • exposed anode surface area refers to the area of the apertures in the coating. It is realized that in partly consumed anodes, however, the surface .area exposed to electrolyte may be larger than the aperture area. The ion path to the cathode remains the same (i. e., through the apertures).
  • the coated anode data for the graph in Fig. 10 were obtained by varying the number of A2" diameter apertures 28 in the top surface 32 of a coated anode. However, the current line 40 in Fig. 10 is approximately the same when apertures 28 of other diameters (but of the same total area) are used.
  • the aperture diameter is chosen depending upon at least two factors.
  • the strength of the covering 26 of the anode should be maintained at a high value in order to lessen the tendency of the cover 26 to tear away from the anode body '22 when subjected to external forces.
  • the apertures 28 must be large enough to permit the anode corrosion product to be washed out of the casing. The anode material may influence the characteristics of the corrosion product.
  • cover apertures 28 which are in diameter have proven very satisfactory.
  • the thickness of the cover 26 may vary according to the material used and the installation of the anode, that is, whether the anode will be used in quiet or fast moving electrolyte.
  • thickness of .09 proved satisfactory for use in Water moving at a speed of 25 per second.
  • Fig. 11 shows the percent of total current versus distance from the anode under depolarized conditions. It may be seen from this graph that although coating the sides of the. anode results in a considerable saving in current at distances close to the anode, the coated and perforated anode of this invention results in a further and substantial reduction of the current to cathodic surfaces which are close to the anode. Bare anodes are even more wasteful of their current output.
  • the anode test setup used in securing the data for the graphs of Figs. 11-14 comprised a series of concentric annular cathode segments made of steel with the test anode mounted in the center of the annular cathode segments.
  • the cathode segments were insulated from each other and each had a flat top surface approximately 3" wide (as measured radially from the center of the annulus).
  • the test setup included 8 of such cathode segments, mounted concentrically as stated above.
  • a steel cathode was used and all the anodes used in the tests were identical in size and shape.
  • the anodes were cylindrical in shape, having a diameter of 3" and a height of 4", and were made of cell grade magnesium.
  • One anode was bare, one anode had its side coated and top bare, and one anode was entirely coated and contained all the /8 diameter perforations which could conveniently be made in the top surface thereof with spacing between adjacent apertures.
  • the bottom surface of each of the anodes was coated to protect that surface from the cathodic surface to which the anode was mounted.
  • the measurements were made with the anodes immersed in sea water moving at a rate of approximately 6 ft./ minute. In those graphs where current values are given, no attempt should be made to relate the currents to that current which is necessary to protect the cathodic surface.
  • the experimental data shows only current distribution from the anode without regard to the current required to achieve protection. Obviously, if more current is needed, larger anodes may be used.
  • Fig. 12 shows current density versus distance from anodeunder depolarized conditions of operation.
  • the graphs of Figs. 11 and 12 were plotted using the same experimental data. It should be noted in Fig. 12 that the current density close to the anode (3 from the anode) is about 7 times as high for a bare anode as for a perf-orated and coated anode in which the perforations were placed as described above. Also, a perforated and coated anode puts a larger part of its'output current farther away from the anode than does the bare anode. This larger far-out current tends to increase the cathode area protected by a coated anode as compared with bare anodes of similar current capabilities. It should be realized that in the graphs of Figs. 11 and 12 the total output current of each of the anodes is different from the output current of the others.
  • the graph shown in Fig. 13 shows current distribution under depolarized conditions in the case of equal total currents of a bare anode whose current output is restricted by a series resistor and a perforated coated anode.
  • the close-in current of the perforated coated anode that is, the current going to the cathodic surface which is closely adjacent to the anode, is considerably lower than the close in current of the resistor-restricted anode.
  • This graph indicates that the resistor in the resistor-restricted anode apparently restricts only the total current output of the anode and has little effect on the current distribution pattern of the anode.
  • Fig. 13 shows current distribution under depolarized conditions in the case of equal total currents of a bare anode whose current output is restricted by a series resistor and a perforated coated anode.
  • FIG. 14 shows that the closein current of the bare anode at 3" distance from the anode is about 4 times the close-in current of a coated and perforated anode.
  • the bare anode is quite wasteful in the usage of its current output in providing close-in protection to a cathodic surface.
  • the galvanic anode structures thus far described have been of the type which are bolted, welded, or otherwise fixedly attached to a structure which is to be cathodically protected.
  • Anretal mounting strap orcable 44 extends from the anode body and is bonded therein.
  • the plastic coating or covering 46 of the anode is provided with perforations 48 (apertures). in order to regulate the current flow from the anode as previously described in connection with other coated. and perforated anodes.
  • the plastic coating 46 as illustrated, usually extends at least part way along the mounting strap or cable 44.
  • the plastic coating or covering of the anode 42 also provides an anode which is cleaner to handle than is a bare anode. It is anticipated that anodes of the type shown in Fig. 7 will find use as readily demountable anodes for use on small vessels. In this type of application, the anodes would normally be stowed away except when the vessel was anchored or tied up at a dock or pier. The anode strap would then be fastened to a cleat mounted on the metal hull of the vessel, completing the protective electrical circuit. Such an anode arrangement has merit for small craft use, since many pleasure craft are docked or anchored far more hours than they are operated.
  • the demountable anode provides cathodic protection, yet may be removed easily so there is no extra drag in the water.
  • the plastic covered anode is neater and more desirable, from a housekeeping standpoint, than is a bare anode. Further, since galvanic anode surfaces become roughened during their consumption and often have small, sharp edges, the plastic coating over the anode results in an anode assembly which is safer to handle than a bare anode.
  • the anode structure may be included as part of or combined with the fenders of the vessel if desired, thus eliminating a separate object to be stowed while the vessel is in use.
  • the covering 46 of the anode 42 need not be applied by dipping the anode body in liquid plastic, but may comprise a permanent casing in which bare anodes may be disposed.
  • Anodes and casings of this general type are described and claimed in applicants copending application, Serial N 0. 485,438, filed February While the advantages of the coated and perforated anodes of this invention have been described mainly in connection with ship hulls, such anodes have many other applications.
  • coated anodes having no perforations may be stock piled and stored without shelter from the weather for long periods of time without loss of anode weight by corrosion.
  • Such anodes are provided with perforations of the required number and size at the time they are sold (or are to be used) for the particular installation in which they will be utilized.
  • Coated and perforated anodes may be used in many applications where resistor-restricted anodes or bare anodes are now used.
  • Pipe line cathodic protection systems can make use of the anodes of this invention by mounting the anodes closer to the line than heretofore has been practical because of the excessive local current to the nearby pipe.
  • a coated and perforated anode in a water tank is illustrated in Fig. 8.
  • the anode indicated generally by the numeral 50, extends upwardly from the bottom of the tank 52, but could be mounted to extend downward from the top of the tank.
  • excessive current usually flows to the mounting end of the tank because the surface 54 from which the anode 50 is mounted is closer to the mounting end of the anode 50 than are the sides of the tank 52.
  • the lower end of the coating 56 on the anode 50 in the tank has smaller apertures 58 than appear in the coating over the remainder of the anode.
  • the smaller apertures 58 near the bottom end of the anode restrict the current which flows from that part of the anode, thus causing a more uniform expenditure of the anode than would occur if the anode apertures were all uniform in size.
  • Such selective current flow from the anode 50 would not be possible in a resistor-restricted anode.
  • the coating 56 provide physical support for the anode 50.
  • Fig. 9 illustrates a cable-core coated and perforated anode, indicated generally by the numeral 60, made in accordance with this invention.
  • the anode coating 62 extends along the mounting cable 64 for a considerable distance from the anode body 66 to prevent strong local current flow between the anode and the nearby mounting cable 64.
  • Such cable anodes are well adapted to be clamped to a submersible metallic net, for example.
  • any of the anode assemblies described above may be coated with an anti-fouling coating in addition to or as a substitute for the previously described coatings.
  • An antifouling coating which is suitable for use on anodes for use in sea water is a copper salt of polyacrylic acid. Such coatings can be made relatively insoluble by controlling the degree of polymerization of the coating material. The coating is physically tough and has a double antifouling action. The copper is toxic to small marine organisms and since the surface of the coating dissolves at a slow rate, the organisms cannot readily adhere to the coating.
  • Another anti-fouling coating may be provided by dispersing copper particles through the non-soluble coating materials.
  • Another use of slowly soluble coating materials is to provide a delayed action anode for use in installations where mounting the anodes is expensive or can be done only at infrequent intervals.
  • an immediately operative anode and a delayed action anode may be installed together with a coating on the delayed action anode which is calculated to expose the galvanic metal of that anode at approximately the time of the end of the useful life of the immediately operative anode.
  • Suitable coatings which will slowly dissolve are polyacrylic acid (or salts thereof), polyvinyl alcohol, methyl cellulose plus enzyme, or natural gums plus bacteria.
  • Arayakraya is an example of a natural gum which may be used. It is realized that not all the above coating materials are suitable for use in mobile installations such as ships. However, many stationary or seldom moved metals in sea-water or other saline electrolyte may be given long range protection by such delayed action anodes.
  • Delayed action anodes may likewise be used in tanks which are used to store or transport petroleum products '10 or other materials.
  • the anode coating for such delayed action use is chosen from substances which have low solubility rates in the electrolyte to which they will be exposed.
  • the present invention provides improved galvanic anodes Which have longer life, have better current distribution, are easier to store, and are more adaptable to a wide variety of corrosion control situationsthan are conventional bare anodes or resistorrestricted anodes.
  • a rectangular. block-shaped galvanic anode assembly comprising a magnesium anode body, a metal core embedded in said anode body and bonded thereto, said core extending from said anode body, and a closely fitted coating of electrically insulating liquid impervious material surrounding said anode body, said coating containing perforations adjacent to at least one surface of said anode body, said perforations are each equivalent to or exceed in area the area of a circle having a diameter of one-eighth inch.
  • a galvanic anode assembly comprising a block-like anode body of a galvanic metal, a strap-like core embedded in and bonded to said body and extending therefrom as mounting means for said assembly, and a closely fitting coating of electrically insulating liquid impervious material surrounding said anode body and extending onto said mounting means, said coating containing perforations on a part thereof which faces at least one surface of said anode, said perforations are each equivalent to or exceed in area the area of a circle having a diameter of one-eighth inch.
  • a galvanic anode assembly comprising a generally rectangular block-like anode body of galvanic metal, said anode containing a depression adjacent to and extending along the peripheral edges of a major surface thereof, a metal core embedded in and bonded to said body, said core extending from said body as the mounting means for, and a closely fitting insulating coating surrounding said anode body and extending into said depression, and a plurality of apertures in that part of said coating lying above the anode area bordered by said depression.
  • a galvanic anode assembly comprising a generally rectangular block of galvanic metal, at least one metal strap-like member extending through said block and bonded thereto, said member extending from said block on each side thereof, said block being covered by a closely fitting coating of flexible, electrically insulating, liquid 1mpervious material, an array of apertures in that part of the coating which covers at least one surface of said block, the apertures being so disposed that the area of the coating lying above said strap-like member contains no apertures.
  • a galvanic anode assembly comprising a generally rectangular block of galvanic metal, at least one metal strap-like member extending through said block and bonded thereto, said member extending from said block on each side thereof, said block being covered by a closely fitting coating of flexible, electrically insulating, liquid impervious material, the coating extending onto that part of said strap-like member which extends from said block, an array of apertures in that part of the coating which covers at least one surface of said block, the apertures being so disposed that the area of the coating lying above said strap-like member contains no apertures.
  • a galvanic anode assembly comprising a blockbody .of galvanic material, a metal core disposed in and bonded to said galvanic material, a close fitting coating of electrically insulating, liquid impervious material surrounding said anode, said coating containing an array of apertures, said array covering a substantial area of 12 at least one surface of said body, said apertures each being equivalent to or exceeding in area the area of a circle having a diameter of one-eighth inch, and means for mounting said anode, said means being in electrically conductive contact withsaid metal core.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Materials Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Combustion & Propulsion (AREA)
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US485373A 1955-02-01 1955-02-01 Galvanic anode Expired - Lifetime US2855358A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US485373A US2855358A (en) 1955-02-01 1955-02-01 Galvanic anode
GB1295/56A GB803864A (en) 1955-02-01 1956-01-13 Improvements in sacrificial anodes for use in cathode protection systems
DED22233A DE1258704B (de) 1955-02-01 1956-01-31 Galvanische Anode fuer den kathodischen Schutz von Metalloberflaechen
FR1146077D FR1146077A (fr) 1955-02-01 1956-01-31 Anode galvanique perfectionnée
US657446A US2882213A (en) 1955-02-01 1957-05-06 Galvanic anode

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US485373A US2855358A (en) 1955-02-01 1955-02-01 Galvanic anode

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US (1) US2855358A (fr)
DE (1) DE1258704B (fr)
FR (1) FR1146077A (fr)
GB (1) GB803864A (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3012958A (en) * 1958-04-17 1961-12-12 Patrol Valve Co Vitreous lined water tanks with sacrificial anodes
US3022242A (en) * 1959-01-23 1962-02-20 Engelhard Ind Inc Anode for cathodic protection systems
US4171254A (en) * 1976-12-30 1979-10-16 Exxon Research & Engineering Co. Shielded anodes
US4175021A (en) * 1978-03-06 1979-11-20 C. E. Equipment Co., Inc. Apparatus for preventing end effect in anodes
US4401540A (en) * 1980-10-29 1983-08-30 C.E. Equipment Co., Inc. Apparatus for reducing end effect in anodes
US6214203B1 (en) 1999-12-06 2001-04-10 United States Pipe Foundry Anodic encasement corrosion protection system for pipe and appurtenances, and metallic components thereof
US6331242B1 (en) 1999-12-06 2001-12-18 United States Pipe And Foundry Company, Inc. Anodic encasement corrosion protection system for underground storage tanks, and metallic components thereof
WO2012082670A2 (fr) * 2010-12-15 2012-06-21 The Government Of The United States Of America, As Represented By The Secretary Of The Navy Appareil avancé pour la génération d'énergie électrique à partir d'interfaces sédiments aquatiques/eau
US20210230752A1 (en) * 2020-01-24 2021-07-29 Richard L. Klopp Corrosion Inhibitor Apparatus for Land Vehicles

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1223658B (de) * 1962-05-19 1966-08-25 Siemens Ag Stabfoermige, aus Teilstuecken zusammengesetzte Elektrode, insbesondere fuer den kathodischen Schutz
EP0156221B1 (fr) * 1984-03-09 1989-12-13 C + F Czepek und Fentross GmbH Chauffe-eau

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE504585A (fr) * 1950-07-12
US915846A (en) * 1907-03-26 1909-03-23 Ernest Friedheim Electrodeposition of metal on hollow articles.
FR1081845A (fr) * 1953-05-06 1954-12-23 Soc Gen Magnesium Protection cathodique contre la corrosion

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
US2435973A (en) * 1941-08-19 1948-02-17 Rusta Restor Corp Method of and means for providing cathodic protection of metallic structures
US2645612A (en) * 1950-06-15 1953-07-14 American Smelting Refining Sacrificial anode

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US915846A (en) * 1907-03-26 1909-03-23 Ernest Friedheim Electrodeposition of metal on hollow articles.
BE504585A (fr) * 1950-07-12
FR1081845A (fr) * 1953-05-06 1954-12-23 Soc Gen Magnesium Protection cathodique contre la corrosion

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3012958A (en) * 1958-04-17 1961-12-12 Patrol Valve Co Vitreous lined water tanks with sacrificial anodes
US3022242A (en) * 1959-01-23 1962-02-20 Engelhard Ind Inc Anode for cathodic protection systems
US4171254A (en) * 1976-12-30 1979-10-16 Exxon Research & Engineering Co. Shielded anodes
US4175021A (en) * 1978-03-06 1979-11-20 C. E. Equipment Co., Inc. Apparatus for preventing end effect in anodes
US4401540A (en) * 1980-10-29 1983-08-30 C.E. Equipment Co., Inc. Apparatus for reducing end effect in anodes
US6214203B1 (en) 1999-12-06 2001-04-10 United States Pipe Foundry Anodic encasement corrosion protection system for pipe and appurtenances, and metallic components thereof
US6331242B1 (en) 1999-12-06 2001-12-18 United States Pipe And Foundry Company, Inc. Anodic encasement corrosion protection system for underground storage tanks, and metallic components thereof
WO2012082670A2 (fr) * 2010-12-15 2012-06-21 The Government Of The United States Of America, As Represented By The Secretary Of The Navy Appareil avancé pour la génération d'énergie électrique à partir d'interfaces sédiments aquatiques/eau
WO2012082670A3 (fr) * 2010-12-15 2014-10-23 The Government Of The United States Of America, As Represented By The Secretary Of The Navy Appareil avancé pour la génération d'énergie électrique à partir d'interfaces sédiments aquatiques/eau
US20210230752A1 (en) * 2020-01-24 2021-07-29 Richard L. Klopp Corrosion Inhibitor Apparatus for Land Vehicles

Also Published As

Publication number Publication date
FR1146077A (fr) 1957-11-06
GB803864A (en) 1958-11-05
DE1258704B (de) 1968-01-11

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