US2541062A - Utilization of aluminous metal electrodes in cathodic protection installations - Google Patents

Utilization of aluminous metal electrodes in cathodic protection installations Download PDF

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Publication number
US2541062A
US2541062A US718595A US71859546A US2541062A US 2541062 A US2541062 A US 2541062A US 718595 A US718595 A US 718595A US 71859546 A US71859546 A US 71859546A US 2541062 A US2541062 A US 2541062A
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United States
Prior art keywords
aluminous
electrode
cathodic protection
anode
mercury
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Expired - Lifetime
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US718595A
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English (en)
Inventor
Raymond B Hoxeng
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Howmet Aerospace Inc
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Aluminum Company of America
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Priority to FR957880D priority Critical patent/FR957880A/fr
Application filed by Aluminum Company of America filed Critical Aluminum Company of America
Priority to US718595A priority patent/US2541062A/en
Priority to GB34223/47A priority patent/GB641021A/en
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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
    • C23F13/06—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
    • C23F13/12—Electrodes characterised by the material
    • C23F13/14—Material for sacrificial anodes

Definitions

  • This invention relates to installations designed to cathodicall protect underground metallic structures against corrosion.
  • the invention is specifically directed to installations of this type which utilize, as the anodic metal, aluminum or aluminum alloy having the electrical characteristics of that metal, such alloys usually being those containing upwards of 50 percent by weight of aluminum.
  • Aluminum and such alloys are generally termed aluminous metal andsuch term is used herein and in the appended claims.
  • Metallic underground structures which may require cathodic protection are of various types, including earth buried linear structures, such as pipe lines for the transport of fluids or gases, and earth buried unit. structures, such as structural tower footings, tanks, oil well casings and the like. In systems designed to cathodically protect such structures against corrosion the metal of the structure is electrically connected, usually by wire or bus, to a separately buried metal piece, called an electrode, which, is
  • buried electrode with a mixture sometimes called a backfill, which. contains, chemicals which are intended to promote the action of the ,celL-increase its efliciency or otherwise benfifi l the. in-
  • Aluminous metal has properties recommending it for use as electrode in such a cathodic protection system.
  • aluminous metal electrodes have rarely been used in such systems despite the fact that theoretical considerations indicate that aluminous metal, electrodes should deliver more ampere hours per pound thanmost metals available for such use.
  • cathodic protection cell utilizing aluminum electrodes and operating at percent efficiency is superior, on the basis of ampere hours per pound of metal, to cells utilizing electrodes made of other commercially available metals if such cells could be operated at 100 percent efficiency, This; is evident upon comparison of the electrochemical equivalents of zinc, magnesium and aluminum as shown in the table on page 486 of the Transactionsof the-Electra chemical Society, vol. (19 16), in an article by H. A. Robinson on Magnesium as a Galvanic Anode. Most buried metallic structures are constructed of metal, such as iron or steel, which is cathodic to aluminous metal, yet aluminous ages of corrosion.-
  • the occurrence of which inactive toward the aluminous anode i. e. it may contain as the other components earth, sand, ash, oellulosic material or other substance relatively inert to the electrode.
  • the other components earth, sand, ash, oellulosic material or other substance relatively inert to the electrode.
  • mercury compound may be added to backfill mixtures including other chemicals added to promote or improve the action of the cell of which the aluminous metal electrode is a part.
  • good results areobtained when the mercury compound is added, in accordance with the principles of this invention, to an alkaline mixture containing inorganic halide such as that described by R. H. Brown in his copending application, Serial No. 693,593, filed August 28, 1946.
  • alkalinity is not necessary to efiicient results, and excellent cell operation has been achieved using a backfill mixture containing 1 to 30 percent by weight of inorganic halide and an amount of mercury salt, the balance being a carrier such as earth or other inactive material of the type above indicated.
  • the effectiveness of the mercury compounds, or their utility is improved by applying the compounds directly to the surface of the aluminous metal anode using the compound in mixture with some substance which will promote adherence of the mercury compound to the anode surface.
  • the coating thus formed which may if desired include-other substances, inert or usefully active to promote cathodic protection should contain at least 0.901 percent by coating weight of the mercury compound. The use of such coatings on the anode surface does not preclude the use of mercury compound in the backfill or other mass with which the anode is eventually 'sur- 45 rounded.
  • Fig. 3 is a cross sectional View of the anode on 60 line 33 of Fig. 2. 7
  • a hole 2 is provided in soil l to receive the aluminous anode 4 and the surrounding backfill 3 containing a mercury-containing compound capable of yielding mercury in 65 contact with the buried anode.
  • the backfill 3 may also contain other chemicals such as alkaline materials and an inorganic halide to promote or which contains the mercury compound and the backfill 1 which does not contain such a compound.
  • the mercur compound may be included, in the baokfill as in the installation shown in Fig. 1.
  • the shape of the anode 4 and the surrounding coating 8 are more clearly seen in the cross'sectional view of Fig. 3.
  • mercurous chloride Of themercury compounds I prefer mercurous chloride, the preference being based on practical considerations, such as availability, cost and relative insolubility under the conditions usually obtaining in cathodic protection installations.
  • minum alloys give better results as aluminous metal anodes than do others but the advantages of my invention in increasing efiiciency and insuring steady cell operation will be secured, regardless of the aluminous metal anodes used, although a cell using such an anode of one specific composition will, as is known, have better overall characteristics than a cell using an aluminous metal anode of other composition. Likewise the advantages and benefits of this invention will be secured when the mixture and the aluminous metal anode are preformed, into a unitar package and installed as such. An example of such a package is'described in the copending application of R. B. Mears, Serial No. 705,508 filed October 25, 1946.
  • an aluminous metal anode may be coated with a mixture containing a mercury compound prior to installation, whether the electrode is used separately or as a part of a unitary package.
  • improved aluminous metal anode operation is obtained by coating the anode with a mixturecontaining mercurous chloride and a protein base or a water paint or a resin emulsion paint, examples of which are known and described in standard works such'as, for instance, Protective and Decorative Coatings, volume III, published by John Wiley 8; Sons, Inc., New York, 1943, pages 470 and 484, prepared under the editorship of Joseph J. Mattiello.
  • the invention is not, therefore, limited in usefulness to a specific aluminous metal electrode or'to a particular form'of cathodic protection system or mixture or backfill, except as indicated in the appended claims.
  • the cathodic protection system illustrated in Fig. 2 is similar to that in Fig. 1 in every respect 1.
  • a cathodic protection installation designed and operative to protect a metallic underground structure against corrosion, and comprising an underground aluminous metal electrode except for the adherent coating 8 on anode 4 separate from said structure, electrically connected to said structure and anodic thereto, the improvement consisting in a backfill in contact with said electrode, said backfill containing at least 0001 percent by weight of a mercury compound capable of yielding metallic mercury when in contact with said underground aluminous electrode.
  • a separately buried aluminous metal electrode anodic to the metal of said structure and electrically connected thereto and a backfill containing at least 0.001 percent of mercury compound in contact with said electrode, said compound being capable of yielding metallic mercury when in contact with said buried aluminous electrode.
  • An anode for use in a cathodic protection installation said anode being formed of a body of aluminous metal the surface of which bears a dry coating containing mercury compound capable of yielding metallic mercury when in contact with said aluminous body in a cathodic protection installation.
  • a cathodic protection installation designed and operative to protect a metallic underground structure against corrosion and including an underground aluminous metal electrode separate from said structure, electrically connected to said structure and anodic thereto, the improvement consisting in an alkaline backfill in contact with said electrode, said backfill containing at least 0.001 percent by weight of mercury compound capable of yielding metallic mercury when in contact with said underground aluminous electrode.
  • a unitary package for use in cathodic protection of underground metallic structures comprising an aluminous metal electrode in contact with a dry mixture containing at least 0.001 percent by weight of mercury compound capable of yielding metallic mercury when in contact with said aluminous electrode in a cathodic protection installation.
  • a cathodic protection installation designed and operative to protect a metallic underground structure against corrosion and comprising an underground aluminous metal electrode separate from said structure, electrically connected to said structure and anodic thereto, the improvement consisting in the fact that the surface of said electrode is covered, at least in part, with a mercury compound capable of yielding metallic mercury when in contact with said underground aluminous electrode.
  • a separately buried aluminous metal electrode anodic to the metal of said structure and bearing on its surface a mercury compound capable of yielding metallic mercury when in contact with said buried aluminous electrode.
  • a separately buried aluminous metal electrode anodic to the said structure and electrically connected thereto and a backfill containing at least 0.001 per cent of mercury compound in contact with said electrode, said compound being capable of yielding metallic mercury when in contact with said buried aluminous electrode, and the ampere output per hour of said electrode being greater than the ampere output per hour of the same electrode in the described combination with said structure but not in contact with a backfill containing said mercury compound.

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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)
US718595A 1946-12-26 1946-12-26 Utilization of aluminous metal electrodes in cathodic protection installations Expired - Lifetime US2541062A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FR957880D FR957880A (fr) 1946-12-26
US718595A US2541062A (en) 1946-12-26 1946-12-26 Utilization of aluminous metal electrodes in cathodic protection installations
GB34223/47A GB641021A (en) 1946-12-26 1947-12-24 Improvements in or relating to installations for cathodically protecting undergroundmetallic structures

Applications Claiming Priority (1)

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US718595A US2541062A (en) 1946-12-26 1946-12-26 Utilization of aluminous metal electrodes in cathodic protection installations

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FR (1) FR957880A (fr)
GB (1) GB641021A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721172A (en) * 1950-07-12 1955-10-18 F A A Hughes & Co Ltd Consumable metal anodes
US2758082A (en) * 1952-08-13 1956-08-07 Frederick A Rohrman Cathodic protection
DE1090049B (de) * 1956-07-02 1960-09-29 Reynolds Metals Co Kathodischer Korrosionsschutz
US4784823A (en) * 1981-02-03 1988-11-15 Nukem Gmbh Corrosion protection
US4890755A (en) * 1987-08-25 1990-01-02 St Onge Hank Internal corrosion protection of metal tanks
US5040599A (en) * 1989-12-04 1991-08-20 Phillips Petroleum Company Cathodic protection

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB437536A (en) * 1934-06-05 1935-10-31 Austin Gordon Lovell Pennock A new or improved galvanic battery

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB437536A (en) * 1934-06-05 1935-10-31 Austin Gordon Lovell Pennock A new or improved galvanic battery

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721172A (en) * 1950-07-12 1955-10-18 F A A Hughes & Co Ltd Consumable metal anodes
US2758082A (en) * 1952-08-13 1956-08-07 Frederick A Rohrman Cathodic protection
DE1090049B (de) * 1956-07-02 1960-09-29 Reynolds Metals Co Kathodischer Korrosionsschutz
US4784823A (en) * 1981-02-03 1988-11-15 Nukem Gmbh Corrosion protection
US4890755A (en) * 1987-08-25 1990-01-02 St Onge Hank Internal corrosion protection of metal tanks
US5040599A (en) * 1989-12-04 1991-08-20 Phillips Petroleum Company Cathodic protection

Also Published As

Publication number Publication date
FR957880A (fr) 1950-02-28
GB641021A (en) 1950-08-02

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