EP0615002A1 - Anode sacrificielle améliorée pour la protection contre la corrosion des structures en mer et procédé pour sa préparation - Google Patents

Anode sacrificielle améliorée pour la protection contre la corrosion des structures en mer et procédé pour sa préparation Download PDF

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Publication number
EP0615002A1
EP0615002A1 EP94200566A EP94200566A EP0615002A1 EP 0615002 A1 EP0615002 A1 EP 0615002A1 EP 94200566 A EP94200566 A EP 94200566A EP 94200566 A EP94200566 A EP 94200566A EP 0615002 A1 EP0615002 A1 EP 0615002A1
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EP
European Patent Office
Prior art keywords
anode
anodic material
spendable
anodic
offshore structure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94200566A
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German (de)
English (en)
Inventor
Mario Draghetti
Gianluigi Valla
Pierluigi Bonora
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agip SpA
Original Assignee
Agip SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agip SpA filed Critical Agip SpA
Publication of EP0615002A1 publication Critical patent/EP0615002A1/fr
Withdrawn legal-status Critical Current

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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
    • C23F13/10—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
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B17/0017—Means for protecting offshore constructions
    • E02B17/0026—Means for protecting offshore constructions against corrosion
    • 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

  • the present invention relates to a novel spendable anode for the anticorrosion protection of offshore structures, which anode, thanks to its particular composite-structure configuration, besides making it possible the necessary amount of anodic material to be decreased with self-explanatory economic advantages, also improves the protection state of the surfaces of the offshore structure, with protective compact deposits being formed in a larger amount.
  • the present invention also relates to the process for accomplishing such a spendable anode.
  • the anticorrosion protection of offshore structures by means of spendable anodes represents today one of the most used techniques in this field, and its developments made it possible optimal anodic material from the viewpoints of efficiency and weight and cost savings to be found out, such as aluminum, zinc and magnesium alloys.
  • the spendable anode made of an anodic material having a more negative electrochemical potential than of the material which constitutes the offshore structure to be protected, generates a bias which in its turn causes a protection current to be established, which causes protective calcareous deposits to be formed on the same strucuture.
  • the above said necessary protection current for the adequate protection of the offshore structure depends, besides such marine conditions as temperature, salinity, oxygen content, and so forth, also, and above all, on the surface conditions of the offshore structure to be protected, i.e., whether calcareous deposits are present or less. From the above it results hence that during the early steps of the life time of the offshore structure to be protected, during which the protective calcareous deposits have not been adequately formed yet, the need exists for having the maximal protection current, which may then decrease during the subsequent life steps of the structure, as a function of the quality of the calcareous deposit formed during said initial step.
  • an essential element in the design of any spendable anode is the ability of the latter to supply the high demand of starting protection current during the initial step of the life of the offshore structure, besides being capable of preserving the protection state of said structure throughout the subsequent steps of the useful operating life of the latter.
  • the starting current which a spendable anode is capable of supplying depends, besides the marine conditions and its electrochemical potential, also on its surface and, consequently, its geometry, the above said condition practically results in that the geometric dimensions and the weight of the spendable anode have to be determined as a function of the starting current required by the offshore structure to be protected, and, respectively, of the protection current which must be generated during the subsequent operating steps of the same structure, after the formation of the protective calcareous deposit.
  • the spendable anode made of magnesium alloy is the optimal solution for the anticorrosion protection of offshore structures because it, by generating a high bias and, consequently, a high initial anodic current, is capable of supplying a very effective protection of the above said structure, by causing compact calcareous deposits to be formed, which reduce the magnitude of the required protection current during the subsequent steps of the useful operating life of said structure.
  • an anode of magnesium alloy by displaying a low anodic efficiency, is not capable of covering the whole useful operating life of the offshore structure to be protected, unless it is used in such large amounts as to render it economically unecceptable, owing to its large weight and high cost.
  • the presently most largely used spendable anodes for the protection of offshore structures are aluminum or zinc alloys which secure, even when small weight amounts thereof are used, the full protection of the structure to be protected throughout the whole life span thereof, with the demand for a high initial current being satisfied by suitably increasing the geometric size of said anodes.
  • the purpose of the present invention precisely is of obviating the above said drawbacks and hence supplying a spendable anode for the anticorrosion protection of offshore structures which is capable of supplying the high starting current which is initially demanded in order to create an effective protective layer of calcareous deposit on the offshore structure to be protected, although its geometrical dimensions are kept small, as well as of securing the anticorrosion protection throughout the operating life span of the structure, with its weight being anyway kept small.
  • the above purpose is substantially achieved by using a composite-structure spendable anode in which the anodic material, generally consisting of zinc or aluminum alloys, which constitutes an external coating applied onto the carrier which supports the same anode, is externally coated, in its turn, by a second anodic material, generally magnesium alloys, having an electrochemical potential still more negative than of the above said zinc or aluminum alloyed-based anodic material.
  • the anodic material generally consisting of zinc or aluminum alloys, which constitutes an external coating applied onto the carrier which supports the same anode, is externally coated, in its turn, by a second anodic material, generally magnesium alloys, having an electrochemical potential still more negative than of the above said zinc or aluminum alloyed-based anodic material.
  • the magnesium alloy which constitutes the outermost coating will operate during the first step of the useful operating life of the offshore structure to be protected, and hence makes it possible the geometric dimension of the same anode to be reduced, whilst the internal anodic material, constituted by aluminum or zinc alloys, which starts acting only after that all of said outermost magnesium coating has been consumed, will operate on surfaces which are already biased and coated by compact calcareous deposits, which hence require low protection current values, with the weight amount of said internal anodic material, necessary in order to protect the structure during the residual portion of the useful operating life of the latter, being consequently decreased.
  • the spendable anode for the anticorrosion protection of an offshore structure comprising a carrier means provided with an external coating made of an anodic material having a more negative electrochemical potential than of the material which constitutes said offshore structure to be protected, is characterized, according to the present invention, in that said anodic material is provided, in its turn, with an external coating of a second anodic material with a still more negative electrochemical potential than of the above said anodic material.
  • the process for manufacturing such a spendable anode, suitable for the anti-corrosion protection of offshore structures comprises the steps of casting said anodic material which constitutes the external coating of the carrier means which supports the same anode into a suitable ingot mould or chill or mould and then casting, into another suitable ingot mould or chill or mould, said second anodic material around the anode formed during the preceding step.
  • the composite-structure anode can also be manufactured by spraying said second anodic material onto said support already coated with the above said anodic material with lower negative electrochemical potential, or coating the latter with said second anodic material by means of a plating process.
  • the carrier means is indicated of the anode to be manufactured, which carrier means, charged to a suitable ingot mould or chill or mould, not shown in Figure, is provided with an external coating by casting an anodic material 2 with a more negative electrochemical potential than of the material which constitutes the structure to be protected.
  • Said coated carrier means is then charged to another suitable ingot mould or chill or mould, also not displayed in Figure, and, in its turn, is provided with an external coating by casting an anodic material 3 with a more negative electrochemical potential than of the anodic material 2.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Prevention Of Electric Corrosion (AREA)
EP94200566A 1993-03-10 1994-03-05 Anode sacrificielle améliorée pour la protection contre la corrosion des structures en mer et procédé pour sa préparation Withdrawn EP0615002A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI930457A IT1272001B (it) 1993-03-10 1993-03-10 Anodo sacrifiziale perfezionato per la protezione anticorrosiva di strutture offshore e procedimento per la sua realizzazione.
ITMI930457 1993-03-10

Publications (1)

Publication Number Publication Date
EP0615002A1 true EP0615002A1 (fr) 1994-09-14

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94200566A Withdrawn EP0615002A1 (fr) 1993-03-10 1994-03-05 Anode sacrificielle améliorée pour la protection contre la corrosion des structures en mer et procédé pour sa préparation

Country Status (7)

Country Link
EP (1) EP0615002A1 (fr)
JP (1) JPH06340986A (fr)
CN (1) CN1107534A (fr)
BR (1) BR9400848A (fr)
CA (1) CA2118658A1 (fr)
IT (1) IT1272001B (fr)
NO (1) NO940787L (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150167178A1 (en) * 2012-07-30 2015-06-18 Construction Research & Technology, Gmbh Galvanic anode and method of corrosion protection
US20150284860A1 (en) * 2012-10-18 2015-10-08 Gareth Glass Protection of steel reinforced concrete elements

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6461082B1 (en) * 2000-08-22 2002-10-08 Exxonmobil Upstream Research Company Anode system and method for offshore cathodic protection
JP5167863B2 (ja) * 2008-02-28 2013-03-21 株式会社Ｉｈｉ 鋼構造物防食電着被膜形成用陽極
CN102328063A (zh) * 2011-03-11 2012-01-25 中国海洋石油总公司 一种镁铝复合牺牲阳极及其制备方法
CN102328064A (zh) * 2011-03-11 2012-01-25 中国海洋石油总公司 镁铝复合牺牲阳极及其制备方法
CN113122852A (zh) * 2021-04-25 2021-07-16 浙江钰烯腐蚀控制股份有限公司 一种镁铝复合阳极的制备方法以及镁铝复合阳极

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1803523B1 (de) * 1968-10-17 1970-03-05 Stein Dr Ing Heinrich Verfahren zur Herstellung von Opferanoden fuer den kathodischen Korrosionsschutz
DE2217716A1 (de) * 1971-04-27 1972-11-09 Schweizerische Aluminium Ag, Chippis (Schweiz) Opferanode
DE2741015A1 (de) * 1976-09-13 1978-03-16 Elf Aquitaine Kathodenschutzvorrichtung fuer eine im meer installierte konstruktion mittels selbstverbrauchender anoden
US4409081A (en) * 1982-02-05 1983-10-11 Terrase Leon J Sacrificial anode
WO1990008204A1 (fr) * 1989-01-11 1990-07-26 Joergen Leon Hoegberg Dispositif de support pour anodes marines

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1803523B1 (de) * 1968-10-17 1970-03-05 Stein Dr Ing Heinrich Verfahren zur Herstellung von Opferanoden fuer den kathodischen Korrosionsschutz
DE2217716A1 (de) * 1971-04-27 1972-11-09 Schweizerische Aluminium Ag, Chippis (Schweiz) Opferanode
DE2741015A1 (de) * 1976-09-13 1978-03-16 Elf Aquitaine Kathodenschutzvorrichtung fuer eine im meer installierte konstruktion mittels selbstverbrauchender anoden
US4409081A (en) * 1982-02-05 1983-10-11 Terrase Leon J Sacrificial anode
WO1990008204A1 (fr) * 1989-01-11 1990-07-26 Joergen Leon Hoegberg Dispositif de support pour anodes marines

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150167178A1 (en) * 2012-07-30 2015-06-18 Construction Research & Technology, Gmbh Galvanic anode and method of corrosion protection
AU2013298781B2 (en) * 2012-07-30 2018-03-01 Sika Technology Ag Galvanic anode and method of corrosion protection
US10227698B2 (en) * 2012-07-30 2019-03-12 Construction Research & Technology Gmbh Galvanic anode and method of corrosion protection
EP2880200B1 (fr) * 2012-07-30 2019-07-03 Construction Research & Technology GmbH Anode galvanique et procédé de protection contre la corrosion
US11519077B2 (en) 2012-07-30 2022-12-06 Construction Research & Technology Gmbh Galvanic anode and method of corrosion protection
US20150284860A1 (en) * 2012-10-18 2015-10-08 Gareth Glass Protection of steel reinforced concrete elements

Also Published As

Publication number Publication date
ITMI930457A1 (it) 1994-09-10
IT1272001B (it) 1997-06-10
NO940787L (no) 1994-09-12
BR9400848A (pt) 1994-11-08
JPH06340986A (ja) 1994-12-13
CN1107534A (zh) 1995-08-30
CA2118658A1 (fr) 1994-09-11
NO940787D0 (no) 1994-03-07
ITMI930457A0 (it) 1993-03-10

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