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Patent 2808397 Summary

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(12) Patent: (11) CA 2808397
(54) English Title: ANODE FOR CATHODIC PROTECTION AND METHOD FOR MANUFACTURING THE SAME
(54) French Title: ANODE DE PROTECTION CATHODIQUE ET SON PROCEDE DE FABRICATION
Status: Granted and Issued
Bibliographic Data
(51) International Patent Classification (IPC):
  • C23F 13/10 (2006.01)
  • B21D 31/04 (2006.01)
(72) Inventors :
  • MOJANA, CORRADO (Italy)
  • TREMOLADA, SIMONE (Italy)
(73) Owners :
  • INDUSTRIE DE NORA S.P.A.
(71) Applicants :
  • INDUSTRIE DE NORA S.P.A. (Italy)
(74) Agent: MACRAE & CO.
(74) Associate agent:
(45) Issued: 2019-12-03
(86) PCT Filing Date: 2011-09-15
(87) Open to Public Inspection: 2012-03-22
Examination requested: 2016-09-01
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/EP2011/066021
(87) International Publication Number: EP2011066021
(85) National Entry: 2013-02-14

(30) Application Priority Data:
Application No. Country/Territory Date
MI 2010 A 001689 (Italy) 2010-09-17

Abstracts

English Abstract

It is described a metal anode for cathodic protection in form of mesh ribbon having meshes whose holes are of rhomboidal shape, characterised by having such holes of rhomboidal shape arranged with the major diagonal oriented along the direction of the ribbon length and by the fact that the side edges along the ribbon length are free from cutting protrusions. It is also described a method for obtaining such anode.


French Abstract

L'invention concerne une anode métallique de protection cathodique se présentant comme un ruban à mailles ayant des mailles dont les trous sont de forme rhomboïde, lesdits trous de forme rhomboïde étant disposés avec la diagonale principale orientée dans la direction de la longueur du ruban, et les bords latéraux dans la longueur du ruban étant exempts de protubérances de coupe. L'invention concerne également un procédé d'obtention d'une telle anode.
Claims

Note: Claims are shown in the official language in which they were submitted.


7
CLAIMS
1. An anode for cathodic protection in form of expanded metal ribbon with
rhomboidal
meshes free of longitudinally-extending solid, non-foraminous sections,
characterised in that
said rhomboidal meshes are geometrically arranged with the major diagonal
parallel
to the direction of the ribbon length, said rhomboidal meshes being obtained
by running
of the metal ribbon through an expanding device equipped with at least one row
of
knives having blades of a first predetermined length arranged parallel to the
direction
of the ribbon displacement and expansion of the metal ribbon by means of
pressing
and punching action of said at least one row of knives,
and in that the lateral edge profiles along the length of said ribbon are free
of
discontinuities, said lateral edge profiles being obtained by formation of
lateral edge
profiles of the expanded metal ribbon by means of pressing and punching action
of a
last row of knives having blades of a second predetermined length higher than
said
first length.
2. The anode according to claim 1, wherein said metal is titanium.
3. The anode according to any one of claims 1 or 2, wherein said metal is
coated with a
catalytic layer.
4. The anode according to claim 3, wherein said catalytic layer comprises
noble metals
or oxides thereof.
5. A method of manufacturing an anode for cathodic protection in form of an
expanded
metal ribbon with rhomboidal meshes free of longitudinally-extending solid,
non-foraminous
sections, comprising the following steps:
- running of a metal ribbon through an expanding device equipped with at
least one
row of knives having blades of a first predetermined length arranged parallel
to the
direction of the ribbon displacement,
- expansion of the metal ribbon by means of pressing and punching action of
said at
least one row of knives, such that the rhomboidal meshes are geometrically
arranged with the major diagonal parallel to the direction of the metal ribbon
length,
- formation of lateral edge profiles of the expanded metal ribbon by means of
pressing
and punching action of a last row of knives having blades of a second
predetermined
length higher than said first length, such that the rhomboidal meshes are
geometrically arranged with the major diagonal parallel to the direction of
the metal
ribbon length, and such that the lateral edge profiles along the length of the
expanded metal ribbon are free of discontinuities.

8
6. A cathodic protection system comprising at least one anode according to
any one of
claims 1 to 4 embedded in a cementitious structure equipped with metal
reinforcement bars.
7. A method for cathodic protection of a reinforced concrete structure
consisting of
applying an anodic potential to said anodes of said cathodic protection system
of claim 6.

Description

Note: Descriptions are shown in the official language in which they were submitted.

1 ANODE FOR CATHODIC PROTECTION AND METHOD FOR MANUFACTURING THE SAME FIELD OF THE INVENTION The invention relates to the field of cathodic protection of reinforced concrete structures, and in particular to a design of anode particularly efficient in terms of electrical resistance per unit length and of flexibility, and particularly safe to install and handle. The invention also relates to the method of production of such anode. BACKGROUND OF THE INVENTION Corrosion phenomena affecting reinforced concrete structures are well known in the art. The steel reinforcement inserted in the cenrientitious structures to improve the mechanical properties thereof normally works in a passivation regime induced by the alkaline concrete environment; however, after some time, the ion migration across the porous surface of the concrete causes a localised attack to the protective passivation film. Particularly worrying is the attack by chlorides, which are virtually present in all kinds of environments where the reinforced concrete structures are employed, and to an even higher extent where an exposure to brackish water (bridges, pillars, buildings located in marine zones), antifreeze salts (bridges and road structures in cold climate zones) or even seawater, such as for instance in the case of piers and docks, takes place. The critical value of chloride exposure has been esteemed around 0.6 kg per cubic metre of concrete, beyond which the passivation state of the reinforcing steel is not guaranteed. Another form of concrete decay is represented by the carbonatation phenomenon, that is the formation of calcium carbonate by reaction of the lime of the cementitious mixture with atmospheric carbon dioxide. Calcium carbonate lowers the concrete alkali content (from pH 13.5 to pH 9) bringing iron in an unprotected state. The presence of chlorides and the simultaneous carbonatation represents the worst of conditions for the preservation of the reinforcing bar of the structures. The corrosion products of steel are more voluminous than steel itself, and the mechanical stress resulting from their formation may lead to concrete delamination and fracturing phenomena, which translate into huge damages from the point of view of economics besides the one of safety. For this reason, it is known in the art that the most effective method for indefinitely prolonging the lifetime of reinforced concrete structures exposed to the atmospheric agents, even in the case of relevant salt concentrations, consists of cathodically polarising the steel reinforcement. In this way, the latter becomes the site of an oxygen cathodic reduction, suppressing the anodic corrosion and dissolution reactions. Such system, known as cathodic protection of reinforced concrete, is practised by coupling anodic structures of various kinds to the concrete, respect to which the reinforcement to be protected CA 2808397 2018-04-06 CA 02808397 2013-02-14 WO 2012/035107 PCT/EP2011/066021 2 acts as a cathodic counterelectrode; the electrical currents involved supported by an external rectifier transit across the electrolyte consisting of the porous concrete partially soaked with a salty solution. The anodes commonly used for the cathodic protection of reinforced concrete consist of a titanium substrate coated with transition metal oxides or other types of catalysts for anodic oxygen evolution. As the substrate it is possible to make use of other valve metals, either pure or alloyed; pure titanium is however the largely preferred choice for the sake of cost. European Patent EP458951 discloses a grid-type electrodic structure for cathodic protection consisting of a plurality of metal ribbons having an electrocatalytic coating, said metal ribbons having voids of different geometries. This type of ribbons can be manufactured by punching of solid metal ribbons or more commonly by the traditional methods of metal expansion wherein a metal sheet is expanded by pressuring and punching through a series of knives arranged orthogonal to the advancement direction of the ribbon itself. This first step allows obtaining an expanded metal sheet. Such sheet is then subjected to a second step of cutting suitable for obtaining ribbons of the required dimensions. Said expanded metal ribbons present meshes having voids of rhomboidal shape with the major diagonal oriented orthogonal to the ribbon length. This method of manufacturing has the inconvenience of producing metal ribbons with meshes having cutting side protrusions automatically formed during the operation of cutting, making these anodes difficult to handle and the installation phase accordingly dangerous. Metal ribbons with smooth lateral edges are disclosed in Canadian Patent Application CA 2078616 Al; by the method described this document, the ribbons obtained present a continuous longitudinally-extending solid section of a certain width, which is invariably formed in the manufacturing process and which can only be used for spot-welding. In present-day cathodic protection systems, however, it is preferred not to weld ribbon anodes at all, but rather to overlay them directly to the reinforcement with plastic spacers arranged in- between. In such case, the longitudinally-extending solid section is just a loss of material, especially because this solid section invariably gets coated with precious metals during the application of the catalytic layer. Such catalytic layer however cannot work properly on a non-foraminous structure and affects the calculation of the actual current density impressed to the anodic structure, thereby complicating the design of the overall cathodic protection system. 3 SUMMARY OF THE INVENTION In accordance with one aspect of the present invention, there is provided a method of manufacturing an anode comprising the following steps: running of a metal ribbon through an .. expanding device equipped with at least one row of knifes of a first predetermined length arranged parallel to the direction of the ribbon displacement, expansion of the metal ribbon by means of pressing and punching action of said at least one row of knives, formation of lateral edge profiles of the expanded metal ribbon by means of pressing and punching action of a last row of knives having blades of a second predetermined length higher than said first length. Under one aspect, the invention relates to an anode in form of mesh ribbon for systems of cathodic protection, for instance of cathodic protection of reinforced concrete structures, overcoming the inconveniences of the prior art, whose edges are substantially free of discontinuities in form of cutting protrusions and have a sinusoidal shape. In the context of the present description reference is made, for the sake of simplicity, to cathodic protection of reinforced concrete structures; it is understood that the invention may be practised in the field of cathodic protection in general, for instance comprising the cathodic protection of metal tank bottoms. Under another aspect, the invention relates to a method for manufacturing said anode. Under a further aspect, the invention relates to a cathodic protection system comprising at least one anode in form of mesh ribbon whose edges are substantially free of cutting protrusions. Some of the most significant results obtained by the inventors are presented in the following description, which is merely provided by way of example without wishing to limit the invention. .. The anode according to the invention consists of a ribbon of expanded metal characterised by meshes with rhomboidal shaped voids with the major diagonal oriented along the direction of the ribbon length. In one embodiment, the lateral edges of the ribbon have a sinusoidal profile and are free of cutting protrusions. The inventors have surprisingly noticed that an anode for cathodic protection as hereinbefore described displays a remarkably reduced ohmic resistance per unit length, for instance up to 4-fold reduced, with respect to the anodes of the prior art. CA 2808397 2018-04-06 3a The lower electrical resistance makes possible to reduce the number of electrical connections, for instance in a grid system, with sensible savings of material and installation time. In one embodiment, the metal mesh ribbon is made of titanium. CA 2808397 2018-04-06 CA 02808397 2013-02-14 WO 2012/035107 PCT/EP2011/066021 4 In another embodiment, the metal mesh ribbon is coated with a catalytic coating containing noble metals or oxides thereof. In one embodiment, the dimensions of the ribbon can have a width ranging from 3 mm to 100 mm with a thickness of 0.25 mm to 2.5 mm and a length of 1 m to 150 m. BRIEF DESCRIPTION OF THE DRAWINGS For the sake of a better understanding of the invention, reference will be made to the following drawings, having the purpose of depicting some preferred embodiments thereof without limiting its extent. - Fig. 1A shows a top-view of a traditional expanded metal anode. - Fig. 1B shows a top-view of an expanded metal anode according to the invention. DETAILED DESCRIPTION OF THE DRAWINGS In detail, Fig. 1A shows a top view of the traditional anode in which are distinguishable cutting protrusions 1 due to the manufacturing method including a cutting step, the rhomboidal geometry with major diagonal 3 of rhomboidal voids arranged in the direction of the ribbon width .. and the minor diagonal 4 of the same arranged in the direction of the ribbon length. Fig. 1B shows a top-view of the anode according to the invention in which are distinguishable non-cutting blunt lateral edges 2, the rhomboidal geometry with major diagonal 3 of rhomboidal voids arranged in the direction of the ribbon length and the minor diagonal 4 of the same arranged in the direction of the ribbon width. EXAMPLE Some of the most significant results obtained by the inventors are reported in Table 1, wherein .. ohmic resistance data of representative anodes of the invention are compared to traditional anodes. Anodes labelled A and B are anodes of rhomboidal geometry with the major diagonal of rhomboids oriented orthogonal to the ribbon length likewise depicted in Fig. 1A, traditionally obtained by longitudinal expansion with respect to the displacement direction of a solid metal ribbon. Anodes labelled C and D are anodes of rhomboidal geometry according to one embodiment of the invention, likewise depicted in Fig. 1B. CA 02808397 2013-02-14 WO 2012/035107 PCT/EP2011/066021 Anodes C and D were prepared by orthogonal expansion with respect to the displacement direction of a solid metal ribbon allowed to run in an apparatus along a parallel row of knives which expand the solid ribbon in an orthogonal direction by pressuring and punching. The ribbon manufacturing is completed by means of a last series of knives, having blades of 5 predefined length higher than the blades of previous knives, which upon applying a pressure are suitable for modelling the lateral edge of the ribbon as depicted in Fig. 1B. Besides the advantages already explained in terms of conductivity due to the anode geometry, this method has the advantage of providing an expanded metal ribbon free of longitudinally- extending solid sections which, being not subsequently cut, does not present any cutting edge and is therefore much safer and easy to handle during the installation. This method moreover allows to advantageously obtain a metal ribbon of the desired length directly upon completion of the expansion. Such method of production furthermore allows obtaining ribbons of higher length than the traditional method thereby facilitating big size installation which would require connections of multiple ribbons, with a lower solidity of the overall anodic system. From the data reported in the table it can be noticed that for a given width, the anodes of the invention display an ohmic resistance about 60% lower. Table 1 Anodes in accordance with Fig. 1A R- Ohmic Resistance A - 20mm wide 0.22 Ohm/m B - 10mm wide 0.43 Ohm/m Anodes in accordance with Fig. 1B R- Ohmic Resistance C - 20mm wide 0.088 Ohm/m D - lOmm wide 0.177 Ohm/m The previous description is not intended to limit the invention, which may be used according to different embodiments without departing from the scopes thereof, and whose extent is univocally defined by the appended claims. Throughout the description and claims of the present application, the term "comprise" and variations thereof such as "comprising" and "comprises" are not intended to exclude the presence of other elements or additives. CA 02808397 2013-02-14 WO 2012/035107 PCT/EP2011/066021 6 The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention before the priority date of each claim of this application.
Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Event History

Description Date
Maintenance Request Received 2024-09-12
Maintenance Fee Payment Determined Compliant 2024-09-12
Common Representative Appointed 2020-11-07
Grant by Issuance 2019-12-03
Inactive: Cover page published 2019-12-02
Common Representative Appointed 2019-10-30
Common Representative Appointed 2019-10-30
Pre-grant 2019-10-10
Inactive: Final fee received 2019-10-10
Letter Sent 2019-04-17
Notice of Allowance is Issued 2019-04-17
Notice of Allowance is Issued 2019-04-17
Inactive: Q2 passed 2019-04-08
Inactive: Approved for allowance (AFA) 2019-04-08
Amendment Received - Voluntary Amendment 2019-01-16
Inactive: S.30(2) Rules - Examiner requisition 2018-07-17
Inactive: Report - QC passed 2018-07-16
Amendment Received - Voluntary Amendment 2018-04-06
Inactive: S.30(2) Rules - Examiner requisition 2017-10-10
Inactive: Report - No QC 2017-10-04
Letter Sent 2016-09-13
Request for Examination Received 2016-09-01
Request for Examination Requirements Determined Compliant 2016-09-01
All Requirements for Examination Determined Compliant 2016-09-01
Inactive: Cover page published 2013-04-22
Inactive: Notice - National entry - No RFE 2013-03-20
Inactive: First IPC assigned 2013-03-19
Inactive: IPC assigned 2013-03-19
Application Received - PCT 2013-03-19
Inactive: IPC assigned 2013-03-19
Inactive: IPRP received 2013-02-15
National Entry Requirements Determined Compliant 2013-02-14
Application Published (Open to Public Inspection) 2012-03-22

Abandonment History

There is no abandonment history.

Maintenance Fee

The last payment was received on 2019-08-16

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Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
INDUSTRIE DE NORA S.P.A.
Past Owners on Record
CORRADO MOJANA
SIMONE TREMOLADA
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Drawings 2013-02-13 1 124
Claims 2013-02-13 1 36
Description 2013-02-13 6 259
Abstract 2013-02-13 2 106
Representative drawing 2013-02-13 1 61
Description 2018-04-05 7 286
Claims 2018-04-05 1 14
Claims 2019-01-15 2 64
Representative drawing 2019-11-11 1 47
Confirmation of electronic submission 2024-09-11 3 74
Notice of National Entry 2013-03-19 1 194
Reminder of maintenance fee due 2013-05-15 1 114
Reminder - Request for Examination 2016-05-16 1 117
Acknowledgement of Request for Examination 2016-09-12 1 177
Commissioner's Notice - Application Found Allowable 2019-04-16 1 163
PCT 2013-02-13 3 81
Request for examination 2016-08-31 1 28
International preliminary examination report 2013-02-14 4 174
Examiner Requisition 2017-10-09 3 220
Amendment / response to report 2018-04-05 8 256
Examiner Requisition 2018-07-16 3 179
Amendment / response to report 2019-01-15 4 110
Final fee 2019-10-09 1 29