Classifications

• • 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
  • C23F13/22—Monitoring arrangements therefor
• • 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
  • 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 sacrificial anode, for example for use to protect metallic structures from corrosion.
• Cathodic protection is commonly used to protect metallic structures from corrosion, often by means of a sacrificial anode. Such anodes will corrode over time in place of the metallic structure to be protected, and thus at some point lose its protective properties when it is dissolved in the galvanic solution.
• the present invention has the objective to provide improved technology and methods relating to sacrificial anodes.
• a sacrificial anode comprising an anode body having at least one cavity within the anode body and a sensor arranged in the cavity.
• Figures 1 a and 1 b are principle drawings of a sacrificial anode according to an embodiment, as seen from different angles, Figure 1 c is a cross-sectional view of the sacrificial anode along line A-A in Figure 1 b,
• Figure 2 is a block diagram of components of a sacrificial anode according to an embodiment
• Figures 3a and 3b are principle drawings of a sacrificial anode provided with wireless communication means, and
• Figures 4a and 4b are principle drawings of a worn sacrificial anode according to an embodiment.
• An embodiment according to the present invention relates to a sacrificial anode arranged for condition monitoring and lifetime prediction by means of continuity measurements inside one or more cavities in the anode body.
• the sacrificial anode may, for example, comprise an anode body provided with several cavities distributed in the anode body for arrangement of sensors.
• the cavities may be shaped with different heights in the anode body.
• Sensors such as sea water sensors, may be arranged in the respective cavities.
• the sensor is formed by one electrode or by two electrodes spaced apart, e.g. a pair of electrodes or several pairs of electrodes.
• the sensor or sensors can, however, be any sensor capable of indicating an ingress of water into the cavity or the opening of a previously closed cavity.
• the sensor may be a pressure sensor which registers a pressure change when the cavity opens to the outside of the anode.
• an indication of the level of wear of the anode can be obtained, and/or information relating to its remaining service life.
• the sensor and the cavity can be designed such that the sensor signal is triggered when the anode has consumed e.g. approx. 75% of its service life.
• the cavities are filled with a gas or a non-conducting material soluble in sea water or permeable, which gas or non-conducting material initially electrically insulating the electrode or electrodes of the sensor.
• the sacrificial anode comprises a microcontroller.
• the sensor may be operatively connected to the microcontroller.
• the electrodes of a respective sensor in a respective cavity can be connected to the microcontroller, such that a voltage potential is established between the electrodes of the sensor.
• the microcontroller may be positioned within the anode body, for example in one of the sensor cavities or in a dedicated cavity for the microcontroller.
• the microcontroller may be fixed on the outside of the anode, e.g. on the anode or near the anode.
• the sacrificial anode is provided with a communication device.
• the communication device is a wireless communication device integrated in the sacrificial anode for direct wireless transmission.
• the communications device may be arranged in one of the sensor cavities, or in a dedicated cavity for the communications device.
• the communication device is a wireless communication device arranged externally of the sacrificial anode and connected to the sensor and/or microcontroller in the sacrificial anode via a wire.
• the communication device is connected to a wire which at its other end is connected to a receiver, for example a receiver located subsea or topside.
• the communication device may, for example, be powered by a galvanic or voltaic cell, such as a battery, or by external power.
• the communication device is powered by a battery located within the anode body.
• the battery may, in a further embodiment, be provided with an isolator, such as a non-conductive material which is soluble in water or which may be washed away by water, and which prevents the communications device from operating until the isolator is removed.
• an isolator such as a non-conductive material which is soluble in water or which may be washed away by water, and which prevents the communications device from operating until the isolator is removed.
• the isolator may, for example, be a non-conductive material electrically separating an electrical conductor between the battery and the communication device, or e.g. a water-soluble material holding a pre-tensioned switch in the "open" position until the material has been dissolved away.
• the non-conductive material may be one permeable by sea water.
• a support member or structure for the anode body is provided. The support member may, for example, extend out of the anode, and may be longer in the longitudinal direction than the body.
• the support member may be an internal support member in the anode body, for example if space requirements require connection bolts to extend through the anode body.
• the anode body may be casted at least partially around the support member or structure, and/or the support member may be casted partially inside the anode body and extending out of it for fixing the anode to a subsea structure for use.
• the support member or structure may be of a different material than the anode body.
• the height of the respective cavities in the anode body is designed to represent general state of the anode body with respect to mass and structural integrity.
• the cavities having different heights in the anode body, as the anode body corrodes, surrounding galvanic solution will penetrate the otherwise closed cavities, triggering sensors in the individual cavities through increased electrical conductivity, at different levels of wear. Accordingly, the sealing of the individual cavities will fail depending on the amount of wear of the anode body and their height in the anode body, providing a predictable pattern and automatic detection of the level of wear of the anode body.
• the height of the individual cavities according to an expected wear pattern of the anode body, the wear of the sacrificial anode can be more accurately detected and monitored. For example, one may arrange the cavities such that a first sensor signal indicates a wear equivalent to approx. 25% of the anode's service life, a second sensor signal at approx. 50%, and a third at approx. 75%.
• a sacrificial anode enabling condition monitoring and lifetime prediction by means of continuity measurements made by sensors arranged in the individual cavity in the anode body.
• Figures 1a and 1 b showing principle drawings of a first embodiment of a sacrificial anode 10 according to an embodiment
• Figure 1c which is a cross-sectional view of the sacrificial anode 10 along line A-A in Figure 1 b.
• the sacrificial anode 10 comprises an anode body 11 , e.g. formed by zinc, but can also be formed by aluminium, magnesium, iron or other suitable metal alloys, casted around a support member or structure 20, extending longer in longitudinal direction than the anode body 1 1 providing fixation points 21a-b at ends thereof outside the anode body 1 1 , via which fixation points the sacrificial anode 10 can be arranged to a structure to be monitored by suitable fastening means, such as welding, screws, bolts or similar.
• suitable fastening means such as welding, screws, bolts or similar.
• the sacrificial anode 10 can also of course be fixed to the structure by other appropriate fastening means well known for a skilled person.
• the anode body 11 is provided with a number of cavities 12 of known geometry, distributed in the anode body 1 1 , in this embodiment distributed in the longitudinal direction.
• the sacrificial anode 10 further comprises sensors 30 arranged in the respective cavities 12, the sensors 30 consisting of two electrodes 31a-b, spaced apart, preferably a pair of electrodes 31a-b or several pairs of electrodes 31a-b.
• the second electric lead being provided by the anode body.
• the sensors 30 are fixed to the support member or structure 20 and have an extension in longitudinal direction of the respective cavities 12.
• the electrodes 31 a-b are fixed to the support member or structure 20 via nonconducting means such that there is no electrical connection between the support member or structure 20 and the electrodes 31a-b.
• the cavities 12 can, for example, be filled with gas (such as air), a non-conducting material soluble in sea water (such as grease), or a material permeable to sea water (such as a perforated or porous, non-conducting material).
• gas such as air
• a non-conducting material soluble in sea water such as grease
• a material permeable to sea water such as a perforated or porous, non-conducting material.
• Suitable materials for this purpose may, for example, be a refractory fiber material or a porous ceramic material. These materials can assist in defining the cavity 12 and keeping molten material out of the cavity when manufacturing the anode, while allowing water to enter the cavity when the anode has corroded sufficiently or is otherwise damaged.
• the cavities 12 are thus enclosed and sealed from the seawater surrounding the sacrificial anode 10, but as the anode body 1 1 of the sacrificial anode 10 corrodes, the seals of the cavities 12 are compromised, allowing the galvanic solution (sea water) to flow into the cavities 12.
• the sensors 30 comprise two electrodes arranged in each cavity 12, and further initially electrically insulated from each other by the mentioned gas, or a non-conducting material inside.
• other sensor types may be equally suitable for use in the cavities, such as a pressure sensor configured to detect a pressure change when the structure around the cavity is compromised and sea water enters.
• FIG. 2 is a block diagram of components of the sacrificial anode 10 showing power and data flows in the sacrificial anode 10.
• the sensors 30 with the at least two electrodes 31a-b in the individual cavities 12 are connected to a microcontroller 40 such that a voltage potential is established between the two electrodes 31 a-b of the sensor 30, and the microcontroller 40 is further arranged to measure continuity between the electrodes 31a-b of the sensors 30, i.e. electrical conductivity.
• the microcontroller 40 will measure no continuity across the at least two electrodes 31a-b (electrode pairs) as long the cavity 12 seal is intact, but as soon as the seal is broken, the galvanic solution, now enclosing the electrodes 31 a-b, will exhibit measurable conductivity, and a current will flow across the electrodes 31 a-b of the sensors 30, which can be registered by the
• microcontroller 40 controls the microcontroller 40.
• a different type of sensor 30 may be used, such as one where a water- soluble isolator mechanically holds a pre-tensioned conductor pin in the "open” state until it is dissolved in the water. Any other type of sensor which is triggered by water ingress into the cavity can also be used.
• the sacrificial anode 10 is further provided with a communication device 50.
• Figure 3a shows an embodiment where the communication device 50 is a wireless communication device integrated/arranged in the sacrificial anode 10 for direct wireless transmission. The communication device may be arranged in one of the sensor cavities, or in a separate cavity for this purpose.
• Figure 3b shows an embodiment where the communication device 50 is a wireless communication device and arranged externally of the sacrificial anode 10 and connected to the microcontroller 40 in the sacrificial anode 10 via a wire 51.
• the wire 51 can extend to a receiver located subsea or topside.
• the wire may extend to a junction box in a subsea installation, whereby the sensor signals may be forwarded to a topside location via an existing
• the cable 51 may itself be a dedicated communications line to topside, or part of an umbilical for this purpose, and lead to a receiver located topside or onshore.
• the microcontroller 40 is integrated with the external wireless communication device 50, and the sensors 30 are connected to the microcontroller 40 via a wire 51.
• the signal medium is water and wireless transmission can, for example, be achieved by means of acoustic transfer, i.e. by means of an underwater acoustic communication (UAC), where an acoustic signal is sent directly from the sacrificial anode 10 or via the external wireless communication device, and received by a receiving unit outside the anode, e.g. at the water surface.
• UAC underwater acoustic communication
• UAC underwater acoustic communication
• UAC underwater acoustic communication
• other wireless communication standards can be used for this purpose.
• Figures 1 a and 1 b show a further embodiment where the communication device 50 is arranged in a wire 51 for wire transmission to a receiver above the water surface.
• Readings or measurements made by the sensors 30 and provided to the microcontroller 40 can be transmitted wirelessly or by wire 51 to a receiver outside the anode, e.g. on the water surface, in turn alerting an operator of the corrosion progression and condition of the sacrificial anode 10.
• the cavities 12 of the sacrificial anode 10 are shaped with different heights in the anode body 11.
• the time needed for the corrosion process to breach the seals to the individual cavities 12 are different between cavities.
• the individual cavities 12 can be designed such that the seals will fail one after the other in a predictable pattern, depending on the wear of the anode body 11. Thereby, the general state of the anode body 1 1 with respect to mass and structural integrity may be inferred from the information about broken and remaining intact cavities 12.
• the wear i.e. status of the sacrificial anode 10 can be monitored, where the condition status of the sacrificial anode 10 is either sent wireless directly to a receiving unit or the condition status is sent via a wire 51 to the water surface, where the signal can be easily accessed by an operator or forwarded to an operator.
• the invention is not limited by the embodiments described above; reference should be had to the appended claims.

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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)

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Citations (8)

• 2018
  • 2018-01-12 WO PCT/NO2018/050009 patent/WO2018132017A1/en active Search and Examination
  • 2018-01-12 PT PT187036488T patent/PT3568506T/pt unknown
  • 2018-01-12 EP EP18703648.8A patent/EP3568506B1/en active Active
  • 2018-01-12 ES ES18703648T patent/ES2860531T3/es active Active
  • 2018-01-12 PL PL18703648T patent/PL3568506T3/pl unknown
  • 2018-01-12 DK DK18703648.8T patent/DK3568506T3/da active
  • 2018-01-12 US US16/477,473 patent/US20190360108A1/en not_active Abandoned

Patent Citations (8)

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