Autonomous impressed current cathodic protection device on metal surfaces with a spiral magnesium anode

Abstract

An autonomous impressed current cathodic protection device utilizes a spiral layout of materials, with a magnesium sheet placed in parallel with a copper sheet, and a foamed material in between as insulation, all placed in a plastic container and solidified after inert fluid material is poured in. At a center of the spiral layout, a magnesium anode core is connected through a wire to the surrounding spiral layout. The device can generate electrical voltage of up to −1.7 volt with increased amperage of up to 500 mA. The presented layout of the materials and components allows for increased flexibility concerning the manufacturing of devices based on the requirements of industrial applications, construction sites, and various needs and demands in marine applications for ships, regardless of size.

Claims

1. An autonomous impressed cathodic protection device, comprising a central magnesium anode core 4; a spiral structure comprising a magnesium anode sheet 8, a copper sheet 6, and a foamed material 7 all formed in a spiral pattern with the foamed material positioned between the magnesium anode sheet and the copper sheet to maintain a constant distance between the magnesium anode sheet and the copper sheet along the spiral structure, the foamed material acting as an electrical insulator and a waste absorber; a plastic container 2; a connection wire 1 secured to both the central magnesium anode core and the magnesium anode sheet, the connection wire extending from the plastic container and attachable to a protected surface; and a terminal 5 secured to the copper sheet, the terminal attachable to a grounding apparatus, wherein the central magnesium anode core and the spiral structure are positioned inside the plastic container, the spiral structure extending around the central magnesium anode core without directly contacting the central magnesium anode core, and an inert material fills a remaining hollow space within the plastic container and between the central magnesium anode core and the spiral structure.

2. The autonomous impressed cathodic protection device of claim 1, wherein the magnesium anode sheet and the copper sheet have identical dimensions, and the magnesium anode sheet forms an innermost layer of the spiral structure and the copper sheet forms an outermost layer of the spiral structure, and the spiral structure forms more than three coils around the central magnesium anode core.

3. The autonomous impressed cathodic protection device of claim 1, wherein a grounding wire is connected to the terminal and to a metallic grounding electrode, the metallic grounding electrode insertable into a ground.

4. The autonomous impressed cathodic protection device of claim 1, wherein a grounding electrode is secured to the terminal, the grounding electrode pierced by a metal rod, externally insulated, and water tight, the grounding electrode insertable in a water pipe network which supplies water to a ship engine or other cooling installation at a point allowing water to constantly and uninterruptedly run over the grounding electrode.

5. The autonomous impressed cathodic protection device of claim 1, wherein the device is configured to impose up to −1.6 volts (V) to a metal surface.

6. The autonomous impressed cathodic protection device of claim 1, wherein the device is configured to provide cathodic protection for up to five years of continual use.

7. A method of manufacturing an autonomous impressed cathodic protection device, comprising: placing a soft, spongy, foamed material over a copper sheet; placing a magnesium anode sheet over the foamed material; coiling the magnesium anode sheet, the copper sheet, and the foamed material in a spiral pattern; inserting the coiled magnesium anode sheet, copper sheet, and foamed material in a plastic container along with a central magnesium anode core; and filling a hollow space within the plastic container with an inert material, wherein the spiral pattern of the coiled magnesium anode sheet, copper sheet, and foamed material extends around the central magnesium anode core more than three complete revolutions.

8. The method of claim 7, further comprising attaching a connection wire to both the central magnesium anode core and the magnesium anode sheet, the connection wire extending from the plastic container and attachable to a protected surface.

9. The method of claim 7, further comprising securing a terminal to the copper sheet, the terminal attachable to a grounding apparatus.

10. The method of 7, wherein the autonomous impressed cathodic protection device comprises: the central magnesium anode core; a spiral structure comprising the magnesium anode sheet, the copper sheet, and the foamed material formed in the spiral pattern with the foamed material positioned between the magnesium anode sheet and the copper sheet to maintain a constant distance between the magnesium anode sheet and the copper sheet all along the spiral pattern, the foamed material acting as an electrical insulator and waste absorber; the plastic container; a connection wire secured to both the central magnesium anode core and the magnesium anode sheet, the connection cable extending from the plastic container and attachable to a protected surface; and a terminal secured to the copper sheet, the terminal attachable to a grounding apparatus.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention will be better understood in with reference to the following:

(2) FIG. 1 is a top view of a device according to an embodiment of the present invention;

(3) FIG. 2 is a side view of an embodiment of the device for marine applications; and

(4) FIG. 3 is an illustration of an embodiment of the device attached to a pipeline.

DETAILED DESCRIPTION OF THE INVENTION

(5) Figure (1) shows the top view of the device inside a plastic container (2). The device consists of:

(6) A central magnesium anode core (4) placed in the center whose upper side is attached to a connection point (1) of the device to the installations. This connection point is led to a local loop connection through a bridge wire (3) which connects the core (4) with the magnesium sheet (8) placed around the perimeter in a spiral manner.

(7) In parallel with the magnesium sheet (8), there is a copper sheet (6) of identical dimensions also placed in a spiral manner. This layout creates the second electrolytic pole in order to produce the difference in potential within the device itself.

(8) Between the two metals, a soft porous material (foam rubber) (7) of identical dimensions is placed. This allows for insulation between the two metals, s constant short distance between them, permeability of ions between the metals and preservation of the necessary level of humidity for the transfer of ions. Furthermore, the foam (7) absorbs the effects of contraction and dilation of the materials due to variations in temperature. Finally, over the life span of the device, the magnesium are is expanded as a result of the process through which the original metal form is gradually turned into magnesium′ oxide and salt, whose combined volume is approximately three times the volume of its original metal form. These waste by-products are absorbed by the foam (7).

(9) The aforementioned material/component layout is placed within a plastic container (2) and then the inert material (11) (plaster etc.) is poured in fluid form so as to fill all the remaining gaps inside the device.

(10) Onto the side part of the container, there is a metal screw type terminal (5) which is attached to the copper sheet (6) inside the container.

(11) This side terminal is connected to a grounding electrode (10) through a wire (9) and it is planted into the ground where the device will be utilized. To achieve the corresponding result in marine applications, the grounding electrode must be installed in a ship sector which is always into contact with sea water. (As described in FIG. 2). The intervention point is a pipe which is run by sea water.

(12) Technical Specifications

(13) A device producing low voltage DC current derived from the difference in potential between metals. This current is impressed on metal surfaces and installations and prevents the emergence of the electrolysis phenomenon.

(14) The produced current can reach up to 1.6 V DC and it is imposed with a negative prefix (−).

(15) The amperage ranges from 50 mA up to 500 mA.

(16) The service life of the device is approximately 5 years after installation.

(17) The device is disposable, it cannot be repaired, and it is replaced by a new one when it reaches the end of its service life.

(18) Materials Required for the Product Manufacture

(19) Exit cable (1) (FIG. 1) for connection to the protected surface. This wire is unipolar, multi strand, flexible and its diameter depends on the size of the device ranging from 6 up to 25 square millimeters (mm.sup.2).

(20) Bridge cable (3) of central magnesium anode core and spiral magnesium sheet. From the anodes up to the loop connection with the exit cable of the device, this wire is unipolar, multi strand, flexible and its diameter depends on the size of the anodes ranging from 2.5 up to 10 (mm.sup.2).

(21) Central magnesium anode core (4) (first anode pole) from magnesium metal of purity 99.9 percent (%) up to 99.95% and fluctuating dimensions according to the desirable size of the device from 25*25*80 millimeters (mm) up to 50*80*250 mm. This is also the mass of the magnesium of the central core which is determined by calculating the desired service life of the device and the desired density of the impressed current.

(22) Magnesium sheet (8) (second anode pole) of thickness ranging from 2 up to 5 mm, length ranging from 800 up to 1500 mm and width ranging from 80 up to 250 mm, depending on the size of the device. This is also the mass of the magnesium which is determined by calculating the desired service life of the device and the desired density of the impressed current as in paragraph 3.

(23) Inert material (11) based on plaster 90% with the addition of bentonite and sodium bicarbonate up to 10% in order to preserve moisture, to solidify the components and materials inside the device as well as to facilitate the flow of ions from the magnesium anodes to the cathodes (circular copper sheets). This mixture is poured into the container in a fluid form in a way that allows it to penetrate into all the points and materials of the device in a uniform manner, covering the entire height of the materials but without engulfing them entirely.

(24) Foamed, soft, spongy material (foam rubber) (7) with fluctuating dimensions depending on the size of the device and of thickness ranging from 10 up to 30 mm and length as well as width equal to the magnesium sheet (1) so that it stands between the magnesium and copper (6) acting as insulation. The presence of this material acts as a water and moisture reserve, both of which are necessary so that ions can flow normally from the anodes towards the cathode. Furthermore, it stabilizes the components and materials of the device and absorbs the dilations of the inert material as it expands due to the deterioration of the anodes over time, which also creates magnesium oxides and salt.

(25) Copper sheet (6) (second cathodic pole) from copper metal of 99.9% purity, of width ranging from 0.10 up to 0.25 mm, as well as length and width same as the magnesium sheet (1) and the foamed material (7).

(26) All the components are placed within a plastic container (2) of corresponding size.

(27) The grounding electrode (10) to be buried into the ground is metallic, made from cast iron, copper or titanium with dimensions of 8 mm up to 20 mm diameter and length ranging from 120 mm up to 250 mm depending on the device.

(28) The grounding electrode to be used in marine applications consists of a screw plug (13) (in FIG. 2) whose diameter ranges from ½ of an inch up to 4 inches. The screw plug has a mounting hole on the top side whose size depends on the diameter of the titanium rod (16) ranging from 4 mm up to 8 mm and length from 50 mm up to 130 mm. This rod is also insulated (14 & 15) so that it does not come into direct contact with the plug which is screwed with a thread in order to be water tight. The upper part of the electrode titanium rod protruding from the plug has a screwed thread with bolts (12) to connect the cable coming from the side of the device (9) (FIG. 1). The bottom part of the electrode titanium rod is rotated spirally and helically from the center towards the outer rim to the point allowed by the size of the plug's internal perimeter.

(29) Manufacturing Process

(30) We assemble a set consisting of successive layers of sheets as follows:

(31) We lay down a copper sheet which has been precut in the following dimensions (100 mm width/9100 mm length). The thickness is 0.12 mm.

(32) On this particular sheet we place a sheet of foamed material (thickness 10 mm) of the same dimensions.

(33) The next step is laying down a magnesium sheet (thickness 20 mm) of the same dimensions.

(34) Finally we place a sheet of foamed material as described above.

(35) All these materials are then rotated, creating a single roll with at least three coils.

(36) This resulting roll is placed within a plastic container. The external view of the roll is the copper sheet which comes into contact with the plastic container. Midway through the height of the plastic container and near the edge of the copper sheet we securely attach a grounding terminal.

(37) From the upper part of the container and in the center of the roll we plant a magnesium rod (core) and fix it into position without coming into contact with any other metal component.

(38) A short wire coming from the central magnesium core is then bridged and connected to the magnesium sheet roll. Midway through the length of this bridging wire we place a loop, to which we attach another wire meant to be connected to the installations themselves.

(39) After all the components and materials have been placed within the container, a mixture of inert material in fluid form is poured into the container so that it can permeate all over the components. Shortly afterwards, this inert material is solidified and stabilizes all the materials. Furthermore, when the mixture is fully solidified, we supplement as much water as the foamed material can absorb.

(40) From this moment onwards, the device is fully functional.

(41) Example of Device Application

(42) An example of the application of this device is a water supply pipeline. We calculate the manufacture of the anodes based on the diameter of the pipe, its length as well as the desirable protection timeframe.

(43) We know that the performance of the magnesium metal according to international standards is 1200 ampere hours per kilogram (AH/kg) mass and metal purity 99.9%.

(44) We also know the total length is 500 meters (m) of steel pipeline (FIG. 3) and its diameter is 500 mm. This data equals a metal surface of 785 square meters.

(45) We also choose the necessity for current density to be impressed to be 3 mA/m.sup.2.

(46) We also take into account a protection time frame of 3 years.

(47) We then calculate 365 days*3=1095 days*24 hours=26280 hours*3 mA=78840 mA/H/1000=78,840 A/H*785 m=61889 AH/1292=47.9 kg of magnesium metal is the amount required for this particular installation.

(48) If we utilized anodes based on the specifications of the U.S. Pat. No. 1,007,131, we would have to manufacture a total of about 26 devices which would have to be distributed along the pipeline length.

(49) Utilizing the presented alternative specification would result in the need for 7 devices to be spread out. The reason is the output of increased current density which means fewer devices for the same installation requirements. Additional benefits include economizing on both the initial outlay and the maintenance inspection expenses involved.