Deep well anode earthing

 

The invention relates to cathodic protection of underground structures from corrosion and solves the problem of increasing the service life by providing a smoother flowing electric current from the electrodes earthing switch in the ground. We offer earthing contains the current lead, located in isolation coaxially inside his shell and separated therefrom by a dielectric, the electrodes are welded to the shell on the outside and among themselves in the amount of 6 pieces and forming a protective cover and additional cover made of electroconductive material, located in the upper part of the earthing switch, protruding above the soil surface and provided with a perforated lid. The membrane and the electrodes are made of steel pipes of the same diameter, and the electrodes along the length exceeds the length of the shell at least three pipe diameter. Earthing fitted with a steel plate with a minimum thickness of the pipe wall thickness, length equal to the length of the electrode, and a width not less than half the diameter of pipe installed between the two electrodes and welded to the shell and to the electrodes, the Electrode weld seams and the seams between the plate and the electrodes are covered outside electroconductive corrosion-protective mastic. Using robust longer ek is the structures, in particular downhole equipment from corrosion. 4 Il.

The invention relates to cathodic protection of underground structures from corrosion.

Known for deep anode ground (SU/s 852969; C 23 F 13/00) that contains two concentrically arranged tubes, the space between which is filled with coke fines, and to the inner tube along the entire length of its working parts are outside of the fixed steel wheels, covering the pipe.

The disadvantage of earthing is its low reliability, due to the feature of the Assembly of earthing for the installation location in the borehole, a large amount of welding and Assembly works. The disks attached to the inner tube are barriers to full without cavities under disk monolithic filling the annulus coke fines in the case of manufacturing of earthing of the prefabricated Assembly sections with already attached disks. For implementation of the stated characteristics of earthing is necessary to coke breeze closely without cavities under the disks from all sides covered inner tube and the disks, so in the description of the method of Assembly: disks welded to the inner pipe and backfilling coke fines proizvoditel backfill detail on high, equal to the distance between the disks, and then welding the disk, then backfill and again inputting disk, etc., Such a welding method, obviously, is only feasible when the length of the outer pipe, not exceeding the length of the welding electrode is 0.3 m If we take the length of the pipe sizes that are supplied by industry - 12 m, you need 40 pieces of pipe (40 welded seams) to make the outer tube corresponding to the length of the range.

Welds are the site of intense corrosion compared to other places in the application of the impact of the electrochemical corrosion process. Obviously, the reliability of the outer tube 40 of the segments is many times smaller than the whole pipe. In addition, with this method of welding, it is obviously possible only one-sided weld attaching the disks to the pipe. Unilateral seam 4 times less reliable than bilateral, as exposed to corrosion from two sides, and two-way is a two-sided seam exposed individually to the effects of corrosion on one side only.

Famous deep well anode earthing (SU/s 1664874 A1; C 23 F 13/00) containing the current lead in isolation, the electrodes and the membrane, which is welded to , and sheath through the longitudinal cavity, moreover, on the outer surface of the housing are made of longitudinal ribs, and the free space between the current lead and the shell is filled with a dielectric, while in the upper part of the earthing provided with an additional protective housing made of electroconductive material, protruding above the ground surface and provided with a perforated lid, in addition, the electrodes and the membrane are made of steel pipes.

The disadvantage of earthing is the low reliability due to the uneven allow the passage of electric current from the ground into the ground, due to the inefficiency of the design.

When carrying electrodes of steel special relief point or area with a minimum radius of curvature zone maximum density draining current focus in these places and in places of welds securing the electrodes to the membrane. Areas of maximum curvature and the welds are destroyed in the first place, which leads to disruption of the electrical connection between the membrane and the electrodes and to the direct access of the electrolyte ground to the shell, which means almost premature destruction of the earth.

When carrying electrodes of steel pipes similar videopresence and between them it is easy to see, what's the last in the queue for welding electrode deprived of the opportunity to be welded to the shell, it is welded only to the adjacent electrodes: the first and next to last in the queue. The last electrode has an electric connection with the current lead through the first and penultimate) electrodes, while remaining associated with the current lead directly through the shell and the adjacent electrodes. It is obvious that the density of current flowing from the last electrode in the soil will be less and it will remain more intact than the other electrodes. That is all electrodes, except the last, will be loaded more, they will take the part of the latter, resulting in the unevenness of density of flowing current through the electrodes will cause uneven wear, premature for most of electrodes that does not meet the objective of the invention is to increase the service life. In addition, the electrode welds are destroyed first electrodes and open access to the electrolyte of the soil to welded joints between the shell and electrolytes, which soon will also be destroyed, which would violate the electrical connection between the membrane and the electrodes and, ultimately, to failure of the earth as a whole before the appointed nicesly essence and the achieved result.

An object of the invention is the creation of deep well anode earthing design that provides uniform draining of current from ground to ground, long service life, reliability, simplicity and manufacturability of the device.

The technical problem is solved due to the fact that in the deep well anode earthing, including the current lead in isolation, situated coaxially inside his shell and separated from it by a dielectric layer; extended electrodes, welded from the outside to the shell and among themselves in the amount of 6 pieces that make up the casing and shell, and the electrodes are made of steel pipes of the same diameter, and the length of the electrodes is greater than the length of the shell 3 of the pipe diameter or more additional protective cover made of electroconductive material in the upper part of the earthing protruding above the soil surface and provided with a perforated lid, according to the invention earthing contains a steel plate with a minimum thickness of the pipe wall thickness, length equal to the length of the electrode, of a width not less than half the diameter of pipe installed between the two electrodes and welded to the shell and the electrodes, in addition, all the interelectrode sworn the report.

The invention is illustrated by drawings: Fig.1 is a longitudinal section of the earthing switch; Fig.2 - cross section a-a ground; Fig.3 - callout B in Fig.2; Fig.4 - callout In Fig.2.

Deep well anode earthing contains the current lead 1, located in the insulation 2, separated by a dielectric layer 3 from the shell 4. Outside to the shell 4 is welded to the extended electrodes 5, forming a shell around 4 protective sleeve with a through cavity 6 for the gas outlet when the electrochemical process. The shell 4 and the casing 5 is made of steel pipes of the same diameter, and the length of the electrodes 5 on three pipe diameter or more than the length of the shell 4. In the upper part of the earthing switch is provided with an additional casing 7 of the electroconductive material, for example polyethylene, perforated top cover 8. The casing 7 is above the ground surface. The electrical contact 9 of the current lead 1 with the shell 4 is carried out by welding to the upper and lower parts of the earth and protected by a cap 10. The electrodes 5 are welded to the shell 4 welds 11 sequentially, starting with I through V, but the sixth electrode 5 has no opportunity to be welded to the shell 4, so between VI and the first electrode 5 is equipped with a steel plate 12, which is the pre-Privodino not less than the wall thickness of the electrodes 5, of a width not less than half the pipe diameter and no longer than the length of the electrode 5. The electrodes 5 are welded welded seam 13 between itself and the plate 11 welded seams 14 to VI and I to the electrodes 5. Welded seams 13 and 14 are covered with electroconductive corrosion-resistant protective coating 15, such as bitumen-rubber mastic.

Earthing works as follows.

Electric current from the current lead 1 via the electrical contacts 9 is supplied to the shell 4. The insulation 2 and the insulator 3 are designed to prevent any unauthorized telecommunications the current lead 1 with the shell 4 in other places besides the electrical contacts 9. Such a connection of the current lead 1 and the shell 4 provides a uniform flow of electric current through the sheath 4, with which the electric current flows through the welded seams 11 to the electrodes 5, I through V. VI electrode 5 has no direct connection with the shell 4, so this is the role of plate 12 welded welded seam 11 to the shell 4 and then welded seams 14 to I and VI electrodes 5, between which it is installed. Between the electrodes 5 are welded welded seams 13, thereby a shroud protecting shell 4 from direct contact with the soil. Electric current from Oboroceanu electric current from the electrodes 5 in the soil is evenly distributed over their surfaces 16, which is a prerequisite for uniform, predictable in time wear of the electrodes 5.

Welded seams 13, 14 are places of intense electrochemical corrosion, and the more welded seam then, undercuts, cracks, etc., i.e. factors that are not subject to precise regulation, the more intensive wear of the joint, the less predictable the time during which electric seam will be destroyed in the resulting direct access of the electrolyte ground to the shell 4 and welded seams 11, which dramatically disrupt the uniformity of the flowing electric current from the ground in soil from the surface 16, as will be violated the uniformity of distribution of the electric current between the electrodes 5. To avoid this case welded seams 13, 14 are coated with a protective coating. Thus, the design of the earthing provides uniform distribution of revenues of the electric current on the surface 16 of the electrode 5, and thus a uniform drip it into the ground, which ensures uniform wear of the electrodes and is the basis for reliable and continuous operation of the earthing switch. Use for the shell 4 and the electrodes 5 of the steel pipes of the same diameter simplifies the design of the earthing increases Telenesti, promotes mandatory gapping ground for earthing and the formation of cavities to remove the gases generated during the electrochemical process. The protrusion of the ends of the electrodes 5 of the shell 4 protects the lower end of the shell from the accelerated dissolution and breach of contact, the current lead 1 with the shell 4 from the effect of the end of the cold current screen formed by the protruding ends of the electrodes 5.

In the upper part there is an additional casing 7 of the electroconductive material with a perforated lid 8, excluding leaking current into the ground, which protects the upper pin connection 9 from destruction, and also reduces the magnitude of the electric potential on the surface of the soil and increases the effect of the deep current spreading, and provides the output generated gases into the atmosphere.

In the first period of operation electrical contact with the soil electrolyte is carried out only on the surface of the electrodes 5, forming a protective casing and after their uniform electrochemical dissolution, comes in the shell 4, and only after its dissolution by replacing tokoprovodom backfill (activator) between the current lead 1 and the shell 4 on the dielectric function elitely term and eliminates one of the disadvantages of the known earth, consisting of a double electrochemical dissolution of the elements of earthing and significant wasteful overspending materials.

Claims

Deep well anode earthing containing the current lead, located in isolation coaxially inside his shell and separated therefrom by a dielectric layer, six electrodes are welded externally to the shell and with each other, forming a shell, the shell and the electrodes are made of steel pipes of the same diameter, and the electrodes along the length exceeds the length of the shell at least 3 pipe diameter, additional housing made of electroconductive material, in the upper part protruding above the soil surface and provided with a perforated lid, characterized in that it has a steel plate with a minimum thickness of the pipe wall thickness, length equal to the length of the electrode, of a width not less than half the diameter of pipe installed between the two electrodes and welded to the shell and the electrodes, all of the electrode weld seams and the seams between the plate and the electrodes are covered outside electroconductive corrosion-protective mastic.

 

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