JP7018194B2 - Electrical anticorrosion device for piping and electrocorrosion protection method - Google Patents

Description

The present invention relates to an electric anticorrosion device and an electric anticorrosion method for preventing corrosion of pipes arranged in a plant or the like when exposed to the atmospheric environment.

Patent Document 1 describes a conventional structure for electrically protecting a pipe formed of a steel material. In this structure, the pipe is inserted inside a sheath pipe buried in the ground, and air mortar is filled between the sheath pipe and the pipe. In the air mortar, the probe is installed in a position close to the pipe, while the electrode is buried in the ground. Then, the pipe, the probe, and the electrode are connected to the DC power source on the ground by the conducting wire, and the electric corrosion protection of the pipe is performed by energizing the DC power source.

In the conventional structure described above, a DC power supply for supplying a current to the piping is provided externally. However, depending on the plant, it may not be possible to install a DC power supply, and in this case, electrical corrosion protection by the conventional structure will not be possible. Further, in the conventional electric corrosion protection, it is applied to the structure in which the pipe is arranged inside the sheath pipe, and measures against corrosion of the contact portion of the pipe supported by the pedestal and exposed to the atmosphere with the pedestal are taken. You can't do it.
Based on the above, the conventional anti-corrosion measures for pipes that are exposed to the atmosphere and supported by the gantry, such as plants, are to lift the pipe from the gantry, separate it from the gantry, remove rust, and apply paint. This suppresses corrosion.

Japanese Patent No. 5820296

However, with conventional corrosion countermeasures, it is necessary to use a machine such as a crane to lift the pipes and to assemble scaffolding for work, which is not only troublesome to work, but also sufficient cleaning and painting even if the pipes are lifted. There is a problem that some parts cannot be used.
Further, in the conventional cleaning and painting, even if the corrosion of the pipe can be temporarily suppressed, the continuous corrosion prevention of the pipe cannot be performed.

The present invention has been made in consideration of such conventional problems, and it is possible not only to eliminate troublesome work but also to reliably prevent corrosion of pipes even while being supported by a gantry. It is an object of the present invention to provide an electric anticorrosion device and an electric anticorrosion method for various pipes.

The electric corrosion protection device for pipes of the present invention is a device for electric corrosion protection for pipes arranged by being exposed to the air environment while being supported by a gantry, and is made of an ion conduction material for electric corrosion protection made of air mortar. The block body was solidified so as to cover the periphery of the contact portion between the pipe and the gantry, and was formed of a metal having a higher ionization tendency than iron, and was embedded in the block body in a state of being conductive with the pipe. It is characterized by having a sacrificial electrode.

In the present invention, the anticorrosion ion conductive material is used with fluidity capable of filling the periphery of the contact portion between the pipe and the gantry.
Further, the sacrificial electrode is any one of magnesium, magnesium alloy, zinc, zinc alloy, aluminum and aluminum alloy.
Further, the air mortar contains an acrylic emulsion for improving durability.

The electric corrosion protection method for pipes of the present invention is a method for electric corrosion protection for pipes arranged by being exposed to the atmospheric environment while being supported by a gantry, and an ion conduction material for electric corrosion protection made of air mortar is used. At the stage of preparing so as to have a fluidity that can be filled so as to cover the periphery of the contact portion between the pipe and the gantry, and a sacrificial electrode made of a metal having a higher ionization tendency than iron is arranged so as to be conductive with the pipe. It is characterized by comprising a step of burying the sacrificial electrode and a step of forming a block body by filling and solidifying the ion conductive material for electrocorrosion so as to cover the periphery of the contact portion. And.

Air mortar is strongly alkaline and has the effect of suppressing corrosion of pipes made of iron or the like by itself. In addition to this, in the present invention, a sacrificial electrode is embedded in a block body made of air mortar, and electrons flow from the sacrificial electrode in the direction of the pipe to reduce the pipe, so that contact with the gantry in the pipe is achieved. Perform electric corrosion protection for the part. As a result, it is possible to prevent corrosion beyond the original corrosion suppressing action of air mortar. Therefore, it is not necessary to lift the pipe from the gantry or repaint the pipe, and it is possible to eliminate the troublesome work for corrosion countermeasures. Further, since the surroundings are surrounded by the solidified air mortar, corrosion prevention is continuously performed and corrosion can be prevented for a long period of time.

It is sectional drawing which shows the electric corrosion protection apparatus of one Embodiment of this invention. It is explanatory drawing explaining the cylinder flow test. It is a potential characteristic diagram when magnesium is used as a sacrificial electrode. It is a potential characteristic diagram when zinc is used as a sacrificial electrode. It is a potential characteristic diagram when aluminum is used as a sacrificial electrode. It is sectional drawing which shows the structure of 2nd Example. It is a photograph which shows the result of the 2nd Example.

FIG. 1 shows an electric corrosion protection device 1 when the present invention is applied to a pipe arranged in a plant.
In the electric corrosion protection device 1, a pipe 3 made of an iron material such as steel is supported on a gantry 2. The gantry 2 is formed of a refractory material such as a steel frame, reinforced concrete, or brick. With respect to the gantry 2, the pipe 3 has a contact portion 4 in which the bottom surface portion facing the gantry 2 is in contact with the gantry 2. The block body 5 covers the periphery of the contact portion 4. A plurality of flat plate-shaped sacrificial electrodes 6 are embedded in the block body 5. Each sacrificial electrode 6 and the pipe 3 are connected by a conducting wire 7 provided in the block body 5. As a result, the pipe 3 and the sacrificial electrode 6 are in a conductive state. When connecting the conducting wire 7, the coating film on the connecting portion of the pipe 3 is removed in advance.
In the present invention, the sacrificial electrode 6 can be arranged so as to be in contact with the outer surface of the pipe 3 to conduct conduction. This can be done, for example, by soldering or screwing the sacrificial electrode 6 to the outer surface of the pipe 3. By adopting a structure in which the sacrificial electrode 6 is arranged in contact with the pipe 3, the lead wire 7 is not required, so that the number of parts can be reduced and the assembly can be simplified.

The block body 5 is formed by solidifying an ion conductive material for electrocorrosion protection. Air mortar is used as an ion conductive material for electrocorrosion protection. The air mortar is a strongly alkaline material, and since the block body 5 is formed by the strongly alkaline air mortar, the corrosion suppressing force of the air mortar itself can be exerted on the pipe 3 at the same time.
When the air mortar is in a liquid state, it is filled so as to cover the periphery of the contact portion 4 of the pipe 3 with the gantry 2, and then solidified to form the block body 5. A mold 8 is used to fill the periphery of the contact portion of the pipe 3 with liquid air mortar.

The formwork 8 is framed so as to surround not only the periphery of the contact portion 4 of the pipe 3 but also the periphery of the arrangement portion of the sacrificial electrode 6 and the conducting wire 7. The block body 5 is formed by filling the mold 8 with liquid air mortar and solidifying it. As a result, the block body 5 made of air mortar covers the periphery of the contact portion 4 of the pipe 3 with the gantry 2, and the sacrificial electrode 6 and the conducting wire 7 are embedded. Further, by forming the block body 5, the pipe 3 can be fixed to the gantry 2. The mold 8 may be removed after the block body 5 is solidified, or may be left as it is.

The sacrificial electrode 6 is arranged as close to the pipe 3 as possible. When the sacrificial electrode 6 is brought into contact with the pipe 3, the sacrificial electrode 6 can be soldered or screwed to the outer surface of the pipe 3.
As the sacrificial electrode 6, a metal having a higher ionization tendency than iron, which is the material of the pipe 3, is used. By connecting a metal having a higher ionization tendency than iron and iron, electrons move toward iron and iron is reduced. Therefore, it is possible to prevent corrosion of the pipe 3 made of iron. Zinc, manganese, aluminum, magnesium, sodium, calcium, and potassium are present as metals having a higher ionization tendency than iron, but the sacrificial electrode 6 is used from the viewpoint of stability, reactivity, handleability, and supply stability. , Magnesium, zinc, or aluminum is preferably used. Further, any of these alloys such as magnesium alloy, zinc alloy and aluminum alloy can also be used.

Air mortar used as an ion conductive material for electrocorrosion is produced by kneading cement as a solidifying material, fine aggregate as an admixture, a surfactant as a foaming agent, and a polymer admixture with water. .. Polymer admixtures are used to impart durability when used outdoors. As the polymer admixture, an acrylic emulsion can be used. The air mortar formed of such a material is an ionic conductor like concrete.

The air mortar is filled in the contact portion 4 of the pipe 3 which is a narrow portion with the gantry 2 and its surroundings. Therefore, the air mortar is used in a state where it has a fluidity that can be filled.
Table 1 shows a formulation example for making an air mortar. Table 1 shows the amount of material used per 1 m ³ .

The air mortar is adjusted so as to have a fluidity that can be filled in the contact portion 4 between the pipe 3 and the gantry 4 and its surroundings. Such fluidity can be specified, for example, by a numerical value obtained by a cylinder flow test. When specified by the cylinder-flow test, the flow value is preferably in the range of 100 mm or more and 300 mm or less. If the flow value is less than 100 mm, the fluidity is small, and if it exceeds 300 mm, the fluidity is large, which is not preferable.

FIG. 2 shows an example of a cylinder flow test. As shown in (A), a cylindrical cylinder 11 having a diameter of 80 mm and a height of 80 mm having upper and lower surfaces open on the flat plate 10 was stationary, and the sample 12 was placed therein up to the top of the cylinder 11. After that, the cylinder cylinder 11 is pulled up in the vertical direction. At this time, since the sample 12 spreads on the flat plate 10, as shown in (B), the circular spread of the sample 12 is measured by the diameter, and this measured value is used as the flow value.

In addition to the above fluidity, the air mortar is preferably lightweight. This is to reduce the load on the gantry 2 as much as possible when the gantry 2 is filled. The density of the air mortar for this purpose is preferably in the range of 100 kg / m ³ or more and 1000 kg / m ³ or less.

Next, the procedure of electric corrosion protection for the pipe 3 will be described. The pipe 3 is arranged by being exposed to the atmospheric environment while being supported by the gantry 2, and the following steps a to c are performed.
Step a: An electrolytic anticorrosion ion conductive material made of air mortar is prepared so as to have a fluidity that can be filled so as to cover the periphery of the contact portion 4 between the pipe 3 and the gantry 2.
Step b: A sacrificial electrode 6 made of a metal having a higher ionization tendency than iron is connected to the pipe 3 via a conductor 7.
Step c: The block body 5 is formed by embedding the sacrificial electrode 6 and filling and solidifying an ion conductive material for electrocorrosion made of air mortar so as to cover the periphery of the contact portion 4.

In step a, the cement, the admixture, the foaming agent, and the polymer admixture are put into water and kneaded, so that the air mortar has a flow value in the range of 100 mm or more and 300 mm or less. Prepare to use as an ion conductive material for electrocorrosion protection. In the adjustment, a foaming agent and water are used to form bubbles by a preform method, and these are added to cement and an admixture to form a slurry-like air mortar. In this case, a polymer admixture can be added to improve outdoor durability.
Since the above air mortar can be mixed and prepared at the site where the pipe 3 and the gantry 2 are present, it is easy to make adjustments that do not take up space. By pouring this air mortar into the mold 8, it can be used without any particular curing.

In step b, any metal of magnesium, magnesium alloy, zinc, zinc alloy, aluminum or aluminum alloy is selected as the sacrificial electrode 6, the sacrificial electrode 6 is placed in the vicinity of the pipe 3, and then by the lead wire 7. The sacrificial electrode 6 and the pipe 3 are connected. If there is a paint film on the surface of the pipe 3, the paint film is removed for connection.

In step c, a slurry-like air mortar is filled so as to cover the contact portion 4 of the pipe 3 with the gantry 2 and the sacrificial electrode 6, and then the air mortar is solidified to form the block body 5. For filling the air mortar, it is preferable to use the formwork 8, and it is preferable to apply caulking (joint material) between the formwork 8 and the gantry 2.
Due to the solidification of the air mortar, the sacrificial electrode 6 is embedded in the block body 5, and the pipe 3 is fixed to the block body 5 in a conductive state connected to the sacrificial electrode 6 via the conducting wire 7. As a result, the pipe 3 can be attached to the gantry 2 in a fixed state.

In such an electric anticorrosion device for pipes, the pipe 3 and the sacrificial electrode 6 made of metal having a higher ionization tendency than iron are made conductive, and the sacrificial electrode 6 is embedded in this state and the pipe 3 and the gantry 2 are in contact with each other. The structure is such that the air mortar is solidified by filling the periphery of the portion 4 with an ion conduction material for electrocorrosion protection made of air mortar.
In such a structure, electrons flow from the sacrificial electrode 6 in the direction of the pipe 3 and the pipe 3 is reduced, so that the electric corrosion protection of the contact portion 4 with the gantry 2 in the pipe 3 can be performed. Therefore, it is not necessary to lift the pipe 3 from the gantry 2 or repaint the pipe 3, and it is possible to eliminate the troublesome work for corrosion countermeasures. Furthermore, since the surroundings are surrounded by solidified air mortar, corrosion prevention is continuously performed, and corrosion can be prevented for a long period of time.

(First Example)
A steel plate made of SPCC having a size of 50 × 40 mm and a plate-shaped sacrificial electrode of the same size are opposed to each other at a distance of about 10 mm, and these are connected by a conducting wire. Covered with mortar. Then, an ammeter was connected to the conducting wire to measure the potential over time. Table 3 shows the characteristic values (measured values) of Formulation Examples A to D.
FIG. 3 is a potential change graph for 0 to 80 days when magnesium is used as a sacrificial electrode, FIG. 4 is a potential change graph for 0 to 80 days when zinc is used as a sacrificial electrode, and FIG. 5 is an aluminum as a sacrificial electrode. It is a potential change graph for 0 to 80 days when used.
The characteristic curves A to D in each figure correspond to the formulation examples A to D shown in Table 2. In these figures, the steel sheet can be protected against corrosion when the potential is lower than −0.8 v. As shown in FIGS. 3 to 5, the strongest anticorrosion is possible when the sacrificial electrode is magnesium.

(Second Example)
As shown in FIG. 6, a steel pipe material 61 having a wall thickness of 2 mm, a diameter of 3 inches, and a length of 150 mm is used as a pipe, and the pipe material 61 is placed on a steel flat plate 62 as a pedestal, and the bottom surface portion of the pipe material 61 is placed. It was in contact with the flat plate 62. An air mortar 63 was prepared according to the compounding ratio shown in Table 4, and 580 ml of this air mortar was filled around the contact portion so as to cover the contact portion between the pipe material 61 and the flat plate 62. Acrylic emulsion was used as the polymer admixture in Table 4. Next, as shown in FIG. 6, as a sacrificial electrode, a magnesium plate 63 having a size of 40 × 50 mm and a thickness of 2 mm was inserted upright on the air mortar 63 so as to be located on both sides of the pipe material 61, and the magnesium plate 63 and the pipe material 61 were inserted. Was connected by a conducting wire 65, and the air mortar 63 was solidified into a block body. The mortar was installed outdoors side by side.
The properties after being exposed to the atmosphere outdoors for one year are shown in FIG. 7, where S1 is a comparative example and S2 is this example. In Comparative Example S1, the tube material has holes, whereas in Example S2, no holes are formed and the surface of the tube material 61 remains as it is, indicating that corrosion protection is well performed.

1 ... Electric corrosion protection device, 2 ... Stand, 3 ... Piping, 4 ... Contact part, 5 ... Block body, 6 ... Sacrificial electrode, 7 ... Conductor, 8 ... Formwork

Claims (4)

It is a device that protects against electrical corrosion of pipes placed by exposing them to the atmospheric environment while being supported by a gantry.
A block body made of an ion conductive material for electrocorrosion protection made of air mortar and solidified while covering the periphery of the contact portion between the pipe and the gantry.
An electrical anticorrosion device for a pipe, which is formed of a metal having a higher ionization tendency than iron, and includes a sacrificial electrode embedded in the block body in a state of being conductive with the pipe. The electric corrosion protection device for piping according to claim 1, wherein the sacrificial electrode is any one of magnesium, magnesium alloy, zinc, zinc alloy, aluminum and aluminum alloy. The electric corrosion protection device for piping according to claim 1, wherein the air mortar contains an acrylic emulsion for improving durability. It is a method of electric corrosion protection against pipes placed by exposing them to the atmospheric environment while being supported by a gantry.
The stage of preparing an ion conductive material for electrocorrosion consisting of air mortar so as to have a fluidity that can be filled so as to cover the periphery of the contact portion between the pipe and the gantry.
At the stage of arranging a sacrificial electrode made of metal, which has a higher ionization tendency than iron, so as to conduct with the pipe.
A pipe characterized by having a step of burying the sacrificial electrode and forming a block body by filling and solidifying the ion conductive material for electrocorrosion so as to cover the periphery of the contact portion. Electric corrosion protection method.

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