JPS6321753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a long-life galvanic anode that can ensure a service life commensurate with the amount of electricity possessed by the anode itself.

Conventionally, as shown in Figure 1, galvanic anodes are used with low resistivity electrolytes such as soil, fresh water, and seawater, while those with high resistivity are left bare to ensure good current generation. The entire circumference was covered with back filler 4. However, in recent years, mainly due to dramatic improvements in the materials used to coat the external surfaces of buried steel pipes,
The anti-corrosion current tends to be drastically reduced, and it has become sufficient to apply the anti-corrosion current only to small defects in the coating or minute defects associated with joint repair. Therefore, when the galvanic anode is used bare or covered with a back film material 4, it generates an excessive current 5 (as shown in Figure 1a).
Not only does this accelerate battery consumption, but over a period of many years, self-corrosion of the surface can cause the generation of corrosive battery current 6 (first
The disadvantage is that the weight consumed by the anode cannot be ignored (the case shown in FIG.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks, and its features include a galvanic anode made of magnesium, zinc, aluminum, etc., whose outer periphery is wrapped with an insulating sheet such as a polyethylene sheet, and only one end of the anode is wrapped with an insulating sheet such as a polyethylene sheet. If necessary, fill this opening with a backfilling agent mixed with bentonite, gypsum, sulfur, etc. to generate the minimum necessary current and at the same time suppress unnecessary self-corrosion. This makes it possible to ensure a service life commensurate with the amount of electricity that the anode itself has.

Hereinafter, a galvanic anode showing one embodiment of the present invention will be described as a second embodiment.
This will be explained based on the diagram.

FIG. 2 is a longitudinal cross-sectional view of the long-life galvanic anode according to the present invention.

As shown in FIG. 2, a galvanic anode main body 1 made of metal such as magnesium, zinc, aluminum, etc. and a lead wire 2 connected to a corrosion-protected object 7 such as a buried pipe are connected to a core metal 8 of the galvanic anode main body 1. The outer periphery of the galvanic anode main body 1 is wrapped with a heat-shrinkable tubular insulating sheet 10, and this is heat-shrinked, the lead wire 2 outlet end is tied and closed, and the other end is opened. If necessary, the open end portion 11 of the tubular insulating sheet 10 is filled with a backfilling agent 4 mixed with bentonite, gypsum, sulfur, etc. Thus, when the lead wire 2 is connected to the object 7 to be corroded, the generated current 5 flows out only from the open part 11, so that excess current generation from the outer periphery is prevented, and the galvanic anode main body 1 is connected to the open part 11. 11 only, back fill agent 4 or electrolytes such as soil and water 3
The structure naturally suppresses self-corrosion because it does not come into contact with the metal.

The opening portion 11 of the insulating sheet 10 has a third
As shown in Figures a and b, when used in soil with high resistivity, it is recommended to fill the backfill agent 4 and widen the opening in order to improve current generation.

When the metals constituting the galvanic anode, such as magnesium, zinc, and aluminum, corrode and dissolve, they form hydroxides, but these are gel-like substances and have a fairly low volume resistivity. Since it is gradually mixed with the filled backfill agent and does not interfere with the backfill effect, the backfill effect can be maintained until the anode material itself is consumed. Note that the same effect can be obtained by applying insulating coating or taping instead of the insulating sheet.

The present invention can be applied to other high-performance coatings and corrosion protection of coated metal structures to maintain a long service life of galvanic anodes.

As explained above, according to the present invention, when a buried pipe equipped with a high-performance coating or various metal structures coated with a high-performance coating is corrosion-protected using a galvanic anode,
Wrap the outer periphery of the galvanic anode body with an insulating sheet such as a polyethylene sheet, leaving only one end open, and if necessary, fill this open part with a backfill agent mixed with pentonite, gypsum, sulfate, etc. to the minimum necessary amount. By supplying an anti-corrosion current and suppressing self-corrosion, it is possible to ensure a service life commensurate with the amount of electricity that the anode itself has.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional galvanic anode.
Figures 1a and 1b are front views showing examples of the use of galvanic anodes either bare or covered with a back film; Figures 1c and d are
2 is a vertical sectional view in the longitudinal direction showing one embodiment of the long-life galvanic anode according to the present invention, and FIGS. 3a and 3b are longitudinal sectional views in the width direction, respectively. FIG. 7 is a longitudinal cross-sectional view showing another example of the open end portion of the electrode anode. DESCRIPTION OF SYMBOLS 1... Galvanic anode main body, 2... Lead wire, 3... Electrolyte, 4... Back fill agent, 5... Generated current, 6... Self-corrosion corrosion battery current, 7... Corrosion protected object, 8... Core metal, 10... Insulating sheet , 11...Open end portion.

Claims (1)

[Claims] 1. In a galvanic anode made of magnesium, zinc, aluminum, etc., its outer periphery is wrapped with an insulating sheet such as a polyethylene sheet, only one end is left open, and if necessary, a backfill agent mixed with bentonite, gypsum, sulfur salt, etc. is applied to this open part. A long-life galvanic anode with a structure that suppresses unnecessary self-corrosion while generating the minimum necessary current.