JP2008008306A - Corrosion prevention structure of pipe material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion prevention structure capable of easily and inexpensively performing corrosion-prevention processing without selecting the shape of a pipe material even for existing piping. <P>SOLUTION: A corrosion prevention sheet 1 comprises a transparent or translucent and extensible film layer 11, and a transparent or translucent and extensible adhesive layer 12, and covers a connection part of a pipe 2 and a pipe joint 3 for connecting it. The connection part can be viewed through the corrosion prevention sheet 1 when the connection part of the pipe 2 and the pipe joint 3 is covered by the corrosion prevention sheet 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an anticorrosion structure for a pipe material that prevents corrosion at a connection portion between a pipe and a pipe joint of ground pipe through which gas or the like flows.

  In general, ground pipes for flowing gas, etc. are covered with a carbon steel pipe for piping with a zinc plating layer on the surface of the steel pipe, or a rust prevention resin layer made of vinyl chloride, polyethylene resin, etc. on the surface of the steel pipe. A coated steel pipe or the like is used. When this type of piping is connected to each other or to a gas meter or the like, the coating layer on the surface is partially removed in order to thread the tip end of the connection, and in this state, it is connected to a joint or a gas meter. The

  FIG. 1 is a perspective view of an example of piping near a gas meter in the prior art, and FIG. 2 is a front view of a connecting portion between piping and a joint in the prior art, with a cross section above the center line and below the center line. The outer surface is shown. In FIG. 1, a gas meter M includes a polyethylene pipe PEP buried in the ground, an electric fusion joint EF, a transition joint TRF, a resin-coated steel pipe CP, an insulation joint ZF, a meter gas plug V, a galvanized steel pipe ZP, a gas meter joint MF, and the like. The gas is introduced and supplied to the gas consuming equipment. At this time, the steel pipe, the joint, and the like excluding the underground piping portion are screwed and connected.

  In FIG. 2, pipe taper screws are provided at the ends of the resin-coated steel pipe 2 a and the galvanized steel pipe 2 b and are connected via a pipe joint 3. At this time, a part of the pipe taper screw 21 used for the screw connection exposes the iron base as the extra screw portion 22, and the corrosion resistance is inferior to that of the portion having the coating layer or the plating layer. In this case, since the steel pipe is exposed at the remaining screw portion where the thread is left or the portion where the covering layer is removed, the corrosion resistance is inferior to the portion where the covering layer is present. For this reason, paint for rust prevention is applied to the surplus screw portion 22 or the exposed portion of the steel pipe, or a rust preventive tape made of, for example, a very soft butyl gol or the like in a strip shape or a tape shape is applied to the surplus screw portion or the exposed portion. The corrosion resistance is improved by wrapping. Moreover, in order to improve airtightness and corrosion resistance, the said soft rust preventive tape is wound around a screw part previously, and screw parts are screwed together in the state which wound this tape.

However, as described above, a soft rust-proof tape made of butyl rubber or the like is wound around the remaining screw part or the exposed part of the steel pipe to maintain the corrosion resistance. In many cases, it is outdoors and the environment is severe to maintain corrosion resistance. For example, in harsh environments where the temperature is below freezing in the winter and exposed to direct sunlight in the summer, the rust-proof tape is exposed to rain, wind, and snow over a long period of time. As a result, the rainwater permeates into the interior and corrodes the remaining screw portion and the steel pipe portion, thereby deteriorating the corrosion resistance.
Further, the rust preventive tape made of butyl rubber or the like is used in an unvulcanized state exclusively in order to provide a shape-free and watertight property. For this reason, there is a problem that it is sticky and has poor workability.

  In view of such a point, for example, Patent Document 1 has a length sufficient to cover the threaded portion exposed in the adjacent portion of the steel pipe and the screw-type pipe joint, and is slightly larger than the diameter of the screw-type pipe joint. There is described a corrosion-resistant overpipe for exposed screw parts such as gas pipes and water pipes in which a filler inlet is provided on the peripheral wall of a cylinder made of a non-erodible material having a large diameter.

  Moreover, in patent document 2, in the protective cover for covering the junction part of piping and the joint for connecting this, it was made to be expandable via a hinge part so that the said junction part might be covered. A portion to which a protective cover is attached using a protective cover provided with a cover main body and a locking mechanism that is provided at both free ends of the cover main body and engages and locks each other when the cover main body is closed It is described that a soft tape-shaped rust-proof tape made of butyl rubber or the like is wound slightly over the entire length.

  Further, in Patent Document 3, a coating layer is provided on the outer surface of a metal joint body with a synthetic resin, and the coating layer includes a cylindrical port that sandwiches a seal ring with a pipe threaded into the joint body. In addition, in the resin-coated joint composed of the coated body formed by projecting the cylindrical port integrally at the end, both the coated body and the cylindrical port are made transparent so that the joint body and the pipe can be seen through. Furthermore, a resin-coated joint with a transparent seal ring is described.

Japanese Utility Model Publication No.57-143486 JP 2003-336787 A JP 11-315975 A

  However, in the corrosion-resistant overpipe described in Patent Document 1, since the filler is filled from the injection port after the exposed screw part is covered with the corrosion-resistant overpipe, is the exposed screw part filled with sufficient filler? It is difficult to determine whether or not, and after construction, it is difficult to check the corrosion state of the exposed screw part. Furthermore, there is a problem that the exposed screw portion of the existing pipe that has already been laid cannot be subjected to anticorrosion treatment.

  Since the protective cover described in Patent Document 2 has a cover body that can be expanded through a hinge portion, the protective cover can be opened to check the connection between the pipe and the joint, or to prevent corrosion of the existing pipe. It is possible to perform processing. However, it is practically impossible to check the connection between many pipes and joints by opening the protective cover at every place, and there are protective covers provided at many pipes and joints. Has the problem that the cost required for anticorrosion becomes enormous.

In the resin-coated joint described in Patent Document 3, since both the coated main body and the cylindrical port are made transparent and the seal ring is made transparent, it is easy to check the corrosion status of the connection part after construction. . However, the problem is that it cannot be applied to various piping materials such as malleable cast iron pipe joints with hot dip galvanized, which is the cheapest and widely used, and the anticorrosion treatment of existing piping is impossible. There is.
Also, with any technique, it can be applied to corrosion prevention of connecting parts with complicated shapes such as connecting parts between valves and pipes, or connecting parts between pipe joints with male threads and pipe joints with female threads. It wasn't.

  The present invention has been made to solve the above-described problems, and it is easy to connect a pipe and a joint without having to select the shape of the piping material, and even in the existing piping already laid. An object of the present invention is to provide an anticorrosion sheet and a pipe material anticorrosion method capable of performing anticorrosion treatment at a low cost and enabling inspection of the corrosion state of the connection portion after the enforcement.

In order to achieve the above object, a pipe member having a thread at a pipe end, a joint member having a screw for screwing and joining to the pipe member, and the pipe member and the joint member are screwed and connected. The anticorrosion structure of the pipe material made of an anticorrosion sheet provided so as to cover the connected portion, wherein the anticorrosion sheet has transparency or translucency, a film layer having extensibility, and transparency or translucency. An anticorrosion structure for a pipe material, which is an anticorrosion sheet, which is formed of an adhesive layer having extensibility, and allows the connection portion to be seen through the anticorrosion sheet when the connection portion between the piping member and the joint member is covered. It is.
Therefore, according to the first aspect of the present invention, since the connection portion between the pipe and the joint is only covered with the anticorrosion sheet, even if the existing pipe is already laid, the shape of the pipe material is not selected. Since the anticorrosion treatment can be easily performed at low cost and the connection portion can be seen through the anticorrosion sheet, it is possible to easily check the corrosion state of the connection portion after enforcement.

At this time, the film layer is preferably an ethylene-acrylic acid copolymer or an ionomer resin, and the film layer preferably contains an ultraviolet absorber and / or an antioxidant.
According to this structure, while making a corrosion prevention sheet share transparency or translucency and extensibility, it can be set as the corrosion prevention sheet which does not deteriorate over a long period of time.

Moreover, it is desirable that the adhesive layer is an acrylic adhesive layer in a closed foam state.
According to this configuration, the anticorrosion sheet can be made to be an anticorrosion sheet that shares transparency or translucency and extensibility and maintains strong adhesion over a long period of time.

Moreover, when it is not necessary to check the corrosion state after construction and importance is placed on aesthetics, according to the invention described in claim 5, a pipe member having a thread formed on a pipe end is screwed and joined to the pipe member. A joint member having a screw for,
The pipe member has a corrosion prevention structure made of a corrosion prevention sheet provided so as to cover a connection portion in which the pipe member and the joint member are screwed and connected,
The anticorrosion sheet is composed of a film layer having extensibility and an adhesive layer having extensibility,
When the connection part of the said piping member and the said joint member is covered, it can be set as the corrosion prevention structure of the pipe material which the said anticorrosion sheet | seat seals the said connection part watertightly.

  According to the present invention, since the connection portion between the pipe and the joint is only covered with the anticorrosion sheet, even the existing pipe that has already been laid can be sealed watertight without selecting the shape of the pipe material, and easily In addition, since the anticorrosion treatment can be performed at a low cost and the connection portion can be seen through the anticorrosion sheet, it is possible to easily check the corrosion state of the connection portion after enforcement.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 3 shows a schematic cross-sectional view of the anticorrosion sheet according to the present invention. FIG. 4 shows an example of a pipe material anticorrosion structure according to the present invention, and shows a cross section above the center line and an outer surface below the center line.

  The anticorrosion sheet 1 shown in FIG. 3 includes a film layer 11 and an adhesive layer 12. For example, a film layer 11 having a thickness of 0.1 mm and an adhesive layer 12 having a thickness of 1.9 mm are laminated, and a tape having a width of 50 mm. In shape, it is wound into a roll through a peeling film, and is cut to an appropriate length when used.

The film layer 11 is made of an ethylene-acrylic acid copolymer or ionomer resin.
An ethylene-acrylic acid copolymer is known as a material having excellent thermal stability, flexibility, excellent extensibility, and transparency. For example, the elongation at break is 100% or more. Therefore, even if the surface of the piping material has an uneven shape, for example, a shape such as a valve having a hexagonal surface that hangs a tool on the outer surface of the connection part, it can be flexibly handled and transparent. Therefore, the corrosion state of the connection portion can be inspected.

The ionomer resin is a resin having a special structure in which the molecules of ethylene-methacrylic acid copolymer or ethylene-acrylic acid copolymer are intermolecularly bonded with metal ions such as sodium and zinc, and the flexibility, It is known for its excellent transparency, toughness, abrasion resistance, low temperature resistance, and the like.
Therefore, even if the surface of the piping material has irregularities, it can respond flexibly and has transparency, so it can inspect the corrosion state of the connection part, and even below the freezing point in winter It can be set as the anti-corrosion sheet | seat which can endure under the environment of this.

Moreover, since the anti-corrosion sheet 1 is an anti-corrosion sheet used for the connection part of outdoor piping, weather resistance is required. Therefore, it is desirable to contain stabilizers such as ultraviolet absorbers and antioxidants.
As the stabilizer, for example, one or more compounds selected from hindered phenols, hindered amines, organic phosphites, organic thioethers, higher fatty acid metal salts, and the like can be used. The content of the stabilizer is selected within a range that does not impair elongation and transparency. For example, the content is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the polymer.

  The adhesive layer 12 is an independently foamed acrylic adhesive layer. The acrylic adhesive layer is mainly composed of carbyl (meth) acrylate such as 2-ethylhexyl acrylate, and a vinyl monomer [(meth) acrylic acid, 2-hydroxyethyl (meth) having a polar group as a component that imparts cohesive strength. Acrylate, vinyl acetate, acrylamide, etc.], which is a copolymer having a relatively low glass transition point and adhesiveness, and further improving the cohesive force, the carboxyl group in the copolymer And a part of the hydroxyl group is crosslinked with a polyisocyanate, an epoxy compound, a polyvalent metal compound, or the like.

  The independent foamed acrylic adhesive layer is excellent in flexibility and transparency, so even if the surface of the piping material is uneven, it is firmly bonded to the piping material and prevents rainwater from entering. In addition, since it has transparency, the corrosion state of the connecting portion can be inspected.

  In FIG. 4, the pipe 2 is, for example, a resin-coated steel pipe 2a and a galvanized steel pipe 2b, and the pipe joint 3 is, for example, a galvanized malleable cast iron pipe joint, both of which have been more versatile than before. It is a piping material used in

  At the end of the pipe 2, a pipe taper screw 21 to be screwed into the pipe joint 3 is formed by cutting. At this time, the galvanized layer is removed from the threaded portion, and the carbon steel surface is exposed. Next, after a sealing agent is applied to the surface of the pipe taper screw 21 or a sealing tape is wound, the pipe is screwed into the connecting portion of the pipe joint 3. At this time, since a pipe wrench or the like is applied to the pipe 2 and the pipe joint 3 so as to be firmly screwed together, a part of the galvanized layer of the pipe 2 and the pipe joint 3 may be damaged and peeled off.

  Further, even after the pipe 2 and the pipe joint 3 are screwed together, the extra thread portion 22 that is not screwed into the pipe joint always remains in the pipe taper screw 21. Since the carbon steel surface is exposed at this location, corrosion proceeds easily unless the anticorrosion treatment is applied.

  The anticorrosion sheet 1 is wound around a connection portion between the pipe 2 and the pipe joint 3 so as to cover the extra screw portion 22. Moreover, you may wind so that the pipe | tube 2 and the pipe joint 3 which were damaged with the pipe wrench may be covered.

  Since the anticorrosion sheet 1 is composed of a film layer having transparency or translucency, extensibility, transparency or translucency, and an adhesive layer having extensibility, the shapes of the pipe 2 and the pipe joint 3 Regardless of this, it can be easily wrapped around a place that requires anticorrosion, prevents corrosion over a long period of time, and easily inspects the corrosion state.

Furthermore, since the anticorrosion treatment can be easily applied to the connecting portion of the existing pipe that has been implemented in the past, it is very useful for extending the life of the existing pipe.
The pipe 2 is not limited to a galvanized carbon steel pipe for piping, but may be a coated steel pipe coated with a resin layer, a pipe joint having a male screw, or the like. Needless to say, the pipe joint 3 is not limited to a malleable cast iron pipe joint, but can be replaced with a valve or the like as long as it is connected to the pipe 2.

  In addition, when emphasizing the aesthetics of the piping structure, the anticorrosion sheet can be colored similar to the color scheme of the pipe and the pipe joint within a range that ensures the translucency of the anticorrosion sheet. In addition, when it is not necessary to inspect the corrosion state of the connection portion between the pipe and the pipe joint, the anticorrosion sheet is colored without transparency, or a colored tape having weather resistance is provided on the outer peripheral surface of the anticorrosion sheet. It can also be wound. Even in these cases, since the anticorrosion sheet has excellent flexibility and weather resistance, the anticorrosion sheet can be anticorrosive over a long period of time by watertightly sealing the connection portion between the pipe and the pipe joint.

  The anticorrosive structure for a pipe according to the present invention is a 3/4 inch malleable cast iron having a 3/4 inch resin-coated steel pipe having a screw formed at the pipe end and a screw for screwing and joining to the resin-coated steel pipe. A film layer made of ionomer resin having a thickness of 0.1 mm and a thickness of 1.9 mm provided so as to cover a pipe joint, a connection part in which the resin-coated steel pipe and the malleable cast iron pipe joint are screw-connected. A self-foaming acrylic adhesive layer was laminated and manufactured from a tape-shaped anticorrosion sheet having a width of 50 mm.

The other end of the resin-coated steel pipe that is not screwed with the malleable cast iron pipe joint of the pipe material anticorrosive structure is closed so as to be sealed, and then exposed to various environmental conditions for a long period of time. The anticorrosion performance was confirmed.
The freezing test was assumed to be buried in snow in the winter and exposed to high temperatures in the summer, and left for 4 months in an environment of 5 degrees below freezing, and then left at room temperature for 1 year. In the burial test, assuming the penetration of moisture in the soil, it was buried approximately 50 cm below the ground and left for one and a half years. The water immersion test was assumed to be infiltration of rainwater, left in water for one month, and then left at room temperature for one and a half years. In the outdoor exposure test, it was left outdoors for a year and a half, assuming the effects of direct sunlight.
In any of the tests, good results were obtained without causing rust at the connection portion between the pipe and the pipe joint and without deterioration of the anticorrosion sheet.

Furthermore, the accelerated weathering test was carried out using a tester conforming to “Sunshine carbon arc lamp type light resistance and weathering tester” prescribed in Japanese Industrial Standard (JIS B7753-1993). Test conditions are
1) Continuous irradiation Black panel temperature 63 ± 3 degrees and humidity 50% RH
2) Precipitation conditions First-time operation with 12-minute rainfall in 60 minutes 3) Operation time 6 months (4320 hours)
The test condition is an accelerated weathering test in which 300 hours correspond to 1 year, and the test period of 6 months corresponds to 14.4 years. Also in this test, good results were obtained without causing rust at the connection portion between the pipe and the pipe joint, and without deterioration of the anticorrosion sheet, and the anticorrosion sheet according to the present invention was obtained over a long period of time. It was confirmed that it is useful for corrosion prevention of the joint with the joint.

It is a perspective view of the example of piping near the gas meter in a prior art. It is a front view (partial sectional view) of a connection portion between a pipe and a joint in the prior art. It is a cross-sectional schematic diagram of the anticorrosion sheet which concerns on this invention. It is one Example of the anticorrosion structure of the pipe material which concerns on this invention.

Explanation of symbols

1: anticorrosion sheet, 11: film layer, 12: adhesive layer 2: pipe, 2a: resin-coated steel pipe, 2b: galvanized steel pipe, 21: taper screw for pipe, 22: extra screw part,
3: Pipe joint M: Gas meter, V: Meter gas plug MF: Gas meter joint, TF: Pressure detection joint, ZF: Insulation joint, TRF: Transition joint, EF: Electric fusion joint ZP: Galvanized steel pipe, CP: Resin coated steel pipe , PEP: Polyethylene pipe

Claims (5)

A pipe member in which a thread is formed at a pipe end; and a joint member having a screw for screwing and joining to the pipe member;
The pipe member has a corrosion prevention structure made of a corrosion prevention sheet provided so as to cover a connection portion in which the pipe member and the joint member are screwed and connected,
The anticorrosion sheet is a film layer having transparency or translucency and extensibility,
Consists of transparency or translucency and an adhesive layer having extensibility,
An anticorrosion structure for a pipe material, wherein the anticorrosion sheet allows the connection portion to be seen through the anticorrosion sheet when the connection portion between the piping member and the joint member is covered.   The said film layer consists of an ethylene-acrylic acid copolymer or an ionomer resin, The anticorrosion structure of the pipe material of Claim 1 characterized by the above-mentioned.   The said film layer contains a ultraviolet absorber and / or antioxidant, The anticorrosion structure of the pipe material in any one of Claim 1 or 2 characterized by the above-mentioned.   The anticorrosion structure for a pipe according to any one of claims 1 to 3, wherein the adhesive layer is an acrylic adhesive layer in a closed foam state. A pipe member in which a thread is formed at a pipe end; and a joint member having a screw for screwing and joining to the pipe member;
The pipe member has a corrosion prevention structure made of a corrosion prevention sheet provided so as to cover a connection portion in which the pipe member and the joint member are screwed and connected,
The anticorrosion sheet is composed of a film layer having extensibility and an adhesive layer having extensibility,
An anticorrosion structure for a pipe material, wherein the anticorrosion sheet seals the connection part in a watertight manner when the connection part between the pipe member and the joint member is covered.

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