JP2002356670A - Sealant for leakage preventing and sealing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant and a sealing method that can effectively prevent a wide kind of gas leakage from pipes, even though the leakage is small. SOLUTION: A reactive or volume-expandable sealing compound is flown in a pipe together with a gas flow in order to plug a leaking part of a pipe and prevent gas leakage. The compound to be sealed is composed of a moisture- reactive monomer (a silane-coupling agent, a cyanoacrylate, or an isocyanate), a radically reactive monomer a (meth)acrylic monomer or the like}, a cationically reactive monomer (a vinyl ether or the like), and a water-absorbing resin particle. The compound to be sealed may comprise a reaction initiator or polymerization initiator. Leaking parts such as those at a joint part may be sealed by introducing a moisture-containing gas into a pipe, and then passing a moisture-reactive monomer together with the gas. Furthermore, the pipe may be heated with heating gas (such as steam or hot air).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealant useful for sealing a leak portion (thread joint, corroded portion, etc.) of a pipe (for example, a pipe for supplying or transporting gas such as a gas pipe) and a sealing agent useful for the same. The present invention relates to a sealing method using a sealing agent. In particular,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing agent useful for suppressing gas leakage from a gas pipe leaking part over a wide range and a sealing method using the same.

[0002]

2. Description of the Related Art Conventionally, when gas pipes have leaked, underground pipes are inspected from the ground by drilling or the like to find a high concentration of leaked gas, and excavation is performed to find a leaking location. Repaired by replacing fittings. However, in this method, if there are many leak locations, many operations such as finding the leak locations, excavation and backfilling are required, and the repair cost is high. Furthermore, this method also cannot preventively prevent pipes (such as joints) that have not yet leaked. Furthermore, although gas leakage due to corrosion in a threaded joint having a smaller diameter than a main pipe having a diameter of 100 A or more is increasing, the above-mentioned method cannot efficiently cope with such a small amount of gas leakage.

A gas conditioning method is one of the current methods of introducing a remaining agent into a pipe in order to prevent gas leakage. In this method, monoethylene glycol (MEG) or the like is inserted together with the gas flow while heating from the governor outlet tube. However, this method
The lead joint yarn of the main pipe made of cast iron (that is, asphalt applied to the seam) is heated and expanded by MEG.
The purpose is to prevent swelling and gas leakage. Therefore, no effect can be expected in preventing gas leakage from a small diameter threaded joint. Furthermore, because of the swelling type, when the introduction of the heating gas flow is stopped, the leakage suppressing property is lost, so it is necessary to continuously introduce the heating gas flow. Also, MEG
Therefore, it is necessary to evaluate the effects on gas workpieces such as joints and valves, rubber materials used for gas appliances, and the like.

[0004] Further, a foam sealing method in which a sealing agent is introduced into a pipe along with air bubbles is also known. However, according to this method, the moving distance of the bubble is restricted. For example, when the height difference is about 10 m or more, the sealant cannot be efficiently transferred together with the bubble. Therefore, in a high-rise building such as a building, it is difficult to seal a gas leak site in a pipe extending to each floor through a common inner pipe.

JP-A-11-140423 discloses a pipe sealant containing a tolylene diisocyanate urethane resin or a diphenylmethane-4,4'-diisocyanate urethane resin. In this document, there is disclosed a spray sealant composition for piping, in which the urethane-based resin prepolymer, a solvent and / or a plasticizer, and a propellant are sprayed, and a piping in which this composition is sprayed to penetrate a leaked portion and cure. Repair methods are also described. However, this method cannot be applied to a long pipeline because the scattering distance of the sealant by injection is as short as about 2 m.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sealant which is effective for suppressing gas leakage from a leak portion of a pipe, and a sealing method using the sealant. .

Another object of the present invention is to provide a sealant useful for suppressing corrosion leakage of a joint (such as a screw joint) over a wide range, and a sealing method using the sealant. .

Still another object of the present invention is to provide a sealant capable of effectively and efficiently sealing a leaked portion even with a small leak of gas, and a sealing method using the sealant.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, heated or heated the pipes or introduced steam or the like as necessary to form a specific sealing compound. When the gas is circulated in the gas pipe as a gas flow, the leak (or defect) can be effectively closed by a reaction or volume expansion at the leak (or defect) of the pipe. The present inventors have found that the present invention can be effectively performed not only by increasing the molecular weight or solidifying by a reaction including a polymerization reaction but also by expanding the volume, and the like, and completed the present invention.

[0010] That is, the sealant of the present invention is a sealant for suppressing gas leakage from a leak portion of a pipe, is capable of flowing together with a gas flow in the pipe, and has a reaction or volume expansion. It is made of a sealing compound capable of closing the leak portion. Examples of such a sealing compound include a moisture-reactive monomer, a radical-reactive monomer, and a cation-reactive monomer. Examples of the reactive compound include various sealing compounds whose viscosity or molecular weight increases due to a reaction or polymerization reaction, for example, silane coupling agents, cyanoacrylates, isocyanates, (meth) acrylic monomers, vinyl ethers , Cationically polymerizable olefins, cycloalkanes, lactones, lactams, cyclic ethers, cyclic sulfides, cyclic imines, and the like. These sealing compounds may be used in combination with a reaction or polymerization initiator. When a sealant capable of reacting with the sealant applied to the threaded joint is used, tight and strong sealing can be achieved. The sealant also includes a powdery water-absorbent resin that can seal a leaked portion by volume expansion.

According to the present invention, there is provided a method for suppressing gas leakage from a leak portion of a pipe, wherein the sealing compound capable of closing the leak portion is caused to flow together with a gas flow in the pipe. A sealing method for suppressing gas leakage from the leakage portion is also included. This method is effective for sealing a wide-area leak location (particularly, a small gas leak location).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In order to suppress gas leakage from a leaking part of a pipe, the sealant of the present invention can flow together with a gas flow in the pipe, and reacts or expands the leaking part (defect). Part) may be made of a sealing compound capable of closing or sealing. The reaction also includes various reactions (solidification reaction and polymerization reaction) that increase the molecular weight. In this reaction, at least viscosity is often expressed by the sealing compound, and usually, it is advantageous that a solidified or cured product is formed by the sealing compound. Also, the sealant
It is preferable to form a viscous material or a solidified or hardened material deposited at the leak portion of the tube.

[0013] The preferable conditions for the sealant include, for example, that polymerization (curing) or deposition due to a reaction occurs at a leak location, that the gas leakage suppressing effect is high, and that polymerization (curing) or deposition due to a reaction is high. It occurs at normal temperature (for example, about 15 to 25 ° C), its components are safe, and it does not adversely affect gas workpieces (such as joints and valves) and equipment that uses gas in pipes (such as gas equipment). , No adverse effect on combustion, low cost, and the like.

Examples of such a sealant include a sealant composed of a moisture-reactive curable component (moisture-reactive monomer), a sealant composed of a radical-polymerizable curable component (radical-polymerizable monomer), and a cationic polymerization-curable component. Includes sealants composed of mold components (cationically polymerizable monomers), sealants composed of components curable with carbon dioxide, and sealants composed of moisture-swellable components (moisture-swellable compounds). . These components (or sealing compounds)
May be used alone or in combination of two or more.

As the moisture-reactive curable component (moisture-reactive monomer), various moisture-reactive monomers, for example,
Organic metal compounds that can be polycondensed by hydrolysis, cyanoacrylates, isocyanates, and the like can be used. Examples of the organic metal compound that can be polycondensed by hydrolysis include hydrolyzable compounds containing a metal such as silicon, titanium, and zirconium (silane coupling agent, titanium coupling agent, zirconium coupling agent, and the like). Examples of such a compound include silicon-containing compounds having a reactive functional group (hydroxyl group, alkoxy group, acryloyl group, vinyl group, epoxy group, etc.) at the terminal, for example, alkyl silanols (eg, methyl silanol, etc.) , Alkoxysilanes (for example,
Tetra C _1-2 alkoxysilane such as tetramethoxysilane, trimethoxymethyl silane, trimethoxypropyl silane, triethoxyethyl silane, triethoxy butyl and the like tri C _1-2 alkoxy mono C _1-4 alkyl silane, di C _{1 -2} alkoxydi C _1-4 alkyl silane, mono C
_1-2 Arukokishitori C _1-4 alkyl silanes, etc.), halogenated silanes (e.g., dichloromethyl silane, dichlorodimethylsilane, trichlorosilane, trichloromethylsilane, tetrachlorosilane, Jikuroroji C _1-2 alkoxysilane, trichloro -2 -Cyanoethylsilane, etc.), epoxy group-containing alkoxysilanes (glycidyloxy C _2-3 alkyltri C _1-2 alkoxysilane, etc.), polymerizable group-containing alkoxysilanes ((meth) acryloyloxy C _2-3 alkyltri C) _1-2 alkoxysilanes, trichlorovinylsilane, dichlorodivinylsilane, dichloromethylvinylsilane, tetramethyldivinyldisiloxane, etc.), amino- or N-substituted amino-group-containing alkoxysilanes (N, N-diC _1-4 alkylamino C _2-3 alkyl tri-C _1-2 A Silane coupling link agent such Kokishishiran etc.), titanium compounds corresponding to these silane coupling agents (titanium coupling agent), a zirconium compound (zirconium coupling agent), such as aluminum compounds can be exemplified. These organometallic compounds can be used alone or in combination of two or more. As the organometallic compound, usually, a silane coupling agent is used.

As the cyanoacrylates, for example,
C cyanoacrylates such as methyl cyanoacrylate, ethyl cyanoacrylate, propyl cyanoacrylate, butyl cyanoacrylate, and t-butyl cyanoacrylate
Examples thereof include _1-6 alkyl esters (particularly, C _1-4 alkyl cyanoacrylate). These cyanoacrylates can be used alone or in combination of two or more.

Examples of the isocyanates include various polyisocyanates such as aromatic polyisocyanates (phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, etc.) and alicyclic polyisocyanates (cyclohexane diisocyanate, isophorone diisocyanate, etc.). And aliphatic diisocyanates (such as hexamethylene diisocyanate) and heterocyclic polyisocyanates. These polyisocyanates can be used alone or in combination of two or more.

As the radical polymerization-curable component (radical polymerizable monomer), various radical reactive monomers,
For example, (meth) acrylic monomers (or (meth) acrylates), vinyl esters (vinyl acetate, vinyl propionate, etc.), aromatic vinyls (styrene, vinyl toluene, α-methylstyrene, divinylbenzene, etc.), Examples include vinylamines, vinyl ketones, olefins, dienes and the like. Examples of (meth) acrylic monomers include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate,
C _1-10 alkyl (meth) acrylates such as butyl (meth) acrylate, hexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; hydroxyalkyl (meth) acrylate such as (meth) acrylic acid Esters: glycidyl (meth) acrylate and the like can be exemplified. These radically polymerizable compounds can be used alone or in combination of two or more.

The cationic polymerization-curable component (cationically polymerizable monomer) contains various cationically reactive monomers, and may be a non-ring-opening polymerizable monomer or a ring-opening polymerizable monomer. Examples of the non-ring-opening polymerizable monomer include vinyl ethers (divinyl ether; vinyl alkyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-propyl ether, vinyl isopropyl ether, vinyl isobutyl ether, and vinyl-n-pentyl ether; Hydroxyethyl vinyl ether, cyclohexane dimethanol divinyl ether, cyclohexyl divinyl ether, hydroxybutyl vinyl ether, propylene carbonate propenyl ether, triethylene glycol divinyl ether, etc., cationically polymerizable olefins (isobutylene, 3-
Methyl-butene) and the like. Examples of the ring-opening polymerizable monomer include, for example, cycloalkanes (cyclopropane, cyclobutane, cyclopentane, etc.
_3-5 alkanes), lactones (β-propiolactone,
γ-butyrolactone, δ-valerolactone, etc.), lactams (β-propiolactam, γ-butyrolactam,
δ-valerolactam, etc.), cyclic ethers (eg, ethylene oxide, propylene oxide, trimethylene oxide, tetrahydrofuran, tetrahydropyran), cyclic sulfides (eg, ethylene sulfide, trimethylene sulfide, tetrahydrothiophene), and cyclic imines (eg, ethylene imine) , Alkyleneimines such as propyleneimine and trimethyleneimine, and heterocyclic imines such as pyrrolidine and piperidine). These cationically polymerizable compounds can be used alone or in combination of two or more.

Conjugated dienes, which are unsaturated hydrocarbons, react with carbon dioxide to form a cured product. Examples of such a reaction-curable component with carbon dioxide include various conjugated dienes such as butadiene, 2,3-dimethylbutadiene, and isoprene.

These sealing compounds may be used in combination with a reaction initiator (reaction catalyst) or a polymerization initiator, and may be further used in combination with an accelerator if necessary. Such an initiator can be selected according to the reaction type of the sealing compound. For example, nitrogen-containing compounds such as amines (tertiary amines such as trimethylamine and triethylamine, secondary amines and primary amines), phosphorus-containing compounds such as triphenylmethanes, sulfur-containing compounds, peroxides (peroxides) Examples thereof include oxygen-containing compounds such as hydrogen, peracetic acid, t-butyl hydroperoxide, di-t-butyl peroxide, acetyl peroxide, and methyl ethyl ketone peroxide.

When a cationically polymerizable compound is used,
Rust generated in the joint leaking portion or cationic polymerization with a sealant (for example, a phenol group of a phenol resin, an epoxy resin, etc.) occurs, and the leaking portion of the joint may be effectively sealed. For example, in triphenylmethanes, a hydrogen atom of a tertiary carbon atom is easily extracted, and dimerization occurs in the presence of a trace amount of oxygen, or peroxide is generated in the presence of oxygen to form a radical polymerization initiator. It also has functions.

These sealing compounds can be used alone or in combination of two or more. It is sufficient that the sealing compound can flow along with the gas flow in the pipe, and the sealing compound having volatility at the operating temperature, for example, a sealing compound having a high vapor pressure or a sealing compound having a low boiling point. It is advantageous to use The boiling point of the sealing compound at normal pressure is 30 to 230 ° C, preferably 50 to 170 ° C, and more preferably about 70 to 120 ° C.

Further, it is preferable that the sealing compound is capable of reacting with a sealant already applied to a leaked part of a pipe (particularly, a joint part of the pipe) in order to enhance the sealing property. Such a sealing compound, depending on the type of the sealant of the leak portion,
For example, it can be selected from a silanol group, an alkoxysilyl group, a carboxyl group, an epoxy group (including a glycidyl group), an imino group, and the like, and may be selected from a cationically polymerizable compound as described above.

As the moisture-swellable component (or the moisture-swellable sealing compound), a powdery water-absorbent resin can be used.
Examples of the water-absorbing resin include conventional resins such as (meth) acrylic acid-based water-absorbing resin, polyvinyl alcohol-based water-absorbing resin, acrylamide-based water-absorbing resin, starch-based water-absorbing resin, and cellulose-based water-absorbing resin. . These water absorbing resins can be used alone or in combination of two or more. The water-absorbing resin may be used in combination with the reactive or polymerizable sealing compound, if necessary.

The average particle size of the water-absorbing resin may be any range as long as the resin can be suspended and circulated together with the gas flow.
The following (for example, 0.01 to 10 μm, preferably 0.0
1 to 2 μm (for example, 0.01 to 1 μm, more preferably about 0.01 to 0.5 μm), and it is advantageous to use it in the form of fine particles. When such a particulate water-absorbing resin is used, the fine particles are scattered over a long distance along the gas flow, and the water-absorbing resin trapped in the leaking portion expands by absorbing moisture, and the leaking portion (or defective portion) is absorbed. Is closed.

The sealant of the present invention is effective for closing a gas leak portion of a pipe body and suppressing or preventing gas leakage from the leak portion. INDUSTRIAL APPLICABILITY The sealing method of the present invention can be applied to various pipes (or pipes) through which gas flows, particularly gas pipes such as city gas, and the pipes are not limited to one flow path but are branched pipes having a plurality of flow paths. You may. The type of pipe is not particularly limited, and various pipes or pipes (for example, an average inner diameter of 15 to 60) are used.
It can be effectively applied to a tube having a diameter of about 0 mm. In particular, it can be effectively applied to a pipe or a pipeline having a joint which is likely to be corroded, for example, a joint of a branch pipe branched from the main pipe (for example, a threaded joint which is apt to cause a small amount of gas leakage). Gas leakage (corrosion leakage) can be effectively suppressed or prevented.

In the method of the present invention, the sealing compound is caused to flow together with the gas flow in the pipe to suppress the gas from leaking from the leak portion. Therefore, the method of the present invention is effective for sealing a wide area of a leak using a gas flow, and there is no need to search for a leak from a gas pipe or the like and repair the gas pipe. In addition, even if piping is performed over a wide area, it is possible to seal even a small leak location where it is difficult to search for a gas leak, so that the leak location can be repaired simply and efficiently.

In this method, the sealing of the leaking part (defective part) can be performed in a single step or in a plurality of steps depending on the type of the sealing compound. For example, when a moisture-curable sealing compound (such as a moisture-reactive monomer such as a silane coupling agent) or a moisture-absorbing and swelling sealing compound is used, a gas containing moisture (moisture) is introduced in advance, and then the sealing compound is used. Is mixed with a gas and allowed to flow through the pipe.
In this method, moisture is adhered to a leak portion or its vicinity by introduction of a gas containing moisture, and the leak portion is efficiently utilized by utilizing a reaction with a moisture-curable sealing compound or moisture absorption by a moisture-absorbing and swelling sealing compound. Can be closed.

Conversely, after introducing a moisture-curable sealing compound or a moisture-absorbing and swelling sealing compound into a pipe together with a gas and flowing the gas, a gas containing water is introduced into the pipe. May be used to seal the leak location.

When the sealing compound is self-reactive such as a coupling agent, it is not always necessary to introduce moisture (moisture). (A gaseous or vaporizable reactant such as moisture (moisture) or water vapor) may be introduced and reacted. The moisture (moisture) may be introduced as steam. If necessary, a catalyst (particularly, a gaseous or vaporizable catalyst such as an amine) can be introduced according to the type of the reaction.

Further, the sealant may be introduced while heating or heating the pipe. The heating or heating of the pipe can be performed by a conventional method, and the pipe may be heated by a heating means (a heater, a heating medium, or the like) from the outside of the pipe, or heated gas (a heating medium such as heated air or heated steam). The pipe may be heated or heated by being introduced into the pipe.

As a preferable method, there can be exemplified a method in which a silicone-based compound such as a silane coupling agent or a vaporizable sealing agent such as a vinyl ether is heated and introduced into a pipe if necessary. Also in this method, a sealant may be introduced together with a heating gas (heating medium such as heating air or heating steam).
It may be used as a reactant. According to such a method, gas leakage can be prevented at a high repair rate even in a pipe having a large difference in height (for example, a pipe of a high-rise building having a height of 10 m or more (a common internal pipe or the like)).

When a polymerizable sealing compound is used, the sealing compound and the gas are mixed and allowed to flow through a pipe without introducing a gas containing water in advance, so that the above-mentioned leakage occurs together with polymerization. Can be sealed. In this method, when a reaction initiator or a polymerization initiator is used, the initiator may be mixed with a gas together with the polymerizable compound and introduced into a pipe, and any one of the polymerizable compound and the initiator may be used. After being mixed with the gas and introduced into the pipe, the other component may be mixed with the gas and introduced into the pipe.

The content of the sealing compound in the gas is as follows:
It can be selected according to the type of the sealing compound, for example, 10 to 50,000 ppm, preferably 20 to 50 ppm on a weight basis.
00 ppm, more preferably about 50 to 1000 ppm.

When a moisture-curable and / or moisture-swelling type sealing compound is used as the sealing compound, the content of water in the gas can be appropriately selected according to the environmental temperature. -100% RH, preferably 60-1
It is about 00% RH, more preferably about 70 to 100% RH. The total amount of water used is, for example, 0.01 to 10 mol, preferably 0.05 to 5 mol, more preferably 0.1 to 3 mol per mol of the moisture-curable sealing compound.
It may be about mol, 0.01 to 1000 parts by weight, preferably 0.1 to 1000 parts by weight, more preferably 1 to 100 parts by weight based on 1 part by weight of the moisture-absorbing and swellable sealing compound.
It may be about 0 parts by weight. In the polymerizable sealing compound, the content of the initiator in the gas is, for example, 10 to 10
000 ppm, preferably about 20-5000 ppm, and more preferably about 50-1000 ppm.

The sealing compound may be constantly circulated through the pipe, but is usually circulated or introduced periodically (for example, at an appropriate time selected from about one week to one year). it can.

According to the present invention, even in the case of corrosion leakage, the leakage portion can be simply and effectively sealed to suppress or prevent gas leakage. Therefore, the present invention can be applied to various gas pipes, for example, city gas or fuel gas pipes (tubes or pipes) that are widely piped.

[0039]

According to the present invention, the use of the sealing compound which can be circulated together with the gas flow makes it possible to effectively suppress or prevent the gas from leaking from the pipe leaking portion. Further, even if the gas leaks very little, the leaked portion can be effectively and efficiently sealed. Therefore, it is useful for suppressing corrosion leakage of a joint (particularly a screw joint) over a wide range.

[0040]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 As a small container, a glass bottle that can be closed with a screw cap using a polyethylene (PE) cap was used. The following sealing agent was placed in a glass bottle, the cap screw was loosened slightly, and the bottle was left at room temperature for one month. Observation of the product gave the following results.

Tetramethoxysilane: A small amount of a glassy reaction cured product is formed around the screw portion of the glass bottle and the cap. The screw stopped turning. Propyltrimethoxysilane: A viscous substance was formed in the screw part.

Example 2 (Leakage suppression experiment using simulated pipe) Using a simulated screw joint made of acrylic resin (inner diameter: 25 mmφ), the joint portion was loosely sealed with a phenolic resin-based sealant to form a U-shaped pipe ( (Pipe extension: about 2 m, joint location: 4 locations), and a simulated pipe was formed. Note that a simulated pipe was formed by allowing the sealant to cure at 50 ° C. for one day. In this pipe, the amount of gas leakage from the joint is 0.02 ml / min (gas pressure: 500 mmH
₂ O).

A circulation circuit is formed by connecting both ends of such a pipe with a line, and a metering pump (flow rate: 1000 L / hour) is provided upstream of the circulation path (one end of the pipe). A bubbleable container was connected to the downstream side of the road (the other end of the pipe). At room temperature (about 20 ° C.), 50 ml of propyltrimethoxysilane was introduced into the pipe together with air while bubbling in the vessel. In addition, 50 ml of propyltrimethoxysilane evaporated in one day. And 1
When left at room temperature for 4 days and subjected to a leak test, no gas leakage was observed, and a sealing effect was confirmed.

Example 3 Screw piping (inner diameter 30 mm, length 500 mm, screw location;
A sealant was applied to the two (2) screw portions and left at 70 ° C. for 7 days. Thereafter, the screw of the screw portion was returned by 1/4 turn and loosened to form a simulated leak portion. In this pipe, the amount of gas leaking from the threaded portion is about 10 mmH ₂ O / min (gas pressure: 3
00mmH was ₂ O).

In such a simulated pipe, (1) propyltrimethoxysilane (30 ml) is sealed and heated at 80 ° C., and (2) water (30 ml) is sealed.
(3) triethylamine (0.3 m
When l) was sealed and heated at 50 ° C., gas leakage from the screw portion could be prevented.

(72) Inventor Shinichi Kawasaki 4-1-2 Hirano-cho, Chuo-ku, Osaka City Inside Osaka Gas Co., Ltd. (72) Inventor Terumitsu Kadomoto 4-1-2 Hirano-cho, Chuo-ku, Osaka City Osaka Gas F term (reference) 4H017 AA04 AB01 AB03 AB17 AC04 AC11 AD06 AE02

Claims (10)

[Claims] 1. A sealant for suppressing gas leakage from a leak portion of a pipe, which is capable of flowing together with a gas flow in the pipe, and capable of closing the leak portion by a reaction or volume expansion. Sealant composed of a sealing compound. 2. The sealant according to claim 1, wherein the sealant comprises a moisture-reactive monomer, a radical-reactive monomer, or a cation-reactive monomer. 3. A silane coupling agent, a cyanoacrylate, an isocyanate, a (meth) acrylic monomer, a vinyl ether, a cationically polymerizable olefin, a cycloalkane, a lactone, a lactam, a cyclic ether, a cyclic sulfide, And at least one selected from cyclic imines.
The sealant described. 4. The sealant according to claim 2, further comprising a reaction or polymerization initiator. 5. The sealant according to claim 4, which contains an amine or a triphenylmethane as a reaction or polymerization initiator. 6. The sealant according to claim 1, which is capable of reacting with a sealant applied to the joint portion. 7. The sealant according to claim 1, wherein the sealant is formed of a powdery water-absorbent resin. 8. A method for suppressing gas leakage from a leak portion of a pipe, comprising: flowing a sealing compound capable of closing the leak portion by reaction or volume expansion together with a gas flow in the pipe. A sealing method for suppressing leakage of gas from the leakage portion. 9. The method according to claim 8, wherein after introducing the gas containing moisture, the moisture-reactive monomer is passed through the pipe together with the gas.
The sealing method described. 10. The method of claim 8, wherein a wide area of the leak is sealed.
The sealing method described.