JP4474637B2 - Pipe line blocking member - Google Patents

Description

  The present invention relates to a pipeline blocking member that closes a pipeline of gas by thermal expansion during a fire.

  When connecting a gas pipe (for example, PE pipe) buried in the ground and a gas meter on the ground, for example, a metal pipe (steel pipe whose outer surface is coated with resin) is connected to the PE pipe, and this resin-coated steel pipe is connected to the ground. The pipe is connected to a gas meter. In this case, on the gas meter inlet side, the resin-coated steel pipe is connected to the gas meter inlet via a gas stopper and a gas meter joint, and the gas meter outlet is connected to the resin-coated steel pipe via a gas meter joint and a test tee. Is done. The gas meter joint, gas plug, and test tee constituting the connection part around the gas meter described above are made of a metal having fire resistance (for example, carbon steel) so that no gas leakage occurs even if a fire occurs. ). However, in order to maintain airtightness, a rubber seal member is provided inside the seal member. Therefore, the seal member may disappear due to a fire and gas leakage from the connection portion may occur.

In order to eliminate gas leakage from the gas pipe connection due to fire or the like, Patent Document 1 discloses that about 2 parts by mass of thermally expandable graphite powder oxidized, washed with water, and dried in a joint in about 100 parts by mass of the rubber raw material. It is described that it contains ~ 30 parts by mass, and contains an unheated plug having a gas flow hole made of a rubber material that expands in volume by about 10 to 500 times and becomes a carbonized hard body at about 180 to 260 ° C. ing. Further, in Patent Document 2, the end of the pipe to be connected is fitted to the tapered surface provided on the inner surface of the end of the joint body, and a fastening fitting is screwed to the end of the joint body to tighten. Natural (synthetic) compounded with a black intercalation compound that thermally expands in a non- foamed state when heated to a temperature of 180 ° C or higher so as to press against each facing surface of the gap formed by the fitting, connected pipe and joint body ) A pipe joint is described in which a rubber packing is formed by pressing and vulcanizing an annular body so that the Shore A hardness determined by JIS-K-6301 is 60 to 80 in a vulcanizing mold. According to these pipe joints, there is an advantage that the gas flow passage is blocked in the event of a fire, and secondary disasters due to leaked gas can be prevented. In addition, in Patent Document 3, for example, a hollow cylindrical thermal expansion member is provided in the middle of the supply pipeline, and the member expands thermally to shut off the supply pipeline, thereby causing a gas due to a fire or the like. It is described that gas leakage from the pipe connection can be prevented.
Japanese Patent Publication No. 61-32548 (page 1-3, FIG. 2) Japanese Utility Model Publication No. 1-23022 (page 2-3) JP 2001-252366 A (page 3-4, FIG. 1 and FIG. 2)

  The closed bodies described in Patent Documents 1 and 2 contain thermally expandable graphite powder (graphite intercalation compound) that undergoes volume expansion when heated to a temperature of about 180 ° C. or higher, so that the pipe joint has a temperature of 180 ° C. or higher. There is a problem that the function of shutting off the circulating gas cannot be exhibited until it is heated to a temperature.

Further, in an actual fire, since gas is flowing, gas pressure acts on the thermal expansion member, and the temperature of the piping portion gradually increases. The temperature rise curve is, for example, a heating curve according to ISO834 (576 ° C when 5 minutes have passed after heating, 678 ° C when 10 minutes have passed, 781 ° C when 20 minutes have passed, 842 ° C when 30 minutes passed) It becomes like this. When the thermal expansion member described in Patent Document 3 is heated, it becomes a brittle lump (burning residue) having small holes and gaps inside, and becomes extremely brittle. Therefore, when the thermal expansion member is gradually heated by a fire, the expansion speed is slow, so that gas flows into the small holes and gaps inside the expansion member (for example, city gas having a pressure of 2.5 KPa is 5 to 5 It flows at a flow rate of 120 m ³ / h), gradually collapses and scatters downstream, and eventually disappears from the gas pipeline. That is, since the conventional blocking structure has only the thermal expansion member installed in the gas pipeline, even if the pipeline is temporarily blocked by the thermal expansion member, the thermal expansion member disappears due to the pressure of the flowing gas, There is a problem that the function of closing the gas for a long time cannot be maintained.

  Accordingly, an object of the present invention is to solve the problems of the conventional pipe blocking member and to provide a pipe blocking member having a function of closing at least a part of the pipe even when the heating temperature is low.

Another object of the present invention is to provide a pipeline blocking member capable of solving the problems of the conventional pipeline blocking member and maintaining the function of closing gas for a long time.

In order to achieve the above-mentioned object, the pipeline blocking member of the present invention is a pipeline blocking member that is attached to a gas pipeline and shuts off the pipeline when the pipeline is heated,
A cylindrical thermal expansion member mainly composed of rubber and expanded graphite, containing 40 to 65 phr of the expanded graphite;
A comb-like deforming portion that is in contact with the inner peripheral surface of the thermal expansion member and has a length such that the inner tips interfere with each other when the inner portion of the pipe is bent along with the expansion of the thermal expansion member ; , and a base portion which is folded back on the outer peripheral side of the thermal expansion member from the root portion of the flexible portion, and a holding member having a U-shaped cross section which holds the thermal expansion member is supported on the conduit,
Is provided .
In the present invention, the expanded graphite preferably starts expanding at a temperature of 170 ° C. or higher and lower than 200 ° C. The expansion start temperature of expanded graphite is most preferably 170 ° C. (or higher). In addition, phr (per hindered rubber) is a unit indicating the blending amount of an additive (for example, expanded graphite) with respect to 100 parts by mass of rubber.

  In the present invention, the shape of the holding member is not limited to a complete cylinder, and may be a cylinder or an arc shape in which a part thereof is cut out along the axial direction.

  In the present invention, the thermal expansion member is formed in a cylindrical shape, and when the diameter of the pipeline is X and the volume of the thermal expansion member / the exit side area of the pipeline is Y, The volume is preferably set so that Y exists in a region above a straight line represented by 0.3246X-0.4334.

  According to the pipeline blocking member of the present invention, since the thermal expansion member contains 40 to 65 phr of expanded graphite, the thermal expansion member can block at least a part of the pipeline at a low heating temperature, causing gas leakage. Can be reliably prevented. In particular, it is effective to use expanded graphite that starts expansion at a temperature of 170 ° C. or higher and lower than 200 ° C.

  According to the pipe line blocking member of the present invention, when the thermal expansion member is supported by the holding member that is deformed in the direction of closing the pipe line, the heated thermal expansion member is prevented from collapsing, and for a long time. The function of closing the pipeline can be maintained.

  According to the pipe line blocking member of the present invention, the holding member has an annular portion that is folded back from the root portion of the comb-like deformed portion to the outer peripheral surface side of the thermal expansion member. Because it is easily deformed by the expansion force of the thermal expansion member and holds its end face, the heated thermal expansion member stays in the pipeline even when subjected to gas pressure, and more reliably closes the pipeline for a long time. Can do.

  According to the pipe line blocking member of the present invention, gas leakage can be prevented more reliably by setting the volume of the thermal expansion member according to the diameter of the joint.

  Hereinafter, the details of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view showing an example of a gas meter portion in which the gas blocking member of the present invention is used, and FIG. 2 (a) shows a main part of a joint for a gas meter having a blocking member for gas piping according to an embodiment of the present invention. 2 (b) is a cross-sectional view taken along the line AA of FIG. 2 (a), FIG. 3 (a) is a cross-sectional view showing the main part of the joint for a gas meter during a fire, and FIG. FIG. 3A is a plan view taken along the line B-B in FIG. 3A, FIG. 4A is a plan view in which the holding member is developed, and FIG. 4B is a side view thereof. FIG. 5 is a diagram showing the relationship between the joint diameter and the volume of the thermal expansion member / the joint outlet area.

  When a metal pipe (resin-coated steel pipe) is connected to a plastic pipe (for example, PE pipe) buried in the ground and this metal pipe is set up on the ground and connected to a gas meter on the ground, for example, as shown in FIG. On the inlet side of the gas meter 1, a resin-coated steel pipe 2 whose outer surface is coated with a resin is connected to the tip of a PE pipe (both not shown) connected to the gas main pipe, and the gas meter joint is started up on the ground. 4 is connected to the inlet of the gas meter 1. On the other hand, on the outlet side of the gas meter 1, a resin-coated steel pipe 3 is connected to a gas meter via a flexible pipe (both not shown) connected to a header in the building, and the resin-coated steel pipe 3 is The joint 4 is connected to the outlet of the gas meter 1. 5 is a gas stopper, and 6 is a test Qi. As the gas meter joint 4, for example, a short type gas meter joint having a joint body and a tightening nut is used, and a thermal expansion member (not shown) having fire resistance is mounted therein.

The thermal expansion member having fire resistance used in the present invention is formed of a material mainly composed of rubber and expanded graphite, and particularly contains expanded graphite that starts thermal expansion at a temperature of 170 ° C. or higher and lower than 200 ° C. Is preferred. This thermal expansion member is obtained by filling a mold with a rubber compound obtained by kneading raw material rubber, expanded graphite that thermally expands in an unfoamed state, and, if necessary, a filler, a softening agent, a vulcanizing agent, and the like. It is manufactured by molding and then press vulcanizing. As the raw material of expanded graphite, graphite having advanced crystallization such as natural graphite, pyrolytic graphite, and cache graphite is used. For example, natural graphite having a layered structure in which a carbon six-membered ring spreads in a network is used as sulfuric acid, nitric acid or By soaking in a mixture or the like, an intercalation compound in which a reactant is incorporated between layers (interlayer spacing is 3.354 angstroms) is obtained. This intercalation compound is a conductive intercalation compound in which the bonding between the reactant and the carbon plane is weak and the carbon atom plane is not lost. When expanded graphite is heated to 17 ° C. or higher, the volume increases several times to several tens of times in a non- foamed state, and when heated to 800 ° C. to 1000 ° C., the apparent volume increases 100 to 250 times. This is because when expanded graphite is heated rapidly, reactants between layers (for example, a compound of bisulfate ions and sulfuric acid formed by a mixed acid of sulfuric acid and nitric acid) gasifies into SOx and water vapor, which are bound at that time. This is because bonds between weak layers are broken and graphite expands in the layer direction. The expansion temperature can be adjusted by adjusting the bulk density of the expanded graphite (the expansion temperature decreases as the bulk density of the expanded graphite increases). In order for the thermal expansion member to start thermal expansion at the low temperature (temperature less than 200 ° C.) as described above, the expanded graphite needs to be contained in 40 phr or more. However, if the content of expanded graphite is too large, kneading of rubber and expanded graphite becomes insufficient, and a normal molded product cannot be obtained, so the content of expanded graphite is 65 phr or less. In the present invention, natural rubber (NR), nitrile butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPDM), silicone rubber (Q) and the like can be used as raw material rubber.

  The thermal expansion member preferably has a mechanical strength that does not collapse even when exposed to a high temperature of 800 ° C. or higher. In order to ensure a good sealing property, the Shore A hardness is 50 to 80 degrees. It is desirable to have a hardness that falls within the range. The above-mentioned thermal expansion member is formed in a cylindrical shape. However, the thermal expansion member is not limited to a complete cylinder, and a part of the thermal expansion member is cut along the axial direction as long as it is in a state of closing the pipe line when thermally expanded. A missing tube or arc shape may be used.

The thermal expansion member may be attached to the outlet side of the gas pipeline (for example, a gas meter joint) alone, but can be attached to the gas pipeline via another member. The pipe line blocking member 7 is provided on the gas outlet side of the joint body 41 where the gas flows in the direction of the arrow as shown in FIG. 2 (a), and has a heat resistance as shown in FIG. 2 (b). It has a cylindrical holding member 8 made of (for example, austenitic stainless steel such as SUS304) and a cylindrical thermal expansion member 9 held therein. As shown in FIGS. 4A and 4B, the holding member 8 is a member having a substantially U-shaped cross section including a base portion 8a and a comb-like deformed portion 8b longer than the base portion 8a. A sheet-like thermal expansion member 9 (not shown in FIG. 4) is inserted in between, and after being rounded, it can be inserted into the joint body 41 as shown in FIG. The pipe line blocking member 7 is prepared by setting a holding member 8 formed in a cylindrical shape in a mold, injecting a raw material into the molding cavity, and molding the thermal expansion member 9 into a cylindrical shape. Also good. When the gas meter coupling shown in FIG. 2 is heated, the inside thereof is in the state shown in FIG. That is, when the thermal expansion member 9 is heated, its volume expands to several to ten times, so that the comb-shaped deformed portion 8 b of the holding member 8 is bent inside the joint body 41. Therefore, even when gas flows in from the direction of the arrow as shown in FIG. 3A, the collapse of the thermal expansion member 9 is prevented by the deformable portion 8b and remains inflated, and the gas pipeline can be closed. it can. For example, a heating curve according to ISO834 is obtained while blowing 2.5 KPa of compressed air at a flow rate of 7 m ³ / h into a short type gas meter joint provided with the pipe line blocking member 7 shown in FIG. 3A on the gas outlet side. As described above, when heated to 1049 ° C. for 2 hours, it was confirmed that the thermal expansion member 9 maintained the expanded state and closed the gas conduit. For comparison, heating was performed while blowing compressed air under the same conditions as above to a short-type gas meter joint in which only the thermal expansion member 9 was provided on the gas outlet side. As a result, the thermal expansion member 9 disappeared from the pipeline, It was confirmed that a cavity penetrating the outlet side was formed.

  The holding member used in the present invention is formed of a heat-resistant metal material. Specific materials include austenitic stainless steel such as SUS304, martensitic stainless steel such as SUS420, silicon manganese steel, Manganese chromium steel, Fe—Mn—Si, Fe—Ni—Co—Ti, and shape memory alloys such as Fe—Ni—C can be used. Since these materials may be exposed to a high temperature of 800 ° C. or higher, it is preferable to use stainless steel heat resistant steel among these materials.

(Experiment 1)
A raw material mixture mainly composed of nitrile butadiene rubber (NBR) and expanded graphite was kneaded, and then filled into a mold, followed by molding and press vulcanization to prepare a cylindrical thermal expansion member. Here, three types of thermal expansion members having different expansion graphite amounts of 40 phr (Example 1), 65 phr (Example 2), and 37 phr (Comparative Example 1) were prepared. After the pipe line blocking member formed by inserting these thermal expansion members into the SUS304 holding member shown in FIG. 4 is disposed on the outlet side of the joint body (diameter: 20A) as shown in FIG. While the compressed air of 2.5 KPa was blown from the inlet side at a flow rate of 7 m ³ / h, it was heated to 1050 ° C. for 2 h so as to have a heating curve according to ISO 834, and then the outer periphery of the joint body was cooled to room temperature. In this heating and cooling process, the temperature when air outflow from the outlet side of the joint body (blocking temperature) and the flow rate of air flowing out from the joint body outlet when the joint is cooled to room temperature (leakage) Amount) was measured. Table 1 shows the blending amount (content) of the expanded graphite, the weight of the thermal expansion member, the cutoff temperature, and the leakage amount in the above Examples and Comparative Examples.
(Table 1)

  From Table 1, when the content of expanded graphite is small (Comparative Example 1), the amount of leakage increases, whereas when the content of expanded graphite is 40 phr and 65 phr (Examples 1 and 2), It can be seen that gas leakage from the outlet side is extremely small, and further, the gas expands at a temperature lower than that of Comparative Example 1 by 30 ° C. or more. Further, although not shown in Table 1, it was confirmed that when the content of expanded graphite exceeds 65 phr, it is impossible to mold the thermal expansion member.

(Experiment 2)
A plurality of thermal expansion members having the composition of Example 1 and different volumes are prepared, and each thermal expansion member is mounted on the outlet side of the joint body as shown in FIG. The compressed air was blown at a flow rate of 7 m ³ / Hr and heated to 940 ° C. for 1 h or 1050 ° C. for 2 h so as to have a heating curve according to ISO 834, and then the outer periphery of the joint body was cooled to room temperature. Here, the diameter of the joint was changed to measure the amount of air leakage, and the result shown in FIG. 5 was obtained. In FIG. 5, the horizontal axis represents the joint diameter (X), the vertical axis represents the volume of the thermal expansion member / the outlet side area (Y) of the joint, and a straight line that satisfies the relationship Y = 0.3246X−0.4334. In the region above, the leakage amount satisfies the standard, and in the region below this line, the leakage amount does not satisfy the standard. From FIG. 5, it can be seen that the volume of the thermal expansion member may be set so as to be within the region above the straight line according to the diameter of the joint.

  In the above description, an example in which the pipe line blocking member is applied to a gas meter joint has been described. However, the pipe line blocking member of the present invention can be applied to members constituting other gas pipes such as a gas plug and a test chee. Of course.

It is a front view which shows an example of the gas meter part in which the pipe line interruption member of the present invention is used. It is sectional drawing {(a)} which shows the principal part of the gas meter coupling concerning embodiment of this invention, and the AA arrow directional view {(b)} of Fig.4 (a). It is sectional drawing {(a)} which shows the principal part of the gas meter coupling | bonding of FIG. 4 at the time of a fire, and the BB arrow line view {(b)} of FIG. 5 (a). It is the top view {(a)} which developed the holding member, and the side view {(b)} of FIG. It is a figure which shows the relationship between the aperture of a joint, and the volume of a thermal expansion member / the exit side area of a joint.

Explanation of symbols

1: Gas meter, 2: Resin-coated steel pipe, 3: Flexible pipe, 4: Gas meter joint, 41: Fitting main body, 5: Meter gas stopper, 6: Test chi, 7: Pipe line blocking member, 8: Holding member, 8a: Base 8b: Deformation part, 9: Thermal expansion member

Claims (2)

A pipe blocking member that is mounted on a gas pipe and shuts off the pipe when the pipe is heated;
A cylindrical thermal expansion member mainly composed of rubber and expanded graphite, containing 40 to 65 phr of the expanded graphite;
A comb-like deforming portion that is in contact with the inner peripheral surface of the thermal expansion member and has a length such that the inner tips interfere with each other when the inner portion of the pipe is bent along with the expansion of the thermal expansion member ; , and a base portion which is folded back on the outer peripheral side of the thermal expansion member from the root portion of the flexible portion, and a holding member having a U-shaped cross section which holds the thermal expansion member is supported on the conduit,
Conduit blocking member comprising a. 2. The pipeline blocking member according to claim 1, wherein the expanded graphite is expanded graphite that starts expanding at a temperature of 170 ° C. or higher and lower than 200 ° C. 3.

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