JP2014185715A - Polyethylene sleeve for preventing pipe erosion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakage of a polyethylene sleeve and erosion of a pipe caused by water intrusion from an end.SOLUTION: In a polyethylene sleeve 11 for preventing pipe erosion covered on an outer periphery of a pipe 1 buried underground, a water-absorbing swelling material 22 is provided on an inner peripheral side of a basic sleeve material 21 constituting an outer layer, and the water-absorbing swelling material 22 is sandwiched between the basic sleeve 21 and the pipe 1. The water-absorbing swelling material 22 on the inner peripheral side of the basic sleeve material 21 functions as a seal material, and thus, water intrusion from an end of the polyethylene sleeve 11 can be prevented. Even when breakage occurs in the basic sleeve material 21, the water-absorbing swelling material 22 swells by intrusion of groundwater, and functions as a self-repair material for closing the breakage, and therefore, water shielding performance can be maintained, and erosion of the pipe 1 can be prevented.

Description

  The present invention relates to a polyethylene sleeve for protecting a pipe embedded in the ground from corrosion.

  For example, when a metal pipe such as a cast iron pipe is buried in the ground as a water pipe, in order to prevent corrosion of the pipe due to contact with corrosive soil or the influence of groundwater, a polyethylene sleeve is put on the outer periphery of the pipe, and the pipe By connecting each other with a joint part, a pipe line is formed in the excavated part of the ground, and a method of backfilling earth and sand by covering the pipe line is performed.

  In this construction method, when the earth and sand are backfilled, a part of the outer periphery with a large step, such as a joint, has a rupture in the polyethylene sleeve due to the impact and weight of the input earth and sand, and the groundwater flows from the rupture into the polyethylene sleeve. There is a risk that the anticorrosion effect may be reduced due to intrusion between the pipe and the humus soil directly in contact with the pipe.

  As a countermeasure against such a phenomenon, in Patent Document 1 below, as shown in FIG. 5, the outer periphery of the tube 1 is covered with a polyethylene sleeve 50, and both ends of the polyethylene sleeve 50 are wound and tightened with a fastening tool 51. A plastic cover 52 divided by cuts extending in the tube axis direction is elastically deformed and externally fitted to the portion 2, and a locking member 53 is fitted to the restored divided portion of the cover 52, so that the cover 52 is divided. A corrosion-proof structure has been proposed in which the portion is closed and both ends of the cover 52 are wound up with the fasteners 54.

  In this anticorrosion structure, the cover 52 can be externally fitted after the pipe 1 is connected by the joint portion 2, so that the workability is good, and the cover 52 can be formed thick, so that the impact of earth and sand during backfilling is reduced. Even if it acts, it is supposed that a breakage is unlikely to occur in the cover 52.

JP-A-7-253190

  However, even in the anticorrosion structure of the pipe as described in Patent Document 1, due to the collision of concrete pieces mixed in the earth and sand to be backfilled, or the drop impact of the earth and sand thrown in with a large drop when the pipe is deep The cover 52 may be broken due to damage.

  Further, there is a problem that the water immersion from the end portions of the polyethylene sleeve 50 and the cover 52 cannot be completely prevented only by winding the polyethylene sleeve 50 and the cover 52 with the fasteners 51 and 54.

  Accordingly, an object of the present invention is to prevent corrosion of a pipe due to water breakage from a polyethylene sleeve break or end.

  In order to solve the above-mentioned problems, the present invention provides a polyethylene sleeve for pipe corrosion protection that covers the outer circumference of a pipe embedded in the ground, and a water-absorbing swelling material is provided on the inner circumference side of a polyethylene basic sleeve material that forms the outer layer. The material was sandwiched between the basic sleeve material and the tube.

  In addition, a water-absorbing swelling material is superposed on and fixed to the inner peripheral surface of the basic sleeve material, and a polyethylene basic sleeve material is laminated on the inner peripheral surface of the water-absorbing swelling material as necessary to improve corrosion resistance. And stuck.

  As this water-absorbing swelling material, bentonite, water-expandable acrylic resin, water-absorbing polyurethane resin or vinyl alcohol / acrylate copolymer processed into a mat shape as a functional material is used.

  The polyethylene sleeve that covers the outer periphery of the pipe is made to overlap the water-absorbing swelling material over the entire inner peripheral surface of the basic sleeve material, thereby improving the corrosion resistance of the entire pipe line.

  Also, in consideration of workability and economic efficiency, the water-absorbing swelling material should be overlapped only in the portion corresponding to the joint portion of the basic sleeve material, or the folding portion of the basic sleeve material that covers the pipe by folding the surplus portion. The water-absorbing swelling material overlaps only near the entrance.

  In this polyethylene sleeve, the water-absorbing swelling material provided on the inner peripheral side of the polyethylene basic sleeve material functions as a sealing material, so that water from the end is prevented.

  In addition, even if a breakage occurs in the basic sleeve material, the water-absorbing swelling material swells due to inundation such as ground water and functions as a self-healing material that closes the breakage, so that the water shielding performance is maintained and corrosion of the pipe is prevented. be able to.

The polyethylene sleeve which concerns on this invention, Comprising: The partially expanded vertical side view which shows embodiment of (a) 2 layer separate type | mold, (b) 2 layer integrated type, (c) 3 layer integrated type Partially enlarged longitudinal sectional side view showing a corrosion prevention structure [Embodiment 1] by a polyethylene sleeve in which a water-absorbing swelling material is provided on the entire inner peripheral surface of the basic sleeve material same as above. Partially enlarged longitudinal side view showing a corrosion-proof structure [Embodiment 2] by a polyethylene sleeve provided with a water-absorbing swelling material only in a portion corresponding to the joint portion of the pipe (A) Partially enlarged longitudinal side view, (b) A cross-sectional view taken along arrow A, showing a corrosion-proof structure [Embodiment 3] by a polyethylene sleeve provided with a water-absorbing swelling material only in the vicinity of the entrance of the foldable portion. Partially longitudinal side view showing the corrosion prevention structure of a pipe described in Patent Document 1

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an enlarged cross-sectional view showing a portion of a laminated structure of polyethylene sleeves 11 and 12 according to the present invention.

  These polyethylene sleeves 11 and 12 are placed on the outer periphery of the metal sleeve 1 to protect it from corrosion, such as a ductile cast iron pipe used for water and sewerage.

  1A and 1B show a polyethylene sleeve 11 having a two-layer structure. These polyethylene sleeves 11 are provided with a water-absorbing swelling material 22 on the inner peripheral side of the basic sleeve material 21 so that the water-absorbing swelling material 22 is sandwiched between the basic sleeve material 21 and the pipe 1.

  Among these, the polyethylene sleeve 11 shown in FIG. 1 (a) is one in which the basic sleeve material 21 and the water-absorbing swelling material 22 are separated, and the outer periphery of the tube 1 is first covered with the water-absorbing swelling material 22 during construction. The basic sleeve material 21 is put on the outside.

  The polyethylene sleeve 11 shown in FIG. 1 (b) is obtained by superimposing a basic sleeve material 21 and a water-absorbing swelling material 22 in advance and fixing them with an adhesive or the like. .

  FIG. 1C shows a polyethylene sleeve 12 having a three-layer structure. The polyethylene sleeve 12 has a water-absorbing swelling material 22 superimposed on an inner peripheral surface of a basic sleeve material 21 forming an outer layer, and is fixed with an adhesive or the like. Further, the basic sleeve material 21 forming the inner layer is superposed on the inner peripheral surface of the water-absorbing swelling material 22 and fixed with an adhesive or the like.

  Thus, the polyethylene sleeves 11 and 12 are obtained by laminating the basic sleeve material 21 and the water-absorbing swelling material 22, and the basic sleeve material 21 is a general single-layer manufactured using a metallocene catalyst or the like. A polyethylene sheet is used.

  As the water-absorbing swelling material 22, bentonite, water-expandable acrylic resin, water-absorbing polyurethane resin or vinyl alcohol / acrylate copolymer processed into a mat shape is used.

  FIGS. 2 to 4 show the first to third embodiments of the anticorrosion structure in the case where the two-layer integrated polyethylene sleeve 11 is used, with respect to a portion where the pipes 1 are joined together by the joint portion 2. Note that the inner peripheral surface of the pipe 1 is provided with a lining 1a such as cement mortar or epoxy resin.

  In Embodiment 1 shown in FIG. 2, the polyethylene sleeve 11 is a long one in which the sheet-like water-absorbing swelling material 22 overlaps the entire inner peripheral surface of the basic sleeve material 21.

  And the polyethylene sleeve 11 is put on the outer periphery of each trunk | drum (straight part) of the pipe | tube 1 over a pipe-axis direction, and the polyethylene sleeve 11 which covers one pipe | tube 1 is extended longer than the edge part of the pipe | tube 1. The extension portion is covered with the joint portion 2, over the joint portion 2 and over the other pipe 1, and the end portion of the polyethylene sleeve 11 and the portion facing the joint portion 2 are wound with a fastener 30 such as a rubber band. Tighten.

  When such a polyethylene sleeve 11 is used, the water absorbing / swelling material 22 provided on the inner peripheral side of the polyethylene basic sleeve material 21 forming the outer layer functions as a sealing material, so that water from the end of the polyethylene sleeve 11 is prevented. Is done.

  Further, even if a breakage occurs in the basic sleeve material 21, the water-absorbing swelling material 22 swells due to inundation such as ground water and functions as a self-repairing material that closes the breakage, so that the water shielding performance is maintained and the pipe 1 is corroded. Can be prevented.

  Further, in this embodiment, since the polyethylene sleeve 11 covers not only the uneven joint portion 2 but also the body portion of the pipe 1, the pipe line can be protected from corrosion as a whole, and the earth covering is prevented. It is also possible to cope with a case where the drop impact due to earth and sand during embedding is large or when the pipe 1 is embedded in highly corrosive soil.

  In addition, since the basic sleeve material 21 and the water-absorbing swelling material 22 are integrated, the construction can be performed quickly. However, if the basic sleeve material 21 and the water-absorbing swelling material 22 are thick and heavy, and are long and difficult to construct, a two-layered polyethylene sleeve 11 as shown in FIG. The swelling material 22 and the basic sleeve material 21 may be sequentially covered on the outer periphery of the tube 1.

  Next, in the second embodiment shown in FIG. 3, as the polyethylene sleeve 11, the sheet-like water-absorbing swelling material 22 overlaps only in the portion corresponding to the joint portion 2 of the basic sleeve material 21. Use a short one that covers only the vicinity.

  In this case, the polyethylene sleeve 50 that covers the outer periphery of each barrel portion of the tube 1 is not a conventional laminated structure, the water-absorbing swelling material 22 of the polyethylene sleeve 11 is placed along the protruding portion of the joint portion 2, and both end portions A portion where the basic sleeve material 21 becomes a single layer is placed on the outer periphery of the polyethylene sleeve 50 of each tube 1, and this portion is wound with a fastening tool 30 such as a rubber band.

  In this embodiment, since only the joint portion 2 that has a large unevenness on the outer periphery and easily breaks is covered with the polyethylene sleeve 11 having a two-layer structure with a short length in the tube axis direction, the construction is easy and corrosion-resistant. The required material cost can also be suppressed.

  Next, in Embodiment 3 shown in FIG. 4, as the polyethylene sleeve 11, the basic sleeve material 21 is an internal space of the polyethylene sleeve 11 in the folded portion 21 a of the basic sleeve material 21 folded at the upper part in the installed state of the tube 1. A portion in which the rod-like water-absorbing swelling material 22 overlaps is used only at the base-point side portion that communicates with and contacts, that is, in the vicinity of the inlet portion 21b of the folding portion 21a.

  In this case, a polyethylene sleeve 11 that covers one of the pipes 1 is placed over the other pipe 1 over the joint portion 2, and the polyethylene sleeve 50 is similarly covered over the outer circumference of the other pipe 1. The position facing the end portion and the joint portion 2 is tightened with a fastener 30 such as a rubber band.

  In this embodiment, even when a breakage occurs in the basic sleeve material 21 in the upper part of the pipe 1 where the earth and sand to be backfilled collide with falling, the water absorption swelling material 22 prevents water from flowing downward from the folding portion 21a. Therefore, the water shielding effect can be obtained and the corrosion of the tube 1 can be prevented only by using a slight amount of the water-absorbing swelling material 22.

  In the first to third embodiments, the case where the polyethylene sleeve 11 having the two-layer structure is used has been exemplified. However, the case where the polyethylene sleeve 12 having the three-layer structure is used has the same anticorrosion structure and further has a water shielding performance. Can be increased.

DESCRIPTION OF SYMBOLS 1 Pipe 1a Lining 2 Joint part 11,12 Polyethylene sleeve 21 Basic sleeve material 21a Folding part 21b Inlet part 22 Water absorption swelling material 30 Fastening tool 50 Polyethylene sleeve

Claims (7)

  In the polyethylene sleeve for pipe corrosion protection that covers the outer periphery of the pipe (1) buried in the ground, a water-absorbing swelling material (22) is provided on the inner circumference side of the polyethylene basic sleeve material (21) forming the outer layer, A polyethylene sleeve for pipe corrosion prevention, characterized in that 22) is sandwiched between the basic sleeve material (21) and the pipe (1).   The polyethylene sleeve for pipe corrosion prevention according to claim 1, wherein a water-absorbing swelling material (22) is superposed and fixed on the inner peripheral surface of the basic sleeve material (21).   The polyethylene sleeve for pipe corrosion prevention according to claim 2, wherein a polyethylene basic sleeve material (21) is further overlapped and fixed to the inner peripheral surface of the water-absorbing swelling material (22).   4. The polyethylene sleeve according to claim 1, wherein bentonite, water-swellable acrylic resin, water-absorbing polyurethane resin, or vinyl alcohol / acrylate copolymer is used as the water-absorbing swelling material (22) as a functional material. Polyethylene sleeve for pipe corrosion prevention, characterized by using a processed product.   A pipe corrosion-proof structure using the polyethylene sleeve according to any one of claims 1 to 4, wherein the polyethylene sleeve is placed over the outer periphery of the pipe (1) over the entire inner peripheral surface of the basic sleeve material (21). An anticorrosive structure for a pipe, characterized in that the water-absorbing swelling material (22) overlaps.   A pipe anti-corrosion structure using the polyethylene sleeve according to any one of claims 1 to 4, wherein a polyethylene sleeve that covers the outer periphery of the pipe (1) joined by the joint (2) is a basic sleeve material (21 The water-absorbing swelling material (22) overlaps only in the portion corresponding to the joint portion (2).   A pipe anti-corrosion structure using the polyethylene sleeve according to any one of claims 1 to 4, wherein the polyethylene sleeve is covered with an extra portion folded on the outer periphery of the pipe (1). A pipe corrosion-proof structure characterized in that the water-absorbing swelling material (22) overlaps only in the vicinity of the inlet portion (21b) of the portion (21a).

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