JP5916477B2 - Construction method of curved part of piping - Google Patents

Description

  The present invention relates to a method for constructing a curved portion of piping configured by connecting a plurality of pipe members.

  In general, piping such as water and sewage and gas is configured by connecting a plurality of pipe members such as straight pipes and curved pipes. The tube members are connected via a joint. Or the other pipe member is inserted and connected to the receptacle attached to one pipe member.

  For example, when such a pipe is embedded in a road, it is arranged along with the road alignment, and at an intersection or a turning corner, a curved portion having an angle according to the road alignment is formed. . Moreover, when other structures, such as a manhole, interfere, it arrange | positions so that another structure may be detoured combining a curve part. And a curved pipe is used for such a curved part as a pipe member. The bent pipe is formed at a bending angle in accordance with a standard at a manufacturing factory, and is shipped after checking whether it is within a preset allowable range (for example, see Patent Document 1).

  In recent years, polyethylene pipes are often used as pipe members. Polyethylene pipes are superior in corrosion resistance compared to steel pipes. Moreover, since it has a certain flexibility, it can follow the deformation of the ground, has excellent earthquake resistance, and is suitable for piping in soft ground. Such polyethylene pipes include straight pipes and curved pipes bent at a predetermined bending angle by plastic deformation, and are arranged in a predetermined linear shape by connecting them in combination.

JP-A-4-315902

  However, a bent pipe formed of a thermoplastic resin such as a polyethylene pipe is bent at a predetermined bending angle by plastic deformation as described above, but there are cases in which residual strain is generated inside by bending. is there. If residual distortion occurs, the bending angle of the bent pipe is within the predetermined tolerance range at the product inspection stage in the factory that manufactures the bent pipe, but it is shipped and delivered to the construction site. During temporary placement until use, there is a case where a so-called bend return occurs in which an action of returning to a straight line occurs and deviates from an allowable range. In particular, when the temperature in summer was high, the temperature of the tube itself was high, so bending back was likely to occur. Further, in a pipe member having a large diameter such as a sewage pipe and a pipe member having a large bending angle, the amount of plastic deformation at the time of bending increases, so that residual strain is likely to occur, and therefore, bending back tends to occur.

  If such a bending return occurs, the product falls outside the allowable range and becomes a non-standard product and cannot be used. For this reason, when the bent pipe is bent back, the bent pipe in which the bent return has occurred is returned to the factory or disposed of and used within the allowable range. Alternatively, a bent pipe that has been bent back has been re-bent and used so as to be within an allowable range at the construction site. However, in the former, it is necessary to prepare a curved pipe within a new allowable range, and there is a problem that it takes time and cost to prepare. In the latter case, there is no dedicated device for bending at the construction site, it must be done manually by the operator, and it is very laborious and accurate so that it is within the allowable range. It was extremely difficult to perform bending. In particular, in recent years, pipe members formed of thermoplastic resin are being applied to large diameter pipes having a diameter of 350 mm or more, and it is extremely difficult to bend such large diameter pipes on site.

  This invention is made | formed in view of the situation mentioned above, Comprising: Even if bending return arises in a curved pipe, it provides the construction method of the curve part of piping which can be constructed easily and correctly.

In order to solve the above problems, the present invention proposes the following means.
The present invention is a method for constructing a curved portion of a pipe configured by connecting a plurality of pipe members made of a thermoplastic resin, and is used for the curved portion, from a curved portion having a curvature and an end of the curved portion. A bending angle inspection process for confirming whether or not the bending angle of the bent pipe having the extending straight portion is within an allowable range, and bending the bent pipe so as to be within the allowable range when the bending angle is out of the allowable range. A re-bending process step and a bent pipe connecting step for connecting the bent pipes whose bending angle is within an allowable range, wherein the re-bending step includes the bent portion and the straight portion of the bent pipe. A heating step of holding both ends of the bent tube for a predetermined time in a state of being pulled so as to increase the curvature of the bent portion using a traction tool while the bent portion is heated, and after the heating step, Cooling step that cools while pulled by a towing tool It is characterized by having and.

  According to this method, when the bending angle of the bent pipe is outside the allowable range in the bending angle inspection process, the rebending process is performed. In the rebending process, as a heating step, the curved portion heated by the traction force of the traction tool can be easily plastically deformed by pulling with the traction tool while heating the curved portion having the curvature in the curved pipe, and the allowable range. The inner bending angle can be changed. And, as a cooling step, by cooling while pulling with a towing tool, the residual strain is removed in a state where the bending angle is within the allowable range, and a bent tube with the bending angle within the allowable range is obtained, The curved pipe can be connected as one configuration of piping in the curved pipe connecting step.

  Moreover, in the construction method of the curved portion of the pipe, the rebending step includes a traction member connecting step for connecting a pair of traction members to both ends of the curved pipe, and in the heating step, It is characterized by pulling the ends of the pulling members protruding from both ends of the curved pipe.

  According to this method, in the heating step, the ends of the pair of traction members connected to both ends of the curved pipe in the traction member connection step are pulled by the traction tool. For this reason, it is possible to increase the distance from the bent portion to be bent in the bent pipe to the position to be pulled by the traction tool, thereby increasing the bending moment acting on the bent portion and effectively bending the bent portion. be able to. Further, since the end of the curved pipe is not directly pulled by the traction tool, it is possible to reliably prevent the curved pipe itself from being damaged by the traction force of the traction tool.

  Moreover, in the construction method of the curved part of the piping, the heating step is characterized in that a covering sheet is covered in a heating range, and a heater is disposed on the outer peripheral surface of the covering sheet to heat.

  According to this method, in the heating step, by heating with the heater from the outer peripheral surface of the covering sheet, only the portion where the heater is disposed is not locally heated, and the range covered with the covering sheet is made uniform. The range can be bent and deformed uniformly by heating.

  Moreover, an aluminum foil is used as the covering sheet.

  According to this method, by using the aluminum foil as the covering sheet, the heat of the heater can be effectively and uniformly transferred to the bent portion of the bent tube and heated.

  According to the construction method of the curved portion of the pipe of the present invention, the curved portion of the pipe can be easily and accurately constructed even if the bent pipe is bent back.

It is a perspective view explaining an outline of piping of an embodiment of the present invention. It is a top view explaining the detail of the curved pipe used by the curve part in piping of embodiment of this invention. It is explanatory drawing explaining a bending angle test process and a bending angle confirmation process in the construction method of the curved part of piping of the embodiment of the present invention. In the construction method of the curved part of piping of an embodiment of the present invention, it is an explanatory view explaining connecting a member for traction at a heating step. In the construction method of the curved part of piping of the embodiment of the present invention, it is explanatory drawing explaining pulling while heating a curved pipe in a heating step. In the construction method of the curved part of piping of the embodiment of the present invention, it is a perspective view showing the 1st modification of the member for traction. In the construction method of the curved part of piping of the embodiment of the present invention, it is a perspective view showing the 2nd modification of the member for traction.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 shows a pipe 100 configured by connecting polyethylene pipes as a plurality of pipe members 1 to each other. Such a pipe 100 is used for a sewer pipe, a water pipe, a gas pipe or the like, and is generally buried under a road.
As shown in FIG. 1, for example, when the pipe 100 is buried under a road, the pipe 100 is buried along the road alignment, and thus has a straight line portion 101 and a curved portion 102 according to the road alignment. . In the straight part 101, a straight pipe 10 made of polyethylene is used as the pipe member 1. The straight pipe 10 has a fixed length, for example, a fixed length pipe 10a having a length of 5 m, and a cut tube 10b obtained by cutting the fixed length pipe 10a into a predetermined length. By combining these, a predetermined length is obtained. The linear part 101 is comprised. Further, the curved portion 102 uses a bent tube 20 bent at a predetermined angle.

  As shown in FIG. 2, the curved pipe 20 includes a curved portion 21 that is curved with a constant curvature, and a straight portion 22 that extends from both ends 21 a and 21 a of the curved portion 21. The straight portion 22 has at least a length for connecting to the other pipe member 1 adjacent to the bent pipe 20. Also, the bending angle θ of the bent portion 21 of the bent tube 20, that is, the center line L22b of the other straight portion 22 with respect to the extension line of the center line L22a of one straight portion 22 extending from both ends 21a and 21a of the bent portion 21 is There are multiple types of angles to make. For example, a bent tube 20 having a bending angle θ of 11.25 °, 22.5 °, 45 °, 90 °, etc. is prepared, and an appropriate bending angle θ according to the bending angle in the curved portion 102 of the pipe 100 is prepared. The curved pipe 20 is selected and used.

  As shown in FIG. 1, the straight pipes 10 and the curved pipes 20 are connected to each other using a joint 23. The joint 23 is a cylindrical member whose inner diameter is substantially equal to the outer diameter of the straight pipe 10 and the curved pipe 20, and each end of the pipe member 1 is inserted from both ends. Then, the pipe members 1 are connected to each other through the joint 23 by being energized and electrically welded with the pipe members 1 inserted from both ends.

Next, the construction method of such a piping 100, especially the construction method of the curved part 102 are demonstrated in detail.
First, the pipe member 1 required as the piping 100 is prepared as a preparation process. Specifically, a straight pipe 10 used for the straight part 101 of the pipe 100 and a curved pipe 20 used for the curved part 21 of the pipe 100 are prepared. As the straight pipe 10 used for the straight portion 101, a necessary number of the fixed tubes 10a corresponding to the length of the straight portion 101 are prepared, and the cut tube corresponding to the length of the adjustment portion generated by the plurality of fixed tubes 10a. 10b is prepared by cutting the fixed tube 10a. Moreover, as the curved pipe 20 used for the curved part 102, what has the bending angle (theta) according to the bending angle in the curved part 102 of the piping 100 is prepared.

Next, as a bending angle inspection step, it is confirmed whether or not the bending angle θ of the bent tube 20 used for the curved portion 102 is within an allowable range.
The bent tube 20 is manufactured and shipped at a factory so that the bending angle θ is generally within an allowable range defined by a tolerance set in advance with a design angle as a reference. However, due to residual strain, bending back may occur during shipment until it is temporarily placed on site and disposed as part of the pipe 100. In the bending angle inspection step, it is confirmed whether or not the bending angle θ of the bent tube 20 to be used has deviated from the allowable range by bending back.

  Specifically, as shown in FIG. 3, the curved pipe 20 is disposed on the mounting surface 200 a of the flat table 200. At this time, the bent pipe 20 is arranged in the direction along the center lines L21, L22a, and L22b so that no gap is generated between the bent pipe 20 and the mounting surface 200a of the table 200. As a result, the bent tube 20 is arranged such that its center lines L21, L22a, L22b are parallel to the mounting surface 200a of the table 200.

  In this state, the bending angle θ of the bent tube 20 is measured by applying the angle measuring device 30 to the upper portion of the outer peripheral surface of the bent tube 20. The angle measuring device 30 extends, for example, in a straight line, and a first ruler 32 having a protractor 31 attached to one end thereof, and a center point 31a of the protractor 31, and one end thereof being rotatable with respect to the first ruler 32. And a second ruler 33 attached thereto. One end of the second ruler 33 is provided with a needle 34 that extends beyond the center point 31a of the protractor 31 that is the center of rotation and that reads the displayed scale on the protractor 31. And the 1st ruler 32 is arrange | positioned so that it may become parallel to the centerline L22b in the upper part of one straight part 22 in the curved pipe 20. FIG. In addition, the second ruler 33 is arranged above the other straight portion 22 of the curved pipe 20 so as to be parallel to the center line L22a. And the bending angle (theta) is measured by reading the scale displayed on the protractor 31 which the needle | hook 34 shows in this state. When the bending angle θ is within the allowable range, the bent pipe 20 is used in a bent pipe connecting process described later. On the other hand, when the bending angle θ is outside the allowable range, the following rebending process is performed.

  In the rebending process, the bending pipe 20 having a bending angle θ outside the allowable range is bent. Specifically, the rebending process of the present embodiment includes a traction member connecting step for connecting a pair of traction members to both ends of the curved tube 20 and the curved portion 21 of the curved tube 20 while being heated. There are a heating step for holding the bent tube 20 at both ends pulled so as to reduce the distance between them, and a cooling step for cooling for a predetermined time after the heating step while being pulled. Details will be described below.

  As shown in FIG. 4, first, in the traction member connecting step, one end portions 40 a of a pair of traction members 40 are connected to both ends of the curved pipe 20. The pair of pulling members 40 are tubular members in the present embodiment, and the outer diameter thereof is set to be approximately equal to the inner diameter of the bent tube 20. For this reason, the pulling member 40 is in a state in which one end portion 40 a is fitted to the end portion of the bent tube 20 and the other end portion 40 b protrudes from the end portion of the bent tube 20. The material of the pulling member 40 is not particularly limited, but a material that does not bend and deform when pulling in a heating step and a cooling step described later is preferable, and polyethylene of the same material, steel having high rigidity, or the like is selected.

  Next, a heating step is performed. Specifically, as shown in FIG. 5, a traction tool 50 for traction is engaged with the other end portion 40 b of each traction member 40. As the traction tool 50, in this embodiment, a chain block 51 with two levers is used in combination. The chain block 51 includes a traction portion 52, a first hook 53 attached to the traction portion 52, a chain 54 extending from the traction portion 52, and a second hook 55 attached to one end portion of the chain 54. . The traction part 52 is cylindrical and has a winding part (not shown) around which the other end of the chain 54 is wound, a reduction gear mechanism (not shown) that rotates the winding part, and a reduction gear mechanism that is connected to the reduction gear mechanism in only one direction. A ratchet mechanism (not shown) that rotates the speed reduction mechanism and a lever 56 that rotates the ratchet mechanism are included. Therefore, by reciprocating the lever 56, the chain 54 can be wound around a winding portion (not shown) of the pulling portion 52, and thereby the distance between the first hook 53 and the second hook 55 is shortened. It is possible. In addition, a reduction mechanism (not shown) of the traction portion 52 can reduce the distance between the first hook 53 and the second hook 55 by applying a force acting on the lever 56 with a boost. Then, the first hooks 53 of the two chain blocks 51 are engaged with each other, and the second hooks 55 of the chain blocks 51 are engaged with the other ends of the pair of pulling members 40. Here, at the peripheral edge 40c of the other end portion 40b of the pulling member 40, the position where the second hook 55 of the chain block 51 is engaged is a position which is the inside of the curved portion 21 of the curved pipe 20 in the radius direction of curvature. . More specifically, a position including the center lines L22a and L22b of the straight portions 22 of the curved pipe 20 and the peripheral edge 40c of the traction member 40 intersect each other on the inner side in the curvature radius direction of the curved portion 21. Thereby, the other end portions 40b of the pair of traction members 40 are pulled by the traction tool 50 so as to reduce the distance between each other, and the curvature of the curved portion 21 is increased via the traction member 40. It is possible to bend it to be larger.

  In addition, a heater 60 is installed as a heating means on the outer peripheral surface of the curved portion 21 that becomes the heating range in the curved tube 20. In this embodiment, first, the outer peripheral surface of the curved portion 21 in the bent tube 20 is covered with an aluminum foil as the covering sheet 61. Next, a plurality of strip-shaped heaters 60 are installed on the covering sheet 61. At this time, the plurality of heaters 60 are arranged at intervals along the center line L21 of the curved portion 21 of the curved pipe 20, and the longitudinal directions thereof are along the circumferential direction of the curved pipe 20, respectively. Place around the circumference. Then, the curved portion 21 of the bent tube 20 is heated by energizing the heater 60 from the power source. The heating temperature of the bent tube 20 needs to be not less than the temperature at which it can be plastically deformed and less than the melting temperature in consideration of the melting point of polyethylene as a material. Specifically, in this embodiment, the heating temperature is 120 to 130 ° C.

  At this time, the plurality of heaters 60 are arranged at intervals along the center line L <b> 21 of the curved portion 21 of the bent tube 20, and the longitudinal direction thereof is along the circumferential direction of the bent tube 20. By arrange | positioning in the perimeter, the whole curved part 21 of the curved pipe 20 can be heated uniformly. Further, since the heater 60 is heated through the covering sheet 61, the heater 60 is heated directly and more uniformly without locally heating only the contact surface with the heater 60 on the outer peripheral surface of the bent portion 21 of the bent tube 20. Can be heated. Moreover, since the coating sheet 61 is an aluminum foil, the thermal conductivity is improved, and the curved portion 21 of the bent tube 20 can be heated uniformly and effectively.

  And if it can confirm by the temperature measurement by a thermometer etc. that the curved part 21 of the curved pipe 20 was heated by the heater 60 to the said heating temperature, it will be pulled by the chain block 51 which is the traction tool 50 next. Specifically, the lever 56 of one or both chain blocks 51 is reciprocally rotated. Accordingly, the chain 54 is gradually wound up in accordance with the reciprocating rotation number of the lever 56, and the distance between the first hook 53 and the second hook 55 is reduced. Thereby, the other end portions 40b of the pair of pulling members 40 are pulled so as to reduce the distance between each other, and the curved pipe 20 increases the curvature of the curved portion 21 via the pulling member 40. It is bent by plastic deformation.

  Here, by using the chain block 51, the bent pipe 20 can be bent with a small traction force and a small traction amount with a small traction force and a large operation amount. Further, by bending the bent tube 20 via the pair of pulling members 40, a bending moment can be effectively applied to the bent tube 20 with a small pulling force. Moreover, it can prevent that the edge part of the curved pipe 20 will be damaged because the tractive force does not act on the curved pipe 20 directly from the chain block 51 which is the traction tool 50. FIG.

Then, the angle measuring device 30 measures the bending angle θ of the curved pipe 20 while being pulled by the chain block 51 that is the pulling tool 50. When the bending angle θ measured by the angle measuring device 30 falls within the allowable range, the operation of the chain block 51 is stopped. In this state, the heater 60 is heated so as to maintain the heating temperature and held for a predetermined time. In this embodiment, it is held for about 3 to 4 hours.
And if it heats so that heating temperature may be maintained for a predetermined time, a heating step will be complete | finished.

Next, a cooling step is performed.
In the cooling step, the bent pipe 20 is cooled while being pulled by the chain block 51 which is the traction tool 50. In this embodiment, the cooling is performed by natural cooling. The cooling is performed for a preset time. In this embodiment, cooling is performed for 2 hours. And after cooling for a fixed time, the state pulled by the chain block 51 is cancelled | released, the chain block 51 is removed, a cooling step is completed, and all the steps of a rebending process are completed.

  Next, as a bending angle confirmation process, the reconfirmation of the bending angle θ of the bent pipe 20 subjected to the rebending process is performed. The method for measuring the bending angle θ is the same as the bending angle inspection process performed before the rebending process, and is therefore omitted. When the bending angle θ of the bent tube 20 is within the allowable range, the process proceeds to the next step. If the bending angle θ is outside the allowable range in this step, the rebending step is performed again.

  Next, a straight pipe connecting process and a curved pipe connecting process are performed as the pipe member connecting process. That is, as shown in FIG. 1, in the straight portion 101 of the pipe 100, the straight pipe 10 prepared in the preparation process is connected via the joint 23. Further, in the curved portion 102 of the pipe 100, the bent pipe 20 whose bending angle θ is within the allowable range in the bending angle confirmation process is connected via the joint 23. The pipe member 1 and the joint 23 are fixed by electric welding as described above.

  As described above, according to the construction method of the curved portion 102 of the pipe 100 of the present embodiment, when the bending angle θ of the bent tube 20 is outside the allowable range in the bending angle inspection process, the rebending process is performed. By doing so, the bending angle θ can be processed easily and accurately within the allowable range at the construction site. Therefore, even if the bent pipe 20 is bent back, the curved portion 102 of the pipe 100 can be constructed easily and accurately. Further, in the heating step in the rebending process of the present embodiment, the other end portions 40b of the pair of traction members 40 connected to both ends of the bent tube 20 in the traction member connection step are pulled by the traction tool 50. For this reason, the distance from the bending part 21 which bends the bending pipe 20 to the position to be pulled by the traction tool 50 can be increased, thereby effectively increasing the bending moment acting on the bending part 21. Bending can be applied. Further, since the end portion of the curved pipe 20 is not directly pulled by the traction tool 50, the curved pipe 20 itself can be reliably prevented from being damaged by the traction force of the traction tool 50.

  In the present embodiment, in the heating step, the heater 60 is heated from the outer peripheral surface of the covering sheet 61, so that only the portion where the heater 60 is arranged is covered with the covering sheet 61 without being locally heated. The range can be heated uniformly to bend and deform the range uniformly. And since the covering sheet 61 is an aluminum foil, the heat of the heater 60 can be effectively and uniformly transferred to the bent portion 21 of the bent tube 20 and heated.

  In the above embodiment, the two chain blocks 51 are used as the traction tool 50. However, the present invention is not limited to this, and the first hook 53 is engaged with one of the traction members 40 with one chain block 51. Then, the second hook 55 may be engaged with the other pulling member 40. The traction tool 50 is not limited to the chain block 51 with a lever, but may be any type of chain block that pulls the chain itself without a lever, or any other device that generates traction force. It is preferable that the apparatus is capable of displacement control and includes a speed reduction mechanism.

  In the above embodiment, the traction member 40 is a tubular member and is inserted into the end portion of the bent tube 20, but is not limited thereto. For example, like the traction member 45 shown in FIG. 6, the traction member 45 may be connected to the end portion of the curved pipe 20 by using the joint 23 so as to be equal to the outer diameter of the curved pipe 20. Further, the pulling member does not need to be a tubular member, and may be a solid columnar member. At least the end of the bent tube 20 may be attached so as to protrude from the end, and the traction tool 50 may be attached to the vicinity of the protruding end. Further, in the present embodiment, the engaging member 40 is engaged with the peripheral edge 40c of the other end portion 40b of the pulling member 40, which is a tubular member. However, like the pulling member 46 shown in FIG. You may make it provide the notch 40d. By doing in this way, the traction tool 50 can be easily engaged at a position where bending can be performed within the plane including the center lines L22a and L22b, and the position where the traction tool 50 is engaged during towing is shifted. Can also be prevented.

  Moreover, in the said embodiment, although the strip-shaped heater 60 which is a heating means shall be arrange | positioned over the perimeter of the curved pipe 20, it is not restricted to this, but it arrange | positions by arrange | positioning over the perimeter. The curved portion 21 of the tube 20 can be uniformly plastically deformed in the entire circumferential direction. Further, by disposing the heater 60 at least on the inside and outside of the radius of curvature, the portion on the inside of the radius of curvature where the compressive deformation is relatively large, and the tensile deformation is on the outside of the radius of curvature. The portion can be effectively plastically deformed. The shape of the heater 60 is not limited to a strip shape, and may be, for example, a disk shape or a sheet shape that can cover the entire curved portion 21.

  Moreover, in the said embodiment, although the piping 100 shall connect the pipe member 1 which consists of the straight pipe 10 or the curved pipe 20 with the coupling 23, and it joins by electric welding, it does not restrict to this. A rubber ring is provided on the inner peripheral part of the joint, and a type that is sealed with a rubber ring or a type that is screwed can be applied. Further, the present invention can be applied to a type in which a receiving port is provided at one end of the pipe member 1 and can be connected without using a joint. Moreover, in the said embodiment, although the polyethylene pipe was mentioned as an example as the pipe member 1, it is not restricted to this, It can apply to the piping comprised by connecting the pipe member which consists of a thermoplastic resin at least.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

DESCRIPTION OF SYMBOLS 1 Pipe member 20 Curved pipe 21 Curved part 40, 45, 46 Towing member 50 Towing tool 61 Cover sheet 100 Piping 102 Curved part (theta) Bending angle

Claims (4)

It is a construction method of a curved portion of a pipe constituted by connecting a plurality of pipe members made of thermoplastic resin,
A bending angle inspection step for confirming whether or not the bending angle of a curved pipe having a curved portion and a straight portion extending from an end of the curved portion is within an allowable range.
When the bending angle is outside the allowable range, a rebending step for bending the bent pipe so as to be within the allowable range;
A bent pipe connecting step of connecting the bent pipes whose bending angle is within an allowable range,
In the rebending step, the curvature of the curved portion is increased by using a traction tool at both ends of the curved tube while heating the curved portion of the curved portion and the straight portion of the curved tube. A heating step for holding for a predetermined time in a pulled state,
And a cooling step for cooling the pipe while being pulled by the traction tool after the heating step. In the construction method of the curved part of piping according to claim 1,
The rebending step includes a traction member connecting step for connecting a pair of traction members to both ends of the bent pipe,
In the heating step, the end portion of each of the pulling members protruding from both ends of the bent pipe is pulled, and the method of constructing the curved portion of the piping is characterized by. In the construction method of the curved part of piping according to claim 1 or claim 2,
In the heating step, a method for constructing a curved portion of a pipe is characterized in that a covering sheet is covered in a heating range, and a heater is disposed on the outer peripheral surface of the covering sheet to heat. In the construction method of the curved part of piping according to claim 3,
An aluminum foil is used as the covering sheet, a method for constructing a curved portion of piping.

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