JP6099932B2 - Freezing method for fluid transport pipelines - Google Patents

Description

  The present invention relates to an improvement in a method for freezing a fluid transport pipe, mainly a tap water pipe.

  Conventionally, when a part of a water supply pipe is damaged or a valve attached to a pipe line becomes defective, the pipe or valve is repaired or replaced, so the water is temporarily cut off. As a result, a large amount of tap water was wasted, and after the completion of the construction work, it was necessary to vent the air that had entered the pipe.

  Focusing on the problems of the conventional construction method, in recent years, pipes have been designed to minimize water outage (water stoppage) in a minimum area, shorten the work time, and eliminate the need for air venting after completion of construction. Road freezing methods have been developed and are being implemented in practice.

  In this freezing method, when a part of a pipe line, particularly when an existing pipe is a welded pipe, a box of liquid air or liquid nitrogen serving as a freezing means is attached at a distance of about 20 cm or more from the welded part. This is to prevent the weld from cracking due to freezing, and the cutting of the pipe and the new welding are performed at a position about 50 cm or more away from the freezing means. This is to prevent frost generated by freezing from thawing and causing pinholes in welding. In addition, when performing new welding near freezing means, in order to prevent the ignition by a spark, the liquid of 100% of nitrogen which is an inert gas will be used.

  In this freezing method, the freezing means is attached to a part of the pipe, the fluid (tap water) in the pipe corresponding to the attached part is frozen, and the water flow in the pipe is temporarily stopped by the ice block. It is said. However, since the quality of the tube itself has improved recently and the inner surface is also smooth, it is swept away by the fluid pressure of the fluid (water tap water) applied to the primary side of the ice mass, and the water stop effect is achieved. It has become difficult to obtain.

JP 2009-127206 A

  The problem to be solved by the present invention lies in the conventional method for freezing a fluid transport pipe, in which a part of the pipe is frozen and the fluid in the pipe is frozen in the corresponding portion of the pipe to freeze. The ice block thus made is pushed by the fluid pressure from the primary side, and the secondary side is washed away because of no pressure, and the intended water stop effect cannot be obtained.

In order to solve the above-described problems, the fluid transport pipe freezing method according to the present application distributes through the pipe at intervals of several centimeters to several tens of centimeters depending on the target pipe diameter in at least two places of the fluid transport pipe. A freezing method for a fluid transportation pipeline in which freezing means for freezing fluid is arranged , wherein the fluid is water supply water, the freezing means is a liquid air box or a liquid nitrogen box, and the transportation pipe is The ductile cast iron pipe has a mortar lining or powder coating on the inner surface, and gradually transmits cold heat from the pipe wall side to each of the freezing means and the corresponding pipe inner part. to form a first and second ice blocks, conducts the heat to very low temperature from both sides from the two frozen means described above, the outer between gradually first and second ice blocks to synergistically act the heat transfer In There freezing method of fluid transport conduit to form a third block of ice to be bulging curved first and the second, it is integrated third ice block, the core of the integrated ice blocks The inner wall surface of the fluid transport pipe is pressed in a direction orthogonal to the center of the third ice block .

  The freezing method of the fluid transport pipeline according to the present invention is configured as described above. Cold heat is gradually transmitted at least in the pipe corresponding to the freezing means to form first and second ice blocks having a substantially drum shape, and then the outer surface is bulged and curved between the first and second ice blocks. The three ice blocks are conveniently formed at the freezing point, and the three ice blocks are integrated into the ice centered on the third ice block, and these ice blocks are volumetric. Since the pressure that presses the inner wall of the pipe line from the inside is generated and it strungs strongly against the inner wall of the pipe, it is swept away within the time required for the work even if fluid pressure or impact on the primary side is applied. The position is not moved, the work safety is ensured, and the water stop effect can be sufficiently exhibited.

It is sectional drawing which shows the state which implemented this invention. It is a figure which shows the attachment state of the box which is a freezing means.

  This was realized by configuring as illustrated in the drawings and described in the examples.

  Next, an example of a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a state in which the present invention is implemented, and FIG. 2 is a view showing an attached state of a box which is also a freezing means.

  In these drawings, reference numeral 1 indicates a water supply pipe for supplying water to a water supply facility. The water supply pipe 1 is used in a smooth state in which the inner wall surface is processed so as not to cause adhesion of impurities or rust, specifically, mortar lining or resin powder coating is used. .

  At least two or more refrigeration means such as liquid air boxes 2a and 2b or a liquid nitrogen box are provided on the primary side of a part of the water pipe 1 where the pipe is repaired or replaced, for example, a close distance, for example, several cm to It is set with an interval of several tens of centimeters. This distance is set by the pipe diameter of the water supply pipe 1. In FIG. 1, the tap water may flow from any direction of the tap water pipe 1.

  The liquid air boxes 2a and 2b are formed of styrene foam and have a rectangular parallelepiped shape that can withstand ultra-low temperatures, and the inside is hollow. The liquid air boxes 2a and 2b are attached to the lower portion of the liquid air boxes 2a in a state where the above-described water supply pipe 1 passes therethrough. In other words, a communication hole matched with the pipe diameter of the water supply pipe 1 is drilled in the lower portion and inserted into the water supply pipe 1, and the leakage prevention is fixed between the communication hole and the outer surface of the water supply pipe 1. An agent (caulking agent) must be applied.

  Also, the liquid air boxes 2a and 2b described above are opened on the upper surface, and liquid air 3 filled in a cylinder of, for example, 30 liters, 50 liters, etc. is injected from the upper surface opening on site. Become. Further, the upper surface opening is covered as necessary.

  Thus, when liquid air, or in some cases liquid nitrogen, is injected into the two liquid air boxes 2a and 2b, the water supply pipe 1 in the injected part is cooled to an ultra-low temperature, and the heat transfer from the cold water supply pipe 1 is performed. As a result, the internal tap water gradually freezes to form the first ice block 4a and the second ice block 4b with the cross-section being substantially drum-shaped.

In this embodiment, inside the water pipe 1 sandwiched between the liquid air boxes 2a and 2b, the ultra-low temperature from the liquid air boxes 2a and 2b is transferred from both sides, and the heat transfer acts synergistically. during gradually first ice block 4a and the second ice blocks 4b Te was the outer surface and the bulging curved, i.e., the third matching the outer surface of the first ice block 4a and the second ice blocks 4b An ice block 4c is formed, and the three ice blocks 4a, 4b, 4c are integrated.

  The ice blocks 4a, 4b, and 4c are densely formed within the inner diameter of the water supply pipe 1, and the ice blocks 4a, 4b, and 4c are formed in the water supply pipe 1 by freezing water and increasing its volume. Press the inner diameter of. This pressing particularly acts on the inner wall surface of the water supply pipe 1 in a direction perpendicular to the center of the ice block 4c which is an integral core (see arrow in FIG. 1).

  By this action, the ice blocks 4a, 4b, and 4c temporarily stop the water flow in the water supply pipe 1, and are not swept away by the water flow pressure. Also, the ice blocks 4a, 4b, 4c are integrated, and the pressing force is dispersed by acting also in the axial direction of the water supply pipe 1, causing the water supply pipe 1 to rupture or cause cracks. There is no.

  The freezing method of the fluid transmission pipeline according to the present application is configured in this way. Therefore, the ice block formed by the fluid flowing in the pipe line provides a water shutoff effect for at least the time required for construction work, which eliminates the need for wide-area water breaks as in the past, and removes air after construction. Therefore, it is possible to carry out a construction that requires only a very short time and is inexpensive.

  Here, the results of the pressure resistance experiment using the freezing method according to this example are shown in Table 1 for mortar lining and Table 2 for powder coating, respectively. As a result, in any case, the ice blocks 4a, 4b and 4c were integrated, but there was no movement within the tube. For a tube diameter of 200 mm or less, a pressure resistance of approximately 2.5 MPa was obtained, and there was no problem in construction. In the case of a tube diameter of 250 mm, 1.75 MPa was set as the maximum pressure resistance for safety reasons due to facilities.

  In addition, since the mortar state after freezing does not leak due to the adhesive (caulking agent) that fixes the boxes 2a and 2b during freezing, there was no change in the outer diameter of the tube, and there was no damage such as cracks after freezing. . As a safety standard, an estimated water hammer pressure of 0.5 MPa is added to a hydrostatic pressure of 0.5 MPa, and a safety factor of 1.5 to 2.0 is considered in all of the experimental results. This method is understood to be appropriate and effective. In Tables 1 and 2, the notation “double” means that two freezing means (boxes) are used.

  Although the said Example demonstrated the water supply pipe 1, this invention is not limited to this water supply pipe 1, and if the fluid can be frozen about other liquids and gas, it will be performed. In many chemical facilities, plants, etc., it is possible to repair and replace pipes and attached valves without the need to close valves and empty pipes.

  Two or more freezing means can be arranged at appropriate intervals, but even if the freezing means is formed long along the axial direction of the tube, the pressure resistance of the ice block obtained is the size used in the examples. Experiments have shown that it is no different from one case.

1 Water supply pipe 2a Liquid air box 2b Liquid air box 3 Liquid air 4a First ice block 4b Second ice block 4c Third ice block

Claims (1)

A fluid transport pipe freezing method in which freezing means for freezing a fluid flowing through the pipe at intervals of several centimeters to several tens of centimeters according to a target pipe diameter is disposed in at least two places of the fluid transport pipe , The above-mentioned fluid is tap water, the freezing means is a liquid air box or a liquid nitrogen box, the transport pipe is a ductile iron pipe, and the inner surface is mortar-lined or powder-coated, First and second ice blocks having a drum shape in cross section are formed by gradually transmitting cold heat from the tube wall side to the corresponding pipe inner portion corresponding to each freezing means, and the ultra-low temperature from the two freezing means described above is generated from both sides. heat transfer, contact freezing method of fluid transport conduit outer surface to form a third block of ice as a bulging curved between the heat transfer to synergistically act gradually first and second ice cubes The first, second, and third ice blocks are integrated, and the inner wall surface of the fluid transport pipe is pressed in a direction orthogonal to the center of the third ice block that becomes the core of the integrated ice block. freezing method of fluid transport conduit according to claim.

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