JP5740816B2 - Piping freezing method - Google Patents

Description

  The present invention relates to a pipe freezing method, and more specifically, in the vicinity of a place where a pipe is to be repaired, freezing means for freezing the fluid in the pipe is provided, and when the place to be repaired after freezing the fluid, the freezing is performed. The present invention relates to a pipe freezing method that is advantageously used in providing the means.

  In the conventional pipe freezing method, a method of circulating a liquid nitrogen by installing a jacket at a pipe freezing site (for example, Patent Document 1) is performed. There is also a method (Patent Document 2) in which dry ice is put into a two-divided box surrounding a pipe.

JP-A-51-102220 JP-A-53-50528

  In the above-mentioned background art, the method of covering the piping completely with the jacket and flowing the liquefied gas is expensive because it is necessary to manufacture a dedicated jacket according to the diameter of each piping, and basically the straight pipe portion is targeted. Therefore, there was a problem (problem) that the construction place was also limited. Further, the method using the two-divided box has no problem when using solid dry ice, but has a problem (problem) that leakage occurs when liquefied gas is used.

The present invention has been made to provide a piping freezing method that solves the above-described problems, can be carried out at a low cost without selecting a construction site, and does not cause liquefied gas leakage. It is as follows.
(1) In a pipe freezing method in which the fluid in the pipe of the pipe is frozen using liquefied gas, the heat insulating box is processed to form a pipe penetration portion in accordance with the pipe shape of the pipe, and the heat insulating box is opened to the top The heat insulation box is attached to the pipe so that the pipe passes through the formed pipe penetration portion, and the processed portion is sealed with a liquid packing of silicon rubber , and then the liquefied gas is introduced into the heat insulation box. A pipe freezing method characterized by storing and immersing the pipe in the box, and freezing the fluid in the pipe with the upper portion of the heat insulating box open.
(2) The pipe freezing method as described in (1) above, wherein the heat insulating box is a foamed polystyrene box.

  According to the present invention, there is an effect that construction can be performed at a low cost and at any place without leakage of liquefied gas.

Schematic showing an example of the embodiment of the present invention (for horizontal piping) Schematic showing the processing procedure of insulation box Schematic showing how to install the insulation box on the piping Schematic showing the state of storing liquefied gas in the heat insulation box Schematic showing another example of an embodiment of the present invention Partially cut-away bird's-eye view showing examples of application of the present invention to each of horizontal piping (a), vertical piping (b), and elbow section (c)

  1, 2, 3, and 4 are schematic views illustrating an example of an embodiment of the present invention when horizontal piping is targeted. FIG. 1 is a schematic view after a heat insulating box is attached to a pipe, (a) is a plan view, and (b) is a side view. FIG. 2 is a process diagram of the heat insulation box, and FIG. 3 is a process diagram for mounting the heat insulation box on the piping. These figures are views taken along the line B-B in FIG. FIG. 4 is a cross-sectional view showing a state in which the heat insulation box is attached to the pipe and the liquefied gas is stored in the heat insulation box, and is a view taken along the line AA in FIG. 1 to 4, 1 is a heat insulating box, 2 is a processed part, 3 is a liquid packing, 4 is a liquefied gas, 10 is a pipe, and 11 is a fluid in the pipe. As shown in the figure, in the present invention, the heat insulating box 1 is used to freeze the in-pipe fluid 11 of the pipe 10 to be frozen. The heat insulation box 1 is processed to form a pipe penetration part 2A in accordance with the pipe shape (FIGS. 2 (a), (b), (c)), and the heat insulation box 1 is formed as an upper open type and formed as described above. The heat insulating box 1 is attached to the pipe 10 so that the pipe 10 passes through the pipe penetration part 2A, and the processed part 2 is sealed with the liquid packing 3 (FIG. 3). Then, the liquefied gas 4 is stored in the heat insulation box 1, and the piping 10 in the heat insulation box 1 is completely immersed (FIG. 4).

Thus, in the present invention, when freezing the fluid in the pipe of the pipe, the upper open type heat insulation box is processed according to the local pipe, and the heat insulation box having a height exceeding the liquid surface of the liquefied gas is used. Since the processed part is sealed with liquid packing, it is not necessary to prepare a special jacket or circulation device in advance, and it can be applied anywhere.
The heat insulating box is preferably a foamed polystyrene box from the viewpoint of low cost and ease of processing. If it is a Styrofoam box, it is extremely easy to process in accordance with the local piping shape regardless of the construction site. In addition to the expanded polystyrene box, a box made of a material having a low thermal conductivity and other heat insulation such as polyurethane can be used as the heat insulation box.

Further, if the length of the heat insulation box is sufficient, the smaller the cross-sectional area in the range in which the pipe is immersed, the less liquefied gas is consumed. For example, as shown in FIG. If there is no insulation box 1 (Fig. 5 (a)), a partition 5 is inserted in the insulation box 1 with, for example, a foamed polystyrene plate to reduce the consumption of the liquefied gas 4 as the minimum required internal volume (Fig. 5 (b) )) Can be easily done.
Moreover, since the shape of the heat insulation box can be easily changed according to the local piping, it can be applied not only to the straight pipe part but also to the elbow part, the branch pipe part, the header part and the like. For example, FIG. 6 shows a partially cut-away bird's-eye view of an application example of the present invention to each of the horizontal pipe (a), the vertical pipe (b), and the elbow part (c). 6 (b) and 6 (c), the processed portion 2 and the liquid packing 3 are not shown.

  The liquefied gas is preferably liquid nitrogen from the viewpoint of low cost. Since the heat insulation box is an open top type and has a structure in which internal pressure is not applied, liquefied gas can be sufficiently stored even with liquid packing without using a complicated seal to prevent leakage of liquefied gas. For example, silicon rubber can be used as the liquid packing.

Embodiments in which the present invention is implemented in the form of application to horizontal piping shown in FIGS. 1 and 5A will be described with reference to FIGS.
The side 7 perpendicular to the box length direction of an open top polystyrene box (used as heat insulation box 1) with the pipe length direction as the box length direction and a box length of 5D (D is the outer diameter of the pipe) or more is opposed. As shown in FIG. 2 (a), a U-shaped cut 20a whose upper part is connected to the upper open end 40 side of the side face 7 was made in the two faces 7a and 7b. The diameter of the arc at the bottom of the U-shape was substantially the same as the outer diameter of the pipe 10. The U-shaped foamed polystyrene material 30 cut off by the cut 20a was removed from the side surface 7, and a U-shaped pipe introduction part 50 was formed on the side surface 7. A cut 20b is further cut into the removed U-shaped foamed polystyrene material 30, a portion corresponding to the cross section of the pipe 10 at the bottom of the U-shaped foamed polystyrene material 30 is removed, and a circle having the same diameter as the outer diameter of the pipe 10 is provided at the bottom. An arcuate recess 51a was formed and used as a backfill piece 51. The above process is a process for forming the pipe penetration part. The backfill piece 51 is inserted into the pipe introduction part 50 on the side surface 7, and the arcuate recess 51a of the backfill piece 51 and the lower arcuate part of the pipe introduction part 50 are inserted. By forming one circle with 50a, this circle becomes the pipe penetration portion 2A.

Next, as shown in FIG. 3 (a), silicon rubber (used as the liquid packing 3 for sealing) is applied to the lower arcuate portion 50a of the pipe introduction portion 50, and as shown in FIG. 3 (b), The heat insulation box 1 was attached from below the pipe 10. Here, the lower part of the pipe 10 was brought into contact with the lower arcuate part 50a of the pipe introduction part 50.
Then, as shown in FIG. 3 (c), the backfill piece 51 is inserted into the pipe introduction part 50 on the side surface 7 with its arcuate recess 51 a abutting against the upper side of the pipe 10, and the pipe introduction part 50. The groove space other than the block 10 covered with the pipe 10 was backfilled with the backfill piece 51.

In addition, before the backfilling, silicon rubber was also applied to the pipe contact portion of the backfill piece 51 and the contact portion with the side surface 7. Thus, the processed part such as the cut was sealed with the liquid packing (silicon rubber) 3.
At the time of freezing, liquefied gas 4 (here, liquid nitrogen was used) was stored to a depth that the entire inside of the heat insulating box 1 of the pipe 10 was immersed, as shown in FIG. The liquefied gas 4 is replenished only in an amount that decreases with evaporation. Since the time required for freezing varies depending on the pipe diameter and the type of fluid 11 in the pipe, verification is required in advance. In the present example, the pipe fluid 11 was a fatty acid ester hydraulic oil, and the time required for freezing in this case was 20 minutes for a pipe diameter of 50A and 50 minutes for 80A.

1 Insulation box (Styrofoam box)
2 Processed parts
2A Pipe penetration
3 Liquid packing
4 Liquefied gas
5 partition
10 Piping
11 Pipe fluid

Claims (2)

In the pipe freezing method in which the fluid in the pipe of the pipe is frozen using liquefied gas, the heat insulating box is subjected to processing to form a pipe penetration portion in accordance with the pipe shape of the pipe, and the heat insulating box is an upper open type, The heat insulating box is attached to the pipe so that the pipe passes through the formed pipe penetration part, and the processed part is sealed with a liquid packing of silicon rubber , and then the liquefied gas is stored in the heat insulating box. A pipe freezing method characterized by immersing the pipe in the box and freezing the fluid in the pipe while opening the upper part of the heat insulating box.   The pipe freezing method according to claim 1, wherein the heat insulating box is a foamed polystyrene box.

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