JPS61263685A - Method of cleaning inner surface of pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is used to remove iron rust, etc. adhering to the inner wall surfaces of ductile cast iron pipes for water supply buried underground, existing water pipes in buildings, etc. However, this method relates to a method for completely cleaning the inner surface of pipes, and is used in the field of pipe rehabilitation work in which the inner surface of these pipes is coated with epoxy resin paint.

[Conventional technology]

Conventionally, the cleaning method for removing iron rust, etc. adhering to the inner wall surface of a pipe is to put sand, slag, or other abrasive material into the pipe, and to blow a large amount of air from the inlet side of the pipe. A widely used method is to flow an abrasive material at high speed, use the impact force to scrape off attached iron rust, and discharge it to the outlet side of the pipe.

[Problems to be solved by the present invention]

However, according to research conducted by the present inventors, it has been found that the conventional cleaning method described above has the following problems.

(b) In the straight pipe section of the pipe, the conventional method is effective in removing iron rust, etc. (2) that adheres thickly as the inner diameter of the pipe (1') becomes narrower, as shown in Figure 5. However, after removing some of this, the pipe (
It is impossible to completely remove iron rust etc. (2) that are thinly adhered to the inner wall surface of 1').

This is because in this state, the inner diameter of the pipe through which it can flow expands, so the velocity of the pressure-fed air is higher in the central part (i) than in the ring-shaped peripheral part (1'a) that contacts the inner wall surface of the pipe.
'b) becomes faster, and most of the abrasive material in the air gathers in the center of the tube and flows at high speed.

The abrasive that slightly hits the inner wall of the pipe also moves in the flow direction.
In other words, the cutting force caused by the impact is weakened because the cutting force flows along the axial direction of the pipe and hits the pipe.

If the inner surface of the pipe is painted with such iron rust remaining and the surface preparation is incomplete, the paint film will not adhere to the pipe material and will cause problems such as lifting and peeling.

Therefore, in order to remove the above-mentioned thinly adhered iron rust, etc., it is necessary to increase the amount of abrasive according to the expansion of the inner diameter of the pipe that can flow, but this not only requires a large amount of abrasive, but also requires a work process. has diversified and air compressor! However, since it requires a large capacity, it is expensive, uneconomical, and is not used in practice.

(b) Concave portion of pipe joint 1 For example, in the concave portion of the inner surface of the pipe that is seen in the elbow pipe shown in Fig. 7, the reduced entry pipe shown in Fig. 8, etc., in the conventional method, the concave portion on the air pumping side (upstream side) Since a swirl of air is generated at (3') and the abrasive material does not collide, this concave portion (31) is not cleaned in a ring shape.

In addition, in the conventional method, a reciprocating double-sided cleaning method is performed in which air is pumped from the inlet side of the pipe and then air is pumped conversely from the outlet side. 3'') is on the downstream side, so it has been cleaned to some extent, but since it is cleaned only once by air pressure from one side, iron rust etc. cannot be sufficiently removed.

(c) In the bent pipe portion of the pipe, for example, the elbow pipe shown in Fig. 7, in the conventional method, the inner wall surface (4'
) is cut more than necessary.

This means that the speed of air in a straight pipe is generally 80 to 120 m.
This is because the abrasive material in this pressurized air collides violently with the inner wall surface of the curved pipe facing directly at the above speed.According to an example of experimental results, the air speed is 120 m/sec, the abrasive tool used is When cleaning with an input amount of 56fi, the wall thickness of the inner wall surface of the elbow pipe before air pressure is 4.
．． It was observed that the distance was 091m, but it was 1.961m after cleaning was completed.

As mentioned above, cutting the inner wall surface more than necessary has the problem of weakening the pressure resistance at the bent pipe portion and shortening the life of the pipe.

The present invention solves all the above-mentioned problems, and its method, operation, and effects are as follows.

〔Method〕

The cleaning method of the present invention includes connecting divided fluids at appropriate intervals that expand conically in the direction of air outflow and whose maximum diameter is smaller than the inner diameter of the pipe, and inserting the divided fluids into the pipe. The gist of this method is to separate air and abrasive material flowing at a predetermined speed in a centrifugal direction using a fluid divider, and cause the abrasive material to collide with the inner wall surface of a pipe at an acute angle.

[Effect]

In the cleaning method of the present invention, the abrasive is introduced from the inlet side of the pipe as in the past and is caused to flow with air at the required speed. Since the expanding dividing fluid is inserted through the pipe, the air and abrasive material are separated in the centrifugal direction by the conical surface of the dividing fluid, and the distance between the maximum diameter part of the dividing fluid and the inner surface of the pipe is narrow. The abrasive material is rapidly accelerated and collides with the inner wall surface of the pipe at an acute angle. As a result, the impact force of the abrasive increases, and thin iron rust etc. adhering to the inner wall surface of the pipe are completely scraped off.

The air and abrasive material that have rapidly passed through the gap slow down until the next divided fluid because the flow area in the pipe becomes wider, but the same action is repeated again in the second divided fluid. , this process is repeated one after another, and finally it flows out from the outlet of the pipe - at this time, fine pieces such as crushed iron rust are also discharged at the same time.

During the above operation, if the connecting member of the fluid is pulled for one minute to gently move the position of the fluid, the inner surface of the pipe between the adjacent fluids can be completely cleaned.

Furthermore, if one of the fluid dividers is placed near the joint, for example, the concave part on the upstream side of the elbow pipe, the air and abrasive material will be diverted in the centrifugal direction by the fluid divider, as described above, and will also flow into this concave part. Since it flows, the abrasive material also collides with the recessed portions without creating swirls, and iron rust etc. are completely removed.

Furthermore, in the case of bent pipes such as elbow pipes, after cleaning as described above, one of the divided fluids is brought into contact with the inner wall surface directly facing the straight pipe.

Collision of the abrasive material with this inner wall surface is reliably blocked,
Excessive cutting can be prevented.

Note that when air is reciprocated from the openings at both ends of the pipe, a fluid divider having symmetrically formed conical expansion surfaces is used.

〔Example〕

Figures 1 to 4 show specific examples of the method of the present invention, in which the dividing fluid (5) having a conical widening surface is made of a material having high hardness and wear resistance, such as F, R, P, etc. The conical surface is formed smoothly, and its maximum diameter is smaller than the inner diameter of the pipe, and when it is inserted into the pipe, there is a gap (m) between it and the inner wall surface of the pipe, as shown in ) is maintained.

The divided fluids (5) are connected and attached to connecting members (6) (vinyl strings in this embodiment) at appropriate intervals with their conical surfaces facing in the same direction, and are inserted into the pipe (1). For this insertion, the air receiver is connected to a connecting member (6
) can be easily connected to the outlet side of the pipe by connecting one end of the pipe and forcing air to be led by the V-shaped pig.

Note that when the inner surface of the pipe has thick iron rust, etc., as shown in Figure 5, it is desirable to perform the first step of cleaning using the conventional method before inserting the pipe.

Air and abrasive material are pumped for one minute from the pipe end on the conical surface side of the fluid (5). In this case, the connecting member (6) on the end side
One end is fixed with an appropriate means, and while air is being pumped, the connecting member (6) is slowly pulled by a length approximately corresponding to the length between each fluid division (5), and each fluid division (5) is pulled slowly. 5) Move. The movement of the divided fluid (5) may be a reciprocating movement.

Figure 3 shows a case where a fluid divider with symmetrical conical surfaces is used, and Figure 4 shows a case where a fluid divider (5) is brought into contact with the inner wall surface (4) of a bent pipe directly opposite a straight pipe. , its action is as described above.

〔effect〕

As described above, the cleaning method of the present invention is as follows: (a) air and abrasive material are accelerated and separated in a centrifugal direction by the conical surface of the fluid dividing fluid that expands in the air outflow direction, and the abrasive material is applied to the inner surface of the pipe at an acute angle; Because it will cause a collision.

It is possible to reliably remove thin and adherent iron rust, which was difficult to remove using conventional methods. (b) The abrasive material is separated by a divided fluid and its direction is given so that it reliably collides with the inner surface of the pipe, so the amount of abrasive material used can be reduced.
C) Air and abrasive material are rapidly accelerated when passing through a narrow gap and have sufficient impact force, so a small capacity near compressor is sufficient, reducing air volume especially when cleaning large diameter pipes. It is economical because it can be done. Effects such as this are achieved.

[Brief explanation of the drawing]

Figures 1 to 4 show specific examples of the method of the present invention, in which Figure 1 is an explanatory diagram of the action in a straight pipe section, Figure 2 is a cross-sectional view taken along line A-A in Figure 1, and Figure 3 is a fluid separation diagram. 4 is an explanatory diagram of the operation of the bent pipe section, FIGS. 5 and 6 are explanatory diagrams of the operation of the conventional method in the straight pipe section, and FIGS. 7 and 8 are the same pipes. FIG. 1... Pipe, 5... Fluid division, 6... Connecting material. Patent applicant Obayashi Corporation Sunida Co., Ltd.

Claims (1)

[Claims] Air that expands in a conical shape in the air outflow direction and whose maximum diameter is smaller than the inner diameter of the pipe is connected at appropriate intervals and inserted into the pipe to flow at a predetermined speed. and a method for cleaning the inner surface of a pipe, characterized in that the abrasive material is separated in a centrifugal direction by the divided fluid, and the abrasive material collides with the inner surface of the pipe at an acute angle.