JPS5811268B2 - pipe cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cleaning existing pipes such as water supply mains, water supply pipes for housing complexes, and domestic water pipes.

Steel pipes, cast iron pipes, and other iron pipes are often used for water supply equipment and air conditioning equipment piping.

Steel pipes seem to be strong and inexpensive.

However, iron pipes tend to rust on the inside after long-term use, and this rust gradually grows and eventually becomes lump-like.
This results in a significant reduction in the pipe cross-sectional area.

In fact, most of the water supply pipes in buildings, company housing, condominiums, etc. that have been buried for more than 10 years are experiencing problems due to rust scale.

Rust is made of ferric oxide, which makes the water in the tap water red and cloudy.
The water becomes unsuitable for drinking or washing.

In addition, as rust galls grow large, the inside of the pipe becomes blocked, making it difficult for water to flow out, resulting in insufficient flow.

Furthermore, as the rust spreads, the pipe becomes brittle and can crack due to external impact.

Therefore, it is necessary to remove rust from these existing pipes while they are still buried.

Conventionally, a bullet-shaped object called a pig is inserted into one end of the pipe, and compressed air or high-speed water is used to fly it through the pipe at high speed.
A method was adopted in which the rust particles adhering to the inside of the pipe were caused to come off by colliding with them.

However, with this method, the scale peeling force depends on the momentum of the pig, so it is necessary to use a pig with a weight above a certain level, but if you use a large pig from the beginning, it will stop midway, so start with a small diameter pig and gradually You need to try to use larger pigs.

In other words, it is necessary to prepare pigs of various sizes, and since the pigs must be passed through many times, it becomes a time-consuming and heavy-duty operation.

On the other hand, another known cleaning method uses an electric cutter.

This has a rotating blade at the tip, and the rotational force is transmitted by the flexible tube, and the scale is scraped off as it moves gradually inside the tube. However, this method can only polish the pipe up to the length of the flexible tube, so Not suitable for pipelines.

Moreover, the rotating blade used is much smaller than the pipe diameter, so the wall surface will not be finished smoothly.

The third method is a cleaning method using chemicals, and is the most conventional method.

This method involves dissolving and removing scale by passing sulfuric acid into the piping, for example, and relies on a chemical reaction without using physical force.

However, methods using chemicals have problems in terms of toxicity and are not necessarily satisfactory in terms of their effects on the human body.

The present invention aims to solve the above-mentioned problems in the conventional method of cleaning existing piping.
Even if the pipe line is relatively long and has many curves, and the scale is thick and adhered, the scale can be completely removed by grinding safely in a short period of time, resulting in a smooth finished surface. The object of the present invention is to provide a cleaning method that allows for cleaning.

In the present invention, silica sand of an appropriate particle size is mixed into an air flow in a mixing ejector 6 to form a mixed flow of air and silica sand, and then the mixed flow is applied to a high-speed air flow in an accelerating ejector 7 and swirled. A high-speed mixed flow of silica sand and air is formed, and the high-speed mixed flow is ejected from one end of the existing piping from IB to 3B to maintain a constant flow rate, and the scale, etc. stuck to the inner wall of the pipe is ground and peeled off. The basic structure is to

In addition, with this configuration, even if the pipe line is relatively long with many bends and the scale is thick and adhered, it is possible to safely and completely remove the scale within a short period of time. Become.

The details will be explained below based on the embodiments of the present invention shown in FIGS. 1 to 6.

FIG. 1 is a system diagram showing a first embodiment of the method of the present invention.

1 is an existing piping line to be cleaned, and U is scale adhering to its inner surface.

The pipe line 1 to be cleaned is any existing pipe line such as a city water main, an industrial water pipe, a water pipe of an apartment complex, a heat exchanger, a cooling water pipe, an oil pipeline, a gas pipe, or the like.

Of course, during construction, it is necessary to create the inlet and outlet of the sand jet, and for this purpose, joints and valves at appropriate locations are removed and these are used as the inlet and outlet of the sand jet.

2 is a compressor, 3 is a drain separator, and dry high pressure air is created by this, and three paths a, b,
It is assigned to c.

5 is a sand tank containing dry silica sand, and silica sand of sizes 4 to 6 (20 to 48 mesh) is used.

Air coming from path a is guided into sand tank 5 through valve 14 and regulator 4.

A mixing ejector 6 is provided at the lower end of the sand tank 5 via a valve 18.

Air coming from path b passes through valve 15 and enters mixing ejector 6.

Here, the dry silica sand supplied from the sand tank 5 is blown away to form a mixed airflow of silica sand and air, and the mixed airflow passes through path d and reaches the accelerating ejector γ.

On the other hand, the high-speed airflow passing through path C enters the accelerating ejector 7 through the valve 17.

In the accelerating ejector γ, as shown in FIG. 1, the mixed flow is applied to the high-speed air flow in a substantially perpendicular direction, and as a result, the two mix together to form a swirling high-speed mixed air flow.

Note that the conveyance pressure of the high-speed mixed gas flow is 1 to 5 kg/cm2.

The swirling high-speed mixed gas flow exiting the accelerating ejector 7 is injected into the pipe line 1 to be cleaned via the jet valve 21, and its flow velocity is 100 m/s or more.

The mixed flow S containing silica sand that has entered the pipe moves forward while colliding with the scale U while rotating at high speed, thereby giving the scale U momentum and displacing it, and eventually peeling off.

Furthermore, since the silica sand is continuously blown away, the scale is gradually scraped away and worn away, and is carried forward and disappears.

After a while, all the large scales such as rust lumps will come off.

Even after large scales have been removed, the silica sand flow continues to fly while scraping the inner wall surface of the pipe, and because it flies at high speed, surface irregularities are completely erased and the surface smoothness is extremely improved, making it easy to clean with pigs and chemicals. It is possible to create a surface that is so smooth that it would never be possible to achieve with the method.

In fact, according to this method, the specular reflectance of the inner surface of the pipe is 80
%.

Compared to chemical cleaning, which is only 70% at most, and electric cutter, which does not exceed 60%.
The achievement of superior smoothness of the present invention has been demonstrated.

The scale-containing mixed fluid S passes through the pipe line 1 and reaches the water mixer 8, where it is impregnated with water and then enters the recovery tank 9.

The reason why water is injected into the mixed fluid S by the water mixer 8 is to moisten and make the silica sand heavy so as to prevent it from scattering outside from the tank 9.

The amount of water is regulated by a valve 24.

When the scale removal process using the mixed fluid S (sand jet) is completed, the valves 14, 15, 17, 21, etc. are closed to stop the sand jet.

Next, the valves 23 and 22 are opened, and a high-speed air flow containing water is passed through the water mixer 10 into the pipe line 1, thereby flushing the inside of the pipe.

That is, the flushing removes the silica sand inside the pipe and cleans it.

Further, the valve 23 is closed and only the air flow is allowed to pass through the pipe to ensure sufficient drying.

This completes the cleaning work.

Subsequently, the inner wall surface may be lined by some method C.

Then, the cleaning device is removed from the piping path 1, and a joint, a faucet, etc. are attached.

In this way it returns to its original state.

Figure 2 is a system diagram when used in collective housing such as housing complexes.

In housing complexes and the like, water is usually once pushed up to an elevated tank 30, from where it is sent to each floor and each room.

To carry out this cleaning method, remove the water tap in each room and use this as the inlet of the sand jet.

Also, remove the joint at the bottom of the elevated tank 30 and use it as an outlet for the sand jet.

The cleaning system of the present invention is shown by a broken line, and the sand jet can clean the pipe line from the faucet to the elevated tank.

Of course, each room must be cleaned in turn,
Since the inlet of the sand jet changes each time, operations such as removing the faucet and installing the nozzle are required.

However, it is convenient because the outlet is common.

FIG. 3 shows the case where it is used for cleaning the pipes of the heat exchanger 35.

The sand jet, which is turned into a single high-speed stream by the accelerating ejector 7, rushes into the pipe from the injection nozzle 36.

The sand jet, which has proceeded while removing scale, is removed from the discharge nozzle 3γ, and then is collected in the collection tank 9 by being sprayed with water.

The method of cleaning existing pipes according to the present invention uses a swirling high-speed silica sand flow, so scale inside the pipes can be almost completely removed, and the surface smoothness becomes ideal.

FIG. 4, FIG. 5, and FIG. 6 are actual measurement examples of the degree of unevenness along the longitudinal direction of the inner wall surface when using the method of the present invention, the chemical cleaning method, and the electric cutter method, respectively.

According to the present invention, all irregularities exceeding ±10μ disappear.

Furthermore, since no chemicals are used, there is no need to worry about toxicity, which is preferable from a hygienic point of view.

Furthermore, compared to the electric cutter method and the pig method, it can be widely applied to pipes with a smaller diameter (chewing inch) to 3B (3 inches) inner diameter.

Of course, if the pipe diameter differs, the sand jet flow rate also needs to be changed appropriately.

According to the results of cleaning tests, it is best to maintain the following flow rates for each pipe diameter:

In other words, it is.

Note that each of the above numerical values is an optimum flow rate value, and it goes without saying that cleaning can be carried out even if the flow rate is slightly increased or decreased from this value.

However, from the viewpoint of cleaning efficiency and prevention of damage to the inner wall surface of the pipe, it is desirable that the flow rate of the mixed fluid be within a range of about ±15% of the optimum flow rate value.

In the present invention, since a high-speed mixed fluid of silica sand and air with a relatively large particle size is used, not only can the inner wall surface of the pipe be ground to an extremely smooth finish as described above, but also the mixed fluid can bend freely. Therefore, there is no problem even if elbows etc. are placed in the middle of the pipe, and a sufficient effect can be achieved even in a pipe with many elbows, such as a water pipe in a housing complex.

Also, there is no problem even if the diameter-reduced part or the enlarged-diameter part is located in the middle of the pipe.
Since materials such as coarse silica sand are inexpensive and the time required for the work is short, cleaning costs can be significantly reduced.

As mentioned above, the present invention has excellent practical utility.

[Brief explanation of drawings]

Figure 1 is a system diagram showing an embodiment of the present invention, Figure 2 is a piping diagram when applied to a housing complex, Figure 3 is a piping diagram when applied to a heat exchanger, Figures 4, 5, and 6. The figure is a regular view of the uneven side of the inner wall of the conduit when the method of the present invention, the chemical cleaning method, and the electric cutter method are used. 1 is a pipe line to be cleaned, 2 is a compressor, 3 is a drain separator, 4 is a regulator, 5 is a sand tank, 6 is a mixing ejector, 7 is an accelerating ejector, 8 is a water mixer, 9 is a recovery tank, U is a scale, S is a mixed fluid (sand jet).

Claims (1)

[Claims] 1. A mixed flow of air and silica sand is formed by mixing silica sand into the air flow in the mixing ejector 6, and then the mixed flow is applied to the high-speed air flow in the accelerating ejector 7 to create a high-speed swirling system. A mixed flow of silica sand and air is formed, and the high-speed mixed flow is
From one end of the existing piping line B, the flow rate is maintained in the following range for each pipe size, 1B...2.6-3.5m3/m1n 2B...10.8-13.8m3 /m1n3B...=23
．． A method for cleaning an existing pipe line, which comprises grinding and peeling off scale, etc. on the inner wall surface of the pipe line at θ~3i, 1 m3/min.