JPH0141103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved lining method that is applied after grinding the scale of buried pipes such as water pipes and equipment pipes, and allows the thickness of the lining film to be easily and accurately adjusted to a desired value. The present invention relates to a method for lining pipe inner walls that can be controlled and greatly improve working efficiency.

The applicant previously developed a method to forcefully feed a fluid mixture of a two-component epoxy resin paint and compressed air into the pipe from one end of the pipe to be treated, as a means of protecting the inner wall surface of the pipe after grinding of scale, etc. However, Japanese Patent Laid-Open No. 55-39274 discloses a technique for forming a lining film of a constant thickness on the inner wall surface of a pipe by sequentially flowing forward a paint layer adhered to the inner wall at the inlet end of the pipe.

Furthermore, the applicant has disclosed a technique as shown in FIG. 1 as a method of controlling the paint film thickness in the above-mentioned lining method in Japanese Patent Laid-Open No. 105271/1983. That is,
An accelerator 2 and a mixing nozzle 4 equipped with a paint ejection tube 3 having an inner diameter of _φ2 are connected to the base end of the tube to be treated 1 having an inner diameter of _φ1 .
At the same time, the valves 5 and 6 are adjusted so that the air flow speeds in the pipe to be treated 1 and the paint ejection pipe 3 are approximately the same. Adjust the flow rates F ₁ and F ₂ of streams A and B.

Next, when the thickness of the lining film on the pipe to be treated 1 is set to d, the opening degree of the paint adjustment valve 7 is adjusted so that the flow rate F ₂ ' of the mixing air flow B is approximately equal to the initial set value F ₂ . (φ ₂ −2φ ₁ /φ ₂ d/φ ₂ ) Adjust the supply amount of paint C so that it is ^doubled . Thereafter, the opening degree of the valve 7 is adjusted, and while the F ₂ ' is maintained at a predetermined value, the air flow A,
The supply of paint B and paint C will continue. still,
In Fig. 1, 8 is a paint mixer, 9 is an epoxy resin paint supply device, 10 and 11 are flow meters, and 12
is a compressor.

The technique disclosed in Japanese Patent Application Laid-Open No. 57-105271 expands the film thickness d in the large-diameter treated pipe 1 by replacing it with the film thickness in the small-diameter paint ejection pipe 3, and expands this by replacing it with the film thickness d in the small-diameter paint ejection pipe 3. Since it is configured to read as a change in the flow rate of (air flow B), extremely fine film thickness control can be performed.

Accordingly, in the control method, when the air flow velocity v ₁ in the tube to be treated 1 and the air flow velocity v ₂ in the paint supply tube 3 are equal, the thickness d ₁ of the film formed on the inner wall surface of each tube is
It was developed on the premise that the relationship d ₁ /d ₂ =φ ₂ /φ ₁ holds between and d ₂ .

However, the length of the tube 1 to be treated is usually 30~30 mm.
Since the length is about 100 m, as the paint layer flows forward and a lining film is formed, the air resistance of the pipe increases, and as a result, the air pressure at the inlet end of the pipe to be treated 1 increases. Flow velocity of accelerated airflow A v ₁
decreases. This is because the air flow velocity v ₁ in the pipe is
This is because when the pipe diameter and air supply amount are constant, the pressure increases inversely to the absolute pressure. Therefore, there is no particular problem when the pipe length of the pipe to be treated 1 is relatively short and the diameter is large, but if the pipe length is small and the pipe length is long, the inlet end of the pipe to be processed 1 The paint layer supplied to the tube and deposited on the inner wall surface does not flow forward smoothly, resulting in a large difference in coating thickness between the inlet and outlet sides of the tube 1, or the paint layer at the inlet end of the tube. However, there is a problem in that "paint drips" or, in extreme cases, "paint clogging" occurs.

Due to the problems mentioned above, in actual construction, in order to make the film thickness uniform on the inlet and outlet sides of the pipe 1 to be treated, and to adjust the finish of the film thickness itself, the paint layer is After the paint C flows out from the outlet side and the supply of paint C is stopped, a constant flow rate of film thickness adjustment air is continuously flowed to adjust the film thickness. That is, before the start of lining, the pipe to be treated 1
A predetermined flow rate Q _S of air for film thickness adjustment is flowed into the interior, the supply air pressure P ₁ at that time is measured, and after stopping the supply of paint C, the air flow for film thickness adjustment is the same as the predetermined flow rate Q _S. is continuously supplied, and when the ratio (P ₂ /P ₁ ) between the air pressure P ₂ supplied at that time and the air pressure P ₁ reaches a predetermined value, the air flow for adjusting the film thickness is stopped. In other words, the air flow for adjusting the film thickness
The paint layer on the inner wall of the tube is entirely pushed out by Q _S , and the P ₂ gradually decreases over time. As a result, when conditioning air is flowed for a long time (P ₂ / P ₁
When P 2 /P 1 becomes large), the film thickness becomes thinner, and when airflow is applied for a short period of time (P ₂ /P ₁ becomes large), the film thickness is adjusted to be thicker.

However, such film thickness adjustment work is time-consuming, and there is a problem in that the film thickness cannot be adjusted sufficiently once the paint begins to harden, further increasing unnecessary paint consumption.

The present invention aims to solve the above-mentioned problems in the conventional pipe inner wall lining method, and it is possible to control the film thickness without separately performing the film thickness adjustment work as in the past. It is an object of the present invention to provide a method for lining the inner wall of a pipe, which makes it possible to form a lining coating film having a uniform thickness without any cracks.

Therefore, when an air flow with an inlet air pressure P1 and a flow rate Q is passed into the pipe ₁ to be treated having a length L and an inner diameter D, and the outlet pressure is _P2 , the pipe 1 to be treated before lining treatment is The pressure drop ΔP within is ΔP=P ₁ − P ₂ ……. In addition, a lining coating film is formed on the inner wall of the tube 1 to be treated (the inner diameter is D'), and when an air flow of flow rate Q' is passed through it at an inlet air pressure P ₁ ', the outlet pressure is P ₂ ′, the pressure drop ΔP′ inside the pipe to be treated 1 after the lining treatment is ΔP′=P ₁ ′−P ₂ ′ .

On the other hand, the pressure drops ΔP and ΔP' before and after the lining process can be calculated using the so-called Bellmouth formula, and the ratio of the two is ΔP'/ΔP = λ'・L/D'・k'・1/D ′ ⁴・Q′ ² /(P′ ₁ +P
' ₂ )/2/λ・L/D・k・1/D ⁴・Q ² /(P ₁ +P ₂ )
/2... is given by. Now, make the air flow rates Q and Q' the same before and after lining treatment,
And if the definitions λ=λ' and k=k', then the above,
From the formula, P ₁ ′ ² = D ⁵ /D′ ⁵ (P ₁ ² −P ₂ ² )+P ₂ ′ ² …….

In the above equation, if the diameter and length of the tube to be treated and the inlet air pressure P ₁ before lining treatment are determined, the outlet air pressure P ₂ is uniquely determined. In addition, the outlet air pressure P ₂ ′ after the lining treatment is
It can be set to be approximately equal to P ₂ . Then,
Inlet air pressure after lining treatment when the air flow rate Q supplied to the pipe to be treated is always constant
P ₁ ' can be obtained by solving the above equation.
For example, when the pipe diameter is 25 mm, the inlet air pressure before lining treatment is P ₁ = 5 Kg/cm ² , and the outlet air pressure is 2 Kg/cm ² , the coating film thickness is d = 1 mm (D' = 23 mm).
When the lining treatment is performed, the inlet air pressure P ₁ ' after the lining treatment is approximately 5.96 Kg/cm ² . or,
Coating film thickness d = 0.5 mm (D' = 24 mm) for the same treated pipe
In this case, P ₁ ' becomes 5.45Kg/cm ² .

Figure 2 shows how the inlet air pressure changes in the example where the coating film thickness d = 1 mm, and the inlet air pressure P ₁ = 5 kg/cm 2 before lining is changed to approximately 6 kg/cm ² after lining is completed. cm ² , during which the inlet air pressure changes approximately linearly with respect to time T.
It has been confirmed through experiments that this tendency to change linearly does not change even if the pipe length, pipe diameter, and coating thickness vary.

Therefore, from the diameter and length of the pipeline to be treated, as well as the coating film thickness d to be formed, the inlet air pressure P ₁ before lining and the inlet air pressure P ₁ ' after lining are completed, and during the lining treatment, the inlet air pressure P 1 ' is calculated. ₁ , the air flow rate is held constant. Then, the amount of paint supplied into the pipe is adjusted so that the inlet air pressure P ₁ ' at the time when the paint flows out from the end of the pipe to be treated and lining is completed becomes exactly the preset value. By controlling the inlet air pressure P ₁ ', it is possible to form a coating film having a predetermined thickness d inside the pipe.

The present invention has been developed based on the above-mentioned logic, and involves supplying a mixed fluid of epoxy resin paint and air to the inlet end of a pipe to be treated, and depositing a paint layer on the inner wall surface of the pipe. By sequentially moving the mixed fluid forward by the airflow that forms it,
In a pipe inner wall lining method in which a coating film is formed on the inner wall surface of the pipe, the flow rate of air supplied into the pipe to be treated is maintained at a constant value during the lining process, and the amount of paint supplied is adjusted. The basic idea is to control the air pressure at the inlet end of the processing tube to a preset pressure value depending on the thickness of the coating film to be formed, thereby forming a lining coating film of the desired thickness. be.

Hereinafter, details will be explained based on an embodiment of the present invention shown in FIGS. 3 and 4. FIG. 3 is an implementation system diagram of the lining according to the first embodiment of the present invention, and the same reference numerals are used for the same parts as in FIG. 1.

When lining the tube to be treated 1, first the compressor 12 is started, and the pressure regulator 13 is adjusted to set the discharge air pressure P in advance according to the diameter and length of the tube to be treated 1 and the film thickness to be formed. Adjust the pressure so that it is close to the pressure value (3 to 7 Kg/cm ² ).

Next, the regulating valve 6 is opened to supply the accelerating air flow A to the accelerator 2 to completely purge the inside of the tube 1 to be treated, and at the same time, the accelerating air flow A at the inlet end of the tube 1 to be treated is The opening degree of the regulating valve ₆ is adjusted to a flow rate F1 such that the flow velocity is about 40 to 100 m/sec.

When the flow rate adjustment of the acceleration air flow A is completed, the opening degree of the regulating valve 5 is subsequently adjusted, and the flow rate of the mixing air flow B is adjusted.
Let F ₂ be F ₂ = (φ ₁ /φ ₂ )F ₁ . That is, by the adjustment operation, the air flow velocity in the paint jetting pipe 3 v ₂
This means that the air flow velocity v ₁ at the inlet end of the tube 1 to be treated is adjusted to be approximately the same. Note that when the mixing air B flows, the accelerating air flow A changes slightly. However, the flow rate _F2 is the flow rate of the acceleration air A.
Since the amount is small compared to F ₁ , there is usually no need to readjust the variation in F ₁ caused by flowing F ₂ .

After adjusting the flow rate F ₁ of the acceleration air flow A and the flow rate F ₂ of the mixing air flow B, the epoxy resin paint supply device 9 is started, the paint adjustment valve 7 is opened, and the mixing air flow B is adjusted. The opening degree is adjusted until the flow rate F ₂ ′ decreases to F ₂ ′=F ₂ ×(φ ₂ −φ ₁ /φ ₂ d/φ ₂ ) ² . However, in the above equation, d is the thickness of the lining coating film to be formed on the tube 1 to be treated.

In this embodiment, as described above, the paint C and the air flow B are mixed in advance in the mixing nozzle 4, and the mixed fluid of the paint C and the air flow B is passed through the paint ejection pipe 3 to the accelerator 2. As shown in FIG. 4, the paint C is sprayed at a constant flow rate determined experimentally in advance according to the pipe diameter φ ₁ of the pipe to be treated 1 and the thickness of the coating film to be formed. Direct accelerator 2
Of course, it may also be configured to eject inward.

The paint C ejected into the accelerator 2 is supplied into the tube 1 to be treated while being mixed with the accelerating air flow A, and is successively deposited and laminated on the inner wall surface near the inlet end. Then, the paint layer deposited on the inner wall of the tube is transferred to the accelerator 2.
The accelerating air flow A that is released in a swirling manner within the tube causes it to flow sequentially forward along the tube wall, forming a coating film. The thickness of the coating film formed on the inner wall surface of the pipe is mainly determined by the flow rate of the paint layer and the amount of paint supplied, and as the lining film is formed inside the pipe to be treated 1, The air resistance increases, the reading of the pressure gauge 14 increases, and the indicated value F ₁ of the flow meter 10 changes.

In the present invention, the signal Sa from the flowmeter 10
Accordingly, the regulating valve 6 is controlled via the control panel 15, and the flow rate of air supplied to the pipe to be treated 1 is maintained at substantially the same value as the initial set value during lining construction.

On the other hand, as described above, due to the increase in air resistance accompanying the formation of the lining coating film, the indicated value of the pressure gauge 14 also changes, and the inlet air pressure P ₁ ' of the tube to be treated 1 gradually increases. In the present invention, the indication signal Sp of the pressure gauge 14 is applied to the paint regulating valve 7 via the control panel 15, and as explained in FIG. 2, the indication value of the pressure gauge 14 ( In order to control the inlet air pressure P ₁ ') of the pipe to be treated 1, the opening degree of the paint regulating valve 7 is adjusted to adjust the amount of paint supplied into the pipe. For example, if the diameter of the tube to be treated 1 is 1B (25mmφ),
Inlet air pressure before lining P ₁ = 5.0Kg/cm ² , outlet air pressure P ₂ = 2Kg/cm ² , lining thickness d = 1mm
In this case, set the pressure gauge 14 so that the air pressure P ₁ ' at the inlet of the pipe to be treated is approximately 6 kg/cm ² when lining is completed.
The opening degree of the paint regulating valve 7 is adjusted by the signal Sp from the controller. Incidentally, since the viscosity of the epoxy resin paint changes greatly depending on the temperature, the flow rate of the paint layer also changes depending on the temperature. However, generally the coating thickness is 0.5
~1.2mm, the flow velocity is 1.0~2.5m/
If the lining coating thickness d and the length of the tube 1 to be treated are determined, the lining completion time T can be calculated relatively accurately. As a result, the control program for the inlet air pressure P ₁ ′ can be found relatively easily, and in the case of the above example (temperature = 20°C to 25°C), the paint flow rate
Lining time T = 35/ as Vp = 2.0m/min
20≒18 minutes, and set a program in which the inlet air pressure P ₁ ' changes linearly at a rate of approximately 6-5/18 (Kg/cm ² ·min). Then, the opening degree of the paint regulating valve 7 is adjusted so that the inlet air pressure P ₁ ' changes based on the program. If there is a slight error in the setting of the lining time T and the lining is completed earlier than the set time T (paint flows out from the pipe end), the paint will continue to be supplied and the inlet air pressure P ₁ ' will be maintained at the predetermined level. Value (P ₁ ′≒6Kg/cm ² )
Stop the supply of paint and air when the amount decreases to . Conversely, if the lining setting time T is short and the lining is not completed, the paint supply amount is increased slightly to continue supplying the paint and air, and when the lining is completed, P ₁ ′≒6Kg/cm Adjust the paint adjustment valve 7 so that the amount becomes ² .

Further, in this embodiment, the air flow rate adjustment valve 6 and the paint adjustment valve 7 are automatically controlled, but it goes without saying that they may also be controlled manually.

As described above, the present invention maintains the air flow rate in the tube to be treated 1 constant, adjusts the amount of paint supplied into the tube, and adjusts the inlet air pressure P ₁ ' of the tube to be treated 1 according to a preset program. Therefore, since it is controlled, a coating film having a predetermined and uniform thickness can be formed on the inner wall surface of the pipe. the result,
There is no need for the coating film thickness adjustment process after the lining process as in the past, which significantly improves work efficiency and significantly reduces paint loss.

In addition, the inlet air pressure P ₁ before and after lining treatment,
It is an excellent practical product that allows you to obtain the desired coating thickness extremely easily by simply changing P ₁ ′, and can quickly form a coating film with an even thickness over the entire length of the pipe to be treated. It has a positive effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the lining method according to Japanese Patent Application Laid-Open No. 57-105271. FIG. 2 is a diagram showing changes in the inlet air pressure P ₁ ' during lining construction when the air flow rate in the pipe to be treated is constant.
FIG. 3 is an implementation system diagram showing a first embodiment of the present invention. FIG. 4 is an implementation system diagram showing a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Pipe to be treated, 2...Accelerator, 3...Paint ejection pipe, 4...Mixing nozzle, 6...Flow rate adjustment valve, 7...Paint adjustment valve, 10...Flowmeter, 1
4...Pressure gauge, 15...Control panel, A...Air for acceleration, B...Air for mixing, C...Paint.

Claims (1)

[Claims] 1. A fluid mixture of epoxy resin paint and air is supplied to the inlet end of the pipe to be treated, and the paint layer adhered to the inner wall of the pipe is sequentially flowed forward by the air flow, thereby coating the inner wall of the pipe. In a method of lining the inner wall of a pipe to form a film,
By keeping the flow rate of air supplied into the tube to be treated at a constant value during the lining process and adjusting the amount of paint supplied, the air pressure at the inlet end of the tube to be treated can be adjusted to the desired coating thickness. A pipe inner wall lining method characterized by controlling the pressure to a preset pressure value to form a lining coating film of a desired thickness.