JPH0221971A - Method of lining inside 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] [Industrial Application Field] The present invention relates to a method for lining the inner surface of a pipe, and in particular, to an existing water supply pipe in an apartment complex, an existing hot water pipe in an office building, or a cold/hot water pipe for air conditioning. This invention relates to a method for lining the inner surface of a pipe, which can be used suitably for the rehabilitation of pipes, etc.

[Conventional technology]

Galvanized steel pipes are used for water pipes in buildings such as office buildings, condominiums, apartment complexes, schools, hospitals, hotels, etc. built from the 1950s to around 1970.
Meanwhile, during this period, water quality at water sources deteriorated and the amount of chlorine used at water treatment plants increased, corrosion of the galvanized water pipes progressed in a short period of time, and then the steel pipes themselves corroded. has occurred and has become a problem.

Therefore, in order to solve such problems, the rehabilitation of existing water supply pipes, etc. has become an important issue, and various methods have been proposed for lining the inner surface of the pipes. Publication No. and Special Publication No. 58-13
The methods described in Japanese Patent Publication No. 226 and Japanese Patent Publication No. 58-14826 are known.

[Problem to be solved by the invention]

The methods described in these publications apply a swirling flow to the paint to coat the inner surface of the tube, so there is a problem that spiral streaks are formed in the paint film due to the swirling, resulting in uneven paint film thickness. there were.

The present invention was made to solve these conventional problems, and provides a coating method that can uniformly coat the inner surface of a tube.

[Means to solve the problem]

In order to solve the above problems, the present invention employs the following means.

That is, in the present invention, after putting paint into a paint storage pipe connected to the inlet of a pipe to be painted, dry compressed air is introduced from the inlet of the paint storage pipe, and the painting is carried out by this compressed air flow. This is a method of lining the inner surface of a pipe, in which the paint is applied by flowing it into the pipe without swirling it.

Hereinafter, specific embodiments of the present invention will be explained.

First, in the present invention, a paint storage pipe is connected in advance to the inlet of the pipe to be painted before painting. As this paint storage pipe,
Any type of material that can store paint may be used, such as one pipe bent into a TJ shape, three wooden pipes connected in a U shape, etc.

Next, when the method of the present invention is used to rehabilitate a pipe whose inner surface is rusted, the inner surface of the pipe to be rehabilitated must be polished to remove rust before construction. The method is to completely dry the rust lumps inside the pipe with heated dry compressed air, then put a certain amount of abrasive material into the paint storage pipe and let the abrasive material pass through the pipe with a high-speed air flow made of compressed air. Repeat this several times.

In the drying and polishing process, the temperature of dry compressed air is between 5 and 8.
A high temperature of 5°C, especially 40 to 70°C is best, especially 50 to 70°C.
60℃ is suitable, and the degree of drying is 1 to 5 g of absolute humidity.
/Nm3 is good. Also, the speed of compressed air is 100 m/s
The flow rate of compressed air (Nm3/min) is preferably determined by the relationship between this flow rate and the inner diameter of the pipe to be rehabilitated.
, pressure (kg/cm2·G) is determined.

In addition, it is desirable to carefully select the abrasive material with emphasis on hardness, specific gravity, balance of shape, etc., and the hardness is 6 on the Mohs scale.
-7, a specific gravity of 1.5, and a particle size of about 3 to 5 mm, sharply angular crushed stone can be suitably used. When polishing using such an abrasive material, it is not necessary to use a swirling flow as in the case of painting.

The above polishing method removes rust extremely quickly, reduces the amount of abrasive used to about one-tenth of the conventional method, eliminates over-sharpening of the pipe, and causes problems such as holes forming in the pipe before the rust lumps are removed. is gone. In addition, the pipe can be polished uniformly over the entire length of the pipe, and the inner wall surface of the pipe is roughened to enhance the anchor effect (a state in which the pipe is caught like an anchor), making it possible to improve adhesion with paint. . and,
Since dry compressed air, especially high-temperature dry compressed air, is used, it is possible to dry and remove rust in a short time even during the rainy season, when the humidity is the highest.

Completion of polishing is judged based on three levels: the amount of decrease in air pressure, the amount of increase in air flow rate, and the point at which the red rust color disappears from the transparent tube provided at the outlet of the construction tube. The three levels of polishing finish are determined in advance by comparing the conditions using a fiberscope.

Then, after applying this type of surface treatment, by lining it with dry compressed air using the paint below,
The adhesive strength of the coating film can be increased by more than 5 times compared to conventional methods.

Next, as the paint used in the present invention, various synthetic resin paints can be used, but when used for water supply pipe rehabilitation, safety and hygiene (harmless and odorless), durability (no cracking or blistering), It requires good workability (good fluidity, thick coating, and fast curing).

A paint that can meet these demands is a paint with a viscosity of 800, which is made by adding a curing agent to an epoxy resin and completely mixing it.
0~35000CP, preferably 1oooo~2000
A 0CP epoxy paint is preferably used. Further, similar urethane resin paints can also be suitably used.

Here, viscosity is important in ensuring fluidity and thick coating, but since the value of this viscosity changes depending on the temperature of the paint, it is influenced by the air temperature at the time of construction and the temperature of the pipe. Therefore, it is important to change the basic viscosity adjustment of the paint between summer and winter in order to achieve good lining.

The amount of paint used for one lining is determined by the coating area, which is determined by the inner circumference and length of the pipe.

After putting this one-time amount of paint into the paint storage tube,
Dry compressed air is introduced from the inlet of the paint storage pipe, and the paint is carried by this compressed high-speed air flow into the pipe to be painted without swirling, thereby coating the paint.

Here, the dry compressed air is 5 to 65°C, preferably 5 to 4°C.
Dry compressed air at a low temperature of 5°C, more preferably 10 to 30°C is preferable, and the degree of dryness is 1 to 3 g/Nm3 of absolute humidity.
Good. By using low-temperature compressed air, the thick coating properties of the paint are maintained, and combined with the paint's high water resistance and high heat resistance,
A coating film with outstanding durability can be obtained.

In addition, the speed of the compressed air is preferably 100 m/s or more, and depending on the relationship between this flow speed and the inner diameter of the pipe to be coated,
Compressed air flow rate (Nm3/m1n) Pressure (kg/cm")
・G) is determined.

Next, in the present invention, the meaning of "flowing the paint without swirling" includes not giving a swirling flow to the paint and applying restrictions so that swirling flow does not occur. Simply sending the paint placed in a storage pipe into the pipe to be coated on a compressed air flow does not create a swirling flow in the paint, and the paint is simply swept away with the compressed air flow, which naturally causes swirling. It means not going with the flow. Furthermore, the term "swirling flow" as used herein refers to a manner in which the flow flows in the axial direction of the tube while rotating around the axis of the tube.

[Effect]

After the paint is put into the paint storage pipe, dry compressed air is introduced from the inlet of the paint storage pipe, and the paint pushed by the compressed air flows in one lump (plug flow). During this time, the inner surface of the tube is painted one after another, and the amount of paint lumps gradually decreases until the compressed air penetrates these lumps, and after that, the paint rides on the compressed air flow and spreads in order, forming an annular shape inside the pipe without swirling. It flows (annular gas-liquid two-phase flow) and the inner surface of the tube is painted.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(A) Example 1 As shown in Fig. 1, a U-shaped tube 2 is connected to one end of a horizontal tube 1, paint is stored in this U-shaped tube 2, and compressed air is supplied from the end of the U-shaped tube 2. The inner surface of the tube was lined by causing a gas-liquid two-phase flow of air and paint.

The detailed implementation conditions are as follows.

■Pipe Material: Transparent synthetic resin Pipe diameter: 1 inch for both horizontal pipe and U-shaped pipe Length: In Figure 1 a=0.5m b=0.5m c=8m ■Paint type: Main agent and curing agent 235g of mixed epoxy resin paint 30℃ (outside temperature 7℃) 15,000 centivoice (cp) Amount: Temperature: Viscosity: ■Air flow rate: 3. 6 Nm3/min pressure crab 5kg/
crn"G Temperature: 17°C Absolute humidity: 2g/Nm3 Next, the progress of the pipe lining according to this example was observed.

First, the paint prepared as described above was put into the U-shaped tube 2, and dry compressed air was introduced from the end of the U-shaped tube 2. U-shaped tube 2
The paint stored inside was pushed by compressed air and started flowing. At the beginning of the flow, the paint became an elongated lump with a rounded tip, flew out of the U-shaped tube 2 at high speed like a bullet, and started running inside the horizontal tube 1 [Figure 3 (a)]
]. As the paint lump travels while lining the inner surface of the tube, it becomes shorter by the amount consumed by the lining, and gradually accelerates until it can no longer resist the air pressure and bursts, scattering in the direction of travel [Figure 3 ( b)]. This rupture point is U
The point was approximately 2.5 m from the connection point between the double pipe 2 and the horizontal pipe 1. ■ Plug flow and baldness of paint up to this point. This plug flow was a straight flow, and no swirling flow was observed.

After installation point P, the flow of paint became an annular flow, and no swirling flow was observed [Figure 3 (C)]. Here, the annular flow refers to a state in which the paint flows in an annular shape along the inner surface of the tube, and the flow is linear in the flow direction.

The annular flow of air and paint as in this example is called a gas-liquid annular two-phase flow in fluid mechanics.

After painting, the pipe was cut and the state of the paint film was visually observed. There were no streaks or other uneven coating on the paint film surface, and the thickness of the paint film was uniform with an average of 0.5 mm. Thermal shock resistance test (JWWA
K115), there were no peeled parts, bulges, cracks, etc.

(B) Example 2 As shown in FIG. 1, this example was carried out in the same manner as in Example 1 under the following conditions, using a tube in which a U-shaped tube 2 was connected to one end of a horizontal tube 1.

The detailed implementation conditions are as follows.

■Pipe Material: Made of transparent synthetic resin Pipe diameter: 2 inch length for both water pipe and U-shaped pipe In Figure 1, a=0.5m b=0.5m c=8m ■Paint type: Sato Temperature viscosity: ■ Supplied air flow rate: Pressure crab temperature 24-70 g of epoxy resin paint mixed with main agent and curing agent 26°C (outside temperature 8°C) 15,000 centivoise (cp) 13.2 Nm”/min 3.5] (g/cm2・G 20°C Absolute humidity: 2.5 g/Nm3 Next, the progress of the pipe lining according to this example was observed.

As in Example 1, paint was put into the U-shaped tube 2, and compressed air was introduced. The flow of paint was initially a plug flow, and after the rupture point Q, it became a circular flow. The rupture point Q was the connection point between the U-shaped pipe 2 and the horizontal pipe 1. No swirling flow was observed in the paint flow at any point in the tube.

After painting, the pipe was cut and the state of the paint film was visually observed. There were no streaks or other uneven coating on the surface of the paint film, and the thickness of the paint film was uniform with an average of 0.6 mm. Thermal shock resistance test (JWWA
K115), there were no peeled parts, bulges, cracks, etc.

(C) Example 3 In Example B, as shown in FIG. 2, the tube 1 cranked at a constant pitch was used and conducted under the following conditions.

The detailed implementation conditions are as follows.

■Pipe Material: Transparent synthetic resin pipe Caliber: 1 inch Length: a=0.5m in Figure 2 b=0.5m Number of mountains due to crank = 4 ■Paint kinds: amount temperature: viscosity: ■Supplied air Flow rate: pressure crab temperature: Absolute humidity: Mixed base agent and hardening agent epoxy resin paint 000g 22°C (outside temperature 8°C) 15000 centipoise (cp) 3.6 Nm3/m in 51 (270m2◆G 18°C 2.2g/Nm3 next, The progress of the pipe lining according to this example was observed.

As in Examples 1 and 2, the flow of the paint was initially a plug flow, and after the fall of the porcelain point, it became a circular flow. The rupture point R was the exit point over the first peak of the crank. No swirling flow was observed in the paint flow at any point in the tube.

After painting, the pipe was cut and the condition of the paint film was visually observed. There were no streaks or other uneven coating on the paint film surface, and the thickness of the paint film was uniform with an average of 0.7 mm. Thermal shock test (JWW) where hot water at ℃ and cold water at 20℃ are repeated
When I performed A K115), there were peeling parts, swelling,
There were no cracks or the like.

(D) Example 4 In this example, instead of lining a transparent synthetic resin tube, a galvanized steel tube whose inner surface was actually rusted was lined. In this example, as shown in FIG. 1, a horizontal galvanized steel pipe with one end ζ-shaped U-shaped tube 2 connected was used, and after polishing the inner surface of the galvanized steel pipe with an abrasive, Painted the same way.

The detailed implementation conditions are as follows.

■Pipe Material: Galvanized steel pipe (sample with rusted inside) Diameter: Horizontal pipe (galvanized steel pipe) and U-shaped pipe both 2 inches long (in Figure 1 a = 0.5 m b = 0.5 m c = 8 m Abrasive material: Copper slag 4 kg ■Polishing conditions Dry compressed air flow rate: pressure crab) Temperature: Absolute humidity Polishing number of times: 13, 2Ntn3/m1n 3.5 kg/cm2・G 50°C 2.5 g/Nm3 80 times (abrasive material (Additional amount: 50g at a time) ■Paint type: Epoxy resin mixed with base agent and hardening agent Paint amount: 2470g Temperature: 26℃ (outside temperature 8℃) Viscosity: 15,000 centivoise (cp) ■Painting conditions Inlet air M amount: 1 3. 2 Nm"/min pressure crab 3.5kg/cm"+G Temperature: 22℃ Absolute humidity: 2.4g/Nm3 After painting, the pipe was cut and the state of the paint film was visually observed, and the paint film surface was There are no streaks or other uneven coating, and the coating film has a uniform thickness of 0.6 mm on average.It has also been tested in a shock resistance test (JWWA) of repeatedly passing hot water at 80°C and cold water at 20°C.
K115), there were no peeled parts, bulges, cracks, etc.

Furthermore, when the adhesive strength was measured using the JIS-6849 method, it was 185 kg/cm2, which was 4.7 times better than the conventional method, which was 39 kg/cm21. Further, when a pinhole test was conducted according to the specifications of J WWAG 112, no pinholes were found.

〔Effect of the invention〕

Since the present invention does not rely on swirling flow, it is possible to obtain a coating film with uniform thickness without coating unevenness, and since it uses dry compressed air, moisture that can cause cracks and blisters can be obtained. It is possible to obtain a highly durable coating film without invading the coating film.

In addition, the polishing method ζ Koyore according to the present invention can reduce the amount of abrasive, and therefore can be performed with small and compact equipment (abrasive material injector, dust collector, etc.), and can be used for pipes. This eliminates problems such as holes forming in the pipe, and if the surface is treated with this polishing method before painting, the adhesive strength between the paint film and the pipe can be extremely high.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the tube used in Examples 1 and 2 of the present invention,
FIG. 2 is a schematic diagram of a tube used in Example 3 of the present invention, and FIGS. 3(a), (b), and (c) are diagrams showing the flow state of the paint. - Pipes to be painted (horizontal pipes, crank pipes), 2◆ - Paint storage pipe (U-shaped pipe), - Paint.

Claims (4)

[Claims] (1) After putting paint into the paint storage pipe connected to the inlet of the pipe to be painted, dry compressed air is introduced from the inlet of the paint storage pipe and carried by this compressed air flow into the pipe to be painted. A method for lining the inner surface of a pipe, characterized in that the paint is applied by flowing it without swirling it. (2) The method for lining the inner surface of a tube according to claim 1, wherein the temperature of the dry compressed air is 5 to 65°C. (3) After drying the inner surface of the pipe to be painted by flowing dry compressed air, a predetermined amount of the abrasive material is introduced into the pipe to be painted using the compressed air flow to polish the inner surface of the pipe, and then the inner surface of the pipe is polished. Claim 1 characterized in that it is painted with paint.
The method for lining the inner surface of a tube according to item 1 or 2. (4) The method for lining the inner surface of a tube according to claim 3, wherein the temperature of the dry compressed air is 5 to 85°C.