JPH10192753A - Pipe inside coating device for existing line, and coating method using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform thin film lining on the inner wall surface of a pipe at low cost. SOLUTION: This coating device has a coating cartridge 2 at the front side of the advancing direction, a coating spraying cup 4 freely rotatably supported on an axial body 3A at the back side of the advancing direction, and a joint part 3 between the two. An air stream in a pipe flowing along the inner wall surface of the pipe is caused to detour and flow toward a rotary blade provided on the coating spraying cup 4 by a seal ring provided on the joint part 3 to obtain rotation energy of the coating spraying cup 4, thereby centrifugally spraying paint from a coating jetting hole formed in the coating spraying cup 4 to perform thin film lining to the inner wall surface of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for coating an existing pipe in a pipe and a method for coating the pipe using the same. More specifically, the present invention relates to an apparatus for coating a resin liquid (paint) on the inner surface of an existing pipe. TECHNICAL FIELD The present invention relates to an apparatus for forming a thin resin lining and a method for forming a resin lining using the same.

[0002]

2. Description of the Related Art Metal pipes such as steel pipes and cast iron pipes and resin pipes such as hard vinyl pipes are used for existing pipes such as gas pipes, water pipes, and communication pipes buried underground. However, when the burial period is long, the aging phenomenon due to corrosion or the like progresses, and a defect such as a leak hole may occur in the pipe. This phenomenon is particularly remarkable when a metal tube is used.

Conventionally, for gas pipes and water pipes that require airtightness for the purpose of repairing a defective portion and preventing the progress of the phenomenon against the aging phenomenon, a seal tube is lined on the inner surface of the pipeline. In addition, a repair and repair technique has been developed in which a resin liquid is lined on the inner surface of the pipe to improve the sealing property of the pipe.

On the other hand, among the above-mentioned pipes, a communication pipe such as a cable pipe has a plurality of pipe groups buried in advance at a laying position. The pipeline for inserting the cable from the empty pipeline in the group can be selected. As a result, when a new cable is laid, the trouble of burying a communication conduit again can be omitted. However, if rainwater or earth and sand penetrate from the corrosive holes formed in the pipes forming the empty pipes and rust etc. are generated in the pipes, it is possible to insert a new cable by reducing the inner diameter of the pipes. May not be possible. For this reason, a lining construction for applying a rust-preventing resin liquid to the inner wall surface of an empty pipeline is performed.

[0005]

Conventionally, as a method of applying a resin lining to an inner wall surface of a pipe, when a pipe such as a gas pipe or a water pipe is required to be air-tight, a resin pipe is provided in the pipe. There is a method in which a liquid is introduced, and the resin liquid is caused to flow by a pig or a differential pressure in a pipe to perform lining.

However, this method has the following problems. That is, in this method, the resin coating film formed in the tube is often made relatively thick for the purpose of ensuring airtightness. For this reason, when applied to a communication pipeline, the inner diameter of the pipeline is reduced due to the thick coating film, which deteriorates the cable insertability. In addition, since the amount of the resin liquid used increases in proportion to the film thickness, the repair cost becomes high including the case where the entire area in the pipeline is lined.

[0007] In the case of a communication pipe, unlike other pipes, it is not necessary to consider airtightness in the entire pipe much, and it is possible to insert a cable. Since the thickness may be relatively thin, using the above-described method as it is, in which the amount of the resin liquid used is large, results in an increase in cost.

On the other hand, as a lining technique, there has been proposed a lining technique of a packer system in which a coating material is centrifugally sprayed (for example, Japanese Patent Publication No. 51-41655). Since the lining technology described in the above publication has a structure in which the paint spraying cup is rotated by an air motor, incorporating the air motor not only increases the size of the device itself, but also increases the cost of the device. In addition, not only equipment such as piping for supplying air to the air motor is required, but also the operation of inserting the piping into the pipeline is required. Workability at the time of insertion into the device becomes poor.

The present invention has been made in view of the above problems in the conventional in-pipe coating apparatus and coating operation, and is intended to provide an in-pipe coating apparatus capable of forming a thin film lining on the inner wall surface of an existing pipe at low cost and an in-pipe coating method using the coating apparatus. It is intended to provide.

[0010]

In order to achieve this object, the invention according to claim 1 is characterized in that, in the process of being introduced into a pipe from one end opening of an existing pipeline and moving toward the other opening,
An in-pipe coating apparatus for spraying paint onto a pipe inner surface from a rotating paint spray cup to apply the paint, wherein the in-pipe coating apparatus is disposed at a front portion in a traveling direction of the paint cartridge and is capable of storing paint. A paint spraying cup disposed at a rear portion in the direction, and a joint portion disposed at an intermediate portion between the two, and the paint cartridge has a required width at an outer peripheral portion with respect to an inner diameter of the existing pipeline. The joint portion is formed with an outer diameter dimension that can form an air flow passage, and the joint portion has a shaft body that opens a paint passage capable of supplying paint in the paint cartridge to the paint spraying cup at a center portion, and an outer peripheral portion. A seal ring which is arranged and circulates in a direction in which the air flow in the pipe flowing through the air flow passage is detoured toward the center of the pipe away from the pipe inner wall surface, and wherein the paint spraying cup is provided with the shaft body. It is rotatably supported at the rear end position,
The outer peripheral portion includes a paint ejecting head communicating with the paint passage, and a plurality of rotating blades arranged along the circumferential direction inside the outer peripheral portion, and the rotating blades are bypassed by the seal ring of the joint portion. It is characterized in that it is arranged at a position facing the air flow in the pipe to be circulated and is driven to rotate by the air flow in the pipe.

According to a second aspect of the present invention, there is provided an in-pipe coating method using the in-pipe coating apparatus according to the first aspect, wherein the inside of the pipe in the moving direction front side of the coating apparatus is installed with respect to an existing pipeline into which the in-pipe coating apparatus is introduced. Means for generating a required pressure difference between the inner pipe and the rear pipe, and by introducing and moving the coating apparatus in the existing pipe with the pressure difference being applied, the paint spraying is performed by the pipe differential pressure. The rotational energy of the attached cup,
The coating is performed by centrifugally spraying the paint flowing out from the paint jet head onto the inner wall surface of the pipe.

According to a third aspect of the present invention, in the in-pipe coating method according to the second aspect, the pressure difference includes a blowing pressure in a pipe in a front side in a moving direction of the in-pipe coating apparatus, and a rear side in a moving direction of the in-pipe coating apparatus in a moving direction. Is generated by applying a negative pressure to the.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a cross-sectional view of an essential part of the in-pipe coating apparatus according to the present invention, showing a configuration of the in-pipe coating apparatus taken along a longitudinal center line L in the longitudinal direction. In FIG. 1, an in-pipe coating apparatus 1 includes a paint cartridge 2 located on a front side in a traveling direction of the in-pipe coating apparatus 1 indicated by an arrow A, a paint spray cup 4 located on a rear side, and an intermediate part between these two. And a joint portion 3.

Hereinafter, each member will be described as follows. The paint cartridge 2 is a member filled with a resin liquid (paint) used for painting, and is a holding member 2A.
And a bag 2B inserted into the holding member 2A.

The holding member 2A is an outer member of the in-pipe coating apparatus 1, and as shown in FIG. 2, a sheet metal member 2A1 having hinge joints corresponding to a plurality of joints is connected and folded along the circumferential direction. Is possible. The holding member 2A whose diameter has been expanded from the folded state has a polygonal cross-sectional shape when the hinge connection portion abuts on the inner wall surface of the pipe 10, and when the diameter is expanded, the inside of the pipe 10 1 and 2, the outer diameter of the sheet metal member 2A1 excluding the hinge connection portion that is in contact with the wall surface is set to a size that can form an air passage having a required width P with respect to the inner wall surface of the tube 10. ing.

In FIG. 1, the holding member 2A is fastened and fixed at one end in the extension direction to a shaft 3A, which will be described later, and at the other end in a mandrel 2C corresponding to a core material. ing.

A filling space 2C1 communicating with one end opening of the bag 2B is formed in the mandrel 2C, and a filling passage 2C2 for filling paint from outside is connected to the filling space 2C1. Have been. Filling passage 2C2
Are closed by bolts 5 used to fasten the holding member 2A. In the mandrel 2C, a bracket 6 is attached to a surface corresponding to the front side in the traveling direction of the in-pipe coating apparatus 1 by using the above-mentioned fastening portion, and the bracket 6 has a traction member 7 attached thereto.
One end can be locked.

The bag 2B is made of a flexible member that can be contracted and deformed, and each end of the bag 2B in the direction of extension is made smaller in diameter than the other portions, and is fixed to a shaft 3A and a mandrel 2C described later. When the paint is filled in the inside, as shown in FIG. 2, the diameter of the holding member 2A is expanded so as to be inscribed in the holding member 2A. The bag body 2B can be contracted and deformed. In this embodiment, air in the pipe is used as the acting force for the deformation. That is, as shown in FIG. 1, a plurality of air intake ports 2A2 for introducing air in the tube toward the bag body 2B located inside are formed at a plurality of ends in the extending direction of the holding member 2A along the circumferential direction. In addition, an inclined surface where the outer diameter of the bag body 2B turns to a reduced diameter is located at a position facing the air intake 2A2. Thereby, when the in-pipe coating apparatus 1 advances, a part of the in-pipe air existing on the front side in the advancing direction is changed to the state shown in FIG.
Since the air is introduced into the air intake 2A2 as shown by the arrow B in the middle, the position near the end of the bag 2B is pressurized.

On the other hand, as shown in FIG. 3, the joint part 3 includes a shaft body 3A and a seal ring 3B. A paint passage 3A1 opened in the center of the shaft 3A along the traveling direction of the in-pipe coating device 1 is formed. One end of the paint passage 3A1 communicates with one end opening of the bag 2B of the paint cartridge 2. The other end is closed by a bolt 8. As shown in FIG. 4, the end of the shaft 3A, which is located on the paint cartridge 2 side, is extended to a position divided into four equal parts along the circumferential direction with an outer diameter equal to the outer diameter of the paint cartridge 2. A spoke portion 3A2 is provided, and the holding member 2A and the bag body 2B of the paint cartridge 2 are attached by bolts 9.

In FIG. 4, the area not occupied by the spokes 3A2 communicates with the inside of the tube 10, so that air in the tube can be taken in as shown by an arrow C in FIG. At the end of the shaft 3A, there is provided a paint reservoir 3A3 formed of a concave step communicating with the paint passage 3A1. The paint storage section 3A3 corresponds to a connection position of the paint spray cup 4 described later with the paint introduction path 4A, and constitutes a paint supply section to the paint spray cup 4.

In FIGS. 3 and 4, a seal ring mounting portion 3A4 is provided at the end opposite to the spoke portion 3A2 in the axial direction of the shaft body 3A with a phase difference of 90 ° in the circumferential direction from the spoke portion 3A2. The seal ring 3B is fixedly held by the seal ring attaching portion 3A4 and the spoke portion 3A2.

In attaching the seal ring 3B to the seal ring attaching portion 3A4, as shown in FIG. 3, a seal ring attaching piece 11 fastened to the seal ring attaching portion 3A4 is used. Has a width along the traveling direction of the in-pipe coating device 1 and straightens the in-pipe air flowing from a range not occupied by the spokes 3A2 and discharges the air toward the paint spraying cup 4 described later. It has a stationary wing that can be used.

In FIG. 3, the seal ring 3B is made of an elastic body having a convex portion which is continuous in the traveling direction of the in-pipe coating device 1, and the convex portion has a pressure allowing the advancing of the in-pipe coating device 1. It is in contact with the inner wall surface of the pipe, and maintains the airtightness between the front side and the rear side in the traveling direction of the coating apparatus 1.

The seal ring 3B shields the front side and the rear side in the traveling direction of the moving body 1 in the pipe, because the convex portion is in contact with the inner wall surface of the pipe. Detour circulation near the center of the pipe away from the inner wall of the pipe,
The flow can be made to flow toward the seal ring mounting piece 11 located on the shaft body 3A side via the non-occupied range of the spoke portion 3A2.

The paint spraying cup 4 has a shaft 3A at the rear side of the seal ring 3B in the traveling direction of the in-pipe coating apparatus 1.
, Which is rotatably supported by bolts 8 to prevent the shaft 3A from coming off. The paint spraying cup 4 is a member that can be inserted into the pipe body 10 and has a cup-shaped cross-sectional shape whose outer diameter is set so as not to interfere with the coating film applied to the inner wall surface of the pipe. In addition, the inertial mass is reduced by being made of a lightweight member such as aluminum. As shown in FIG. 5, the paint spray cup 4 has a shaft body 3 having a phase of 180 °.
A paint introduction path 4A communicating with the paint storage section 3A3 of A is formed inside. Due to such a positional relationship of the paint introduction path 4A, the paint in the paint storage section 3A3 flows effectively into the paint introduction path 4A because of the centrifugal force generated when the paint spray cup 4 rotates. Will be promoted.

The beginning of the paint introduction path 4A is opposed to the paint reservoir 3A3 on the side of the shaft 3A, and the end reaches the paint spray head 4B located on the outer peripheral wall of the paint spray cup 4. Thus, the paint is filled in a range from the paint storage section 3A3 of the shaft body 3A to the paint jet head 4B via the paint introduction path 4A. As shown in FIG. 3, an outer peripheral wall 4A1 surrounding the outer periphery of the paint reservoir 3A3 of the shaft 3A is provided at the start end side of the paint introduction path 4A, and the outer peripheral wall 4A1 is A closed space for storing the paint is formed by pressing against the outer peripheral surface of the body 3A.

The outer peripheral wall 4A1 and the outer peripheral surface of the shaft body 3A are arranged such that one outer peripheral wall 4A1 rotates while the other outer peripheral surface is immovable. The rotation of the outer peripheral wall 4A1 can be allowed through the intermediary, and the airtightness is maintained so that the paint does not leak. The above function may be exerted by selecting the material of the outer peripheral wall 4 </ b> A <b> 1 and the outer peripheral surface without being limited to providing a special sealing member.

As shown in FIG. 3, the paint spraying head 4B comprises a paint chamber 4B1 provided inside the outer peripheral wall of the paint spraying cup 4, and the chamber 4B.
A paint inlet 4B2 composed of a plurality of openings formed in the outer peripheral wall of B1 in the circumferential direction and along the traveling direction of the in-pipe coating apparatus 1, and the paint introduction path 4A and the paint are formed by centrifugal force obtained when rotating. Storage chamber 4B1
Can be ejected from the paint ejection port 4B2.

The paint spraying cup 4 is provided with a plurality of rotating blades 4C along the circumferential direction on the inner side closer to the center than the paint spraying head 4B2. The rotary blade 4C is disposed to face the seal ring mounting piece 11 that can discharge the airflow in the pipe bypassed by the seal ring 3B. In the present embodiment, the number of rotating blades 4C is
As shown in (1), the number of pieces is larger than the number of the seal ring attachment pieces 11, so that the in-pipe air flow which is bypassed and discharged toward the seal ring attachment piece 11 by the seal ring 3B can be efficiently received.

Since the present embodiment has the above configuration,
When the traction member 7 is pulled, the in-pipe coating device 1 is shielded by the seal ring 3 </ b> B provided in the joint portion 3.
When the pressure on the front side in the traveling direction becomes higher than the pressure on the rear side, a pressure difference is generated, and an air flow is generated in the pipe 10.

As shown by an arrow B in FIG. 1, a part of the air flow in the pipe acts on the bag body 2B from the air intake port 2A2 provided in the holding member 2A of the paint cartridge 2 and the bag body 2B.
1 and 3, the remainder is circulated by the seal ring 3B toward the seal ring attachment piece 11 of the shaft 3A as shown by the arrow C in FIG. 1 and FIG. 3, and the paint is sprayed from the seal ring attachment piece 11. The ink is discharged toward the rotating blade 4C on the cup 4 side. The bag body 2B pressurized by the airflow in the pipe is easily contracted and deformed, and the discharge of the paint contained therein is promoted.

On the other hand, when the air in the pipe flowing through the seal ring mounting piece 11 is discharged toward the rotating blades 4C, a rotational force is generated in the paint spraying cup 4, and the rotational force causes the paint introduction path 4A and the paint spray head 4B to rotate. The paint filled in the paint containing chamber 4B3 is centrifugally sprayed from the paint injection port 4B2 toward the inner wall surface of the tube, and a thin lining 11 is formed on the inner wall surface of the tube body 10.

The rotation speed of the paint spraying cup 4 can be changed by adjusting the pressure difference. Therefore, the thickness of the coating film according to the centrifugal spray amount obtained by the rotation speed is set to a required thickness. Can be adjusted. When the paint is centrifugally sprayed from the paint injection port 4B2 by the rotation of the paint spray cup 4, the paint spray cup 4 side has a negative pressure tendency compared with the bag body 2B side in the paint filling range. Until the spray cup 4 stops, the bag 2B is easily pulled out from the inside.

According to this embodiment, since the rotational energy of the paint spraying cup 4 can be obtained by the air in the tube, there is no need to prepare a special rotary drive source, and the structure can be simplified.

Next, an in-pipe coating method using the in-pipe coating apparatus 1 having the above configuration will be described. When lining is applied to the inner wall surface of the tube 10, as shown in FIG.
The in-pipe coating device 1 is inserted from one end of the existing pipe in the extension direction. In this case, the traction member 7 having one end connected to the winch 12 is attached to the in-pipe coating apparatus 1, and the traction member 7 is driven by a motor 13 </ b> A on the rear side in the traveling direction of the in-pipe coating apparatus 1 (direction indicated by the arrow A). A duct 14 connected to a vacuum pump 13 is connected from the manhole 15 to the tube 10.

The in-pipe coating apparatus 1 travels in the pipe by being pulled by the pulling member 7 connected to the winch 12. At this time, the vacuum pump 13 is operated to apply a negative pressure to the rear side in the traveling direction of the in-pipe coating device 1.

When the in-pipe coating apparatus 1 advances in the pipeline, a positive pressure acts on the front side in the traveling direction and a negative pressure is applied on the rear side in the traveling direction, so that a pressure difference occurs before and after in the traveling direction. Is done. For this reason, an air flow in the pipe is generated before and after in the traveling direction of the coating device 1 in the pipe, so that the air flow in the pipe flowing along the inner wall surface of the pipe is circulated by the seal ring 3B toward the center of the pipe away from the inner wall surface of the pipe. It is caused to flow toward the seal ring mounting piece 11 having the same. The air flow in the pipe introduced toward the seal ring attachment piece 11 is discharged toward the rotating blades 4C of the paint spraying cup 4, and imparts rotational energy to the paint spraying cup 4 to rotate the paint spraying cup 4 at high speed.

When the paint spraying cup 4 rotates at a high speed, the paint filled in the paint introduction path 4A and the paint accommodating chamber 4B1 of the paint ejecting head 4B is ejected from the paint ejection port 4B2 by centrifugal force, and is applied to the pipe inner wall surface. A thin film lining is formed by centrifugal spraying.

The positive pressure acting on the front side in the traveling direction of the in-pipe coating device 1 may be generated by a blower or the like (not shown) in addition to using the wind pressure generated when the traction member 7 is pulled. In this case, the rotational speed of the paint spraying cup 4 can be increased by changing the pressure difference by adjusting the air blowing amount. Further, as the adjustment of the pressure difference, the towing speed may be adjusted. Thereby, the paint spraying cup 4
The thickness of the coating film on the inner wall surface of the tube can be set to a required thickness by a combination of the rotation speed of the tube and the traveling speed of the inner tube coating device 1.

According to the above-described configuration, the centrifugal spraying of the paint on the inner wall surface of the pipe can be performed by a simple operation of generating a pressure difference between the front side and the rear side in the traveling direction of the in-pipe coating apparatus 1. Become. Moreover, since the pressure difference can be set by the set values of the positive pressure and the negative pressure or by the traction speed of the traction member 7, the coating material can be applied to the in-pipe coating apparatus 1 without using a speed increasing mechanism using a reduction mechanism or the like. By controlling the rotation speed of the spray cup 4 and performing higher-speed rotation, it becomes possible to form a thin film lining.

The present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist.
For example, a guide portion is formed so that air in the pipe that has collided with the rotary blade 4C of the paint spraying cup 4 can be sprayed on the inner wall surface of the pipe in front of the paint injection port 4A2 in the traveling direction. It is also possible to remove foreign substances such as dust adhering to the inner wall surface of the pipe before attaching.

Further, as a configuration for cleaning the coated surface before the coating of the paint, a brush may be provided on the outer peripheral portion of the paint spraying cup 4 to constitute a rotating brush. By providing the paint spraying cup 4 with a functional component different from paint spraying as described above, the spraying of paint and the pretreatment thereof can be performed by the same member, so that operations such as replacement of the operating member can be performed. It becomes unnecessary and the working time can be shortened. Further, if the in-pipe coating apparatus 1 is equipped with a mechanism capable of measuring the moving distance, or a rotation stopping mechanism is added to the paint spraying cup 4, or if a paint supply stopping means is provided, the coating amount can be changed according to the movement amount. It is also possible to perform a partial lining construction on the existing pipeline to be constructed.

[0043]

As described above, according to the first aspect of the present invention, there is provided a seal ring capable of circulating the air flow in the pipe toward the center of the pipe away from the inner wall surface of the pipe. Since the energy to rotate the paint spraying cup is obtained by the detoured air flow in the pipe, the thin film lining can be performed by centrifugal spraying by high-speed rotation of the paint spraying cup without providing a special rotation drive source. Construction can be performed. This makes it possible to reduce the cost required for lining the thin film on the inner wall surface of the existing pipe. In addition, since the paint spraying cup can be rotated at a high speed, the paint filling portion on the paint spraying cup side can have a negative pressure tendency as compared with the paint cartridge side. And no special mechanism for supplying paint is required. This also makes it possible to reduce the cost required for the thinning of the thin film on the inner wall surface of the existing pipe.

According to the second and third aspects of the invention, a required pressure difference is generated between the front side and the rear side in the traveling direction of the in-pipe coating apparatus, so that the in-pipe air flow is used as rotational energy of the paint spraying cup. As a result, there is no need for a special structure as a rotational energy source for obtaining a thin film lining on the inner wall surface of the tube. As a result, in-pipe coating can be performed at low cost.

[Brief description of the drawings]

FIG. 1 is a local sectional view showing a configuration of a main part in an embodiment of an in-pipe coating apparatus according to the present invention.

FIG. 2 is a sectional view taken in the direction of an arrow L2 in FIG.

FIG. 3 is an enlarged sectional view of a main part shown in FIG.

FIG. 4 is a sectional view taken in the direction of an arrow L4 in FIG.

FIG. 5 is an arrow view in a direction indicated by reference numeral L5 in FIG.

FIG. 6 is a schematic diagram for explaining the outline of the in-pipe coating method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 In-pipe coating apparatus 2 Paint cartridge 3 Joint part 3A shaft 3A1 Paint passage 3B Seal ring 4 Paint spray cup 4A Paint introduction path 4B Paint spray head 4B2 Paint spray port 4C Rotating blade

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI B05D 7/22 B05D 7/22 N (72) Inventor Nobukatsu Ike 3-18-3 Daikan, Yamato-shi, Kanagawa Pref. Hakko Technology Co., Ltd. Inside the Development Center (72) Inventor Isamu Yuki 3-18-3 Daikan, Yamato-shi, Kanagawa Prefecture Inside the Hakko Technology Development Center Co., Ltd. (72) Inventor Takuya Hasegawa 3-18-3 Daikan, Yamato-shi, Kanagawa Prefecture Hako Technology Co., Ltd. Inside the Development Center (72) Inventor Kenji Takaba 3-18-3 Daikan, Yamato-shi, Kanagawa Inside the Hakko Technology Development Center Co., Ltd.

Claims (3)

[Claims] 1. An in-pipe coating apparatus for spraying paint from a rotating paint spray cup onto the inner surface of a pipe in a process of being introduced into the pipe from one end opening of an existing pipe line and moving toward the other opening. The in-pipe coating device is disposed at a front portion in the traveling direction and is capable of storing paint, a paint cartridge disposed at a rear portion in the traveling direction, and is disposed at an intermediate portion between the two. The paint cartridge is formed to have an outer diameter dimension capable of forming an air flow passage having a required width at an outer peripheral portion with respect to an inner diameter of the existing pipeline, and the joint portion is provided at a central portion. A shaft that opens a paint passage through which paint in the paint cartridge can be supplied to the paint spray cup; and a pipe airflow that is arranged on the outer periphery and flows through the airflow passage from the pipe inner wall surface. A seal ring for bypassing and flowing toward a center side of the pipe, wherein the paint spraying cup is rotatably supported at a rear end position of the shaft body, and a paint spray head communicating with the paint passage on an outer peripheral portion thereof. And, comprising a plurality of rotating blades arranged along the circumferential direction inside the outer peripheral portion, the rotating blades are arranged at a position facing the airflow in the pipe bypassed by the seal ring of the joint portion. An in-pipe coating apparatus, which is driven to rotate by an in-pipe air flow. 2. An in-pipe coating method using the in-pipe coating apparatus according to claim 1, wherein an inner pipe in which the in-pipe coating apparatus is introduced is moved forward and backward in the moving direction of the coating apparatus. A means for generating a required pressure difference is provided, and the rotational energy of the paint spraying cup is changed by the differential pressure in the pipe by introducing and moving the coating apparatus in the pipe in the existing pipe with the pressure difference applied. In addition, a paint flowing out of the paint jet head is centrifugally sprayed onto an inner wall surface of the pipe to perform coating work. 3. The in-pipe coating method according to claim 2, wherein the pressure difference applies a blowing pressure to a pipe in a front side in a moving direction of the in-pipe coating apparatus and a negative pressure to a rear side in a moving direction of the in-pipe coating apparatus. An in-pipe coating method characterized by being caused by the following.