JPH01310763A - Corrosion-inhibitive lining and its device - Google Patents

Abstract

PURPOSE:To make possible the prevention of deterioration of working environments, improvement of material yield and application of a uniformly thick coat by ejecting resin powder in a spraying box, and applying/melting the resin powder on the surface of a metal to be heated, while aspirating and recovering a floating resin powder which does not stick and melt. CONSTITUTION:An exposed metal section 12 is heated from an opposite side to a spraying box 42 by a burner 21 of a heating device 2 at more than a melting-point temperature of resin powder 63. Consequently, the resin powder 63 ejected from a spray nozzle 45 in the spraying box 42 melts, and sticks and melts with the existing lining coat into a mixed film. The portion which does not stick and melt of the resin powder 63 ejected from the spray nozzle 45 floats in the spraying box and then is sucked into a powder recovery device 6. Thus the density of powder can be controlled. Therefore, the coat thickness can be controlled by adjusting the spraying time or the movement speed of the spraying box 42. This makes it possible to obtain a uniformly thick lining at all angles of spraying.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for applying an anticorrosion coating to a welded joint or defective lining of plastic-lined metal.

[Prior art] Pipes used for cooling circulating water pipes in sewers, nuclear power plants, thermal power plants, seawater intake pipes, etc. are made of metal pipes lined with plastic such as polyethylene on the inside to prevent corrosion. has been done. The main part of these metal pipes is lined with plastic at the factory, but the end part of the pipe is left as a metal pipe with a certain width because it burns out due to welding heat when welding and joining at the piping site. On-site,
Lined after welding.

Lining this on-site welded joint was extremely difficult as it required complete contact with the existing lining material on the main pipe side.

The present inventors have already filed Japanese Patent Application No. 58-217103 regarding a method and apparatus for anticorrosive coating on the inner surface of a tube. This method involves applying an anticorrosion coating to the exposed metal part of the inner surface of a lining tube that has a plastic lining coating on the inner surface of the tube. The exposed metal portion of the surface and the lining coating in the vicinity are heated from the outside of the tube to a temperature higher than the melting point of the powder resin, and the powder resin is heated to the metal by a powder spray nozzle that moves circumferentially along the inner surface of the tube. The anti-corrosion coating is formed by spraying the lining coating on the exposed portion and its vicinity, allowing it to adhere and melt.

That is, as shown in Fig. 4, after heating the metal around the welded joint from the outside of the tube by means such as high-frequency heating, a powder spray nozzle rotates in the circumferential direction with the center of the tube as the rotation axis. By spraying powder resin onto the exposed portion of the EL (gold) EL, the powder resin is adhered and melted to the tube body to form a lining.

[Problems to be Solved by the Invention] However, in this method, the powdered resin ejected from the spray nozzle that is not melted and adheres to the pipe wall is scattered around, which worsens the working environment and reduces the material yield. However, it had some disadvantages.

In addition, powdered resin that is not attached to the tube wall is deposited and melted on the bottom of the tube, so the lower lining tends to be thicker than the upper one, making it difficult to control to achieve a uniform lining thickness. .

=3- [Means for Solving the Problems] The present invention solves the drawbacks of the invention of Japanese Patent Application No. 58-217103, and is aimed at solving the problems of powder powder in a spray box with an open side facing the lining surface. Powdered resin with good thermal fusibility is ejected from a nozzle, adheres to the metal wall heated above the melting point of the powdered resin, and melts it. At the same time, the powdered resin that does not adhere and melt is collected by suction and reused. This improves the material yield by eliminating the scattering of powder resin on the lower lining, and by simultaneously ejecting powder resin in the spray box and collecting it by suction, the powder resin accumulates on the lower lining and reduces the lining thickness. without increasing.

This allows the lining thickness to be uniform in all postures.

The second invention also relates to an apparatus for advantageously carrying out the method of the first invention, in which the spray box is moved over the surface to be lined. To heat the metal pipe, seal the surface of the softened lining agent and the molten lining agent adhering to the metal surface with the open end of the spray box, and be careful not to let the lining material loose when moving. In addition, the powder resin sprayed into the spray box must be prevented from dispersing.

To solve this problem, the present invention uses fluorine-based resin, which is a heat-resistant, non-adhesive material, for the sealing material at the open end of the spray box to prevent the lining material from adhering to the sealing material and separating it. A movable roller is provided on the spray box so as to contact the lining surface with a constant pressing force, and the spray box is fixed to a movable cart and moved via a pressing device that presses the spray box in the direction of the lining surface.

[Example] Figures 1 to 3 show an example apparatus in which the present invention is applied to on-site lining of a welded joint of an internally lined steel pipe.

The apparatus related to the present invention includes a heating device 2 that heats the steel pipe from the back side of the pipe 1 to be lined, a moving cart 3 that is movable in the axial direction inside the tube, and a rotating shaft of a reduction motor fixed to the moving platform type 3. It consists of a spraying device 4 that can move forward and backward toward the pipe wall from the spraying device, a powder supplying device 5 that supplies powdered resin to the nozzle of the spraying device, and a powder recovery device 6 that collects powdered resin from the spraying device. There is.

Since it is necessary for the heating device 2 to heat the steel pipe 1 to be lined to a temperature higher than the melting point of the powdered resin 63, a known heating method such as a gas burner 21 or electric induction heating is appropriately employed. The heating range may be applied to the entire circumference of the width to be lined, but in the case of large-diameter pipes, a large amount of heat is required and this becomes uneconomical, so a local heating device larger than the area of the spraying device is used along the outer circumference. It is also possible to use a method of moving it by hand.

The spraying device 4 inserted into the pipe is connected by a coupling 34 to a rotary shaft 33 in which the shaft of a deceleration motor 31 fixed to the movable cart 3 is supported by a bearing.

The axis of the rotating shaft does not need to completely coincide with the center of the steel pipe, and may be misaligned as long as it is within the stroke range of the pressing device 41, which will be described later.

The proximal ends of a plurality of pressing devices 41 are fixed to the rotary shaft 33 protruding from the bearing, and the spray box 42 is fixed to the movable end so that they can freely move forward and backward along the inner wall of the steel pipe.

Although the pressing device 4 uses a pneumatic cylinder in this embodiment, it may also be of a hydraulic type.

Alternatively, a spring method may be used.

The spray box 42 held by the pressing device 41 is
As shown in the figure, the outside (the surface to be lined) is open, and a sealing material 43 is attached along the periphery of the open end. The sealing material needs to be made of a heat-resistant, non-adhesive material that adheres to the molten powder resin and does not peel off.

In addition to being heat resistant and non-adhesive, fluorocarbon resin has a low coefficient of friction and low affinity with resins, making it the most suitable material for this purpose.

The shape of the sealing material 43 is a brush-like shape made by bundling a large number of filamentary bodies into a belt shape, so as to seal the gap and unevenness between the arcuate lining surface and the open end of the spray box 42.

Two pairs of wheels 44 are provided on both sides of the spray box 42. The wheels 44 are used to keep the spray box at a constant distance from the lining surface and run, and are arranged at a height such that the sealing material 43 comes into appropriate contact with the lining surface. . The spray nozzle 45 is fixed to the back surface of the spray box 42 so as to be oriented toward the lining surface. In this embodiment, three spray nozzles are installed in communication, but the number may be increased or decreased depending on the size of the spray box 42.

Alternatively, one spray nozzle 45 may be used to oscillate the spray direction.

A flexible supply pipe is connected to the spray nozzle 45, and the hose 5 is connected to the spray nozzle 45 through a coupler 47 provided at the end of the rotating shaft.
Connected to 1.

The end of the hose is connected to the compressor 5, and a powder supply hose 54 connected to the outlet of the hopper 53 is connected to the middle of the hose 51.

That is, the powdered resin 63 is sucked into the compressed air in the hose sent from the compressor 52 and is ejected from the spray nozzle 45.

It should be noted that the compressor 52 is used not only for pumping the powder resin 63 but also as an air source for the pressing device 41 of the spray box. In addition, each hose is provided with a valve 55 for selection.

A recovery port 48 is provided on the side surface of the spray box 42 for sucking and recovering powdered resin 63 that is not melted and is connected to the powder recovery device 6 via a flexible recovery pipe 49 and a powder recovery hose 61. .

The powder recovery device 6 may use a vacuum pump instead of the method in which the air inside the container is evacuated and depressurized using the blower 62 as in this embodiment.

FIG. 3 shows an embodiment in which an exposed metal portion 12 of a welded joint 11 is lined using a device according to the invention.

The exposed metal portion 12 is on the opposite side (back side) of the spray box 42
The powder resin 63 is heated by the burner 21 that constitutes the heating device 2.
When the resin powder 63 is heated to a temperature higher than the melting point of the powder and comes into contact with the powder resin 63 ejected from the spray nozzle 45 in the spray box 42, it adheres and melts together with the already lined film 13 to form a film.

The part of the powder resin 63 that is ejected from the spray nozzle 45 that is not adhered and melted remains in a floating state within the spray box and is sucked from the side into the powder collection bag W6, so that the powder concentration can be controlled as appropriate.

Therefore, the film thickness can be controlled by adjusting the spray time or the moving speed of the spray box 42, and it is possible to provide lining with a uniform film thickness over all positions.

[Effects of the Invention] According to the present invention, powder resin is ejected from a nozzle in a spray box, and floating powder that has not adhered and melted is collected by suction, while the powder resin is adhered to and melted on a heated metal surface to form a lining. Therefore, there is no scattering of powdered resin to the surrounding area, which prevents deterioration of the working environment and has a remarkable effect of improving material yield. Furthermore, since the powder resin does not accumulate on the lower lining, the film can have a uniform thickness in all positions.

Furthermore, when applied to large-diameter pipes, the lining can be performed without successively heating only the area of the spray box, which has the effect of reducing the amount of energy required for heating.

In the second invention, the opening end of the spray box is sealed with a sealing material using fluorocarbon resin, and the spray box is held down by a pressing device so that the movable roller that reaches a predetermined height comes into contact with the lining surface. Therefore, the distance between the spray boxes and the lining surface is always maintained constant, and the sealing material can be brought into stable contact with the lining surface.

Furthermore, since the sealing material is made of a fluorine-based resin with excellent heat resistance and non-adhesive properties, it will not adhere to the powdered resin that is being run when the spray box is moved and will not peel off.

Therefore, it is particularly effective when welding and lining large-diameter pipes at construction sites, which is impossible with other methods.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a lining device according to an embodiment of the present invention;
FIG. 2 is a detailed view of the spray box, FIG. 3 is a diagram of the lining of the welded joint, and FIG. 4 is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Steel pipe 2... Heating device 3... Moving trolley 4... Spraying device 5... Powder supply device 6... Powder recovery device 11... Melting joint part 12
...Metal exposed portion 14...Coating 15...
Factory coating 21... Burner 31... Reduction motor 33... Rotating shaft 34... Coupling 4
1... Pressing device 42... Spraying box 45.
・・Spray nozzle 43 ・・Seal material 44 ・・Wheel
47...Coupler 48 ・Recovery port 4
9... Recovery pipe 51... Hose 52... Compressor 53... Hopper 54... Powder supply hose 55... Valve 61... Powder recovery hose 6
2...Blower 63...Powder resin 31: Deceleration motor 33: Rotating shaft 34 Old coupler spring: Pressing device 42: Spraying box 43: Sealing material 44 Two wheels 45: Spraying nozzle 47: Coupler 4 total collection port 51: Hose 52: Compressor 53: Hopper 54 = Powder supply hose 55: Valve 61: Powder collection hose 62 Nibro Aro 3: Powder resin second figure

Claims (1)

[Claims] 1. In a method of applying an anti-corrosion lining to an exposed metal part of a metal covered with a plastic lining, a powder resin with good heat fusibility is selected as the lining material, and the exposed metal part is coated from the back side of the lining surface. Heat the powder resin to a temperature higher than its melting point, place a spray box with only the side facing the lining surface open at the position to be lined, and use the powder nozzle to apply the powder resin to the exposed metal surface in the spray box and its surroundings. An anti-corrosion lining method characterized by spraying to adhere and melt, and at the same time, suctioning and collecting powdered resin that is not adhered and melted from inside the spray box and reusing it. 2. It is equipped with a heating device placed on the back side of the surface to be lined and a spray box with only the lining surface open, and the spray box has a powder nozzle connected to a powder resin supply device and a hose. , a powder resin collection port connected to a suction device and a hose, a seal using a fluororesin resin along the opening, and a moving roller attached at a predetermined height, and the spray box is connected to the lining surface. An anti-corrosion lining device, characterized in that it is fixed to a movable trolley via a pressing device that presses it against.