JP2010194394A - Method of drying in-pipe surface coating and cap for pipe body protection used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly discharge a volatilized solvent to the outside of a pipe in the case of performing solvent coating on the in-pipe surface of an inlet and powder coating on the in-pipe surface of a straight pipe part. <P>SOLUTION: In the method of drying in-pipe surface coating in which the solvent coating is applied to the in-pipe surface of a pipe end part on the side of the reception port 3 and the powder coating is applied to the in-pipe surface more at the back of parts A and B where the solvent coating is applied, for a pipe body p provided with an insertion port 2 at one end and the reception port 3 at the other end holding the straight pipe part 4 therebetween, a gap 10 having a function of preventing the intrusion of light from the side of the socket 3 to a part C where the powder coating is applied is attached to the boundary part of the parts A and B where the solvent coating is applied and the part C where the powder coating is applied, and the solvent coating is dried in the state. Since the pipe end part on the side of the reception port can be opened for the part where the solvent coating is applied, the volatilized solvent is smoothly discharged to the outside of the pipe. The intrusion of light and foreign matters is eliminated by the cap for the part where the powder coating is applied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for drying a pipe inner surface coating and a cap for protecting a pipe body that is fitted to an end of the pipe body when the pipe inner surface coating is dried.

  Various coatings are applied to the inner peripheral surfaces of various pipes used in waterworks and sewers in order to protect the inner surfaces. Particularly in cast iron pipes and the like, in order to protect them, pipe inner surface coating is often applied by mortar lining or powder coating (for example, epoxy resin powder coating).

  In these tubes, caps for protecting the tube made of synthetic resin are fitted to both ends of the tube in order to avoid fouling and deterioration of the tube inner surface coating during transportation and storage. This has been done conventionally.

  In particular, in a powder coated tube, the coated surface on the inner surface of the tube may be deteriorated by light inserted from the end of the tube. Therefore, during transportation or storage of the tube, both ends of the tube It is important to close the tube with a tube protection cap.

  As shown in FIG. 5, this type of tubular body p generally has one end in the tube axis direction with the insertion port 2 and the other end adjacent to each other with a straight tube portion 4 having a constant tube diameter in the tube axis direction. It is the receiving port 3 which can receive the insertion port 2 of the other tubular body p in the inner side.

  Therefore, for example, as shown in FIG. 6, the cap 1 is fitted to the outer surface 2 b of the end of the insertion port 2 that is the end of the tube body p on the narrow diameter side, and has a diameter. In the receiving port 3 which is an end portion on the thick side, the tube is fitted into the tube inner surface 3a at the end portion (see, for example, Patent Document 1).

  In the tubular body p, the tube inner surface 3a has a lot of irregularities in the portion near the receiving port 3 in the coating range of the tube inner surface. This unevenness corresponds to the shape of the packing, lock ring or the like used when receiving the insertion opening 2 of the adjacent tubular body p, or the outer shape of the insertion opening 2 itself.

In general, the inner surface of the receiving port 3 is coated with a solvent-based paint (hereinafter, “solvent-based coating”). That is, powder coating as primary coating is performed on the pipe inner surface 4a (including the inner surface 2a of the insertion port 2) of the straight pipe portion 4, and then the secondary surface is applied to the pipe inner surface 3a near the receiving port 3 with many irregularities. Solvent-based coating is applied.
The epoxy resin powder coating range is defined in JWWA G 112 (Japan Waterworks Association Standard).

It is necessary to remove the odor of the solvent-coated portion at the time of shipment of the pipe body. If the volatilized solvent remains in the tube, the tube is saturated with the volatile solvent, which may hinder further volatilization of the solvent from the coating film. If it becomes like this, a coating film cannot fully be hardened.
With regard to this point, for example, with regard to a cast iron pipe for water supply, it is said that there is no problem with odor at the time of shipment in the Japan Water Works Association Standard JWWA K139.

  Therefore, for example, as shown in FIG. 6, a hole 6 is drilled in the bottom of the cap 1 so that the volatilized solvent can be discharged out of the pipe. If there is a hole 6 in the cap 1, the volatile solvent can escape to the outside of the pipe through the hole 6, and odor residue can be suppressed.

Utility Model Registration No. 3099749

  Thus, in order to smoothly discharge the volatilized solvent to the outside of the tube, it is preferable that the hole 6 provided in the cap 1 for protecting the tube body has a cross-sectional area as large as possible.

  However, in the cap 1 shown in FIG. 6, if the number of the holes 6 is increased or the size of the holes 6 (the cross-sectional area of the holes 6) is increased, it will lead to the intrusion of foreign matter into the entire tube, which is not preferable. In addition, increasing the number of holes 6 or increasing the size of the holes 6 leads to an increase in the amount of light entering the pipe, and therefore has an effect on the powder coating applied to the pipe inner surface 4a of the straight pipe portion 4. Concerned.

  Therefore, the present invention has an object of facilitating the discharge of the volatilized solvent out of the pipe when solvent-based coating is applied to the pipe inner surface of the receiving port and powder coating is applied to the pipe inner surface of the straight pipe portion. .

  In order to solve the above-mentioned problems, the present invention provides a solvent on the inner surface of the tube end portion on the receiving end side with respect to a tubular body having a straight tube portion and an insertion port at one end and a receiving port at the other end. In the method of drying the inner surface of the pipe in which powder coating is applied to the inner surface of the pipe at the back of the portion to which the solvent-based coating is applied, the solvent-coated portion and the powder coating are applied. A cap having a function of preventing light from entering the part coated with the powder coating from the receiving port side is attached to the boundary part with the part or the back part from the boundary part, and in the state, the solvent system A method for drying the inner surface of the pipe, which is characterized by drying the coating, was adopted.

According to this method, the solvent-coated portion can open the tube end on the receiving side, so that the volatilized solvent can be smoothly discharged to the outside of the tube and the powder coating is applied. The cap can eliminate the intrusion of light and foreign matter with the cap.
In addition, the inner surface of the receiving port has been conventionally removed by air blow etc. prior to painting before shipping, etc., so foreign matter that has entered the tube on the receiving side of the cap is appropriately blown by air blow etc. Can be removed.

The method for drying the pipe inner surface coating having this configuration has a stepped portion whose diameter decreases from the other end side toward the one end side at the boundary between the straight pipe portion and the receiving port. The cap may be configured to be attached to the stepped portion.
In general, this type of tubular body has a specification in which the shape of the inner surface of the receiving port varies depending on the type of the tubular body, even if the straight tubular portion has the same inner diameter. For this reason, conventionally, a cap matched to the inner diameter of the receiving port has to be prepared each time. However, as described above, if the cap is attached to the step at the boundary between the straight pipe portion and the receiving port, the cap is removed if the inner diameter of the straight pipe portion is the same regardless of the shape of the inner surface of the receiving port. Can be used in common.
Moreover, the effect that the positioning with respect to the pipe body of a cap is easy is also expectable by making a step part and a cap contact.

  In addition, when the step portion is a boundary portion of the coating, when the boundary portion is in the end surface (surface facing the other end side) of the step portion, or the end surface of the step portion and the inner surface of the straight pipe portion And a corner portion (a corner portion located on the innermost diameter side of the step portion) where there is a boundary portion. It is desirable that the cap has a shape and a size that do not cover at least a portion to which solvent-based coating is applied as much as possible.

The cap has a tapered surface that decreases in diameter from the other end side toward the one end side, and the tapered surface is in contact with a corner portion located on the innermost diameter side of the step portion over the entire circumference. A configuration can be employed.
When the taper surface of the cap abuts on the corner portion of the stepped portion, the cap and the tube body are in a line contact state, and light leakage can be more effectively prevented. Further, since the cap fits firmly against the tube, it is possible to prevent the cap from falling off.

In the configuration in which the cap has a tapered surface, the cap has a protruding portion extending from the tapered surface to the outer diameter side, and the protruding portion is a corner portion of the stepped portion or the other end side of the stepped portion. It is possible to employ a configuration in which the cap is positioned in the tube axis direction with respect to the tube body by abutting on the surface facing toward.
If the projecting portion comes into contact with the corner portion of the stepped portion or the surface facing the other end side, it is easier to position the cap with respect to the tubular body.

In addition, the structure which is a flange part provided continuously in the perimeter around a pipe axis can be employ | adopted for the said protrusion part.
If the protruding portion is a flange portion, the flange portion is opposed to the surface facing the other end side of the stepped portion, which is effective in preventing entry of foreign matter and light into the straight pipe portion.

Furthermore, in each of these configurations, the cap has a gripping portion on the other end side with respect to the protruding portion, and by having the gripping portion, the boundary portion of the cap or a deeper portion than the boundary portion. The structure which attaches or detaches can be adopted.
If there is a grip, it is convenient to attach and detach the cap. In particular, according to the present invention, since the cap is attached to the end of the tube body from the end on the receiving side to the back, such a gripping portion is compared with the case where the cap is attached to the tube end as in the prior art. The effect of providing is high.

Further, in the case where the cap includes a main body portion having a hollow portion therein and a bottom portion that closes an end portion on one end side of the hollow portion, the gripping portion extends from the bottom portion or the main body portion to the hollow portion. The structure which protrudes in the other end side rather than the said main-body part through can be employ | adopted.
Since the gripping part extends from the bottom part or the main body part to the other end side and further protrudes to the other end side from the main body part, the cap can be easily attached and detached from the outside of the tube.
Moreover, if it is set as the structure which the holding part is extended from the center of the bottom part, the pushing force at the time of attaching a cap and the pulling-out force at the time of removing will spread over the whole main-body part.
In addition, if the said holding | grip part protrudes out of the pipe | tube from the edge part of the other end side of the said pipe body, attachment or detachment of a cap is further easy.

The following can be adopted as a cap used in the drying method of the pipe inner surface coating composed of each of these components.
That is, the configuration is such that a solvent-based coating is applied to the pipe inner surface of the pipe end on the receiving side, with respect to a pipe body that is inserted at one end with the straight pipe portion sandwiched between the opening and the receiving end at the other end. Powder coating is applied to the inner surface of the pipe at the back of the part to which the system coating is applied, and the boundary between the part to which the solvent coating is applied and the part to which the powder coating is applied or more than the boundary It is a cap for protecting a tubular body, characterized in that it is attached to the inner part and has a function of preventing light from entering the powder coated part from the receiving side.

  In the present invention, the cap is attached to the boundary portion between the solvent-coated portion and the powder-coated portion or to the back of the boundary portion. Thus, the solvent can be smoothly discharged to the outside of the pipe, and light and foreign matter can be prevented from entering the portion on which the powder coating has been applied by the cap.

1 shows an embodiment, (a) is a cross-sectional view, (b) and (c) are enlarged views of the main part of (a). The perspective view of the cap of the embodiment (A) (b) (c) (d) (e) is a perspective view of a cap according to another embodiment, respectively. (A) (b) (c) is sectional drawing which shows embodiment in the tubular body which has a different shape Cross-sectional view showing the division of coating on the tube Cross section of conventional example

  Embodiments of the present invention will be described with reference to the drawings. In this embodiment, when pipe inner surface coating is performed on a pipe body (cast iron pipe) p used for waterworks or the like, the pipe inner surface coating drying method and the pipe body protection used for the pipe inner surface coating drying method are described. This relates to the cap 10 for use.

  As shown in FIG. 5, the tubular body p is provided with an insertion port 2 at one end shown on the right side in the drawing and a receiving port 3 at the other end shown on the left side, with a straight pipe portion 4 having a constant inner and outer diameter. .

  In this embodiment, predetermined coating (outer surface coating) is performed on the outer surface of the tubular body p, and then powder coating (primary coating) is performed on portions indicated by reference numerals B and C in FIG. As this powder coating, for example, epoxy resin powder coating can be adopted. In this embodiment, the coating thickness of the primary coating is 300 μm or more.

Thereafter, solvent-based coating (secondary coating) is applied to the inner surface of the tube end portion on the side of the receiving port 3 indicated by symbol A. As this solvent-based coating, for example, an epoxy resin paint can be employed. In this embodiment, the coating thickness of the secondary coating is 60 μm.
In this embodiment, as shown in the figure, a part of the inner surface of the receiving port 3 that has been subjected to solvent-based coating indicated by symbol A and a part that has been subjected to powder coating indicated by symbol B are partially Overpainting is performed. However, in addition to the portion indicated by symbol A, the entire region indicated by symbol B may be overcoated (overcoated) with solvent-based coating.

  Thereafter, the tube body p is transferred to a drying process, and the painted surface is dried by primary coating and secondary coating on the inner surface of the tube.

  At the time of drying the painted surface by the primary coating and the secondary coating, a cap 10 for protecting the tubular body is attached as shown in FIG. The cap 10 is fitted and fixed to a step portion 5 at the boundary between the straight pipe portion 4 and the receiving port 3 of the pipe body p.

  The stepped portion 5 has a shape that decreases in diameter from the other end side (receiving port 3 side) to the one end side (inserting port 2 side) of the tube body p. The cap 10 includes a main body portion 14 having a hollow portion therein and a bottom portion 15 that closes an end portion on one end side of the hollow portion. Since the main body portion 14 has a tapered surface 11 whose diameter decreases from the other end side toward the one end side, the outer surface of the cap 10 as a whole forms a truncated cone shape.

  For this reason, when the cap 10 is attached to the step portion 5, the tapered surface 11 of the main body portion 14 is in contact with the corner portion 5a located on the innermost diameter side of the step portion 5 over the entire circumference. . Since the taper surface 11 and the corner portion 5a are in contact with each other, a so-called line contact state is obtained, and the degree of adhesion is increased. The loosening of the cap 10 is also prevented.

  The cap 10 has a protruding portion 12 that extends from the tapered surface 11 to the outer diameter side. In this embodiment, as shown in FIG. 2, the protruding portion 12 is formed so that its outer surface protrudes in an arc shape along the tube axis direction, and is continuous with the entire circumference around the tube axis in that shape. Provided.

  As shown in FIG. 1A, the protruding portion 12 abuts on a corner portion 5 a of the step portion 5 or a surface 5 b facing the other end side of the step portion 5. By this contact, the cap 10 is positioned in the tube axis direction with respect to the tube body p. Further, the cap 10 is prevented from being bitten into the stepped portion 5 by being strongly pushed from the other end side toward the one end side.

  That is, when the solvent-based coating as the secondary coating is applied only to the portion indicated by the symbol A, the cap 10 is deeper than the boundary portion between the solvent-coated portion and the powder-coated portion. In other words, when the solvent-based coating as the secondary coating is applied to the entire region indicated by the symbol B in addition to the portion indicated by the symbol A, it is attached to the boundary portion.

With the cap 10 attached in this manner, the painted surface is dried by primary coating and secondary coating.
At this time, since the cap 10 has a function of preventing light from entering the straight pipe portion 4 from the receiving port 3 side, that is, the portion C subjected to powder coating, solvent-based coating was applied. The solvent volatilized from the portion A (or A and B) can be smoothly discharged out of the pipe. In addition, the cap 10 can eliminate the intrusion of light and foreign matter into the portion C to which the powder coating is applied.

  After the drying of the painted surface by the primary coating and the secondary coating is completed, the cap 10 is removed and the pre-shipment coating is performed on the inner surface of the receiving port 3. Specifically, before or after removing the cap 10, the inner surface of the receiving port 3 is cleaned by air blow or the like, and thereafter, a portion indicated by a symbol D (in this embodiment, a portion indicated by a symbol A and a symbol B) The coating is pre-shipment by overcoating with solvent-based paint. As the solvent-based coating in the pre-shipment coating, for example, an acrylic resin coating can be employed. In this embodiment, the coating thickness is 20 μm.

  FIG.1 (b) is a cross section which shows the principal part of the receiving port 3 before performing the coating before shipment. FIG.1 (c) is a cross section which shows the principal part of the receiving port 3 after performing the coating before shipment.

When the pre-shipment coating is finished, finally, a shipping cap is fitted to the end of the receiving port 3 to dry the pre-shipment coating applied to the inner surface of the receiving port 3. The cap at the time of shipment exhibits a function of preventing foreign matter from entering the receiving port 3. The tube p is shipped and stored with the shipping cap attached.
For example, the conventional cap 1 shown in FIG. 6 can be used as the cap for shipping.

  The cap 1 shown in FIG. 6 is of a type that fits on the inner surface of the end of the receiving port 3, but may be of a type that fits on the outer surface of the end of the receiving port 3. In any case, as in the conventional example, a hole 6 that communicates the inside and the outside of the pipe can be provided in the attached state. By providing this hole 6, the solvent volatilized from the part that has been painted before shipment can be discharged out of the pipe through a relatively long time during subsequent shipment, transportation, and storage. Moreover, you may provide the hole 6 which connects the inside and outside of a pipe | tube to the cap 1 by the side of the insertion port 2. FIG.

  3A to 3E are modified examples of the cap 10.

  The cap 10 shown in FIG. 3A is provided with a gripping portion 13 on the other end side with respect to the protruding portion 12. For this reason, the operator can attach or remove the cap 10 by holding the grip portion 13. Since the cap 10 is attached to the inner portion of the receiving port 3, the cap 10 can be easily attached and detached if the grip portion 13 is provided.

  In this example, the outer surface of the protruding portion 12 is formed so as to protrude in a rectangular shape along the tube axis direction, and is continuously provided around the tube axis in that shape. The surface direction of the end surface of at least one end side (insertion port 2 side) of the projecting portion 12 is a form orthogonal to the tube axis direction. As a result, the projecting portion 12 comes into surface contact with the surface 5 b facing the other end side (receiving port 3 side) of the stepped portion 5 with respect to the stepped portion 5 at the boundary between the inner surface of the straight pipe portion 4 and the inner surface of the receiving port 3. Intrusion of light into the straight pipe portion 4 can be more reliably suppressed.

  Next, the cap 10 shown in FIG. 3B is provided with a recess 16 that is recessed toward the other end in the center of the bottom 15 that closes the end on one end of the hollow portion. The recess 16 increases the rigidity of the cap 10. Further, the cap 10 shown in FIG. 3C is obtained by omitting the protruding portion 12.

  The cap 10 shown in FIG. 3 (d) includes a grip portion 13 that protrudes from the bottom portion 15 through the hollow portion thereof to the other end side of the main body portion 14. Since the grip portion 13 protrudes to the other end side, the operator does not need to insert his hand deeply into the receiving port 3. For this reason, the operation | work at the time of attaching / detaching the cap 10 to the inner part in the receptacle 3 is easy.

In addition, since the holding | gripping part 13 is extended from the center of the bottom part 15, the pushing force at the time of attaching the cap 10 and the pulling-out force at the time of removing are easy to spread over the main-body part 14 whole.
Moreover, the holding part 13 can also be set as the structure which protrudes outside the pipe | tube from the edge part of the other end side of the said tubular body p in the attachment state to the said boundary part. According to this configuration, the cap 10 can be easily attached and detached.

  Further, the grip 13 can be attached to and detached from the cap 10. For example, by pressing the gripping part 13 into the main body part 14 toward the bottom part 15, the gripping part 13 is press-fitted and fixed to the inner periphery of the main body part 14, and if the gripping part 13 is pulled, the structure is released from the main body part 14. can do. In this way, when the gripping portion 13 is press-fitted and fixed to the inner periphery of the main body portion 14, for example, as shown in FIG. 3 (e), if the back end portion 13a of the gripping portion 13 is plate-shaped, The increase in weight due to the attachment / detachment of the gripping part 13 is minimized, and the press-fitting and fixing are solid. In addition, in FIG.3 (e), although the plate-shaped back end part 13a is made into the disk shape, as long as it is the shape which can be press-fitted in the inner periphery of the main-body part 14, another shape may be sufficient. In other words, the back end portion 13 a can have various shapes according to the cross-sectional shape of the inner peripheral surface of the main body portion 14.

  4A and 4B show a state where a cap 10 for protecting a tubular body is attached to a tubular body p having another cross-sectional shape. Thus, the pipe inner surface p which can employ | adopt the drying method of the pipe inner surface coating by this invention and the cap 10 for a pipe body protection used for it is not limited to embodiment.

  In each of the above embodiments, in the state where the primary coating and the secondary coating are completed, the boundary between the solvent-coated portion and the powder-coated portion is a straight pipe of the tubular body p. The cap 10 is located on the other end side (the receiving port 3 side) of the step portion 5 at the boundary between the portion 4 and the receiving port 3 or the step portion 5, and the cap 10 is fitted and fixed to the step portion 5. Although the description has focused on the aspect, as another embodiment, a form in which the cap 10 is attached to a portion other than the stepped portion 5 is also conceivable.

For example, as shown in FIG. 4 (c), the boundary between the solvent-coated portion A and the powder-coated portion (part of C and B) is the inner surface of the receiving port 3 and the straight pipe. In the case where the cap 10 is positioned on the other end side (receiving port 3 side) than the step portion 5 provided at the boundary with the portion 4, the cap 10 is fixed to the boundary portion.
Also in this aspect, as long as it is related to the prevention of intrusion of light and foreign matter into the powder coated part, a predetermined effect can be exhibited. In this case, the cap 10 may be fixed using the recess 3c in the drawing corresponding to the lock ring or the like, or may be press-fitted into the flat tube inner surface 3a of the receiving port 3 and fixed.

1, 10 Cap 2 Insertion slot 3 Receptor 4 Straight pipe part 5 Step part 5a Corner part 5b Surface facing the other end (end face)
6 hole 11 taper surface 12 protrusion 13 gripping part 14 body part 15 bottom part 16 recessed part p tubular body

Claims (10)

The tube inner surface of the tube end portion on the side of the receiving port (3) with respect to the tube body (p) having the straight port portion (4) with the insertion port (2) at one end and the receiving port (3) at the other end. In the drying method of the tube inner surface coating, where the solvent coating is applied to the inner surface of the tube and the powder coating is applied to the inner surface of the tube behind the portion where the solvent coating is applied.
Light from the receiving port (3) side to the portion where the powder coating is applied at the boundary portion between the portion subjected to the solvent-based coating and the portion subjected to the powder coating or at the back of the boundary portion A method for drying a tube inner surface coating, comprising: attaching a cap (10) having a function of preventing invasion of the tube and drying the solvent-based coating in that state.   The tubular body (p) has a step portion (5) whose diameter decreases from the other end side toward the one end side at the boundary between the straight pipe portion (4) and the receiving port (3), The method of drying a pipe inner surface coating according to claim 1, wherein the cap (10) is attached to the step (5).   The cap (10) has a tapered surface (11) whose diameter decreases from the other end side toward the one end side, and the tapered surface (11) extends over the entire circumference, and is the innermost diameter side of the stepped portion (5). The method for drying a pipe inner surface coating according to claim 2, characterized in that it is in contact with the corner portion (5a) located at the top.   The cap (10) has a protruding portion (12) extending from the tapered surface (11) to the outer diameter side, and the protruding portion (12) is a corner portion (5a) of the stepped portion (5), or The cap (10) is positioned in the tube axis direction with respect to the tubular body (p) by contacting the surface (5b) facing the other end of the stepped portion (5). Item 4. The method for drying a tube inner surface coating according to Item 2 or 3.   The said protrusion part (12) is a flange part provided continuously in the perimeter around a pipe axis, The drying method of the pipe inner surface coating of Claim 4 characterized by the above-mentioned.   The cap (10) has a grip portion (13) on the other end side than the protrusion (12), and has the grip portion (13) so that the boundary portion of the cap (10) or its The method for drying a pipe inner surface coating according to claim 4 or 5, wherein attachment or detachment to the back part is performed rather than the boundary part.   The cap (10) includes a main body portion (14) having a hollow portion therein, and a bottom portion (15) that closes an end portion on one end side of the hollow portion, and the grip portion (13) includes the bottom portion (13). 15. The method for drying a pipe inner surface coating according to claim 6, wherein the pipe inner surface coating projects from the main body part (14) through the hollow part to the other end side of the main body part (14).   The cap (10) includes a main body portion (14) having a hollow portion therein, and a bottom portion (15) that closes an end portion on one end side of the hollow portion, and the grip portion (13) includes the bottom portion (13). The method for drying a pipe inner surface coating according to claim 6, characterized in that it projects from the center of 15) to the other end side through the hollow portion and to the other end side of the main body portion (14).   The pipe inner surface coating according to any one of claims 6 to 8, wherein the gripping part (13) protrudes from the end of the other end side of the pipe body (p) to the outside of the pipe. Drying method.   It is a cap (10) used for the drying method of pipe inner surface coating as described in any one of Claims 1 thru | or 9, Comprising: A straight pipe part (4) is inserted in one end, and an opening (2) is made in the other end. For the pipe body (p) provided with the receiving port (3), a solvent-based coating is applied to the inner surface of the tube end on the receiving port (3) side, and the inner part of the tube body (p) is deeper than the portion where the solvent-based coating is applied. Powder coating is applied to the inner surface of the pipe, and is attached to a boundary portion between the portion to which the solvent coating is applied and the portion to which the powder coating is applied or to a portion deeper than the boundary portion. A cap for protecting a tubular body, which has a function of preventing light from entering the portion coated with powder from the side.

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