JP2011255322A - Method and apparatus for preventing generation of coating material degenerating mist in inside coated pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of conveyance fluid with coating material degenerating mist in an inside coated pipe.SOLUTION: A heading device 20 is disposed on the outer surface of an inside coated conduit 10 on a processed place subjected to a specific heating process and heats in advance an outer surface of an inside coated conduit 10 within a heating temperature range that does not generate coating material degenerating mist in the conduit 10. The heating device 20 includes a flame jet portion 21 which forms a flame jet space S opposing to the outer surface of the conduit 10 partially or fully enclosing the outer surface, a gas supplying portion 22 which supplies combustion gas to the flame jet portion 21, and a gas supply adjusting portion 23 which adjusts the amount of gas supplied to the flame jet portion 21 from the gas supplying portion 22.

Description

  The present invention relates to a paint alteration mist generation inhibiting method and a paint alteration mist occurrence inhibiting device in an inner surface coating conduit.

  The inner surface of a steel conduit is generally provided with an inner surface coating for rust prevention or the like. When such an inner surface coated conduit is heated from the outer surface for welding or cutting, the paint on the inner surface of the conduit is changed into a mist due to alteration by heating, and the mist component is mixed with the carrier fluid in the conduit and is downstream. It has been confirmed that there is a problem that attaches to a fluid device such as a valve connected to a conduit and adversely affects its operation. Such a misting component is produced by heating the paint applied to the inner surface of the conduit in a short time at high temperature, and this product is condensed and sticky when cooled, The trouble which adheres to the operation | movement part of a fluid apparatus and obstructs operation | movement generate | occur | produces. Such a misting component is hereinafter referred to as a paint-modified mist.

  For example, the following Patent Documents 1 and 2 have been proposed as countermeasures against the paint alteration mist. Patent Document 1 describes that the coating layer on the inner surface around the through hole formed in the gas conduit is removed with an inner surface polishing jig, and the coating around the through hole is removed with the inner surface polishing jig. When the plug is attached to the through-hole and welded, paint-modified mist is prevented from being generated. Patent Document 2 describes that a gas flow containing paint-modified mist is guided to a mist removing device, and the paint-modified mist is collected by a mist removing filter in the mist removing device.

JP 2007-15049 A JP 2008-246351 A

  As in Patent Document 1, the paint layer on the inner surface of the conduit can be removed with a polishing jig only when the interior of the conduit is partially or entirely open. On the other hand, there is a case where the heat cut is performed by interrupting the flow in a partial section in the conduit. In this case, since the cut portion is not opened, the coating layer cannot be removed by inner surface polishing, and the paint-modified mist is mixed with the transport fluid in the conduit to be cut.

  After connection work is performed on the cut pipe, work to replace the internal fluid with clean transport fluid (purge work) is performed, but this purge work itself is time-consuming work and the construction period This is one of the factors that prolong the period. In addition, it is difficult to completely replace a fluid containing paint-modified mist with a clean transport fluid. Even if a small amount of paint-modified mist is mixed in the replaced transport fluid, equipment failure may occur at the end of the conduit. There was a problem that caused problems.

  In addition, when the conduit is cut off for a predetermined section and the pipe is drilled or cut in the section, if the inner surface polishing work in the conduit is performed after drilling or cutting, the work period after the pipe is cut off will be the inner polishing work. There is a problem that the supply stop of the transport fluid is prolonged on the downstream side of the shut-off section.

  On the other hand, when paint-modified mist is mixed in the transport fluid, as described in Patent Document 2, the transport fluid containing the paint-modified mist is guided to the mist removing device and collected by collecting the paint-modified mist. However, the filter of the mist removing device connected to the downstream side of the construction must be replaced every time construction is performed, and there has been a problem that requires a large amount of capital investment and labor.

  This invention makes it an example of a subject to cope with such a problem. That is, even when heating work such as cutting is performed on an active tube in which no opening is formed, it is possible to prevent the paint-modified mist from entering the transport fluid in the tube, and to shut off the conduit. When construction such as cutting is performed, the construction period should not be prolonged, the suspension of fluid supply downstream of the shutoff point should not be prolonged, and the avoidance of malfunctions due to paint alteration mist can be avoided with less capital investment and labor. It is an object of the present invention that it can be realized, that the purge work can be avoided and the construction period can be shortened.

  In order to achieve such an object, the paint alteration mist generation inhibiting method for an inner surface coating conduit according to the present invention specifies a construction site that involves heat treatment for the inner surface coated conduit, and the construction site On the other hand, the outer surface of the conduit is pre-heated at a heating temperature in a range in which no paint alteration mist is generated in the conduit, and the paint in the conduit is vaporized and removed at the construction site.

  A paint alteration mist generation inhibiting device for an inner surface coating conduit according to the present invention is attached to the outer surface of a construction site with a specified heat treatment for a conduit that has been subjected to inner surface coating, and the paint alteration mist is contained in the conduit. It is characterized by comprising heating means for preheating the outer surface of the conduit at a heating temperature in a range where no occurrence occurs.

  Since the present invention can remove the paint in the pipe around the construction site with heating so as not to generate paint alteration mist by preheating, the heating work such as cutting the pipe in an active pipe state in which no opening is formed Even in the case of applying, it is possible to prevent the paint-modified mist from being mixed into the transport fluid in the pipe. When work such as cutting is performed while cutting off the fluid transport of the conduit, the polishing work of the paint can be omitted, so that the work period can be shortened. Since paint alteration mist is not generated during construction with heating, it is not necessary to install a mist removal device on the downstream side of the construction, and the avoidance of problems due to paint alteration mist can be avoided with less capital investment and labor. The purging work is no longer necessary, and the construction period can be shortened compared to the conventional work that had to be purged.

The flowchart of the construction which suppressed generation | occurrence | production of the paint alteration mist beforehand by the paint alteration mist generation | occurrence | production suppression method in the inner surface coating conduit which concerns on embodiment of this invention. Explanatory drawing which showed the example of the aspect of the preheating of the coating-material alteration mist generation | occurrence | production suppression construction method which concerns on embodiment of this invention. Explanatory drawing explaining the coating-material alteration mist generation | occurrence | production suppression apparatus which concerns on embodiment of this invention. Explanatory drawing explaining the coating-material alteration mist generation | occurrence | production suppression apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The paint alteration mist generation deterring construction method and the paint alteration mist occurrence deterring device in the inner surface coating conduit according to the embodiment of the present invention are generated when the paint alteration mist rapidly heats the paint in the conduit at a high temperature and gradually at a certain low temperature. This is based on the knowledge obtained from the test result that the paint in the conduit can be vaporized and removed without generating paint alteration mist when the paint in the conduit is heated.

  That is, the paint alteration mist generation suppression method in the inner surface coating conduit according to the embodiment of the present invention specifies a construction site with heat treatment for the inner surface coated conduit, The outer surface of the conduit is preheated at a heating temperature that does not cause paint alteration mist, and the paint in the conduit is vaporized and removed at the construction site.

  It has been known for a long time that paint-modified mist is generated when paint (rust-proof paint) such as epoxy resin applied to the inner surface of a conduit is rapidly heated at high temperatures during conduit welding or heat cutting. Yes. On the other hand, when the outer surface of the conduit is heated at a relatively low temperature over time, the paint applied to the inner surface of the conduit is vaporized and mixed into the transport fluid flowing in the conduit. , It does not become paint alteration mist that adheres to downstream fluid equipment, etc., and adversely affects the operation of fluid equipment. If heating is continued under these conditions, the paint on the inner surface of the heated part is removed. It was newly found from the test results. By performing heating in a range in which paint alteration mist does not occur as preheating before construction involving high-temperature heating such as welding or heat cutting, the paint in the conduit at the heating location can be vaporized and removed. Then, by performing welding or heat cutting work, it is possible to prevent the occurrence of paint alteration mist.

  By performing the construction with the flow shown in FIG. 1 based on such knowledge, it is possible to prevent the occurrence of paint-modified mist. First of all, a construction location where a construction involving a heat treatment such as welding or heat cutting is performed on the inner surface painted conduit to be constructed is identified (identification of construction location; S1). Next, the outer surface of the conduit is pre-heated at a heating temperature in a range where no paint alteration mist is generated in the conduit for the specified construction site (pre-heating; S2). A construction involving heating such as welding or heat cutting is performed on the construction site from which the paint in the conduit has been removed by preheating (construction construction; S3).

  Aspects such as the heating temperature in the preheating described above are appropriately set according to the material of the paint applied to the inner surface of the conduit. When the coating material is an epoxy resin, paint-altering mist is generated by rapid heating to a temperature exceeding 250 ° C, and even when it is continuously heated at a low temperature that does not reach 250 ° C or when it exceeds 250 ° C. Slow temperature rise enables preheating without generating paint-modified mist.

  FIG. 2 is an explanatory diagram showing an example of preheating in the paint alteration mist generation inhibiting method according to the embodiment of the present invention. In the example shown in FIG. 5A, the preheating gradually increases the heating temperature in a range where no paint alteration mist is generated in the conduit. In this way, when the heating temperature is gradually increased from around room temperature T0, even if the temperature reached after sufficient time has exceeded 250 ° C., paint alteration mist does not occur. In the example shown in FIG. 5B, the preheating increases the heating temperature in a range where no paint alteration mist is generated in the conduit in a stepwise manner. In this way, when the heating temperature is raised stepwise from around room temperature T0, no paint alteration mist is generated even if the temperature reached after sufficient time has exceeded 250 ° C. In the example shown in FIG. 5C, the preheating is performed by continuing a constant heating temperature in a range where no paint alteration mist is generated in the conduit for a set time. In this example, although the coating quality change mist does not occur, the heating temperature at which the coating material can be vaporized is kept constant, and the heating is continued until the time when all the coating material at the heating location is vaporized.

  The preheating requires a gradual temperature increase, and the average increase of the heating temperature with respect to the heating time is 100 ° C./min or less, preferably 30 ° C./min or less, more preferably about 10 ° C./min. Thus, the paint on the inner surface of the conduit can be vaporized and removed without generating paint-modified mist. Such preheating can be performed by attaching a flame heating means to the outer surface of the conduit so as to surround the construction site using a paint alteration mist generation suppressing device as shown below.

  3 and 4 are explanatory views for explaining the paint alteration mist generation inhibiting device according to the embodiment of the present invention. 3A is a front view, and FIG. 3B is an AA cross-sectional view. 4A is a front view, and FIG. 4B is a BB cross-sectional view.

  The paint alteration mist generation inhibiting device 1 (1A, 1B) shown in FIG. 3 and FIG. 4 is attached to the outer surface of the construction site with the specified heat treatment with respect to the conduit 10 on which the inner surface coating is made. Heating means 20 is provided for preheating the outer surface of the conduit 10 at a heating temperature in a range in which no paint alteration mist is generated in the conduit 10. The heating means 20 includes a flame radiating portion 21 that forms a flame radiating space S that partially or entirely surrounds the outer surface of the conduit 10 and faces the outer surface, and a gas supply portion 22 that supplies combustion gas to the flame radiating portion 21. And a supply gas amount adjusting unit 23 for adjusting a gas supply amount supplied from the gas supply unit 22 to the flame radiating unit 21.

  The example shown in FIG. 3 includes heating means 20 for heating the entire circumference of the conduit 10 simultaneously. The flame radiating portion 21 in this example includes a space forming portion 21A that forms a flame radiating space S, and a gas flow path a and a gas discharge port b are formed inside the space forming portion 21A. Moreover, the flame discharge | release part 21 is formed so that it may divide | segment along the pipe-axis direction, and it can mount | wear now with the conduit | pipe 10 by combining the flange parts c and c of a division body.

  Combustion gas supplied from the gas supply unit 22 via the supply gas adjusting unit 23 is supplied to the gas flow path a of the flame radiating unit 21, and the combustion gas released from the gas discharge port b using an ignition means (not shown). Is ignited, and a flame is emitted into the flame discharge space S. By adjusting the supply gas adjusting unit 23 manually or automatically, the heating temperature in the preheating can be appropriately adjusted. In the automatic adjustment of the supply gas adjusting unit 23, the valve opening degree of the supply gas adjusting unit 23 is adjusted by an output from a controller (not shown).

  The example shown in FIG. 4 includes a heating means 20 that partially heats the outer surface of the conduit 10. The flame radiating portion 21 in this example includes a space forming portion 21A that forms a flame radiating space S, and a gas flow path a and a gas discharge port b are formed inside the space forming portion 21A. The heating means 20 is mounted so as to cover the space forming portion 21 </ b> A on the specified construction site of the conduit 10.

  By the coating material alteration mist generation inhibiting device 1 (1A, 1B) according to such an embodiment, preheating of the above-described coating material alteration mist occurrence inhibiting method can be performed. As a result, the paint in the pipe around the construction site with heating can be removed by preheating so as not to cause paint alteration mist.

  By such preheating, even when heating work such as cutting is performed on an active tube in which no opening is formed, it is possible to prevent the paint-modified mist from being mixed into the transport fluid in the tube. it can. When work such as cutting is performed while cutting off the fluid transport of the conduit, the polishing work of the paint can be omitted, so that the work period can be shortened.

  Since paint alteration mist is not generated during construction with heating, it is not necessary to install a mist removal device on the downstream side of the construction, and the avoidance of problems due to paint alteration mist can be avoided with less capital investment and labor. The purging work is no longer necessary, and the construction period can be shortened compared to the conventional work that had to be purged.

1 (1A, 1B): Paint alteration mist generation suppression device,
10: conduit, 20: heating means, 21: flame discharge section, 22: gas supply section,
23: Supply gas amount adjusting section, S: Flame radiation space

Claims (8)

For the pipes that have been painted on the inside, identify the construction site that involves heat treatment,
Preheating the outer surface of the conduit at a heating temperature within a range in which paint alteration mist does not occur in the conduit at the construction location, and evaporating and removing the paint in the conduit at the construction location. A method for preventing the occurrence of paint alteration mist in the inner paint conduit.   The said pre-heating raises the said heating temperature gradually, The paint alteration mist generation | occurrence | production suppression method in the inner surface coating conduit | pipe of Claim 1 characterized by the above-mentioned.   The said preheating raises the said heating temperature in steps, The paint alteration mist generation | occurrence | inhibition construction method in the inner surface coating conduit | pipe of Claim 1 characterized by the above-mentioned.   The said pre-heating continues the fixed said heating temperature for the set time, The paint alteration mist generation | occurrence | inhibition construction method in the inner surface coating conduit | pipe of Claim 1 characterized by the above-mentioned.   The said preheating makes the average raise with respect to the heating time of the said heating temperature 100 degrees C / min or less, The paint alteration mist generation | occurrence | inhibition construction method in the inner surface coating conduit | pipe of Claim 1 characterized by the above-mentioned.   The said preheating is performed by attaching a flame heating means to the outer surface of the said conduit so that the said construction site may be enclosed, The paint alteration mist generation | occurrence | inhibition construction method in the inner surface coating conduit | pipe of Claim 1 characterized by the above-mentioned. Installed on the outer surface of the construction site with the specified heat treatment for the conduit that has been internally coated,
A paint alteration mist generation inhibiting device comprising heating means for preheating the outer surface of the conduit at a heating temperature in a range where no paint alteration mist is generated in the conduit. The heating means includes
A flame radiating portion forming a flame radiating space facing the outer surface partially or entirely around the outer surface of the conduit;
A gas supply unit for supplying combustion gas to the flame radiating unit;
The paint alteration mist generation suppression device according to claim 7, further comprising a supply gas amount adjusting unit that adjusts a gas supply amount supplied from the gas supply unit to the flame radiating unit.

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