JP5610715B2 - Pipe welding method and shielding gas filling foaming agent - Google Patents

Description

  The present invention relates to a pipe welding method and a shielding gas filling foaming agent, and more particularly to a pipe welding method and a shielding gas filling foaming agent capable of improving shield gas retention performance and workability.

  In recent pipe material welding methods, for example, when welding steel pipes, alloy steel pipes, stainless steel pipes, aluminum pipes, etc., a foam layer is formed inside the pipe material and the inside of the pipe material is sealed, and the foam layer is sealed. A method is used in which the space is filled with a shielding gas (back shield) and the pipe material is welded. Moreover, the foaming agent for shielding gas filling is used for formation of this foam layer. And by this welding method, the shielding gas atmosphere inside a pipe material is appropriately hold | maintained with a foam layer, and the improvement of the quality of welding is aimed at.

  The technique described in Patent Document 1 is known as such a conventional welding method for pipe materials. In addition, as a foaming agent for filling a shielding gas, a technique using a alkanolamine salt of a saturated fatty acid, an alkanolamide of a saturated fatty acid, and a chemical mixed with water and alcohol as a solvent, as described in Patent Documents 1 to 3, is known. It has been.

Japanese Examined Patent Publication No. 6-75788 Japanese Patent Publication No. 8-26301 Japanese Patent No. 3233747

  In the pipe material welding method, it may take a long time from the formation of the foam layer to the welding of the pipe material, and a long-term holding performance over several days may be required for the convenience of construction. In the foaming agent for filling a shielding gas, it is required that the formed foam layer can be stably held for a long time. However, in the prior art, the formed foam layer can be held for 24 hours or more. However, the retention performance for multiple days or more is not clear. Therefore, in order to cope with actual construction without any problem, further improvement in shielding gas retention performance has been demanded. Also, in actual construction, foam may need to be filled from the gap after groove alignment, such as partial repair, but the conventional technology has a problem that it cannot be handled because it is difficult to fill the foam from the gap. Therefore, improvement of workability in addition to shielding gas retention performance has been desired.

  Then, this invention is made | formed in view of the above, Comprising: It aims at providing the welding method of a pipe material and the foaming agent for shielding gas filling which can improve the shield gas retention performance and workability of a foam layer.

In order to achieve the above object, a method for welding pipes according to the present invention is a method for welding pipes by forming a foam layer inside the pipe and filling a space sealed by the foam layer with a shielding gas. In the welding method, a foaming agent for filling a shielding gas containing a keratin protein at a concentration of a mass fraction of 0.1 [%] to 5 [%] is used for forming the foam layer.

The shield gas filling foam material according to the present invention is a shield for the blowing agent to seal the pipe to form a foam layer by foaming is injected into the conduit, the mass fraction 0. A keratin protein is contained at a concentration of 1% to 5%.

  In the pipe material welding method and the shielding gas filling foaming agent according to the present invention, the foam layer has a foam layer in comparison with the configuration in which the shielding gas filling foaming agent not containing protein and the shielding gas filling foaming agent containing collagen protein are used. Since retention and pressure resistance are improved, there is an advantage that shield gas retention performance is improved. In addition, the keratin protein has amphipathic properties, which lowers the viscosity of the foam and lowers the pressure loss that occurs at the nozzle during spraying. There are advantages to doing.

FIG. 1 is an explanatory view showing a pipe welding method according to this embodiment. FIG. 2 is an explanatory view showing a pipe material welding method according to this embodiment. FIG. 3 is an explanatory view showing a pipe welding method according to this embodiment. FIG. 4 is an explanatory view showing a pipe welding method according to this embodiment. FIG. 5 is an explanatory view showing a pipe welding method according to this embodiment. FIG. 6 is an explanatory view showing a spray device used in the pipe material welding method described in FIGS. 1 to 5. 7-1 is a table | surface which shows the result of the performance test regarding the retainability of a foam layer. 7-2 is a table | surface which shows the result of the performance test regarding the retainability of a foam layer. FIG. 8 is a table showing an evaluation method of a performance test related to the retention of the foam layer. FIG. 9 is a block diagram showing a foam layer evaluation apparatus. FIG. 10 is a table showing the results of a performance test regarding the pressure resistance of the foam layer. FIG. 11 is a table showing an evaluation method of a performance test regarding the pressure resistance of the foam layer. FIG. 12 is an explanatory diagram showing a test method of a performance test regarding the moving distance of the foam layer. FIG. 13 is a table showing the results of a performance test regarding the moving distance of the foam layer.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pipe material welding method]
For example, when welding steel pipes, alloy steel pipes, stainless steel pipes, aluminum pipes, etc., this pipe material welding method forms a foam layer inside the pipe material and seals the inside of the pipe material, and is sealed by this foam layer. This method is applied to a pipe welding method in which a shield gas (back shield) is filled in a closed space to weld the pipe. Hereinafter, this pipe material welding method will be described in detail with reference to the drawings (see FIGS. 1 to 6).

  In this pipe material welding method, first, a pair of pipe materials 1 and 1 to be welded are arranged with their welds abutted against each other (see FIG. 1). For example, in this embodiment, a pair of long and narrow cylindrical tubes 1 and 1 are arranged with their end portions abutted against each other.

  Next, a foam layer S is formed at a predetermined position in the tube material 1 (see FIG. 2). For example, the nozzle 22 of the spray device 2 is inserted into the cylindrical tube 1 from the abutting portion of the cylindrical tubes 1 and 1, and a foaming agent for filling a shielding gas is injected into the tube material 1 through the nozzle 22. And foaming foam layer S is formed in the predetermined position in the pipe material 1 by foaming the foaming agent for shielding gas filling. Moreover, this foam layer S is formed in both of the pair of pipe materials 1 and 1 which were faced | matched, respectively (refer FIG. 3). The shielding gas filling foaming agent will be described later.

  The spray device 2 is a device for injecting a shielding gas filling foaming agent, and has, for example, a main body 21, a nozzle 22, and a stopper (guide) 23 (see FIG. 6). The main body 21 is a container that contains a shielding gas filling foaming agent. The nozzle 22 is a long tube drawn from the main body 21 and serves as an injection path for the shielding gas filling foaming agent. The nozzle 22 is made of a flexible material (for example, a resin material such as plastic or fluororesin) so that the nozzle 22 can be inserted into the tube 1 while being curved. For example, in this embodiment, the nozzle 22 is made of a fluororesin material. As a result, the foamability of the foaming agent for filling the shielding gas and the wear resistance of the nozzle 22 are enhanced. Further, the nozzle 22 made of such a fluororesin is preferable because it does not damage the inner wall of the tube material 1. The tip shape of the nozzle 22 is configured by, for example, an open end shape, a trumpet shape, or a shape having an injection hole on a side portion. The stopper 23 is a member that regulates the insertion length of the nozzle 22 with respect to the tube material 1 and is made of, for example, a silicon rubber material. The stopper 23 comes into contact with the butted portion of the pipe materials 1 and 1 when the nozzle 22 is inserted into the pipe material 1 from the end thereof. Thereby, the insertion length of the nozzle 22 with respect to the pipe material 1 is regulated, and the end of the nozzle 22 is arranged at a predetermined position (position where the foam layer S should be formed). The length of the nozzle 22 is set in the range of 30 [cm] to 50 [cm], in which foam can be formed at a distance sufficiently away from the welded portion so as not to be affected by the heat generated during welding.

  Next, the shielding gas G is filled into the tubular material 1 from the butted portion of the tubular materials 1 and 1, and a shielding gas atmosphere is formed between the foam layers S and S (see FIG. 4). And after the edge part of the pipe materials 1 and 1 is faced | matched, the welding of the pipe materials 1 and 1 is performed in this shield gas atmosphere. At this time, since the shielding gas atmosphere inside the tube material 1 is appropriately maintained by the foam layer S, oxidation of the weld metal on the inner surface is suppressed, and the quality of welding is improved. Thereafter, the inside of the tube material 1 is washed with water, and the foam layer S is removed (see FIG. 5). At this time, since the foam (foaming agent for filling the shield gas) that forms the foam layer S is water-soluble, the foam layer S can be easily washed with water, and the residual foreign matter in the tube material 1 is reduced. For the shielding gas G, for example, an inert gas such as argon gas or helium gas is used. Moreover, for example, an arc welding machine is used for welding the pipe material 1.

[Foaming agent for shielding gas filling]
Here, in this pipe material welding method, in forming the foam layer S, it is preferable to use a foaming agent for filling a shield gas containing keratin protein. In such a configuration, compared with the configuration in which the shielding gas filling foaming agent not containing protein and the shielding gas filling foaming agent containing collagen protein are used, (1) the retention property of the foam layer S (foam foam property) is higher. And (2) there is an advantage that the pressure resistance of the foam layer S is improved. Moreover, since keratin protein has amphipathic property, there exists an advantage which the viscosity of (3) foaming agents falls.

  For example, (1) When the retainability of the foam layer S is improved, the shield gas atmosphere is properly maintained for a long time. At the construction site of pipe welding, a certain period of time may be provided from the formation of the foam layer S of the pipe welding method to the welding of the pipe 1 for the convenience of the whole process. For this reason, the longer the time that the foam layer S can be held, the longer the time from the formation of the foam layer S to the welding of the pipe 1 can be set, and the adjustment of the welding method of the pipe and other processes becomes easier. It is preferable for the convenience of construction.

  Further, (2) when the pressure resistance of the foam layer S is improved, the foam layer S is held at a predetermined position without flowing due to the pressure of the shield gas G. In addition, at the construction site for pipe welding, a difference in the specific gravity of the atmosphere may occur due to a temperature difference in the unit, and a differential pressure may be generated inside the pipe. At this time, if the foam layer S flows inside the tube due to the differential pressure, the shielding gas atmosphere may be deteriorated. Therefore, this situation is prevented by improving the pressure resistance of the foam layer S.

  Moreover, (3) When the viscosity of a foaming agent falls, since the viscosity of the foam injected becomes low and the freedom degree of construction spreads, it is preferable. For example, the lower the foam viscosity, the smaller the pressure loss that occurs at the nozzle during injection, so the foam layer is formed using a longer and narrower nozzle (for example, a nozzle having an inner diameter of 2 [mm] and a length of 500 [mm]) 22. S can be formed. Then, since the nozzle 22 can be inserted even from a narrow gap between the butted portions of the pipe materials 1 and 1, the foam layer S can be formed regardless of the timing before and after the groove alignment. Thereby, it is not necessary to adjust another process for forming the foam layer S. Moreover, it is possible to cope with the case where the foam needs to be filled from the gap after the groove alignment such as partial repair. The blending ratio of LPG is preferably in the range of 10 [%] to 40 [%], and more preferably in the range of 15 [%] to 35 [%].

  The keratin protein is extracted from animal hair, skin keratin, hair, nails and the like, and particularly constitutes 80% or more of human hair. The amino acid composition of keratin protein contains about 10% of cystine which is hardly present in other proteins. Since cystine has a disulfide bond (SS bond) in the molecule, the peptide chain of keratin protein is networked by disulfide bonds derived from cystine, and as a result, keratin protein has a certain mechanical strength. It has been known.

  In this pipe material welding method, it is preferable that the concentration of the keratin protein applied to the shielding gas filling foaming agent is 0.1 [%] or more and 5 [%] or less. In such a configuration, the foam retention property, pressure resistance, and viscosity of the shielding gas filling foaming agent are optimized, and thus there is an advantage that both the shielding gas retaining performance and workability of the shielding gas filling foaming agent can be achieved. For example, if the concentration of keratin protein exceeds 5%, the foam viscosity becomes excessive, and workability is lost. Further, if the concentration of keratin protein is less than 0.1 [%], the effect of improving foam retention and pressure resistance due to the addition of keratin protein does not appear sufficiently, which is not preferable.

  In this example, performance tests on the retention property, pressure resistance, and travel distance of the foam layer S were performed on the foaming agents for filling the shielding gas having different components. Hereinafter, these performance tests will be described.

[Performance test on foam layer retention]
In the performance test regarding the retention of the foam layer, first, the prepared shielding gas filling foaming agent and LPG (Liquefied petroleum gas) as a propellant were in a weight ratio of 2: 1 (LPG weight ratio of 33.3 [%]). ) Is filled in the spray can 2 (see FIG. 6). Next, the foaming agent for filling the shielding gas is injected into the cylindrical acrylic tube (inner diameter 50 [mm] and length 300 [mm]), and the foam layer S is formed inside the acrylic tube. Then, the acrylic tube with both ends open is left standing under the condition of a temperature of 20 [° C.] in a vertical state. Thereafter, the properties of the foam layer S after the elapse of a predetermined time are visually observed and evaluated. The evaluation is performed in four stages of 、, ○, Δ, and ×, and the ◎ side is more preferable (see FIG. 8).

  In FIG. 7-1, the foaming agent for filling a shield gas of Example 1, Comparative Example 1 and Comparative Example 2 is (a) stearic acid triethanolamine salt, (b) coconut oil fatty acid diethanolamide, (c) alcohol, (D) Protein, (e) Prepared with water. (A) Stearic acid triethanolamine salt and (b) coconut oil fatty acid diethanolamide are used as a foaming agent for stabilizing fine bubbles (foam). (C) Alcohol is used as a solvent and a stabilizer. (D) Protein is mainly used to ensure foam water retention and adhesion to metal. (E) Water is used as a solvent. In addition, the compounding ratio of these components can be optimized within the range obvious to those skilled in the art. Moreover, (d) Other components except protein are common (refer FIG. 7-1). Regarding this protein (d), in Example 1, keratin protein (blending ratio 5 [%]) is used. In Comparative Example 1, collagen protein is used, and in Comparative Example 2, casein protein is used. On the other hand, the conventional foaming agent for filling a shielding gas is a commercially available product (trade name “Sunfoam P-30”) and does not contain keratin protein.

  As shown in the test results, in Example 1, the foam properties immediately after injection and after being left for 24 hours are maintained as “「: hard and stable foam ”, which is preferable to Comparative Example 1 and Comparative Example 2 (FIG. 7-1 and FIG. 8). Further, the foam properties after standing for 48 hours remain at “◯: relatively hard foam (decrease in bubble density)”, which is more preferable than the conventional example in which “Δ: loss of foam density”. Thus, it turns out that the retainability of foam layer S improves because the foaming agent for shielding gas filling contains keratin protein.

  Moreover, in FIG. 7-2, the foaming agent for shielding gas filling of Example 6, Example 7 and Comparative Example 3 is (a) stearic acid triethanolamine salt, (b) coconut oil fatty acid diethanolamide, (c) It is prepared with alcohol, (d) keratin protein, and (e) water. In addition, (d) the ratio of keratin protein is selected from 0.5 [%], 0.1 [%] and 0.0 [%], and (e) the ratio of water is adjusted accordingly. Has been.

  As shown in the test results, in Examples 6 and 7, the foam properties immediately after injection and after standing for 48 hours are maintained as “◯: relatively hard foam”, which is preferable to Comparative Example 3 (FIG. 7). -2 and Figure 8). Thus, it turns out that the retainability of foam layer S improves because the foaming agent for shielding gas filling contains keratin protein. In particular, even when a small amount (0.1 [%]) of keratin protein is blended as in Example 7, a preferable test result is obtained over Comparative Example 3 in which no keratin protein is blended. . Further, when Example 6 and Example 7 are compared, Example 6 having a blending ratio of 0.5 [%] has a foam property of “Δ: loss of bubble density” after one week. And more preferable than Example 7 having a blending ratio of 0.1 [%]. Therefore, it can be seen that the retention of the foam layer S is improved by optimizing the blending ratio of the keratin proteins.

[Performance test on pressure resistance of foam layer]
In the performance test relating to the pressure resistance of the foam layer, the spray can 2 was prepared at a ratio of 2: 1 (weight ratio 33.3 [%] of LPG) of the prepared shielding gas filling foaming agent and LPG propellant. (See FIG. 6). Next, the foaming agent for filling the shielding gas is injected into the cylindrical acrylic tube 10 (inner diameter 50 [mm] and length 300 [mm]), and a foam layer S is formed inside the acrylic tube 10. The Next, the acrylic tube 10 whose both ends are opened is left in a vertically placed state at a temperature of 20 [° C.]. Next, after leaving for a predetermined time, the evaluation apparatus 3 is used to apply an internal pressure to the acrylic tube 10. Then, the internal pressure is increased at a rate of 5 [mmH20 / min], and the internal pressure when the increase in the internal pressure stops (the foam layer S collapses) is measured and evaluated (see FIG. 9). The evaluation is performed in four stages of ◎, ◯, Δ, and ×, and the bubble is less likely to collapse as it is on the ◎ side (see FIG. 8).

  The evaluation device 3 includes a pressure adjusting acrylic tube 31, a flow meter 32, a manometer 33, a pressure adjusting valve (flow variable valve) 34, and an internal pressure releasing valve 35 (see FIG. 9). Further, the pressure-adjusting acrylic tube 31 and the acrylic tube 10 on which the foam layer S is formed are connected via a connecting tube 36. In this evaluation device 3, the compressed air is introduced into the pressure adjusting acrylic tube 31 via the flow meter 32. The manometer 33 and the pressure adjusting valve 34 are used to adjust the air pressure in the pressure adjusting acrylic tube 31. Thereby, the air pressure in the acrylic tube 10 is adjusted.

  In FIG. 10, the foaming agents for filling the shield gas of Examples 2 to 5 are (a) stearic acid triethanolamine salt, (b) coconut oil fatty acid diethanolamide, (c) alcohol, (d) keratin protein, (E) It is prepared with water and has common components. However, the blending ratio of (d) keratin protein is selected from 3.0 [%], 4.0 [%] and 5.0 [%], and other components (a) to (c) are selected accordingly. ) And (e) are adjusted. On the other hand, the conventional foaming agent for filling a shielding gas is a commercially available product (trade name “Sunfoam P-30”) and does not contain keratin protein.

  As shown in the test results, in Examples 2 to 5, the pressure resistance of the foam layer S immediately after injection is at the level of “◎: 20 [mmH20 / min]”, and “Δ: 5 [mmH20 / min]”. Is more preferable than the conventional example (see FIGS. 10 and 11). Thus, it turns out that the pressure resistance of foam layer S improves because the foaming agent for shielding gas filling contains keratin protein. Furthermore, in Example 2 and Example 3, the pressure resistance of the foam layer S after standing for 1 week is at the level of “◯: 10 [mmH20 / min]”, which is more preferable than Example 4 and Example 5. Thus, it turns out that the pressure resistance of the foam layer S improves by optimizing the ratio of (d) keratin protein.

[Performance test on moving distance of foam layer]
In the performance test relating to the movement distance of the foam layer, the spray can 2 was prepared at a ratio of 2: 1 by weight (the LPG weight ratio of 33.3 [%]) to the prepared shielding gas filling foaming agent and the propellant LPG. (See FIG. 6). Next, the foaming agent for filling the shielding gas is injected into the cylindrical stainless steel tube 20 (inner diameter 50 [mm] and length 600 [mm]), and a foam layer S is formed inside the stainless steel tube 20. The Next, the internal pressure 5 [mmH20] is applied to the stainless steel tube 20 by using the evaluation device 3 (see FIG. 9). Then, the stainless steel tube 20 is placed vertically and left under the condition of a temperature of 20 [° C.] (see FIG. 12). Next, after leaving for a predetermined time, the length and the moving distance of the foam layer S are measured. And evaluation is performed based on this measurement result.

  In the performance test, the shielding gas filling foaming agent of Example 1 containing keratin protein (see FIG. 7-1) and the conventional shielding gas filling foaming agent are compared.

  As shown in the test results, the foaming agent for filling a shielding gas of Example 1 has a shorter moving distance of the foam layer with respect to the elapsed time than the foaming agent for filling a shielding gas of the conventional example (see FIG. 13). That is, in the foaming agent for filling a shielding gas of Example 1, the foam layer S is difficult to move even when a differential pressure is generated inside the pipe material 1 due to a difference in the specific gravity of the atmosphere due to a temperature difference in the unit at the construction site. Compared to the conventional example, the shielding gas atmosphere is more appropriately secured. Therefore, it can be seen that when the shielding gas filling foaming agent contains keratin protein, the shielding gas retention performance under the differential pressure condition is improved.

  As described above, the pipe welding method and shielding gas filling foaming agent according to the present invention are useful in that the shielding gas retention performance and workability can be improved.

1 Pipe material 2 Spray device (spray can)
21 Main body 22 Nozzle 23 Stopper 3 Evaluation device 31 Pressure adjusting acrylic tube 32 Flow meter 33 Manometer 34 Pressure adjusting valve 35 Internal pressure release valve 36 Connecting tube 10 Acrylic tube 20 Stainless steel tube G Shielding gas S Foam layer

Claims (2)

A method of welding a pipe material, wherein a foam layer is formed inside the pipe material and a space sealed by the foam layer is filled with a shielding gas to weld the pipe material,
In forming the foam layer, a foaming agent for filling a shielding gas containing a keratin protein at a concentration of a mass fraction of 0.1 [%] to 5 [%] is used. A foaming agent for shielding that seals the pipeline by forming a foam layer by being injected and foamed into the pipeline,
A foaming agent for filling a shielding gas, comprising keratin protein at a mass fraction of 0.1 [%] to 5 [%].

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