JPH083829Y2 - Centering jig - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a centering jig capable of accurately centering a fitting with respect to a main pipe in a fitting mounting operation in a hot tap method.

[Prior Art] The hot tap method has been conventionally used in gas and water works. This is a construction method for repairing a scratch generated in the main pipe while keeping the fluid flowing in the main pipe without lowering the fluid pressure in the main pipe. Hereinafter, the outline of the conventional hot tap method will be described with reference to FIGS.

FIG. 5 is a view showing a state where fittings are attached to both sides of the damaged main pipe, and FIGS. 6 and 7 are configuration diagrams of the fittings and detailed views of the mounting state.

As shown in FIG. 5, when a damage 101 occurs in a part of the main pipe 100 due to external work or the like, fittings 10 are attached to both sides of the damage 101 by welding. This fitting
As shown in FIG. 6, reference numeral 10 denotes an upper fitting 11 divided into upper and lower halves, a lower fitting 12, and a neck fitting 13 integrated on the upper fitting 11 by butt welding 21 and the neck fitting 13 It is composed of a seal plug 14 screwed to. The neck fitting 13 has a toothed flange 15.

To attach the above fitting 10 to the main pipe 100, as shown in FIG. 7, first attach the upper and lower fittings 11 and 12 to the main pipe 100 by fillet welding 22, respectively, and then butt the both fittings 11 and 12 together. Join at weld 23. Finally, the seal plug 14 is screwed to the neck fitting 13. In this way, the inside of the fitting 10 is sealed, and the attachment with the main pipe 100 is completed.

Next, FIG. 8 is an explanatory view of the main pipe perforating work after the fitting 10 is attached. That is, the gate valve 102 and the punching machine 103 are sequentially flange-connected and set on the neck fitting 13. Although not shown in the figure, the seal plug 14 is removed before setting the gate valve 102 and the like.

The drilling machine 103 includes a center drill 104 and a cylindrical cutter 105 coaxial with the center drill 104, and the drill 104 and the cutter 105 are rotated by an external drive source (for example, an engine). The punch 103 has a closed structure,
A through hole 106 is formed in the main pipe 100 by the rotation of the drill 104 and the cutter 105.

After perforating the main pipe 100, the gate valve 102 is closed and hermetically closed, and the perforator 103 is removed. Then, instead of the punching machine 103, a stopping machine 107 is attached as shown in FIG. 9, the gate valve 102 is opened again, and the stopper 108 is inserted into the through hole 106 of the main pipe 100 by the stopping machine 107.

Here, the stopper 108 has a structure in which a rubber plate 111 is attached to the surface of a cylindrical body 110 having a slit 109 as shown in FIG. And this stopper 108
As shown in FIG. 11, the slit 109 is inserted into the through hole 106 in the direction a of the fluid flow, and the stopping machine 1
By the operation of 07, the cylindrical body 110 is expanded in the radial direction and the rubber plate 111 is brought into close contact with the through hole 106.

The above-mentioned perforation and stopper insertion are performed for each fitting, and finally, between the bypass mounting ports 112 provided in both stopping machines 107, as shown in FIG.
If connected at 13, the fluid in main 100 will flow through bypass pipe 113 as indicated by the arrow. On the other hand, the fluid in the pipe at the damaged portion 101 of the main pipe 100 stops the flow.

After that, the fluid in the pipe at the damaged portion is removed, the pipe is replaced with a new pipe, and the work reverse to the above steps is performed for repair. That is, the stopper 108 is contracted and removed, the gate valve 102 is closed, and then the bypass pipe 113 and the stopping machine 107 are removed. Then, a plug tightener (not shown) equipped with the sealing plug 14 is mounted on the gate valve 102, the gate valve 102 is opened, and the sealing plug 14 is screwed to the neck fitting 13. The seal plug 14 has a 13th
An O-ring 16 is provided as shown in the figure.
16 closely contacts a sealing surface 17 provided at the female screw inlet of the neck fitting 13 to seal the internal fluid. This completes the repair work.

In the above hot tap method, it is the most important point to completely shut off the fluid flow in the pipe at the damaged portion by the stopper 108. Therefore, in the drilling work by the cutter 105, it is indispensable to cut almost the center of the wall thickness of the main pipe 100 as shown in FIG. This is because it is necessary to machine the through-hole 106 having the arcuate portions 106a and 106b with which the stopper 108 can closely adhere to the thick portions on both sides.

In order to obtain such symmetrical arc portions 106a and 106b, the main pipe 100
It goes without saying that an accurate centering of the fitting 10 with respect to should be ensured. Under this premise, the cutter
The center 105A of 105 is vertically aligned with the axis 100A of the main pipe 100. If they do not match, a gap 114 is formed on one side when the stopper 108 is inserted as shown in FIG. 15, and fluid leaks through this gap 114.

However, in the prior art, as described above, it was difficult to perforate with the center position aligned, and a mismatch (center misalignment) often occurred, which was a problem. After investigating the cause,
Upper fitting as shown in Figures 16 (a) and (b)
It was found that this was due to the disagreement between the center 11A of the neck fitting outlet 18 of 11 and the center 11B of the main arc-shaped main pipe mounting portion 19. This is the top fitting 11
Since it is a forged product, its wall thickness is not uniform, and since it is necessary to weld fillet with the main pipe 100 as shown in FIG. 17, the thickness t of the main pipe mounting portion 19 will be uniform in the subsequent process. However, as a result, when the upper fitting 11 is welded to the main pipe, a misalignment δ occurs between the center 11A of the outlet 18. This is a butt weld when the neck fitting 13 and the upper fitting 11 are welded at the factory (welding line 21), so the centerline of the neck fitting 13 and the centerline of the upper fitting 11 are eliminated in order to eliminate misalignment. This is to match

Therefore, in order to correct this misalignment, conventionally, a means for aligning the center of the neck fitting 13 with the center of the main pipe mounting portion 19 using a centering jig as shown in FIG. 18 has been taken. .

The centering jig 25 is provided with a disc 26 that is screwed to the neck fitting 13, and a pin 28 having a tip 27 on the center of the disc 26.
Can be seen.

Specifically, the centering work in the factory is performed as follows.
First, on a cylindrical master member 120 having the same outer diameter as the main pipe 100, two scoring lines 1 horizontally and vertically as shown in FIG.
21,122 are inserted in the axial direction, and a punch hole 123 is provided in one of the score lines 122. Next, as shown in FIG. 18, the abutting surface 20 of the upper fitting 11 is attached to the horizontal marking line 121
Install it on the master member 120 so that the neck fitting 13 is placed on the master member 120, and further align the centering jig 25.
The disk 26 of is screwed. Then, the centering jig 25 and the neck fitting 13 are moved so that the pin tip 27 of the centering jig 25 matches the punch hole 123, and when they match, the neck fitting 13 and the upper fitting 11 are clamp-welded, and then both are joined. Perform main welding.

The upper fitting 11 thus integrated and centered is welded to the actual main pipe 100 in the local hot tap work, and the neck fitting 1
Align the center of 3 with the cutter 105 as described above
Perforated 0.

[Problems to be Solved by the Invention] However, the conventional centering jig 25 may be inclined due to the clearance of the screw, and even if the inclination is within the allowable limit of screw manufacturing, the center position of the main pipe 100 is The misalignment δ becomes large as shown in FIG. That is, if the centering jig 25 is tilted, even if the pin tip 27 is in the punch hole 12
Center 1 of neck fitting 13 even if it matches 3
3A passes through a position away from the center O of the master member 120. 2
5A is the center of the centering jig 25, and of course passes through the center O. Due to such misalignment δ, the main pipe through hole 106
Are not even as shown in Fig. 14, resulting in stopper 10
Occasionally, a sealing failure of 8 occurred.

In order to show the degree of conventional misalignment δ, δ will be obtained for a 300 A carbon steel pipe for pipe (JIS G3452) as an example.

Since the steel pipe has a wall thickness of 6.9 mm and an outer diameter of 318.5 mm, the cutter outer diameter is set to 312 mm, and a female screw inner diameter larger than this is set to 320 mm.
mm.

Now, based on JIS B0211, the screw manufacturing is based on 6 female threads.
With a grade of H, male screw 6g, the dimensional tolerance is calculated as follows (however, since the above standard specifies only the maximum M300 screw, the allowable value of this value will be used). That is, radial gap of the male thread and the female screw, with reference to Figure 21, a _{es / 2 + Td 2/2} + TD 2 /2=0.33mm ( However, es = -0.
080 mm, Td ₂ = 0.315 mm, TD ₂ = 0.425 mm). Therefore, when the plate thickness of the disk 26 of the centering jig 25 is H and the radius of the master columnar body 120 is R, the misalignment δ is δ = R × tan2 × 0.33 / H = 318.6 / 2 × tan2 × 0.66 / 30 = 3.5mm That is, at the center of the main pipe 100, a misalignment of up to 3.5mm may occur.

Now, based on the JIS standard, when the outer diameter is maximum and the pipe thickness is minimum, the dimensional relationship is as shown in Fig. 22.
Since the inner diameter of the main pipe is 315 mm with the outer diameter of the cutter being 318 mm, the inner diameter of the main pipe is not cut if the center misalignment of more than half of the difference is 1.5 mm. Therefore,
Since δ = 3.5 mm in the above calculation, the above-mentioned phenomenon occurs and the interruption by the stopper 108 becomes impossible.

In order to solve the above conventional problems, the present invention aims to provide a centering jig capable of performing accurate centering so that the center line of the neck fitting 13 passes through the center of the main pipe. .

[Means for Solving the Problems] In order to achieve the above object, the centering jig according to the present invention is such that the center line of the neck fitting is matched with the center line of the main pipe in the fitting used for the hot tap method. Which is used when welding the upper fitting and the neck fitting to each other, a disc provided on the neck fitting of the fitting and closely fitted to the sealing surface in the screw coupling portion with the seal plug, and the disc. A center hole provided perpendicularly to the center of the circle, and a hole densely inserted in the center hole and also a hole provided in the diametrical direction of the master member having the same outer diameter as the main pipe. And a shaft rod having a length for piercing the plate and the master member.

[Operation] A hole is provided in the diametrical direction in the master member having the same outer diameter as the main pipe, and the shaft rod is closely inserted into the hole, so that the center of the shaft rod is orthogonal to the axis of the master member. Therefore,
The upper fitting is aligned and set on this master member, and the neck fitting is placed on it.
Furthermore, after fitting the disc to the sealing surface provided on the screw coupling part of the neck fitting sealing plug, insert the shaft rod into the center hole of the disc, and align the neck fitting while adjusting the fitting. I do. Then, the centers of the upper fitting and the neck fitting are held by this shaft rod so as to be orthogonal to the axis of the master member. In this state, if the upper fitting and the neck fitting are clamp-welded and then main-welded, the neck fitting and the main pipe are accurately centered.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional front view of a centering jig according to the present invention. This centering jig 30 is composed of two members, a disc 31 and a shaft rod 32. The disc 31 has an outer diameter that allows a tight fit with the sealing surface 17 of the neck fitting 13. Here, “tightly” means that the gap between the two members that are in a fitting relationship is extremely small. In addition, the center hole is perpendicular to the center of the disc 31.
33 is provided, and in order to stabilize the axial rod 32 by lengthening the length of the central hole 33 to some extent, the cylindrical body 34 is preferably provided.
Is provided. The shaft rod 32 is composed of a straight round rod that is closely inserted into the center hole 33. At the same time, its length is long enough to penetrate the pipe-shaped master member 120.
The master member 120 is provided with holes 125 and 126 having the same inner diameter as the central hole 33 in the diameter direction. The master member 120 has the same outer diameter as the main pipe 100, and may be a columnar body.

2A and 2B are external views of the disc 31 and the shaft rod 32, respectively, and FIG. 3 is an external view of the master member 120. The disc 31 is provided with a suitable viewing window 35. In addition, the master member 120 has marking lines 12 at 90 ° intervals in the axial direction.
1, 122 are inserted, and the above holes 125, 126 are provided on the score lines 122 facing each other by 180 °.

The procedure of the centering work with the centering jig 30 configured as described above is as follows.

First, as shown in FIG. 4A, the master member 120
Butt face 2 of upper fitting 11 on horizontal score line 121 of
The upper fitting 11 is set on the master member 120 so that 0 matches. Then, the shaft 32 is attached to the master member
Insert into holes 125 and 126 of 20.

Next, attach the disc 31 to the sealing surface of the neck fitting 13.
Insert the shaft rod 32 into the center hole 33 while tightly fitting it in 17,
Adjust the neck fitting 13 while adjusting it, and place it on the upper fitting 11. Then, after both of them are clamp-welded, main welding is performed.

As described above, the neck fitting 13 is integrated with the upper fitting 11, and the centering around the shaft rod 32 is completed.

Then this integrated neck fitting 13
And remove the upper fitting 11 from the master member 120,
If the main pipe 100 is set on the actual main pipe 100 and the main pipe 100 is perforated by the perforator 103 on the center of the neck fitting 13, the cutter 105 will cut almost the center of the wall thickness of the main pipe 100, as shown in FIG. A symmetrical through hole 106 is formed as shown.

 The amount of misalignment by the centering jig 30 will be calculated.

The gap between the seal surface 17 of the neck fitting 13 and the disc 31 is δ ₁ = 0.2 mm, the length of the center hole 33 is l = 100 mm, and the gap between the center hole 33 and the shaft rod 32 is δ _2. = 0.2mm, 300A
In the case of the main pipe, the center misalignment δ of the main pipe is the core misalignment due to the inclination of the shaft rod 33 δ = R × tanδ ₂ /l=318.6/2×tan 0.2 / 100 = 5.5 × 10 ⁻³ mm It can be seen that the misalignment due to the parallel movement of the rod 33 is δ = δ ₁ + δ ₂ = 0.4 mm, which is significantly smaller than the conventional one.

[Advantage of the Invention] As described above, according to the present invention, a hole is provided in the diameter direction of the master member having the same outer diameter as the main pipe, and the center of the disc is centered on the shaft rod densely inserted in the hole. This shaft rod is passed through, and the disc is closely fitted to the sealing surface of the neck fitting to perform centering. Accurate centering is possible without the plate tilting.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a centering jig showing an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are external views of a disk and a shaft rod which are constituent members of the jig. Fig. 3 is an external view of a master member used during centering work, Figs. 4 (a) and 4 (b) are diagrams showing a procedure of centering work, and Figs. 5 to 14 are explanations of a conventional hot tap method. In the figure, FIG. 5 is an explanatory view of a state in which a fitting is attached to the main pipe, FIGS. 6 and 7 are configuration diagrams and an attachment state diagram of the fitting, and FIG. 8 is an explanatory diagram of perforating the main pipe, FIG. 9 is an explanatory view of inserting the stopper into the main pipe, FIG. 10 is an external view of the stopper, FIG. 11 is an explanatory view showing a state where the stopper is inserted into the main pipe, and FIG. 12 is a main pipe. Explanatory drawing showing the state where the bypass pipe is attached to the 13th
Figure is a detailed view showing the screw connection state with the seal plug of the neck fitting, Figure 14 is a view showing the preferable state of the through hole drilled in the main pipe, and Figure 15 is the stopper in the case of misalignment. FIG. 16 (a) and FIG. 16 (b) are illustrations showing a state where the core is misaligned in the upper fitting, FIG. 17 is an illustration of a main fitting part of the upper fitting, and FIG. Fig. 19 is a block diagram of the centering jig. Fig. 19 is an external view of a master member used during conventional centering work.
The figure is an explanatory view showing the state where misalignment occurs due to the conventional centering jig, Fig. 21 is an explanatory view used to determine the gap between the male screw and the female screw, and Fig. 22 is the dimension when drilling the main pipe It is a figure which shows a relationship. 10 …… Fitting 11 …… Upper fitting 12 …… Lower fitting 13 …… Neck fitting 14 …… Seal plug 17 …… Seal surface 30 …… Centering jig 31 …… Disc 32 …… Shaft rod 33 …… Central hole 100 …… Main pipe 120 …… Master member 125,126 …… Hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Unemoto 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Yuuo Ooka 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd. (72) Inventor Osamu Arata 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd. (72) Inventor Masami Ishikawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) Inventor: Akira Sasaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) References: Jikkyohei 1-8303 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A centering jig used for welding an upper fitting and a neck fitting so that the centerline of the neck fitting is matched with the mainline of the main pipe in the fitting used for the hot tap construction method. A disc that is provided in the neck fitting and that closely fits the sealing surface of the screw coupling portion with the seal plug, and a central hole that is provided perpendicularly to the center of the disc,
A shaft rod which is densely inserted in the central hole and is also densely inserted in a hole provided in the diametrical direction of the master member having the same outer diameter as the main pipe, and has a length for piercing the disc and the master member. And a centering jig.