JPH07256449A - Method for welding end of tube - Google Patents

Abstract

PURPOSE:To operate welding over all the circumference from an upper side or a lateral side, to improve the workability and to reduce the working space by putting a liquid inside a sheath tube and welding while floating a inserting main tube and rotating it. CONSTITUTION:A water stop cap 31 is attached at a side end of an arrival vertical shaft of a sheath tube 30, and a water stop packing 34 opening a main tube inserting hole is attached at a side end of a starting vertical shaft 10 side end. A main tube 40 attached with a water stop cap 41 at its front end is pulled inside the sheath tube 30 that water is supplied to a prescribed height position. Then, the main tube 40 is sequentially welded as it is floating in the water inside the sheath tube 30. In this time, a new main tube 40b is horizontally placed on a stand 50 inside the starting pit 10, and it can be freely rotated by rollers 51 on the stand 50. Further, in a time of welding a rear end of the main tube 40a and a front end of the main tube 40b, because the main tube 40 inside the sheath tube 30 is floating in the water, it can be freely rotated. Accordingly, because welding can be executed only at the upper position showing in an arrow mark, the workability is remarkably excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe end welding method for coaxially welding a front end of a new main pipe to a rear end of a main pipe inserted into a sheath pipe while leaving a rear end portion in a shaft.

[0002]

2. Description of the Related Art For example, a double pipe consisting of a sheath pipe and a main pipe may be used as a pipe buried in the ground for sending high-pressure gas, in order to maintain the strength of the pipe. Also, when burying this double pipe in the ground, rather than excavating and burying a long and narrow groove along the route to be buried from the ground, a predetermined vertical shaft is dug and the horizontal wall of this vertical shaft is removed. A so-called propulsion method of propelling the pipe in the longitudinal direction may be adopted. In adopting this propulsion method,
If the main tube is propelled together with the sheath tube, the main tube may be damaged or the main tube may be distorted.To avoid this, usually only the sheath tube is propelled, and then the main tube is pulled into the sheath tube. Alternatively, the pushing method is adopted.

When inserting the main pipe into the sheath pipe, a process of coaxially welding a main pipe having a length of, for example, about 6 m and inserting the welded main pipe into the sheath pipe is repeated.

[0004]

When welding main pipes together, it is necessary to perform welding along the entire circumference of the main pipes, whether using a welding machine or manually. When the lower side of the welding is performed, the welding is performed in an unnatural posture in the manual welding, the workability is poor, and the quality of the welding is likely to cause a problem. In addition, when welding is performed using a welding machine, a wide space for the welding machine to pass through is also required at the bottom of the main pipe, and the vertical shaft is dug deeply for the space to propel the sheath pipe and insert the main pipe. Therefore, there is a problem in that the cost of burying the pipe is increased.

In view of the above circumstances, it is an object of the present invention to provide a pipe end welding method in which workability in the case of manual welding and space reduction by welding using a welding machine are achieved.

[0006]

The pipe end welding method of the present invention which achieves the above-mentioned object is a front end of a new main pipe at the rear end of the main pipe inserted into the sheath pipe while leaving the rear end portion in the shaft. In a pipe end welding method of coaxially welding, the main pipe inserted into the sheath pipe by putting a liquid in the sheath pipe is floated in the sheath pipe, and while rotating the main pipe, the rear end and the front end are welded. It is characterized by that.

[0007]

In the pipe end welding method of the present invention, the main pipe is floated in the liquid (typically water) in the sheath pipe and the welding is performed while rotating the main pipe. It is possible to perform welding over the entire circumference of the main pipe at a position where it is easy to perform welding, etc., improving workability and reducing space.

[0008]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a schematic view of an embodiment of the pipe end welding method of the present invention. In FIG. 1, the thrust of the sheath pipe 30 between the starting shaft 10 and the reaching shaft 20 is completed, and the main pipe 40 is replaced by the winch wire 6
FIG. 1 is a view showing a state in which the sheath tube 30 is pulled in halfway while being sequentially welded by No. 1.

A water stop cap 31 is capped on the front end of the sheath tube 30 on the reaching shaft 20 side, and a hole for inserting the main pipe is formed in the center on the rear end of the sheath tube 30 on the starting shaft side. The water-stop packing 34 is attached, water is supplied into the sheath pipe 30 via the water supply pipe 32, and the water is discharged via the drain pipe 33, whereby a constant amount of water is constantly stored in the sheath pipe 30. It is kept.

In this way, the main pipe 40 having the front end covered with the water blocking cap 41 is drawn in by the winch wire 61 into the sheath pipe 30 to which water is supplied to the predetermined height position. In this way, the main pipe 40 is drawn in a state of floating in the water in the sheath pipe 30 and sequentially welded, and as shown in the drawing, the rear end portion of the main pipe 40a welded to the rearmost portion is placed in the vertical shaft. The main pipe 4 welded to this rearmost portion is assumed to have advanced to the remaining state.
A case of welding the rear end of 0a and the front end of the new main pipe 40b will be described.

The new main pipe 40b is suspended by a crane or the like (not shown), and placed horizontally on the pedestal 50 in the starting shaft 10. The gantry 50 is provided with rollers 51 for receiving the main pipe 40b.
After being mounted on the gantry 50, it can rotate freely. Further, the gantry 50 has a position adjusting mechanism (not shown) that coaxially aligns the rear end of the main pipe 40a already drawn into the sheath pipe 30 and the front end of a new main pipe 50b placed on the gantry 50. It is equipped.

In this way, the new main pipe 40b is attached to the mount 5.
When the main pipe 40a is placed at 0 and the alignment is completed, the rear end of the main pipe 40a and the front end of 40b are welded. At the time of this welding, the main pipe 40 already drawn into the sheath pipe 30 is
Since it floats in water inside 0, it is free to rotate, so here the welding is performed while rotating the main tube 40 only in the upper position shown by the arrow in the figure. Thus, according to this embodiment, welding with extremely good workability is performed.

When the welding is completed, an X-ray inspection of the welded portion is carried out, the gantry 50 is removed, and if the X-ray inspection is passed, the rear end of the new main pipe 40b welded by the winch wire 61. Only the part is drawn into the sheath pipe 30 to a position where it remains in the shaft 10. By repeating the above, the welded main pipe 40 is inserted into the sheath pipe 30. As described above, when the main pipe 40 is drawn to the reaching shaft 20,
The water in the sheath pipe 30 is drained, and accordingly, the main pipe 40 is placed on the lower portion of the inner wall of the sheath pipe 30, and mortar remains between the sheath pipe 30 and the main pipe 40 in this state. It is injected and the main tube 40 is fixed in the sheath tube 30.

[0014]

As described above, according to the present invention,
Welding is performed with extremely good workability and in a small work space.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a pipe end welding method of the present invention.

[Explanation of symbols]

 10 Starting shaft 20 Reaching shaft 30 Sheath pipe 31 Water stop cap 32 Water supply pipe 33 Drain pipe 34 Water stop packing 40 Main pipe 41 Water stop cap 50 Stand 51 Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shingo Nagashima 1-7-7 Suehiro-cho, Tsurumi-ku, Yokohama City, Tokyo Gas Co., Ltd. Conduit Technology Center (72) Minor inventor Minoru, Suehiro-cho, Tsurumi-ku, Yokohama 7-7 Tokyo Gas Co., Ltd. Conduit Technology Center (72) Inventor Kei Katahira 2-2-2 Matsuzaki-cho, Abeno-ku, Osaka City Okumura-gumi

Claims (1)

[Claims] 1. A pipe end welding method in which a front end of a new main pipe is coaxially welded to a rear end of a main pipe inserted into a sheath pipe while leaving a rear end portion in a shaft, and a liquid is put into the sheath pipe. A pipe end welding method, characterized in that a main pipe inserted into a sheath pipe is floated in the sheath pipe, and the rear end and the front end are welded while rotating the main pipe.