JP3937197B2 - Welding method of double pipe using grooved insert ring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for joining a double pipe composed of an outer pipe and an inner pipe, and more particularly to a welding technique suitable for welding a double pipe via an insert ring.
[0002]
[Prior art]
In a heat exchanger that uses a toxic gas or a fluid irradiated with radiation as a medium, a double tube is usually used as a heat transfer tube. Therefore, when an accident occurs in which the fluid leaks from the heat transfer tube, first, it is possible to immediately identify whether the leak point is from the inner tube or the outer tube, and in order to take measures against the leakage, the inner tube and the outer tube. It is necessary to maintain an appropriate gap between the two.
[0003]
As shown in FIG. 4, the conventional double pipe welding method is as follows. First, the inner pipe 1 and the inner pipe 1 are butt welded, and the hollow semi-cylindrical insert ring 2 shown in FIG. 5 is attached. The outer tube 3 and the outer tube 3 were welded.
[0004]
[Problems to be solved by the invention]
According to the insert ring 2 of the prior art, the outer peripheral surface of the inner tube 1 and the inner peripheral surface of the outer tube 3 may be fused to each other when the outer tube 3 and the inner tube 1 are welded. There was a problem that a gap provided between the inner pipe 1 and the inner pipe 1 was lost. There are straight pipe type, helical type, etc. in the shape of the heat exchanger tube of the heat exchanger, but there are also restrictions on the manufacturing equipment for the double pipe, so long and curved pipes and curved pipes, curved pipes and There are various different conditions such as straight pipe joining, and it is conceivable that the inner tube 1 and the inner tube 1 are welded from the center side, and the outer tube 3 and the outer tube 3 are welded from the outside. Therefore, it is considered that the welding of the inner tube 1 and the inner tube 1 and the outer tube 3 and the outer tube 3 are all conveniently performed from the outside.
[0005]
Since the inner peripheral surface of the conventional insert ring 2 is in contact with the outer peripheral surface of the inner tube 1, the insert ring 2 is deformed, fused, or fused by welding with the outer tube 3. In view of the above-mentioned problem that the separation state between the tube 3 and the inner tube 1 cannot be maintained, by applying a grooved insert ring that can appropriately set and maintain the gap between the outer tube and the inner tube An object is to secure an appropriate gap between the outer peripheral surface of the inner tube and the outer tube to realize separation of the inner tube and the outer tube.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention performs welding between an outer tube and an outer tube using the grooved insert ring according to the present invention after welding the inner tube and the inner tube. It is configured so that an appropriate gap can be maintained between the outer tube and the outer tube. That is, the double pipe welding method of the present invention uses a grooved insert ring made of a pair of hollow semi-cylindrical bodies having an inner diameter into which the inner pipe can be inserted and an outer diameter smaller than the outer diameter of the outer pipe. A method for welding double pipes, wherein the grooved insert ring of the present invention has step grooves on both end surfaces of the hollow semi-cylindrical body, and is parallel to the axis on the inner peripheral surface between the step grooves. It has a feature in that it has a plurality of cylindrical grooves provided in.
[0007]
According to the double pipe welding method using the grooved insert ring of the present invention, first, the inner pipe and the inner pipe are butt-welded, and the grooved insert ring is mounted at a position facing the welded portion. After the insert ring and the outer pipes on both sides are welded, a gap corresponding to the depth of the cylindrical groove is maintained between the inner pipe and the outer pipe by welding the outer pipe and the outer pipe.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of double pipe welding using a grooved insert ring of the present invention. FIG. 2 is a front view (a) and a side sectional view (b) of a grooved insert ring according to the present invention, and FIG. 3 is a process diagram showing an outline of a welding procedure. As shown in FIG. 2, the grooved insert ring 12 of the present embodiment is a hollow semi-cylindrical grooved insert ring having a step groove 13 on the end surface of the semi-cylindrical body and an axis of the hollow semi-cylindrical inner surface. Radial cylindrical grooves 14 are provided in parallel.
[0009]
As shown in FIG. 3, after the inner pipe 1 and the inner pipe 1 are welded (a), the outer peripheral surface of the inner pipe 1 is covered with a pair of grooved insert rings 12 at a position facing the welded portion. The longitudinal surface 4 (FIG. 2) is welded to integrate the grooved insert ring 12 (b). The circumferential surface 5 (FIG. 2) of the grooved insert ring 12 is welded to the outer tube 3, and the remaining portion 6 of the outer tube 3 is welded until it is flush with the outer circumferential surface of the outer tube 3. Perform (c).
[0010]
According to the specification of one example of the present embodiment, welding of a double pipe structure in which an inner tube having an outer diameter of 24.7 mm and a wall thickness of 2.9 mm is inserted into an outer tube having an inner diameter of 25.5 mm and a wall thickness of 3 mm. When implementing the above, a grooved insert ring having a circumferential groove depth of 0.4 mm is employed to form a 0.4 mm gap between the inner tube and the outer tube.
[0011]
The step groove 13 and the cylindrical groove 14 provided in the grooved insert ring 12 prevent welding distortion and angular deformation caused by welding between the outer tube 3 and the outer tube 3, and the outer peripheral surface of the inner tube 1 and the outer tube 3. A space corresponding to the depth of the cylindrical groove 14 is stably secured between the inner tube 1 and the inner tube 1, thereby preventing mutual fusion between the inner tube 1 and the outer tube 3. The intended purpose of separating the outer tube 3 can be achieved. The longitudinal surface 4 of the grooved insert ring 12 of the present invention is formed between the bottom and the outer periphery of the cylindrical groove 14 as shown in FIG. It is preferable in setting.
[0012]
【The invention's effect】
By carrying out the present invention, when welding a double pipe composed of an inner pipe and an outer pipe, an appropriate gap is secured between the outer peripheral surface of the inner pipe and the outer pipe, thereby realizing separation of the inner pipe and the outer pipe. This makes it possible to provide a stable double pipe welded structure.
[Brief description of the drawings]
FIG. 1 is a view showing double pipe welding by a grooved insert ring of the present invention.
FIG. 2 is a front view (a) and a side sectional view (b) of a grooved insert ring according to the present invention.
3 is a process diagram showing a procedure for welding the double pipe of FIG. 1; FIG.
FIG. 4 is a view showing a double pipe welded structure using a conventional insert ring.
5A is a front view of a conventional insert ring, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inner pipe | tube 2 ... Insert ring 3 ... Outer pipe | tube 4 ... Longitudinal surface 5 ... Circumferential surface 6 ... Outer tube remaining part 12 ... Grooved insert ring 13 ... Stepped groove 14 ... Cylindrical groove

Claims (2)

In the welding method of a double pipe consisting of an outer pipe and an inner pipe fitted into the outer pipe,
A process of connecting and welding the inner pipe and the inner pipe;
A grooved insert ring comprising two hollow semi-cylindrical bodies provided with a plurality of radial grooves on the inner peripheral surface parallel to the central axis with respect to the central axis covers the welded outer peripheral surface of the inner tube and the inner tube. A step of inserting and inserting,
An outer tube and an outer tube are connected to both sides of the hollow semi-cylindrical body, and a gap corresponding to the depth of the radiation groove is held between the inner tube and the outer tube, and the outer tube and the outer tube are A method for welding a double pipe, comprising a step of welding. The grooved insert ring is composed of a pair of hollow semi-cylindrical bodies having an inner diameter in which the inner pipe can be inserted and an outer diameter smaller than the outer diameter of the outer pipe,
Step grooves provided on both end faces of the hollow semi-cylindrical body,
Double claim 1, characterized in that it comprises a plurality of radial cylindrical groove on the inner peripheral surface provided parallel to the hollow semi-cylinder of axis between the stepped groove and the step groove Pipe welding method .

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