JPH07243557A - Steel pipe coupling method - Google Patents

Abstract

PURPOSE:To couple steel pipes by simple operations using a compact working space without giving ill influence upon the lining of steel pipe. CONSTITUTION:Stretching in the circumferential direction, a heat insulating layer D is formed on the pipe inside surface of that part S of the first embedded steel pipe 1 which is to be joined with a pipe fitting 3, and a tube 2 is interiorly fitted to provide a lining. and an end treatment is applied for tight attachment of the tube 2 end to the inside surface of the first steel pipe 1. The pipe fitting 3 is fitted on one end of the first steel pipe 1, and the first steel pipe 1 and pipe fitting 3 are welded together at the joint part S, and at the same time, the pipe fitting 3 and second steel pipe 4 are connected together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe for inserting a lining tube into a buried first steel pipe for lining and connecting a second steel pipe to one end of the first steel pipe via a pipe joint. Regarding connection method.

[0002]

2. Description of the Related Art For example, in a pipe joint used for connecting steel pipes which are required to have high airtightness such as a gas pipe, a ring-shaped sealing member is fitted onto the steel pipe so as to fit between the joint body and the steel pipe. There are those that press into close contact for airtight joints (generally called mechanical joints) and sleeve-shaped ones that can be easily joined to steel pipes by welding. Since the structure is complicated, there is a problem that the outer diameter of the joint is large, it is difficult to handle, and a large work space is required at the connection point. The latter pipe joint is often used as a connectable member. Conventionally, as a method for connecting steel pipes of this type, as shown in FIG. 4, a lining tube 2 is internally provided in a buried first steel pipe 1 (see FIG. 4 (a)), and the tube 2 An end portion treatment is performed to bring the end portion into close contact with the inner peripheral surface of the first steel pipe 1 (see FIG. 4).
(See (b)), the pipe joint 3 at one end of the first steel pipe 1.
There is a method of externally fitting the first steel pipe 1 and the pipe joint 3 together and connecting the pipe joint 3 and the second steel pipe 4 (see FIG. 4C).

[0003]

According to the above-mentioned conventional steel pipe connecting method, when the first steel pipe and the pipe joint are connected, the lining layer installed in the first steel pipe is affected by the heat caused by welding. For example, there is a risk that the lining layer may be melted or deformed, resulting in deterioration of the performance of the lining layer.

In order to avoid this problem, if the joining scheduled portion of the pipe joint in the first steel pipe is removed and a lining layer is provided, the lining of the first steel pipe becomes incomplete, and problems such as steel pipe corrosion cannot be solved. A new problem occurs.

Therefore, in view of the above drawbacks, an object of the present invention is to provide a steel pipe connecting method capable of connecting steel pipes by a simple work in a compact work space without adversely affecting the lining of the steel pipes. Where it is.

[0006]

Means for Solving the Problems A characteristic means of a steel pipe connecting method of the first invention for achieving this object is that a pipe inner circumferential portion of a portion to be joined with a pipe joint in a buried first steel pipe has a circumferential direction. After forming a heat-insulating layer along with, lining by lining the tube for lining, to perform an end treatment to bring the end of the tube into close contact with the inner peripheral surface of the first steel pipe, one end of the first steel pipe The pipe fitting is externally fitted to the first pipe, the first steel pipe and the pipe joint are welded at the planned joining portion, and the pipe joint and the second steel pipe are connected to each other.

Further, the characteristic means of the second invention is that after the pipe joint is externally fitted to one end portion of the first steel pipe and welded,
The tube is placed inside and lined, and an end treatment for bringing the end portion of the tube into close contact with the inner peripheral surface of the first steel pipe is performed to connect the pipe joint and the second steel pipe.

In the second invention, the pipe joint is
It is preferable to form a plurality of parts in the axial direction of the joint in advance.

[0009]

According to the characteristic means of the steel pipe connecting method of the first invention,
After forming a heat-insulating layer along the circumferential direction on the pipe inner peripheral portion of the planned joining portion, the lining tube is internally mounted and lined, and the end portion of the tube is brought into close contact with the inner peripheral surface of the first steel pipe. Since the treatment is performed, the lining for the first steel pipe can be surely performed, and further, the pipe joint externally fitted to the first steel pipe is welded at the joining scheduled portion, and the pipe joint and the second pipe are joined together. Since the steel pipe is connected, it is possible to prevent the thermal effect caused by welding from being easily transmitted to the lining layer by the heat insulating layer and prevent the deterioration of the lining layer due to the steel pipe connection. That is, it is possible to perform a reliable steel pipe connection by a simple work in a small work space without adversely affecting the lining layer in the steel pipe.

According to the characteristic means of the second invention, after the pipe joint is externally fitted and welded to one end of the first steel pipe, the tube is internally lined by lining the end of the tube. Is subjected to an end treatment for closely contacting the inner peripheral surface of the first steel pipe, and the pipe joint and the second steel pipe are connected to each other, so that the tube is placed in the first steel pipe after welding the first steel pipe and the pipe joint. Thus, the lining and the connection of the steel pipes can be performed in a state where the tube is not affected by the heat of the welding of the first steel pipe and the pipe joint. As a result, the steel pipes can be reliably connected to each other by a simple welding operation in a small work space without damaging the lining layer formed in the first steel pipe.

In the second invention, the pipe joint is
If a plurality of split pipe joints are formed in advance in the joint axial direction, the length of each split pipe joint will naturally be shorter than the length of a pipe joint that is not split. Therefore, as shown in FIG. In addition, it becomes possible to perform the end treatment of the tube 2 which is performed after the split pipe joint 3a is welded to the connection planned portion S of the first steel pipe 1 at a position close to the opening end, which facilitates the work. At the same time, reliable construction becomes possible.

[0012]

Therefore, according to the steel pipe connecting method of the present invention, the steel pipes can be connected by a simple work in a compact work space without adversely affecting the lining of the steel pipes. It is possible to improve the efficiency of the steel pipe connecting work without deteriorating the quality of the connecting portion.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the parts indicated by the same reference numerals as those in the conventional example indicate the same or corresponding parts.

In this embodiment, as shown in FIG. 3, an existing gas conduit (an example of a first steel pipe) 1 is buried in the ground with one end exposed, and the inside thereof is lined with a lining tube. The new gas pipe (an example of the second steel pipe) 4 is welded to one end of the existing gas pipe 1 through a pipe joint 3 while being lined with the pipe 2.

[First Embodiment] The steel pipe connecting method according to the first embodiment will be described. As shown in FIG. 1 (a), first, the pipe inner circumference of a portion S of the existing gas conduit 1 to be joined with the pipe joint 3 is planned. Part, a heat insulating layer D made of a glass wool sheet is attached along the circumferential direction, and then a resin lining tube 2 is placed inside and lined, and as shown in FIG. Using a special jack 5 that can be pressed outward in the radial direction, the end portion of the tube 2 is brought into close contact with the inner peripheral surface of the existing gas conduit 1, and the end portion treatment is performed, as shown in FIG. , The pipe joint 3 is externally fitted to one end of the existing gas pipe 1, and the existing gas pipe 1 and the pipe joint 3 are welded at the joint planned portion S, and the pipe joint 3 and the new gas pipe 4 are connected. Are to be connected.

[Second Embodiment] A steel pipe connecting method according to a second embodiment will be described. The pipe joint 3 is formed in two parts in the axial direction of the joint in advance, and as shown in FIG. The split pipe joint 3a is externally fitted to one end of the existing gas conduit 1 and welded, and then the tube 2 is placed inside the existing gas conduit 1 for lining, as shown in FIG.
The end treatment is performed in the same manner as in the first embodiment, and as shown in FIG. 2C, the one split pipe joint 3a is connected to the other split pipe joint 3b and the other split pipe joint 3b and the new gas. The conduits 4 are respectively connected by welding.

[Other Embodiment] Another embodiment will be described below.

<1> The heat insulating layer used in the first embodiment is not limited to one formed by attaching a glass wool sheet, and for example, a liquid heat insulating material may be used to form the inner circumference of the joining portion S. The heat insulating layer may be formed in a state where the heat insulating layer is applied and hardened on the surface, in short, as long as it is difficult for heat of welding to be transmitted to the lining layer, they are collectively referred to as a heat insulating layer.

<2> The pipe joint used in the second embodiment is not limited to the pipe joint which is divided into two parts at the substantially central position in the longitudinal direction. For example, the existing gas conduit 1 in the longitudinal direction is used.
If it is divided at a position closer to the side, it becomes possible to further facilitate the end treatment of the lining layer. Further, it may be formed into a plurality of divisions of three or more. Including these, it is generically called a pipe joint.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a steel pipe connecting method according to a first embodiment.

FIG. 2 is a diagram showing a steel pipe connecting method according to a second embodiment.

FIG. 3 is a diagram showing a connection state of steel pipes.

FIG. 4 is a diagram showing a conventional steel pipe connecting method.

[Explanation of symbols]

 1 1st steel pipe 2 tube 3 pipe joint 4 2nd steel pipe D heat insulation layer S joint planned part

Claims (3)

[Claims] 1. A lining tube (2) is inserted into a buried first steel pipe (1) for lining, and a pipe joint (3) is provided at one end of the first steel pipe (1). A steel pipe connecting method for connecting two steel pipes (4), wherein a heat insulating layer is provided along a circumferential direction at an inner peripheral portion of a pipe (S) to be joined with the pipe joint (3) in the first steel pipe (1). After forming (D), the tube (2) is placed inside and lined, and an end treatment is performed to bring the end of the tube (2) into close contact with the inner peripheral surface of the first steel pipe (1). The pipe joint (3) is externally fitted to one end of the first steel pipe (1), and the first steel pipe (1) and the pipe joint (3) are welded at the joint planned portion (S), A steel pipe connecting method for connecting the pipe joint (3) and the second steel pipe (4). 2. The lining tube (2) is inserted into the buried first steel pipe (1) for lining, and at the one end of the first steel pipe (1), a pipe joint (3) is provided. A steel pipe connecting method for connecting two steel pipes (4), wherein the pipe joint (3) is externally fitted to one end of the first steel pipe (1) and welded, and then the tube (2) is internally provided. The pipe joint (3) and the second steel pipe (4) by connecting the pipe joint (3) and the second steel pipe (4) by lining the pipe (2) with the end of the tube (2) in close contact with the inner peripheral surface of the first steel pipe (1). Steel pipe connection method. 3. The steel pipe connecting method according to claim 2, wherein the pipe joint (3) is previously formed in a plurality of divisions in the joint axial direction.