JPH11148589A - T-joint for buried pipes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a T-joint for buried pipe which can reduce influence of a seismic deformation of a straight pipe part upon the straight pipe. SOLUTION: A T-joint 11a is composed of a straight pipe part 12a and a branching part 13a branching to the direction of intersecting the part 12a in the middle part in longitudinal direction. The pipe thickness of a throat part 14a of this pipe fitting 11a is made greater than the pipe thickness on the end 15a side of the branching part 13a and on the end 16a side of the straight pipe part 12a. Thereby the throat part 14a is given a compressive strength larger than the compressive buckling strength of a branch pipe. Accordingly an eventual displacement generated by an earthquake, etc., in the ground in the branch pipe axial direction to yield a compressive deformation in axial direction in the branch pipe will be absorbed by the branch pipe, so that the influence upon the straight pipe part 12a can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a T-joint for a buried pipe.

[0002]

2. Description of the Related Art Buried pipes are often used for pipes for various purposes such as gas, electric power, and water supply. In this case, the buried pipe is connected to a branch pipe to the main pipe so that the pipe can be sufficiently applied to the above-mentioned various uses. When connecting a branch pipe to the main pipe, a T-shaped pipe joint is generally used. The T-shaped pipe joint is generally obtained by a manufacturing method called a ball removal method. FIG. 6 is a plan view of a T-shaped pipe joint obtained by the above manufacturing method, FIG. 7 is a side view having a partial longitudinal section of FIG. 6, and FIG. 8 is a sectional view taken along line AA of FIG.

As shown in FIGS. 6, 7 and 8, a T-shaped pipe joint 1 has a straight pipe portion 2 and a straight pipe portion 2 at an intermediate portion in the longitudinal direction.
And a branch portion 3 which branches in a direction intersecting with the branch portion 3. A main pipe 4 is connected to an end of the straight pipe section 2 by welding or the like, and a branch pipe 5 is connected to an end of the branch section 3 by welding or the like. Usually, the diameter of the branch part 3 is smaller than the diameter of the straight pipe part 2.

A boundary position where the straight pipe portion 2 and the branch portion 3 intersect is generally called a throat portion 6 and a crotch portion 7 (a position where the throat portion 6 is rotated by approximately 90 °). In the case where the T-shaped joint 1 is manufactured by welding the branch portion 3 to the straight pipe portion 2, the boundary position of the throat portion 6 is clear. Here, a portion including the periphery surrounded by a dotted line was defined as a throat portion 6. The position of the throat portion 6 changes depending on the diameter of the branch portion 3, and the tube thickness of the throat portion 6 is liable to be thin particularly when the ball-off method is used.

[0005]

The above-mentioned T-shaped pipe joint 1
Is connected to the straight pipe 4 to be buried and the branch pipe, and the T
Used as a pipe joint. However, T for buried pipes
When a displacement occurs in the ground in the pipe axis direction of the branch pipe due to an earthquake or the like, particularly when the pipe thickness of the throat portion 6 is thin, the U-shaped joint is affected by the ground displacement. FIG. 9 is a cross-sectional view showing a state corresponding to FIG. 8 when the ground is displaced in the pipe axis direction of the branch pipe.

As shown in FIG. 9, the throat portion 6 and its periphery are deformed in cross section to form a deformed portion 8, so that not only the branch portion 3 but also the branch portion 3 is formed.
The straight pipe section 2 also undergoes a large deformation, affecting the main pipe 4.

When the straight pipe portion 2 is deformed as described above, it is difficult to repair it, and it is strongly desired to reduce the deformation as much as possible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a T-shaped pipe joint for a buried pipe which can reduce an influence on a main pipe due to deformation of a straight pipe portion due to an earthquake or the like. And

[0009]

SUMMARY OF THE INVENTION The present invention relates to a T-shaped joint for a buried pipe, comprising a straight pipe section provided at a longitudinally intermediate portion with a branch section branching in a direction intersecting the straight pipe section. The pipe joint is a T-shaped pipe joint for a buried pipe, characterized in that the pipe thickness of the throat section is made thicker than the pipe thickness on the end side of the branch section and on the end side of the straight pipe section.

The present inventors have conducted various studies on the effects on the straight pipe portion due to the above-mentioned earthquake and the like, and have found that the compression buckling strength of the throat portion is smaller than the compression buckling strength of the branch pipe. Thus, the present invention has been achieved.

According to the present invention, even when the ground in the pipe axial direction of the branch pipe is displaced by an earthquake or the like and the branch pipe undergoes compressive deformation in the pipe axial direction, the effect can be absorbed by the branch pipe.
The effect on the straight pipe can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line BB in FIG. 1, and FIG. 3 is a sectional view taken along line CC in FIG. FIG. 4 is a cross-sectional view showing a state corresponding to FIG. 2 when displacement occurs in the ground in the pipe axis direction of the branch pipe according to the present invention.

As shown in FIG. 1, the T-shaped pipe joint 11a is composed of a straight pipe portion 12a and a branch portion 13a at a middle portion in the longitudinal direction thereof, which branches in a direction intersecting the straight pipe portion 12a. 4 is a main pipe, 5 is a branch pipe.

The T-shaped pipe joint 11a has a throat portion 14a having a pipe thickness of the end portion 15a of the branch portion 13a and the end portion 1a of the straight pipe portion 12.
It is made thicker than the tube thickness on the 6a side. Here, the tube thickness of the throat portion 14a is increased toward the inside. As described later, the thickness may be increased toward the outside.

As shown in FIG. 2, the thickness of the throat portion 14a is made thicker than the thickness of the end portion 15a of the branch portion 13a so that the throat portion 14a has a compressive strength not less than the compressive buckling strength of the branch pipe 17. Has been granted.

Then, as shown in FIG. 3, the straight pipe portion 12a
The pipe thickness on the side of the end 16a is made the same as that of the main pipe so as to be smaller than the pipe thickness of the throat section 14a. Straight pipe section 1
This is because the end portion 16a of 2a is less affected by the compressive deformation of the branch pipe 17 in the pipe axis direction.

As a result, as shown in FIG. 4, even if a displacement shown by a thick arrow occurs in the ground of the branch pipe 5 in the direction of the pipe axis due to an earthquake or the like, and the branch pipe 5 undergoes a compressive deformation in the pipe axis direction, the throat Since the compressive buckling strength of the portion 14a is higher than the compressive buckling strength of the branch pipe 5, the branch pipe 5 buckles first to form the buckling portion 17, and the effect can be absorbed by the branch pipe 5. So
The influence on the straight pipe portion 12a can be reduced. Also, the end 16a
The side has a normal pipe thickness, so there is little effect on cost.

FIG. 5 is a sectional view showing another embodiment of the present invention corresponding to FIG. As shown in FIG. 5, the T-shaped joint 11b is composed of a straight pipe portion 12b and a branch portion 13b at a middle portion in the longitudinal direction thereof, which branches in a direction crossing the straight pipe portion 12b. T-joint 11b is throat 14b
Is thicker than the tube thickness on the end 15b side of the branch portion 13b and on the end side (not shown in the drawing) of the straight pipe portion 12b. Here, the tube thickness of the throat portion 14b is increased outward. The outside of the throat portion 14b can be thickened by building up, and the application of the existing T-shaped pipe joint 11b or the like is easy. 5 is a branch pipe.

The T-shaped pipe joints 11a and 11b according to the present invention are manufactured by thickening the portion corresponding to the throat portion of the joint material in advance and manufacturing it by a ball-through method, or by manufacturing the throat portion by welding. And so on.

[0021]

As described above, according to the present invention, the throat portion is branched into the throat portion by a simple structure in which the tube thickness at the end portion of the branch portion and the tube portion at the end portion of the straight pipe portion are made thicker. By providing a compressive strength equal to or higher than the pipe buckling strength, it is possible to overcome the strength weakness of the branch portion, and as a result, it is possible to improve the earthquake resistance of the entire buried pipe.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 1;

FIG. 3 is a sectional view taken along line CC of FIG. 1;

FIG. 4 is a cross-sectional view showing a state corresponding to FIG. 2 when displacement occurs in the ground in the pipe axis direction of the branch pipe according to the present invention.

FIG. 5 is a cross-sectional view showing another embodiment corresponding to FIG. 2 of the present invention.

FIG. 6 is a plan view showing an example of a T-shaped pipe joint obtained by a conventional ball cutting method.

FIG. 7 is a side view showing a part of FIG.

FIG. 8 is a sectional view taken along line AA of FIG. 6;

FIG. 9 is a cross-sectional view showing a state corresponding to FIG. 8 when displacement occurs in the ground in the pipe axis direction of a conventional branch pipe.

[Explanation of symbols]

 4 Principal 5 Branch pipe 11a, 11b T-joint 12a, 12b Straight pipe 13a, 13b Branch 14a, 14b Throat 15a, 15b End of branch 16a, 16b End of straight pipe 17 Branch pipe seat Bend

Claims (1)

[Claims] 1. A T-joint for a buried pipe having a branch portion provided at a middle portion in a longitudinal direction of the straight pipe portion in a direction intersecting the straight pipe portion, wherein the T-shaped joint is a pipe of a throat portion. A T-shaped pipe joint for a buried pipe, wherein the thickness is larger than the pipe thickness at the end side of the branch portion and at the end side of the straight pipe portion.