JPH09318483A - Airtightness forming structure and testing device of airtightness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain airtightness even when a cylindrical pipe has a part of a larger diameter than the outside diameter of the cylinder of a part to be tested, by a method wherein a first through hole is provided in a sealing part of the cylindrical pipe and a cut-in part is formed in a portion from this through hole to the surface of the sealing part of the cylindrical pipe, while a second through hole communicating with the outside of the sealing part of the cylindrical pipe is provided in the intermediate part of the first through hole. SOLUTION: A cut-in part 7 of a sealing part 6 of a cylindrical pipe is opened and the part in the vicinity of a connecting part 3 of cylindrical pipes 2 and 4 is set inside a first through hole 24 from the lateral side. Therefore an airtightness test can be executed even when the sealing part 6 of the cylindrical pipe has a structure not allowing it to be inserted from the end part of the cylindrical pipe 2. The connecting part 3 is positioned at a helium gas seal part 13 in the central part of the through hole 24. Being fixed by screws 8, a fixing part 9 slides on a taper face and fixing parts 10 and 9 are tightened. Thereby the cut-in part 7, the outer peripheral surfaces of the cylindrical pipes 2 and 4 and the inner peripheral surface of the through hole 24 are brought into close contact with one another and the helium gas seal part 13 is made airtight. A through hole 25 is provided in the intermediate part of the through hole 24 and helium gas is injected through an injection pipe 18 therefrom.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtightness forming structure, and more particularly to an airtightness forming structure formed on the outer peripheral portion of a cylindrical tube and an airtightness tester for testing the airtightness of the cylindrical tube against external pressure.

[0001]

2. Description of the Related Art A device such as a submarine repeater that is installed on the seabed and constantly receives a large hydrostatic pressure must keep its internal airtightness against the pressure from the outside. In the airtightness test of such an apparatus, hydrostatic pressure is applied from the outside similar to the environment in which it is used to test the airtightness. However, in the conventional airtightness test, there are many disclosures in which the presence or absence of leak is tested by applying internal pressure, but there are few proposals for the test in which external pressure is applied.

A configuration as shown in FIG. 4 is conceivable as an airtightness test apparatus for applying an external pressure in the airtightness test of a cylindrical tube to which the present invention is applied. In FIG. 4, the cylindrical tube 2 and the cylindrical tube 4 are welded at the connecting portion 3. In order to test the airtightness of such a connecting portion 3, first, a ring-shaped gas sealing tube 22 is inserted from the side of the cylindrical tube 1 to the connecting portion 3. Gas filling tube 2
An O-ring 23 is formed on the inner peripheral surface of 2, and the O-ring and the cylindrical tube 2 and the cylindrical tube 4 between the O-ring and the gas sealing tube 22 are formed.
And form an airtight structure.

A gas injection pipe 18 is formed in the gas injection pipe 22, and a helium gas supply means (not shown) is connected to the gas injection pipe 18. When helium gas is injected to a predetermined pressure from the gas injection pipe 18 and the helium gas leaks from the outside through the connection portion 3, it is detected by the helium gas detector 21 installed at the opening of the cylindrical pipe 4.

[0004]

In the airtightness test of the cylindrical tube shown in FIG. 4, the gas sealing tube 22 must be inserted from the end of the cylindrical tube 4 and moved to the position of the connecting portion 3.
Therefore, when the distance from the end of the cylindrical tube 4 to the connecting portion 3 is long, an O-ring provided to form an airtight state in the gas sealing tube 22 is slid on the outer peripheral portion of the cylindrical tube 4. It is very difficult to move. Further, if there is a portion having a diameter larger than the connecting portion 3 between the end portion of the cylindrical tube 4 and the connecting portion 3 from the end portion, the gas sealing pipe 22 cannot move to the connecting portion 3.

An object of the present invention is, when performing an airtightness test against the external pressure of a cylindrical tube, between the end portion of the cylindrical tube and the portion from the end portion to be tested, a portion having a diameter larger than the outer diameter of the cylinder of the tested portion. Even if there is, it is an object of the present invention to provide an airtightness forming structure that can be appropriately configured in a portion to be tested and an airtightness test device that can perform an airtightness test against external pressure using the airtightness forming structure.

[0006]

The airtightness forming structure of the present invention comprises a cylindrical tube sealing portion and first and second fixing portions for sealing the cylindrical tube sealing portion. The cylindrical tube sealing portion has a first through hole for accommodating the cylindrical tube, and a cut portion is formed along the length direction of the through hole from the through hole to the surface of the cylindrical tube sealing portion. A second through hole communicating with the outside of the cylindrical tube sealing portion is provided in the middle of the through hole.

Next, the first fixing portion is provided with a gas introduction hole for introducing gas into the first through hole of the cylindrical tube sealing portion, and the first and second fixing portions are the outer peripheral portion of the cylindrical tube sealing portion. Placed closely to
In addition, the inner peripheral surface of the first fixing portion and the outer peripheral surface of the second fixing portion are arranged so as to abut each other at a portion thereof.

It is desirable that the intermediate portion of the first through hole of the cylindrical tube sealing portion has an inner diameter larger than that of the other portion of the through hole.

Further, the contact surface between the inner peripheral surface of the first fixing portion and the outer peripheral surface of the second fixing portion may be formed in a tapered shape. The first fixing portion and the second fixing portion can be fixed directly with screws or can be fixed with a tightening jig from the outside. It is desirable that the cylindrical tube sealing portion be made of an elastic body.

Further, an airtightness test apparatus can be constituted by the helium gas detector, the helium gas supply means, and the airtightness forming structure.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a plan view showing an example of the airtight formation structure of the present invention arranged in a cylindrical tube. 2 is a cross-sectional view taken along the line segment AA of the airtight formation structure of FIG. 3 is a sectional view showing an example of the cylindrical tube sealing portion of the present invention.

Referring to FIG. 1, a cylindrical tube 2 having an end portion 1 having a large outer diameter and a cylindrical tube 4 having an end portion 5 having a large outer diameter are welded at a connecting portion 3. These welded cylindrical pipes 2 and 4 are installed in the first through hole 24 in the cylindrical pipe sealing portion 6 (not shown in FIG. 1), and the cylindrical pipe sealing portion 6 is the first through hole 24. It is installed in the fixed part 10. Two second fixing portions 9 are arranged on the cylindrical tube sealing portion 6 and fixed to the first fixing portion 10 with screws 8.

The connecting portion 3 is installed so as to be located at an intermediate portion of the first through hole 24. Further, since the inner diameter of the middle portion of the first through hole of the cylindrical tube sealing portion 6 (not shown in FIG. 1) forms the helium gas sealing portion 13, it is larger than the inner diameters of other portions of the through hole. It is desirable to form it.

A helium detector 21 is arranged in the vicinity of the opening of the inner hole 14 of each of the cylindrical tubes 2 and 4, and a helium molecule leaked into the inside of the cylindrical tube through the connecting portion 3 is detected.

FIG. 2 is a line segment A of the airtight formation structure shown in FIG.
It is sectional drawing in -A. The cylindrical tubes 2 and 4 are installed in the first through holes 24 of the cylindrical tube sealing portion 6. Further, in the cylindrical tube sealing portion 6, a cut portion 7 is formed along the length direction of the first through hole 24 from the first through hole 24 to the surface of the cylindrical tube sealing portion 6. Further, the cylindrical tube sealing portion 6 is formed with a second through hole 25 for introducing helium gas into the first through hole.

A helium gas introduction hole 15 is also formed in the first fixing portion 10, and the helium gas injection pipe 1 is formed in this hole.
8 is installed, and helium gas supply means (not shown) is further connected. The cylindrical tube sealing portion 6 is installed in the first fixed portion 10 such that the second through hole 25 faces the helium gas introduction hole 15 of the first fixed portion 10.

Two second fixing portions 9 are fixed by screws 8 on the cylindrical tube sealing portion 6 installed on the first fixing portion 10. The surfaces of the first fixing portion 10 and the second fixing portion 9 that contact each other are tapered surfaces 11.

FIG. 3 is a cross-sectional view of the cylindrical tube sealing portion 6, in which the central portion has a helium gas sealing portion 1 having an inner diameter larger than that of the other portions.
A first through hole 24 in which 3 is formed and a second through hole 25 for introducing helium gas are formed.

In the above embodiment, the material of the cylindrical tubes 2 and 4 is a metal (in particular, a beryllium copper alloy used in the case of a submarine repeater), and the first and second fixing portions 1
The materials of 0 and 9 are metals such as stainless steel. Further, a material having elasticity such as rubber is desirable for the cylindrical tube sealing portion 6, and silicon rubber is used here. Further, an elastic resin or polymer material can also be used.

Further, the first fixing portion 10 and the second fixing portion 9 are not fixed by the screws 8, but are fixed by being externally tightened by a tightening jig (for example, a vise jig). be able to. The second fixing portion 9 is the cylindrical tube sealing portion 6
If the both ends of the first through hole 24 and the cutout portion 7 can be sufficiently sealed, it is not necessary to be divided into two as shown in FIGS. The cylindrical tube sealing portion 6 does not have to have a rectangular parallelepiped shape as shown in the drawing, but may have a circular cross section. In this case, the internal shape of the second fixing portion 9 is a corresponding cylindrical shape. Even when the second fixing portion 9 is composed of two parts, the second fixing portion 9 has a shape that matches the outer circumference of the cylindrical tube sealing portion 6. Further, the outer peripheral shape can also be made cylindrical in conformity with the inner shape of the second fixing portion.

When high-pressure helium gas is injected into the first through-hole, a slight gap is formed between the inner peripheral surface of the first through-hole and the cylindrical pipe, so that the helium gas-filled portion having a large inner diameter is not necessarily required. It is not necessary to provide 13.

Next, the airtightness test of the cylindrical tube using the airtightness forming structure of the present invention shown in FIGS.
First, the cut portion 7 of the cylindrical tube sealing portion 6 formed of silicon rubber is opened, and the vicinity of the connecting portion 3 of the cylindrical tubes 2 and 4 is installed in the first through hole 24 from the side surface. Therefore, the airtightness test can be performed even with the structure in which the cylindrical tube sealing portion 6 cannot be inserted from the end of the cylindrical tube 2. At this time, the connecting portion 3 is positioned in the helium gas sealing portion 13 at the center of the first through hole 24.

In this state, the cylindrical tube sealing portion 6, the first fixing portion 10 and the second fixing portion 9 are assembled as shown in FIGS. Next, when the second fixing portion 9 is fixed with the screw 8,
The second fixing portion 9 slides along the tapered surface, so that the first and second
Fixing portions 10 and 9 are fastened to each other, and the notch 7 of the cylindrical tube sealing portion 6 and the outer peripheral surfaces of the cylindrical tubes 2 and 4 and the first
The inner peripheral surface of the through hole 24 comes into close contact, and the helium gas sealed portion 13 in which the connection portion 3 is arranged becomes airtight.

Next, helium gas is injected from the helium gas supply means through the helium gas injection pipe 18. The injection pressure can be in the range of several atmospheres depending on the environment in which it is used, and in the range of about 800 atmospheres, which is close to the actual seabed environment.

The helium gas leaked from the connecting portion 3 into the cylindrical tubes 2 and 4 is detected by the helium gas detector 21. The helium gas detector 21 is already widely used, and selects and counts helium molecules by a magnetic field. It should be noted that one opening of the cylindrical tube is arranged higher than the other, and the helium gas detector 21 is installed in this higher opening. The lower cylindrical tube opening may be sealed.

As described above, the airtightness test apparatus of the present invention has an excellent feature that the cylindrical tube can be easily attached to the portion to be tested.

[0028]

As described above, since the airtightness forming structure and the airtightness tester of the present invention are configured such that the notch is provided in the cylindrical tube sealing portion and the notch is directly attached to the measured portion of the cylindrical tube from the side surface, It has become possible to perform an airtight test on the connection part of a cylindrical tube having a structure that could not be tested conventionally.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a cylindrical tube sealing portion used in the airtight formation structure of the present invention.

FIG. 4 is a sectional view of a conventional airtightness test apparatus.

[Explanation of symbols]

 1, 5 Cylindrical pipe end part 2, 4 Cylindrical pipe 3 Connection part 6 Cylindrical pipe sealing part 7 Notch part 8 Screw 9 Second fixing part 10 First fixing part 11 Tapered surface 13 Helium gas charging part 14 Cylindrical pipe inside Hole 15 Helium gas introduction hole 18 Helium gas injection pipe 21 Helium gas detector 24 First through hole 25 Second through hole

Claims (12)

[Claims] 1. An airtight structure having a cylindrical tube sealing portion and first and second fixing portions for sealing the cylindrical tube sealing portion, wherein the cylindrical tube sealing portion accommodates a cylindrical tube. The first through hole is provided, and a notch is formed along the length direction of the through hole from the through hole to the surface of the cylindrical tube sealing portion, and the middle portion of the through hole is outside the cylindrical tube sealing portion. A second through hole communicating with the first pipe, the first fixing portion having a gas introducing hole for introducing gas into the first through hole of the cylindrical pipe sealing portion, and the first and second fixing portions having a cylindrical pipe sealing. An airtight forming structure, which is closely arranged on the outer peripheral portion of the stopper portion, and the inner peripheral surface of the first fixing portion and the outer peripheral surface of the second fixing portion are in contact with each other at a part thereof. 2. The airtightness forming structure according to claim 1, wherein an inner diameter of an intermediate portion of the first through hole is larger than an inner diameter of another portion of the first through hole. 3. The airtightness forming structure according to claim 1, wherein the abutting portions of the first and second fixing portions are tapered surfaces. 4. The airtightness forming structure according to claim 1, wherein the abutting portions of the first and second fixing portions have the first fixing portion having a tapered surface and the second fixing portion having a curved surface portion. . 5. The airtight formation structure according to claim 3, wherein the first fixing portion and the second fixing portion are fixed to each other with screws. 6. The airtightness forming structure according to claim 3, wherein the first fixing portion and the second fixing portion are fixed to each other by a fastening jig. 7. The airtightness according to claim 1, wherein the cylindrical tube sealing portion is installed in the first fixing portion with its second through hole facing the gas introduction hole of the first fixing portion. Formation structure. 8. The airtightness forming structure according to claim 1, wherein the second fixing portion is divided into two parts. 9. The second fixing portion has an integral structure.
8. The airtight formation structure according to No. 10. The airtight formation structure according to claim 1, wherein the cylindrical tube sealing portion is made of an elastic body. 11. An airtightness test apparatus comprising the airtightness forming structure according to claim 1, a gas detector, and a gas supply means. 12. The airtightness test apparatus according to claim 11, wherein the gas is helium.