JPH0860687A - Sealing device for manhole cover for fluid equipment, and leakage test method thereof - Google Patents

Abstract

PURPOSE: To check the firmness of a seal by performing a leakage test in a stage when a manhole cover is mounted before fluid equipment is filled with water. CONSTITUTION: A ring-shaped gasket is duality mounted side by side to a seal surface of a flanged part of a manhole cover 6 inside and out as for a manhole cover attached to liquid equipment intended for a suction-out pipe of a water wheel and a casing, for example, and a leakage test hole 6c is bored at a spot between a gasket 7 on its inner side and a gasket 8 on its outer side. In a stage when the manhole cover 6 is mounted to a manhole on a fluid equipment side before filling the manhole with water, pressure water or compressed air is injected from outside into a clearance between the inner side gasket and the outer side gasket by way of a leakage test hole 6c bored on the manhole cover 6 and sealed. Then, water leakage test is carried out by checking the presence of an operational failure of a sealing device based on changes of the sealing pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device for a manhole cover attached to a tube body such as a suction pipe and a casing of a water turbine, and a water leakage test method therefor.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a water turbine power generator to which the present invention is applied. In the figure, 1 is a water turbine, 2 is a swirl casing, 3 is an inlet valve, 4 is a suction pipe, 5 is a generator, and the swirl casing 2, and the suction pipe 4 have a tubular body at the time of installation of the water turbine or at regular inspection. At times, the manhole is opened so that the inside of the tube can be visually inspected, and the manhole cover 6 is covered there to close it. In addition, this manhole cover 6 has a gasket (a ring-shaped O-ring or the like) interposed between the manhole cover 6 and the manhole mounting seat that is open to the other party's body to prevent water leakage when the turbine is filled with water. Then, the manhole cover 6 is fixed to the mating tube body by a fastening bolt so that the gasket is pressed and brought into close contact.

In this case, the conventional manhole cover has a simple sealing structure in which a gasket is provided only at one place on the sealing surface of the flange portion, and the manhole cover covers the manhole on the other side. After that, the installation work is completed by tightening the bolts, and then, in this state, the water canal is next filled with water to operate the water turbine.

[0004]

By the way, in the above-mentioned conventional sealing device, the soundness of the sealing structure cannot be checked when the manhole cover is attached. For this reason, conventionally, the safety is confirmed by visually inspecting the manhole cover for the presence or absence of water leakage when the water turbine is filled with water.

However, when water leakage from the manhole cover is found in the operating state of the water turbine filled with water in the water conduit as described above, the operation of the water turbine is stopped and the water is temporarily drained from the water conduit. The manhole cover must be removed, and the gasket must be inspected and replaced. Moreover, since it takes a long time to drain water from the water conduit of a turbine in a large-capacity turbine facility, it takes at least 1 to 2 days to restart the operation, which is an operational expense. , And a big loss of time.

The present invention has been made in view of the above points, and an object of the present invention is to solve the above problems and perform a water leak test at the stage of attaching a manhole cover before filling a fluid device with water to check the soundness of a seal. The purpose of the present invention is to provide a sealing device for a manhole lid that can be checked for its performance, and a water leakage test method therefor.

[0007]

In order to achieve the above object, in the sealing device of the present invention, inner and outer double gaskets are installed side by side on the sealing surface of the flange portion of the manhole cover, and the inner peripheral side gasket is mounted. A water leakage test hole shall be drilled between the outer peripheral gasket and the outer peripheral gasket. Moreover, in the said structure, it is good to attach a blind plug to the hole for a water leak test, and to seal it.

On the other hand, the water leakage test of the present invention for the sealing device having the above-mentioned structure is conducted from the outside through the hole for water leakage test drilled in the manhole cover in the state before the water filling with the manhole cover attached to the manhole of the fluid equipment. Pressured water or compressed air is fed into the space between the side gasket and the outer peripheral side gasket to seal it, and the integrity of the sealing device shall be tested based on the change over time of the sealed pressure.

[0009]

According to the above construction, at the stage where the manhole cover is attached, the integrity of the seal of the gasket can be etched before the fluid equipment such as the water turbine is filled with water. In other words, in this leak test, pressure water or compressed air was sent from the outside to the gap between the inner gasket and the outer gasket through the leak test hole drilled in the manhole cover to seal it and to check the change in the sealed pressure with time. Check.
Here, if the sealing function is sound, the enclosed pressure does not change. On the other hand, if there is an abnormality in the sealability, the filling pressure decreases with the passage of time. Moreover, as a result of the water leakage test, even if the sealing property is abnormal, the fluid equipment is in the stage before operation without being filled with water, so after removing the manhole cover without causing a large time loss. , Gaskets can be inspected, replaced and reassembled.

In the event that an abnormality occurs in the gasket on the inner circumference side during the operation of the fluid equipment, the gaskets are installed inside and outside and the water leakage test holes are sealed with blind plugs. However, since the outer gasket serves as a backup gasket, safety against water leakage is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings by taking a manhole cover attached to a suction pipe of a water turbine as an example.
First, FIGS. 1 (a) and 1 (b) show a sealing device according to an embodiment of the present invention, in which two rings are arranged on the sealing surface with respect to a flange portion 6a of a manhole cover 6 in an inner and outer double. -Shaped gasket is installed. This gasket is a rubber O-ring, the inner gasket 7 is fitted to the outer corner of the lid 6b, and the outer gasket 8 is fitted to and supported by a circumferential groove formed on the end face of the flange 6a. There is. Further, a water leakage test hole 6c is opened in the flange portion 6a, which is located between the inner peripheral side gasket 7 and the outer peripheral side gasket 8, and a screw type blind plug 9 is screwed into the hole for sealing. ing.

In order to mount the manhole cover 6 on the manhole opened in the suction pipe 4 of the water turbine, the gaskets 7 and 8 are respectively attached to the manhole mounting seat 4a on the suction pipe side and the tapered surface at the inner peripheral edge thereof. , And the manhole cover 6 is attached to the end face, and the fastening bolts 10 are screwed into the flange portion 6a at a plurality of locations on the circumference to fix the gaskets 7 and 8 to the flange face of the mating side under pressure. To do. The manhole cover 6 is openably and closably attached to the suction pipe 4 via a hinge fitting (not shown).

Next, a water leak test of the sealing device for the manhole cover 6 having the above structure will be described with reference to FIG. In addition,
This water leakage test is performed as described below with the manhole cover 6 attached to the manhole of the suction pipe 4 and before the water wheel is filled with water. First, the leak test hole 6
After removing the blind plug 9 of c, a pressure source (pressure water or compressed air) 11, an on-off valve 12, and a pressure gauge 13 are placed in the hole 6c.
Is connected to the water leakage test circuit 14, and in this state, a predetermined pressure is applied to the gap between the inner peripheral side gasket 7 and the outer peripheral side gasket 8 (when the suction pipe 4 is filled with water, the manhole cover 6
The pressure water or compressed air set to a pressure obtained by multiplying the water pressure applied to the pressure by a safety factor) is sent, and the on-off valve 12 is closed to keep the pressure sealed state. Next, the pressure gauge 13 is monitored to check whether the indicated value changes with time. Here, if the sealing properties of the gaskets 7 and 8 are sound, the filling pressure,
Therefore, there is no change in the indicated value of the pressure gauge 13. On the other hand, if the sealability is incomplete, the indication value of the pressure gauge 13 decreases with the passage of time, so that normality or abnormality of the sealing function can be checked easily.

If the sealing function of the manhole cover 6 is abnormal as a result of the water leak test, the manhole cover 6 is removed and the gaskets 7 and 8 are inspected and replaced. The lid 6 is attached to the manhole to perform a water leak test, and if it is confirmed that the sealing function is normal, the water leak test circuit 14 is disconnected, and then the blind plug 9 is attached to the water leak test hole 6c to complete the assembly. After that, the water conduit including the suction pipe 4 is filled with water to start the operation of the water turbine.

Further, even if an abnormality occurs in the inner peripheral side gasket 7 mounted on the manhole cover 6 during operation of the water turbine, the outer peripheral side gasket 8 functions as a backup gasket, so that the safety against water leakage is increased accordingly. . In the illustrated embodiment, the suction pipe of the water turbine is described, but the manhole cover attached to the spiral casing 2 shown in FIG. 3 is also subjected to the water leakage test before the refilling. Furthermore, the present invention can be similarly applied to various fluid devices other than the turbine equipment, or a manhole cover attached to a pressure vessel filled with fluid.

[0016]

As described above, according to the configuration of the present invention, it is possible to perform a water leak test on the manhole cover to check whether there is an abnormality in the sealing device before the fluid device is filled with water. . Moreover, even if an abnormality is found in the sealing device as a result of the water leak test, the fluid device is not filled up at this point, so the manhole cover must be removed.
You can easily perform gasket inspection, replacement, and manhole cover reattachment in a short time.

[Brief description of drawings]

FIG. 1 is a diagram showing a sealing device for a manhole cover according to an embodiment of the present invention, in which (a) and (b) are a sectional view and a rear view of the manhole cover, respectively.

FIG. 2 is an explanatory diagram of a seal leak test performed on the manhole cover of FIG.

FIG. 3 is a configuration diagram of a water turbine facility that is an example of implementation of the present invention.

[Explanation of symbols]

 4 Turbine suction pipe (fluid equipment) 6 Manhole cover 6a Flange 6c Water leak test hole 7 Inner circumference gasket 8 Outer circumference gasket 9 Blind plug 10 Fastening bolt 14 Leak test circuit

Claims (3)

[Claims] 1. A sealing device for a manhole cover attached to a fluid device intended for a suction pipe, a casing, etc. of a water turbine, wherein ring-shaped gaskets are arranged side by side on the sealing surface of a flange part of the manhole cover. A sealing device for a manhole cover for a fluid device, characterized in that a water leakage test hole is bored between the inner peripheral gasket and the outer peripheral gasket while being mounted. 2. The sealing device according to claim 1, wherein a blind plug is attached to the hole for water leakage test, and the sealing device is for a manhole cover for fluid equipment. 3. A pressure is applied from the outside to a gap between the inner gasket and the outer gasket through a water leakage test hole drilled in the manhole cover at a stage before water filling in which the manhole cover is attached to the manhole on the fluid equipment side. 2. A leak test method for a seal structure according to claim 1, wherein water or compressed air is fed and sealed, and the sealing function is checked based on a change with time of the sealed pressure.