JP2002161708A - Piping pressure sealing method - Google Patents

Abstract

(57) [Summary] [Problem] To shorten the installation period of a bleed pipe installed in a condenser of a nuclear power plant or a thermal power plant and shorten the construction period of the power plant. An expansion joint (3) welded and connected to a low-pressure turbine nozzle (1b) is tightened and tightened with a nut (11a) to provide a gap (G), and a bleed pipe (4) is closed by a pressure-resistant closing plate (12). Thereafter, a pressure test of the extraction pipe 4 is performed. Next, the closing of the extraction pipe 4 is released, and then the nut 11 a is loosened to weld the lower end of the expansion joint 3 to the welding groove 8 a of the extraction pipe 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for closing a pipe in a system in which a flow path is formed by an expansion joint and a pipe in a pressure test of the pipe, and a method for assembling the pipe and the expansion joint.

[0002]

2. Description of the Related Art Nuclear power plants and thermal power plants are equipped with low-pressure turbines that rotate a generator. The low-pressure turbine 1 employs a low-pressure turbine upper casing that houses turbine blades and a low-pressure turbine lower casing 1a. The low-pressure turbine lower casing 1a has, as shown in FIG. 1, an expansion joint 3 welded to a low-pressure turbine nozzle 1b at the lower part of the low-pressure turbine lower casing,
The bleed pipe 4 connected to the expansion joint 3 constitutes a flow path of the bleed system. The bleeding pipe is connected to low pressure feed water heaters 5a, 5b,
5c, 5d.

In the condenser 2 below the low-pressure turbine 1, low-pressure feed water heaters 5a, 5b, 5c and 5d are inserted. The bleeding pipe 4 in the condenser 2 converts exhaust steam in the low-pressure turbine lower casing 1a into low-pressure feedwater heaters 5a, 5b, 5
c, 5d. The low pressure feed water heaters 5a, 5
b, 5c and 5d aim at raising the temperature of the condensed water using the exhaust steam of the turbine.

An expansion joint 3 is arranged at the connection between the low-pressure turbine nozzle 1b and the bleed pipe 4 in order to absorb the thermal expansion of the bleed pipe 4 and the relative displacement due to the thermal expansion of the low-pressure turbine 1.

The low-pressure turbine lower casing 1a and the expansion joint 3 are subjected to a pressure test for each product individually at a factory, checked for soundness, and then delivered to the assembly site. Bleed piping 4
Since the operating pressure at the time of operation is low, the outer diameter is large, and the plate thickness is thin, pipes having a diameter of 450A or more use pipes of a plate-winding pipe welded structure made by bending and welding a plate. .

[0006] The plate-winding pipe welded portion of the bleeding pipe 4 must be in a state in which an appearance inspection can be visually observed at the time of a pressure resistance test. Therefore, the welded portion of the plate-winded pipe welding structure must be entirely exposed.

As shown in FIG. 2, the pressure-resistant closing block used in the pressure test of the extraction pipe 4 has a dummy having a screw hole 6a for detecting pressure at the time of the pressure test at an L-dimension where the expansion joint 3 is installed. The pressure-resistant closing block 6 in which the pressure-resistant closing plate 6c is attached to the pipe 6b has been manufactured in a factory or a local processing plant.

The pressure-resistant closing block 6 and the nozzle 1b of the lower pressure turbine lower casing are subjected to tack welding 7 in a factory or on site. A pressure gauge that welds the pressure-resistant closing block 6 and the bleeding pipe 4 on site and applies a test pressure to the bleeding pipe 4 to visually inspect the welded portion of the plate wound pipe welding structure and measure the pressure in the bleeding pipe 4 A withstand voltage test is performed by inspecting the change in the detected value.

After the pressure test is completed, the pressure blocking block 6
Must be cut and dismantled and taken out of the condenser 2. After that, the nozzle 1 of the low pressure turbine lower casing
The finishing work after cutting the final groove 7b (FIG. 3) and the extra length α (FIG. 2) included in the bleed pipe 4 and the final groove 8a (FIG. 3) are performed.

The expansion joint 3 temporarily placed in the condenser 2 is set at a predetermined mounting position in advance, and the low-pressure turbine lower casing nozzle 1b and the final welding 9 and the bleed pipe 4 and the final welding 10 are performed. Since the low-pressure turbine 1 and the expansion joint 3 have been subjected to a predetermined pressure test at the factory, the final welding points 9, 1
0 is subjected to a nondestructive inspection (for example, a liquid penetration inspection (PT)).

As means for closing the open end of the piping or the nozzle of the pressure vessel before the pressure test, a pressure-resistant closing plate is pressed against the open end via a seal packing to reduce the test pressure during the pressure test. To prevent leakage, see JP-A-11-240547 and JP-A-8-21.
No. 9284 and Japanese Utility Model Laid-Open No. 58-12841.

In the publications described in these publications, a reaction force generated when a pressure-resistant closing plate is pressed against the opening end is supported by a pipe or nozzle having an opening end to be closed.

[0013]

In the prior art using the pressure-resistant closing block 6, the process of manufacturing the pressure-resistant closing block 6 and the nozzle 1b of the pressure-resistant closing block 6 and the low-pressure turbine lower casing 1a are included in the installation process of the bleeding pipe 4. In addition, useless processes such as a process for processing the bleeding pipe 4 at the restart position are included. In addition, in order to remove the pressure-resistant closing block 6 from the condenser manhole outside and remove it, the pressure-resistant closing block 6 is about 20 kg.
It was also necessary to cut into small pieces (the weight that a person can hold) and to clean the inside of the condenser again after cutting.

Since the above wasteful processes and operations are all performed in series, a large number of workers are required, the installation period of the extraction pipe 4 is lengthened, and the construction of a nuclear power plant or a thermal power plant itself is performed. This had the effect of lengthening the construction period.

Further, there is an operation for replacing the pressure-resistant closing block 6 with an expansion joint. Since all the replacement work is performed in a narrow work space in the condenser 2, it is difficult to perform the work, which is an obstacle to shortening the process.

Further, when a method of pressing the pressure-resistant closing plate against the open end of the pipe to close the pressure-resistant pipe is used for pressure-resistant closing of the bleeding pipe, a work space for installing the pressure-resistant closing plate at the open end of the pipe is required. The expansion joint cannot be attached to the nozzle 1b first.

For this reason, the work of attaching the expansion joint 3 to the nozzle 1b must be performed in a narrow working space in the condenser 2, which makes it difficult to work and hinders the shortening of the process. In addition, since the work of attaching the expansion joint 3 to the nozzle 1b is performed in more than ten places, it is a great obstacle to shorten the process.

When performing a pressure test of the extraction pipe 4,
Since it is necessary to secure a working place for the pressure test operator after placing the pressure test equipment in the condenser 2, it is preferable to install the expansion joint on the nozzle 1b before the pressure test of the extraction pipe 4. .

Accordingly, a main object of the present invention is to obtain a closed state of a pipe in a situation in which an expansion joint is previously mounted before a pressure test of the pipe. Another object is to quickly assemble a pipe from closing the pipe to connecting the pipe to an expansion joint.

[0020]

The first means is to contract the expansion joint in a direction away from the pipe before the connection of the pipe connected via the expansion joint, and to reduce the distance between the expansion joint and the pipe. This is a pipe pressure-resistant closing method in which a gap is formed, and a means for closing the end of the pipe is inserted into the gap to close an end of the pipe near the expansion joint. According to this method, even if the expansion joint is installed close to the opening end of the pipe, a situation does not occur in which the expansion joint becomes an obstacle and the pipe closing operation cannot be performed. Therefore, by adopting this closing method, the installation work timing and work place of the expansion joint can be selected without being affected by the pressure test of the pipe, and the process of joining the pipe and the expansion joint with the pressure test is performed. Including piping installation work can be shortened.

The second means is that, in the first means, a pressure-resistant closing plate adopted as means for closing the end of the pipe is pressed against the end of the pipe via a seal packing, and a reaction force of the pressing is applied to the end of the pipe. A pipe pressure-resistant closing method characterized by receiving the pipe itself and closing an end of the pipe.
According to this method, both the action and the reaction required for closing the end of the pipe are received by the pipe itself. Therefore, even when there is no surrounding structure for receiving the reaction force, the action and effect of the first means can be achieved. Can be demonstrated.

The third means is to apply the reaction force generated by compressing the expansion joint to the pressure-resistant closing plate adopted as the means for closing the end of the pipe in the first means, so that the pressure-resistant closing plate is closed. A pipe pressure-resistant closing method characterized in that an end of the pipe is closed by pressing against the end of the pipe via a seal packing. According to this method, in addition to the action and effect of the first means, the pressure-resistant closing plate is pressed against the end of the pipe by the repulsive force due to the compression of the expansion joint to obtain the action force required for closing the end of the pipe. Therefore, the closing structure is simple, the number of parts is small, and closing and releasing of the pipe can be performed quickly.

The fourth means is a method for closing a pressure-resistant pipe according to the third means, wherein a spacer is interposed between the expansion joint and the pressure-resistant closing plate to increase the compression amount of the expansion joint. . According to this method, in addition to the function and effect of the third means, the repulsive force of the expansion joint can be adjusted according to the interposed thickness of the spacer, so that it is easy to obtain the action force required for closing the end of the pipe.

Fifth means is to shrink the expansion joint in a direction away from the pipe before the connection of the pipe connected via the expansion joint to form a gap between the expansion joint and the pipe. A means for closing the end of the pipe is inserted to close the end of the pipe near the expansion joint, and then a pressure test is performed by applying pressure to the inside of the pipe. A method for assembling a pipe to be subjected to a pressure resistance test, which releases a closure and connects the expansion joint and an end of the pipe.

According to this method, similar to the first means, the pipe closing operation can be performed even if the expansion joint is installed prior to the pipe closing operation. Therefore, it is possible to select the installation timing and work place of the expansion joint without being affected by the pressure test of the pipe, and shorten the pipe installation work including the process of joining the expansion joint with the pipe with the pressure test. I can do it.

The sixth means is the fifth means, wherein the end of the pipe is closed using any one of the second to fourth pipe pressure-resistant sealing methods. This is how to assemble the piping. According to this method,
In addition to the function and effect of the fifth means, the function and effect of any one of the second to fourth means can be obtained.

[0027] The seventh means is to compress the expansion joint of the expansion joint and the bleeding pipe constituting the bleeding system flow path from the lower casing of the low-pressure turbine to the low-pressure feedwater heater while the expansion joint is attached to the lower casing of the low-pressure turbine. By doing
A gap is formed between the expansion joint and the end of the bleeding pipe near the expansion joint, and a pressure-resistant closing plate incorporating a seal packing is inserted into the gap, and the pressure-resistant closing plate is subjected to the bleeding through the seal packing. This is a pressure-resistant closing method for the bleed pipe, which presses against the end of the pipe to close the end of the bleed pipe.

According to this method, even if the expansion joint is installed in advance in the lower portion of the lower casing of the low-pressure turbine, there is no occurrence of a situation in which the expansion joint becomes an obstacle and the work of closing the extraction pipe cannot be performed. Therefore, when this closing method is adopted, the installation work timing and work place of the expansion joint can be selected without being affected by the pressure test of the bleeding pipe, and the pipe with the pressure test is joined to the expansion joint. Pipe installation work including the process can be shortened.

Eighth means is to compress the expansion joint, which is an expansion joint and a bleed pipe, forming a bleed system flow path from the lower part of the low-pressure turbine lower casing to the low-pressure feedwater heater, with the expansion joint being attached to the lower part of the lower-pressure turbine lower casing. By doing
A gap is formed between the expansion joint and the end of the bleeding pipe near the expansion joint, and a pressure-resistant closing plate incorporating a seal packing is inserted into the gap, and the pressure-resistant closing plate is subjected to the bleeding through the seal packing. Pressing against the end of the pipe to close the end of the bleed pipe, then pressurizing the inside of the bleed pipe and performing a pressure resistance test, and then releasing the close at the end of the bleed pipe to release the bleed pipe This is a method for assembling a bleed pipe connecting an end portion and the expansion joint.

According to this method, the installation work timing and work place of the expansion joint can be selected without being affected by the pressure test of the bleeding pipe, and the pipe with the pressure test is joined to the expansion joint. Pipe installation work including the process can be shortened.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an improved boiling water reactor (hereinafter referred to as A
It is called BWR. FIG. 3 is a piping diagram of a bleed system of a low-pressure turbine 1 used in a nuclear power plant employing ()).

The low-pressure turbine 1 receives the pressure received from the ABWR and drives the generator to rotate. The low-pressure turbine 1 employs a low-pressure turbine upper casing that houses turbine blades and a low-pressure turbine lower casing 1a. In the lower-pressure turbine lower casing 1a, as shown in FIG. 1, an expansion joint 3 welded and connected to a nozzle 1b provided in a lower part of the low-pressure turbine lower casing, and an extraction pipe 4 welded to the expansion joint 3 are connected. It is equipped so as to constitute the flow path of the extraction system.

The bleeding pipe 4 is connected to low-pressure feed water heaters 5a, 5a.
b, 5c, 5d, the exhaust steam in the low-pressure turbine lower casing 1a is supplied to the low-pressure feed water heaters 5a, 5b, 5
c, 5d, and is used to increase the temperature of condensate water by reusing the exhaust steam of the low-pressure turbine 1. Below the low-pressure turbine 1, low-pressure feedwater heaters 5a, 5b, 5c, and 5d are inserted into the condenser 2, and further in the condenser 2,
A bleed pipe 4 is also provided.

In order to absorb the thermal expansion of the extraction pipe 4 and the relative displacement caused by the thermal expansion of the low-pressure turbine 1, the nozzle 1b
The expansion joint 3 is arranged at a connection portion between the and the extraction pipe 4. As shown in FIG. 5, for example, the expansion joint 3 is integrally formed by welding and fixing in series a plate wound pipe portion 3a and a bellows 3b formed by processing a stainless steel plate like a bellows.
The bellows 3b are arranged alternately in two stages vertically, and the plate winding tube portion 3a is alternately arranged in three stages vertically.

Bolt holders 11b are fixed to the upper and lower plate winding tube portions 3a by welding at equal intervals on the circumference to forcibly expand and contract the bellows 3b. Shipping bolts 11 are passed through through-holes formed in the upper and lower bolt holders 11b, and a nut 11a screwed to the shipping bolt 11 keeps a specified length of the expansion joint.

Each of the bellows 3b is connected to the upper nut 1
By further tightening 1a, it is compressed, and as shown in FIG. 5, the expansion joint 3 is in a contracted state. Since the expansion joint 3 is contracted, a gap G can be provided between the lower end of the expansion joint 3 and the upper end of the bleeding pipe 4. The size of the gap is set to a size necessary for the operation of closing the open end of the upper end of the bleeding pipe 4.

Such a low-pressure turbine lower casing 1
Each of the a and the expansion joint 3 has been subjected to a pressure test for each product at a factory, and its soundness has been confirmed. The bleeding pipe 4 has a low working pressure during operation, a large outside diameter, and a thin plate, so that pipes having a diameter of 450A or more are formed by bending and welding a plate. I'm using

The welded portion 4b of the plate-winding pipe welding structure of the bleeding system pipe 4 must be made visible so that the appearance inspection can be performed at the time of the pressure resistance test. Is done.

When the lower-pressure turbine lower casing 1a and the expansion joint 3 with the nozzle 1b mounted thereon are respectively assembled from the manufacturing and assembling factory and brought to the site, the upper end of the expansion joint 3 is connected to the nozzle 1b. The connection work may be performed at the installation site as described above, or the connection work may be performed at a manufacturing and assembling factory, and then carried into the assembly site. The connection work may be temporary welding or permanent welding.

At the upper end of the bleeding pipe 4, a welding groove 8 a is preliminarily processed for welding with the lower end of the expansion joint 3, and the welding groove 8 a is arranged so as to face the lower end of the expansion joint 3. .

Next, a pressure test of the extraction pipe 4 is performed.
Before the pressure test, the upper end of the bleeding pipe 4 was
, The upper end (open end) of the bleeding pipe 4 is closed.
The closing operation is performed as follows.

That is, by tightening the upper nut 11a, the expansion joint 3 is contracted as shown in FIG. 5, and a gap G is provided between the lower end of the expansion joint 3 and the upper end of the bleeding pipe 4. Next, the pressure-resistant closing plate 12 into which the annular seal packing 12a shaped to cover the upper end of the welding groove 8a is inserted is inserted into the gap G from the side. The pressure-resistant closing plate 12 is placed on the upper end of the bleeding pipe 4 so as to cover the upper end of the welding groove 8a with the seal packing 12a.

Next, the bleed pipe 4 is sandwiched by the pressure-resistant closing plate fixing ring 14 divided into two parts, and the mating flange portion 14a fixed to each of the two divided ends of the pressure-resistant closing plate fixing ring 14 is attached. , Bolt 14b and nut 14c. The position of the pressure-resistant closing plate fixing ring 14 is below the heat-insulating plate mounting seat 4a welded and fixed to the bleeding pipe 4, and the inner diameter of the pressure-resistant closing plate fixing ring 14 in the coupled state is outside the heat-insulating plate mounting seat 4a. It is smaller than the diameter.
Therefore, the ring 14 for fixing the pressure-resistant closing plate in the coupled state is not caught by the heat-insulating plate mounting seat 4a and does not come out upward.

As described above, after the ring 14 for fixing the pressure-resistant closing plate is attached to the bleeding pipe 4, the ring for fixing the pressure-resistant closing plate is formed in the same manner as the through holes formed at four equal angles on the circumference of the pressure-resistant closing plate 12. 14 through the through-holes
3 and a nut 13a screwed to a plurality of bolts 13
Alternatively, tighten the bolt 13 by rotating it.

When the ring 14 is tightened in this manner, the ring 14 for fixing the pressure-resistant closing plate is caught by the heat-insulating plate mounting seat 4a and does not shift upward. Therefore, the pressure-resistant closing plate 12 is pressed against the upper end of the bleeding pipe 4, and the seal packing 12a Is also pressed against the upper end of the welding groove 8a. At this time, the seal packing 12a made of resin prevents the metal pressure-resistant closing plate 12 from being damaged by the welding groove 8a of the metal bleeding pipe 4 being damaged.

When the pressure-tight closing operation of the extraction pipe 4 is completed in this way, the extraction pipe 4 is filled with water and a water pressure is applied. It is visually inspected for water leakage after the welding of the extraction pipe 4 of the welding structure with the water pressure. As an inspection method, a method may be used in which a pressure is applied to the inside of the bleeding pipe 4 and a state in which the pressure decreases is observed with a pressure measuring device. Thus, the pressure test of the extraction pipe 4 is performed.

When the pressure test is completed, the bolt 1
The pressure-resistant closing plate 12, the seal packing 12a and the ring 14 for fixing the pressure-resistant closing plate used for the closing operation by loosening
Is removed from the condenser 2. When the removal is completed, the nut 11a is loosened and the expansion joint 3 is extended. The extended lower end of the expansion joint 3 is maintained in a positional relationship in which it can be welded to the upper end of the welding groove 8 a of the bleed pipe 4. Since the positional relationship can be adjusted by loosening or adjusting the nut 11a, the lower end of the expansion joint 3 is adjusted to the most appropriate position and the distance between the welding groove 8a.

At the lower end of the expansion joint 3, that is, at the lower end of the lowermost plate-winding tube portion 3a, a welding groove is previously manufactured at a manufacturing plant before being brought to the assembly site. Regarding the upper end of one extraction pipe 4, it is not necessary to manufacture the welding groove 8a after the pressure test. Therefore, as described above,
After the positional relationship and posture between the welding groove 8a and the lower end of the lowermost plate winding tube portion 3a are adjusted, the two are welded and joined in the final welding 10, and the pipe assembly proceeds to the state of FIG.
When the installation of the upper end of the expansion joint 3 and the nozzle 1b is in a temporary welding state, the upper end of the expansion joint 3 and the nozzle 1b are welded and joined by final welding 9.

Thereafter, the shipping bolt 11 and the nut 11 a screwed to the shipping bolt 11 are connected to the condenser 2.
It is removed to the outside, so that the expansion joint 3 can expand and contract in the vertical direction.

The above-described method for withstanding the pressure of the bleeding pipe according to the present embodiment is easy even if the long-extended expansion joint 3 welded to the nozzle 1b at the lower part of the lower casing of the low-pressure turbine is installed before the withstand pressure test. Can be.

In the second embodiment of the present invention shown in FIG. 6, the bellows 3b constituting the expansion joint 3 has a spring effect, and the spring constant of the expansion joint 3 itself is calculated at the time of design.
The acting force of the spring effect can be calculated by the product of the spring constant and the amount of deformation of compression or elongation.

The nut 11 on the upper part of the shipping bolt 11
By tightening a, the bellows 3 b is compressed, and a gap G is provided between the expansion joint 3 and the upper end of the bleeding pipe 4. Pressure-resistant closing plate 1 in which seal packing 12a is fitted.
2 is inserted into the gap G from the side and placed on the upper end of the bleeding pipe 4. In this state, the annular seal packing 12a covers the upper end of the welding groove formed on the upper end of the bleeding pipe 4.

Next, the nut 11 a on the upper part of the shipping bolt 11 is loosened so that the lower end of the lowermost plate winding tube portion 3 a contacts the upper surface of the pressure-resistant closing plate 12. At this time, a cushioning material such as a rubber sheet may be placed between the contact surfaces of the lower end of the plate winding tube portion 3a and the upper surface of the pressure-resistant closing plate 12 so as not to damage the lower end. Next, the lower nut 11a of the shipping bolt 11 is loosened until a small gap g is generated between the lower bolt holder 11b and the lower nut 11a.

In this manner, since the expansion joint 3 equivalent to the thickness T of the pressure-resistant closing plate 12 is continuously compressed, the reaction force in the direction in which the bellows 3a tends to expand due to the compressed reaction is applied to the seal packing 12a. And the pressure-resistant closing plate 12 is strongly pressed toward the upper end of the bleeding pipe 4. The pressure-resistant closing plate 12 fitted with the seal packing can be pressed against the bleeding pipe 4 by the spring effect of such an expansion joint.

If the pressing force is insufficient and it cannot be closed against the pressure of the pressure test, as shown in FIG. 7, a gap G is secured in the same manner as in the embodiment of FIG. A pressure-resistant closing plate 12 and a cylindrical cylindrical spacer 15 mounted thereon are put in the inside. Next, the nut 11a on the upper part of the shipping bolt 11 is loosened to put the lower end of the lowermost plate winding tube portion 3a on the upper surface of the cylindrical spacer 15.

After that, the nut 11a at the lower part of the shipping bolt 11 is loosened, so that the lower bolt holder 11b
Then, the nut 11a is loosened until a small gap g is generated in the lower nut 11a. In this way, the bellows 3b of the expansion joint 3 is provided by the thickness T of the pressure-resistant closing plate 12 and the thickness t of the cylindrical spacer 15.
Is compressed, the reaction force due to the compression pushes the seal packing 12 a and the pressure-resistant closing plate 12 toward the upper end of the bleeding pipe 4.

As described above, in the case of FIG. 7, the bellows 3a is further compressed by the thickness t of the cylindrical spacer 15 as compared with the case of FIG.
And the force pressing the pressure-resistant closing plate 12 toward the upper end of the bleeding pipe 4 is increased. Thus, the closing force of the bleeding pipe 4 is adjusted to be insufficient. In the adjustment, the thickness t of the cylindrical spacer 15 is increased or decreased.

As shown in FIGS. 6 and 7, after the bleeding pipe 4 is closed, a pressure resistance test is performed in the same manner as in the embodiment of FIG. When the pressure test is completed, the nut 11a on the upper part of the shipping bolt 11 is further tightened to separate the lowermost plate winding tube portion 3a upward from the pressure-resistant closing plate 12 and the cylindrical spacer 15.

Next, the pressure-resistant closing plate 12 and the cylindrical spacer 15 are removed from the upper end of the bleeding pipe 4 to the outside of the condenser 2, and the lowermost plate winding pipe portion 3a is formed at the upper end of the bleeding pipe 4 as in FIG. The expansion joint 3 is extended downward so that the lower end can be welded, and as shown in FIG. 3, both the welding groove 8a and the lower end of the lowermost plate winding tube portion 3a are welded and joined by final welding 10. Then,
The shipping bolt 11 and the nut 11a are removed out of the condenser 2. If the installation of the upper end of the expansion joint 3 and the nozzle 1b is in a temporary welding state, the upper end of the expansion joint 3 and the nozzle 1b
Are joined by final welding 9. Other configurations and operations are the same as those in the embodiment of FIG.

In the example shown in FIG. 7, the thickness T of the pressure-resistant closing plate 12 in which the seal packing 12a is fitted is a thickness that can withstand the pressure-resistant test, and is the minimum product weight in order to improve the efficiency of loading and assembling. is there. From this, the bleed piping 4
In the case where the pressing force is insufficient, the use of the thick cylindrical spacer 15 has an effect that a sufficient pressing force can be obtained.

In the example of FIGS. 6 and 7, the seal packing 1 is used.
Since the reaction force of the spring effect of the expansion joint 3 is used for the operation force for pressing the pressure-resistant closing plate 12 into which the pressure-resistant closing plate 12 fitted with 2a is fitted to the bleeding pipe 4, a ring for fixing the pressure-resistant closing plate compared to the embodiment of FIG. 14 and a plurality of bolts 13, 14b, nuts 13a,
14c is omitted, and the bolt through hole of the pressure-resistant closing plate 12 in which the seal packing 12a is fitted is also omitted,
The effect of reducing the outer diameter is obtained.

In the examples of FIGS. 6 and 7, the welded portion of the bleeding pipe 4 of the welded structure has a pressure-resistant closing plate fixing ring 14 and
Since there is no shadow of the plurality of bolts 13 and 14b and the nuts 13a and 14c, the visual inspection at the time of the pressure resistance test can be more easily and reliably performed as compared with the example of FIG.

As described above, according to the embodiment of the present invention, it is possible to omit the welding, cutting, and carrying out of the pressure-resistant closing means at the assembly site of the bleeding pipe, and the reworking process such as the opening of the nozzle and the bleeding pipe. The assembly work period is shortened.
As a result, the construction process of the entire nuclear power plant can be shortened. Further, it is possible to greatly reduce the working time at the assembly site.

Furthermore, most of the pressure-resistant closing means such as the pressure-resistant closing plate fixing ring and the pressure-resistant closing plate in each of the above-described embodiments can be reused in the pressure-resistant test of pipes having the same diameter, and the construction cost of the power plant is reduced. As it goes down, chips generated during welding, disassembly and cutting work of the pressure-resistant closing block are eliminated, so that the work environment at the site is greatly improved, work safety is improved, and the labor for cleaning can be reduced.

In each embodiment, the pressure-resistant closing plate 1
2 is provided with an air vent hole for bleeding air from the bleeding pipe 4. For the pressure test of the bleed pipe 4
When the water is filled with water, the air in the bleeding pipe 4 is evacuated from the air vent hole to make it full. Then, a blind screw is screwed into the air vent hole to close the air vent hole, and the pressure test pressure is added to the water in the extraction pipe 4, and the air in the extraction pipe 4 during the pressure test of the extraction pipe 4 has an adverse effect. To prevent

[0066]

As described above, according to the pressure-resistant closing method of the present invention, a method is provided in which a pressure test of a pipe connected to an expansion joint can be performed even in a situation in which the expansion joint is installed in advance. I can do it. Further, according to the piping assembling method of the present invention, the assembling work period of the expansion joint and the piping to be subjected to the pressure test can be shortened.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a bleed system in an embodiment of the present invention.

FIG. 2 is an elevational view showing a conventional pressure-resistant closing structure using a dummy pipe by a partial sectional view.

FIG. 3 is an assembled view showing, in partial cross-section, a pipe assembly state after a pressure test of an extraction pipe is completed.

FIG. 4 is an upper plan view with a partially cutaway view showing the attachment of the pressure-resistant closing plate and the pressure-resistant closing plate fixing ring after the closing operation according to the first embodiment of the present invention, as viewed from the direction of arrows AA in FIG. 5; It is.

FIG. 5 is an elevational view of the expansion joint and the vicinity of the pressure-resistant closing plate after partial closing according to the first embodiment of the present invention, which is displayed in a partial cross section.

FIG. 6 is an elevational view of the expansion joint and the vicinity of a pressure-resistant shut-off plate in a partially sectional view after a closing operation according to a second embodiment of the present invention.

FIG. 7 is an elevational view of the expansion joint and the vicinity of a pressure-resistant closing plate after a closing operation according to a modification of the second embodiment of the present invention, which is displayed in partial cross-section.

[Explanation of symbols]

1 low-pressure turbine, 1a low-pressure turbine lower casing,
1b: Nozzle, 2: condenser, 3: expansion joint, 3a: plate wound pipe portion, 3b: bellows, 4 ... bleeding pipe, 4a: heat shield plate mounting seat, 4b: plate wound tube welding structure welded portion, 5a, 5b, 5
c, 5d: low pressure feed water heater, 11: shipping bolt,
11a, 13a, 14c: nut, 11b: bolt holder, G: gap, 12: pressure-resistant closing plate, 12a: seal packing, 13, 14b: bolt, 14: pressure-resistant closing fixing ring, 14a: mating flange, 15 ... Cylindrical spacer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) F22D 1/02 F22D 1/02 G21C 17/003 G21C 17/00 E G21D 1/00 G21D 1/00 B ( 72) Inventor Satoshi Yoshida 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Inside the Nuclear Power Division, Hitachi, Ltd. (72) Inventor Koichi Goda 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Within the Nuclear Power Business Unit (72) Inventor Yoichi Yamane 3-1-1 Kochi-cho, Hitachi-shi, Ibaraki F-term within Hitachi Ibaraki Business Engineering Co., Ltd. (Reference) 2G075 AA04 BA01 CA13 CA18 DA16 FA03 FC14 FC18 FC19 GA15 GA16 3H104 JA08 JB02 JC08 JD09 LB01 LB38 LF16 LG02

Claims (8)

[Claims] 1. Before the connection of a pipe connected via an expansion joint, the expansion joint is contracted in a direction away from the pipe to form a gap between the expansion joint and the pipe, and the pipe is formed in the gap. Means for closing the end of the pipe by closing the end of the pipe near the expansion joint. 2. A pressure-resistant closing plate employed as a means for closing an end of the pipe is pressed against the end of the pipe via a seal packing, and a reaction force of the pressing is received by the pipe itself so that the pipe can be closed. 2. The method according to claim 1, wherein an end of the pipe is closed. 3. A pressure-resistant closing plate employed as a means for closing the end of the pipe is subjected to a reaction force generated by compressing an expansion joint, whereby the pressure-resistant closing plate is connected to the end of the pipe via a seal packing. The pipe pressure-resistant closing method according to claim 1, wherein the end of the pipe is closed by pressing the pipe against the pipe. 4. The piping pressure-resistant closing method according to claim 3, wherein a spacer is interposed between the expansion joint and the pressure-resistant closing plate to increase the compression amount of the expansion joint. 5. A contraction between the expansion joint and the pipe by shrinking the expansion joint in a direction away from the pipe before the connection of the pipe connected via the expansion joint, wherein the pipe is formed in the gap. A means for closing the end of the pipe is inserted to close the end of the pipe near the expansion joint, and then a pressure test is performed by applying pressure to the inside of the pipe, and then the closing of the end of the pipe is released. Assembling a pipe to be subjected to a pressure test for connecting the expansion joint and an end of the pipe. 6. The method according to claim 5, wherein:
A method for assembling a pipe to be subjected to a pressure test, wherein the end of the pipe is closed by using any one of the pressure sealing methods described above. 7. An expansion joint and a bleed pipe, which constitute a bleed passage from the lower casing of the low-pressure turbine to the low-pressure feed water heater, are compressed by attaching the expansion joint to the lower casing of the low-pressure turbine. Creating a gap between the expansion joint and the end of the extraction pipe near the expansion joint, inserting a pressure-resistant closing plate incorporating a seal packing into the gap, and inserting the pressure-resistant closing plate through the seal packing. A pressure-resistant closing method for an extraction pipe, wherein the extraction pipe is pressed against an end of the extraction pipe to close the end of the extraction pipe. 8. An expansion joint and a bleed pipe forming an extraction system flow path from a lower casing of the low-pressure turbine to a low-pressure feedwater heater by compressing the expansion joint attached to the lower casing of the low-pressure turbine. Creating a gap between the expansion joint and the end of the extraction pipe near the expansion joint, inserting a pressure-resistant closing plate incorporating a seal packing into the gap, and inserting the pressure-resistant closing plate through the seal packing. The end of the extraction pipe is closed by pressing against the end of the extraction pipe, and then the inside of the extraction pipe is pressurized to perform a pressure resistance test. A method of assembling a bleed pipe for connecting an end of the expansion joint to the expansion joint.