JP2011106501A - Method for filling low-temperature tank with pearlite for refrigeration by increasing amount of pearlite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for filling a low-temperature tank with pearlite for refrigeration by increasing an amount of pearlite, in which work for attaching a ball valve to a pearlite filling tube is improved and filling work of pearlite by increasing an amount of pearlite is facilitated. <P>SOLUTION: The method is for filling the low-temperature tank in operation with pearlite by a pearlite filling tube 10 by increasing the amount of pearlite. The low-temperature tank includes an inner tank and an outer tank, low-temperature liquified gas is stored in the inner tank, a portion between a sidewall part of the inner tank and a sidewall part of the outer tank is filled with granular pearlite, and the pearlite filling tube 10 is disposed to a roof part 4c of the outer tank. A seal box 20 is attached to the roof part 4c while covering the pearlite filling tube 10, a closing flange 12 is removed from the pearlite filling tube 10, a test ball 40 is put into the pearlite filling tube 10, and the test ball 40 is inflated to close the pearlite filling tube 10. Then, the seal box 20 is removed, and the ball valve is attached to the pearlite filling tube 10. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for additionally filling pearlite for keeping cold in a low-temperature tank.

  A double-shell ground cryogenic tank that stores low-temperature liquefied gas such as LNG is configured to include an inner tank that is provided on the ground and stores the low-temperature liquefied gas, and an outer tank that covers the inner tank (for example, , See Patent Document 1). In such a low temperature tank, granular pearlite is filled as a cold insulating material between the side wall portion of the inner tank and the side wall portion of the outer tank in order to cool the low temperature liquefied gas in the inner tank.

  The cold insulation material is usually filled when the low temperature tank is constructed. That is, a pearlite filling pipe (perlite nozzle) for filling pearlite is provided in advance on the outer peripheral portion of the roof portion of the outer tub (the shoulder portion in the vicinity of the side wall portion of the roof portion). Before storing the pearlite, the pearlite filling tube is filled with pearlite between the side wall of the inner tank and the side wall of the outer tank.

  However, after filling with pearlite in this way, when the low temperature liquefied gas is put into the inner tank and stored, the inner tank shrinks due to the cold heat of this low temperature liquefied gas, and the side wall portion of the inner tank and the side wall portion of the outer tank The gap between them increases. Then, the pearlite filled in the gap gradually subsided over time, and finally the pearlite was placed at the upper end between these inner tub and outer tub, that is, near the roof of the outer tub. Cavities that do not exist are formed. In addition, formation of such a cavity part also arises when a pearlite changes with age and particle | grains become small and a bulk density becomes large.

When the cavity is formed in this way, the cooling effect in the cavity is remarkably reduced, so that the cold heat of the low-temperature liquefied gas stored in the inner tank is released from the outer tank through the cavity. The Then, in the side wall portion of the outer tub corresponding to this hollow portion, condensation occurs due to the release of cold heat, and sometimes the appearance is impaired due to the growth of moss, and furthermore, the coating on the outer surface of the outer tub peels off Was produced.
Therefore, conventionally, in order to eliminate the problems caused by such a hollow portion, the pearlite filling tube is filled with a short amount of pearlite in a state where the low-temperature liquefied gas is stored in the inner tank, that is, in a state where the low-temperature tank is operated. The pearlite is additionally filled.

  In other words, conventionally, when filling with pearlite, first, a sealed box with a glove is attached to the roof of the outer tub in an airtight manner while covering the pearlite filling tube. This is because the lid is attached to the inner tank, but this lid does not hermetically seal the inner tank, so a part of the low-temperature liquefied gas is vaporized between the inner tank and the outer tank. This is because a gas such as LNG is filled with a pressure of about 1500 mmAq to 2000 mmAq, for example. That is, if the pearlite is simply opened to fill the pearlite from the pearlite filling tube, a gas such as LNG in the low temperature tank will be ejected due to the difference between the internal pressure in the outer tank of the low temperature tank and the atmospheric pressure. It is.

  Therefore, conventionally, as described above, a seal box with a glove is attached, and then the seal box is filled with nitrogen so that the pressure in the seal box and the low temperature tank is almost the same, and the glove is used in this state. Remove the closing flange that closes the opening of the pearlite filling tube. Next, a ball valve prepared in advance in the seal box is attached to the opening of the pearlite filling tube using a glove, and the opening is closed. Next, the seal box is removed from the roof, and a pearlite filling device is attached to the ball valve. Thereafter, the ball valve is opened and pearlite is filled into the pearlite filling tube from the pearlite filling device, and the pearlite is increased and filled between the side wall of the inner tank and the side wall of the outer tank.

JP-A-8-121697

  However, it is very difficult to work in the sealed box using the glove because of its high internal pressure. In addition, although there is a viewing window for viewing the inside of the seal box, it cannot be said that a sufficient field of view is ensured, and therefore the work becomes increasingly difficult due to the unnatural posture during work. Yes. And, in such a difficult situation, it is necessary to attach a ball valve to the opening of the pearlite filling pipe using a glove, and a large number of bolts and nuts are necessary to attach the ball valve to the opening in an airtight manner. This is a very difficult task. In addition, tens of pearlite filling pipes for performing such additional filling of pearlite are provided in one low-temperature tank (for example, 72). Therefore, since the above-mentioned operation is performed on all pearlite filling tubes, this additional filling operation is very complicated and difficult, and there is a strong demand for improvement.

  The present invention has been made in view of the above circumstances, and its object is to improve the operation of attaching a ball valve particularly to the opening of the pearlite filling tube, thereby facilitating the additional filling operation of pearlite. An object of the present invention is to provide an additional filling method of pearlite for cold storage of a tank.

The method of additionally filling a pearlite for cold insulation of a low temperature tank of the present invention has an inner tank and an outer tank that covers the side wall and the roof of the inner tank, stores the low-temperature liquefied gas in the inner tank, Fill pearlite between the side wall of the tank and the side wall of the outer tank, and fill the roof of the outer tank between the side wall of the inner tank and the side wall of the outer tank. For a low-temperature tank in operation comprising a pipe, when filling the pearlite filling pipe with more granular pearlite between the side wall of the inner tank and the side wall of the outer tank,
A step of covering the pearlite filling tube and attaching a gloved seal box to the roof of the outer tub, and storing a test ball having a gas supply hose in the seal box;
Supplying and pressurizing an inert gas into the seal box, and removing a closing flange for closing the opening of the pearlite filling tube using the globe under the pressurized state;
The test ball is inflated by placing the test ball into the opening of the pearlite filling tube using the glove and subsequently filling the test ball with gas from the outside of the seal box through the hose. Closing the opening of the pearlite filling tube,
The seal box is removed from the roof of the outer tub, and then a ball valve is attached to the opening of the pearlite filling tube, and the ball valve is opened and the test ball hose is passed through the ball valve. Process,
Allowing the gas in the test ball to flow out through the hose, shrinking the test ball and taking it out of the ball valve, and subsequently closing the ball valve;
A pearlite filling device is mounted on the ball valve, and then the ball valve is opened and pearlite is filled into the pearlite filling pipe from the pearlite filling device, and between the side wall portion of the inner tank and the side wall portion of the outer tank. A process of increasing and filling pearlite;
It is characterized by having.

  According to this method for additionally filling pearlite for cold storage in a low-temperature tank, the opening of the pearlite filling tube is closed with a test ball in the seal box, and in this state, the seal box is removed from the roof of the outer tank, that is, Since the ball valve is attached to the opening of the pearlite filling tube under the atmospheric pressure without the seal box, the attachment of the ball valve is much easier than in the prior art performed in the seal box.

Further, in the method of additionally filling the pearlite for cold storage in the low temperature tank, prior to the step of covering the pearlite filling tube and attaching the gloved seal box to the roof portion of the outer tub, the fastening means to the opening flange of the pearlite filling tube The closing flange that is fixed by and closing the opening of the pearlite filling tube is fixed to the opening flange with a vise, and then the fastening means is removed and the closing flange is fixed to the opening flange with only the vise. It is preferable to have a step of placing.
In this way, in the process of removing the closing flange that uses the glove in the seal box to close the opening of the pearlite filling tube, it is possible to remove the closing flange by simply removing the vise. The removal work of the flange becomes very easy. Moreover, since the operation | work which fixes a closing flange with a vise and removes a fastening means after that is performed under atmospheric pressure, it can carry out easily.

Further, in the method of additionally filling pearlite for cold storage in a low-temperature tank, in the step of covering the pearlite filling tube and attaching a gloved seal box to the roof of the outer tub, a gas supply hose is provided in the seal box. When the test ball is stored, it is preferable that the hose of the test ball is pulled out of the seal box.
This eliminates the need to pull the hose out of the seal box from the inside of the seal box using a glove for the test ball, improving workability and quickly filling the test ball with gas. It can be carried out.

Further, in the method of additionally filling pearlite for cold insulation in a low-temperature tank, in the step of shrinking the test ball and taking it out from the ball valve, and subsequently closing the ball valve, before the test ball is shrunk, It is preferable to attach a tube having a hole having a smaller diameter than the test ball.
In this way, when the test ball is shrunk and taken out from the ball valve, when the test ball unexpectedly jumps out due to the pressure difference between the pearlite filling tube and the atmospheric pressure, it is captured by the tube. be able to.

  In the method of additionally filling pearlite for cold insulation of the low temperature tank of the present invention, since the ball valve can be installed much more easily than before, it is possible to make the pearlite additional filling operation itself easier than before. As a result, the time required for the additional filling operation can be shortened, and the cost can be reduced.

It is a sectional side view showing the schematic structure of the low temperature tank concerning the present invention. It is a figure which shows the state which fixed the closing flange with the vise. It is a schematic block diagram of a seal box, (a) is a side view, (b) is a plan view. It is a figure which shows schematic structure of a test ball. It is a side view which shows the state which obstruct | occluded the pearlite filling tube with the test ball. It is a side view which shows the state which attached the ball valve to the pearlite filling pipe | tube. It is a side view which shows the state which attached the pipe body on the ball valve.

Hereinafter, the method for additionally filling pearlite for cold insulation in the low-temperature tank of the present invention will be described in detail.
First, a low-temperature tank according to the present invention will be described with reference to FIG. Reference numeral 1 in FIG. 1 denotes a double-shell ground low-temperature tank (hereinafter referred to as a low-temperature tank) that stores a low-temperature liquefied gas such as LNG (referred to as LNG in this embodiment).

  The low temperature tank 1 is provided on the ground 2 and is made of a metal (for example, iron) inner tank 3 for storing a low temperature liquefied gas (LNG) L, and a concrete outer tank 4 covering the inner tank 3. It is comprised with these. That is, a concrete foundation floor slab 5 is installed on the ground 2, and an outer tub 4 including a bottom plate portion 4 a, a side wall portion 4 b, and a roof portion 4 c is installed on the foundation floor slab 5. On the bottom plate part 4 a in the tank 4, the inner tank 3 composed of the bottom plate part 3 a and the side wall part 3 b is installed via the bottom cold insulator 6.

  The inner tub 3 is covered with a lid 7 so as to cover the upper opening, and thus the lid 7 is a roof portion of the inner tub 3. However, the lid body 7 is made of, for example, a thin aluminum plate, and is simply provided so as to cover the upper opening of the inner tank 3 without hermetically sealing. Therefore, between the inner tank 3 and the outer tank 4, that is, in the low temperature tank 1, the LNG gas is filled with a pressure of, for example, about 1500 mmAq to 2000 mmAq, and thereby the internal pressure of the low temperature tank 1 is set to atmospheric pressure. Compared to 1500 mmAq to 2000 mmAq.

A glass wool 8 is laid on the lid 7 as a lightweight cold insulating material. In addition, a partition wall 9 is suspended in a curtain shape from the roof portion 4c of the outer tub 4 above the side wall 3b of the inner tub 3, so that the top of the lid 7 and the outer side of the inner tub 3 are partitioned. Has been.
Between the side wall part 3b of the inner tank 3 and the side wall part 4b of the outer tank 4, for example, a gap of about 1 m is formed, and this gap is filled with granular pearlite 9 as a cold insulating material.
As described above, the pearlite 9 is filled from a pearlite filling pipe 10 which will be described later at the time of construction of the low temperature tank 1. Therefore, at the time of filling, the pearlite 9 is filled up to the vicinity of the roof portion 4c of the outer tub 4 in FIG. .

The perlite for filling the outer peripheral portion of the roof portion 4c of the outer tub 4, that is, the shoulder corresponding to the gap between the side wall portion 3b of the inner tub 3 and the side wall portion 4b of the outer tub 4, with pearlite. A filling tube (perlite nozzle) 10 is provided. The pearlite filling pipe 10 is provided with several tens (for example, 72) of the low temperature tank 1 at equal intervals. The pearlite filling tube 10 has an opening flange 11 at its upper opening. Further, a closing flange 12 is fixed to the opening flange 11 by a plurality of fastening means 13 composed of bolts and nuts. Yes. As a result, the upper opening of the pearlite filling tube 10 is hermetically closed by the closing flange 12.
The lid 7 covering the roof 4c of the outer tub 4 and the inner tub 3 is provided with a supply pipe for supplying a low-temperature liquefied gas from the outside into the inner tub 3 though not shown. Is provided.

  In the low temperature tank 1 having such a configuration, after filling with pearlite after construction as described above, when the low temperature liquefied gas is further stored in the inner tank 3 and the low temperature tank 1 is operated, the inner tank 3 Since it is made of metal, it is shrunk by the cold heat of this low-temperature liquefied gas, and the gap between the side wall 3b of the inner tank 3 and the side wall 4b of the outer tank 4 is expanded. Then, the pearlite 9 filled in the gap gradually sinks, and a hollow portion 14 where the pearlite 9 does not exist is formed at the upper end portion between the inner tub 3 and the outer tub 4 and below the pearlite filling tube 10. Will be. The formation of the hollow portion 14 also occurs when the pearlite 9 changes with age, so that the particles become smaller and the bulk density becomes larger. Moreover, formation of such a cavity part 14 can be easily confirmed from the outside because dew condensation occurs on the outer surface of the side wall part 4b of the outer tub 4 corresponding to this and moss grows.

Therefore, when the formation of the cavity portion 14 is confirmed in this way, the pearlite 9 is additionally filled in a state where the low-temperature liquefied gas is stored in the low-temperature tank 1, that is, the low-temperature tank 1 is operated.
First, the closing flange 12 fixed to the opening flange 11 of the pearlite filling tube 10 by the fastening means 13 is fastened with a plurality of (for example, four) vise 15 as shown in FIG. Remove the bolts (stud bolts) and nuts that make up (not shown). As a result, the closing flange 12 is fixed to the opening flange 11 only by the vise 15 and the opening of the pearlite filling tube 10 is closed. Here, the operation of removing the fastening means composed of the bolt (stud bolt) and the nut in this way is sufficiently easy because it is performed under atmospheric pressure. In addition, when it fixes to the opening flange 11 only by the vise 15 in this way, soap water is apply | coated between the opening flange 11 and the closing flange 12, and the amount of vaporization of the low temperature liquefied gas in the low temperature tank 1 is applied. Check for leaks.

  Next, the pearlite filling tube 10 is covered, and the seal box 20 is attached to the roof portion 4c of the outer tub 4 as shown in FIG. The seal box 20 has a box-like shape having an opening 20a for allowing the pearlite filling tube 10 to pass therethrough and accommodate it therein. FIG. 3A is a side view and FIG. As shown in b), the observation windows 21 are formed on the side surfaces and the upper surface, respectively, and two pairs of globes 22 are attached to the opposite side surfaces, one pair each. In addition, description of the globe 22 is abbreviate | omitted in Fig.3 (a).

  Further, as shown in FIG. 3A, the seal box 20 is detachably attached with a piping system 23 for supplying nitrogen (inert gas) therein. The piping system 23 includes a pressure gauge 24, a flow meter 25, a gate valve 26, and a pressure reducing valve 27 in this order from the seal box 20 side. Further, a nitrogen source 28 made of a gas cylinder is provided upstream of the pressure reducing valve 27. Can be attached. Under such a configuration, the piping system 23 adjusts the nitrogen pressure fed from the nitrogen source 28 to a predetermined pressure by the pressure reducing valve 27, thereby allowing a predetermined flow rate and a predetermined amount to flow into the seal box 20 through the gate valve 26. Supply with pressure. At that time, the flow meter 25 can confirm that the flow rate becomes a predetermined flow rate, and the pressure gauge 24 can confirm that the flow rate becomes a predetermined pressure.

In addition, a safety valve 29 and another gate valve 30 are attached to the seal box 20, and further, though not shown, a through hole is formed through which a hose of a test ball described later is airtightly passed.
And when attaching the seal box 20 which consists of such a structure to the roof part 4c of the outer tank 4, a packing (not shown) is provided between the opening 20a and the roof part 4c, and sufficient airtightness is provided. To secure.
Further, when the seal box 20 is attached to the roof portion 4c in this way and the pearlite filling tube 10 is covered, a test ball 40 as shown in FIG.

  The test ball 40 is a balloon-like one formed so as to be inflatable and deflate, and is a known one configured to detachably connect the hose 41 to the mouth portion 40a. That is, the test ball 40 can be inflated by filling the test ball 41 with air through the hose 41 after the hose 41 is attached. A head cock hose 42 provided with a plug 42a is detachably connected to the mouth of the hose 41 opposite to the test ball 41. After the test ball 41 is inflated, the plug 42a is closed. Thus, the swollen state of the test ball 40 is maintained. Further, by opening the stopper 42a, the air in the test ball 41 can flow out and the test ball 41 can be contracted.

  Further, when such a test ball 40 is accommodated in the seal box 20, the hose 41 connected to the test ball 20 is hermetically sealed in a through hole (not shown) formed in the seal box 20. Insert through and pull out. The head cock hose 42 is connected to the hose 41 outside the seal box 20, and an air supply means (not shown) such as a pump is connected to the head cock hose 42. When the test ball 40 is accommodated in the seal box 20 in this way, the test ball 40 is kept in a contracted state without being filled with air.

  Next, the operator puts both hands into the globe 22, thereby inserting the globe 22 into the seal box 20. In this state, nitrogen is supplied into the seal box 20 from the piping system 23 shown in FIG. 3A, and the pressure inside the seal box 20 is about the same as that in the low-temperature tank 1, that is, 1500 mmAq. Pressurization is performed so as to be about 2000 mmAq.

  Then, under such a pressurized state, the closing flange 12 that closes the opening of the pearlite filling tube 10 is removed by using the globe 22 with a hand inserted into the globe 22. At that time, since the closing flange 12 is only tightened with a vise 15 as shown in FIG. 2, the operation is much easier than in the case of removing the fastening means comprising bolts and nuts as in the prior art. It has become.

  When the closing flange 12 is removed in this manner, the test ball 40 accommodated in the seal box 20 is put into the opening (in the hole 10a) of the pearlite filling tube 10 while using the globe 22 continuously. Then, the test ball 40 is filled with air using an air supply means (not shown) such as a pump connected to the hose 41 via the head cock hose 42 in advance outside the seal box 20. Thereby, as shown in FIG. 5, the test ball 40 is expanded, and the opening (hole 10a) of the pearlite filling tube 10 is closed. Further, when the opening (hole 10a) of the pearlite filling tube 10 is closed with the test ball 40 in this way, the plug 42a of the head cock hose 42 is closed in this state, and the test ball 40 is held in an inflated state.

  Next, the inside of the seal box 20 is gradually returned to atmospheric pressure using the piping system 23 or the gate valve 30. At that time, it is confirmed that the test ball 40 does not come off due to the pressure difference between the inside and outside of the pearlite filling tube 10, and it is also confirmed that there is no leakage of the vaporized component of the low-temperature liquefied gas from the low-temperature tank 1. And if it confirms that there is no trouble about these, the seal box 20 will be removed from the roof part 4c of the outer tank 4. FIG. At that time, the air supply means is removed from the head cock hose 42, and the head cock hose 42 and the hose 41 are removed from the seal box 20.

  Subsequently, as shown in FIG. 6, one side of a known ball valve 45 is attached to the opening flange 11 (opening portion) of the pearlite filling tube 10 packed with the test balls 40, and fastening means comprising a stud bolt and a nut ( (Not shown). At that time, the ball valve 45 is kept open, and the hose 41 and the head cock hose 42 connected to the test ball 40 are passed through the ball valve 45 and pulled out from the other side. Such a mounting operation of the ball valve 45 is conventionally performed by using a glove in the seal box, but in the present embodiment, it can be performed under an atmospheric pressure without the seal box 20, so that it is compared with the conventional case. It is much easier.

  Further, when the ball valve 45 is attached in this way, a tube body 47 is attached to the other side of the ball valve 45 as shown in FIG. 7 and fixed by fastening means comprising a stud bolt and a nut. As the tube body 47, the same inner diameter as that of the pearlite filling tube 10 is used. The tube body 47 is provided with a flange 49 in which a hole 48 having an inner diameter sufficiently smaller than the inner diameter of the tube body 47 is formed on the outer side (the side opposite to the ball valve 45 side). By using the tube 47 having such a configuration, even if the test ball 40 unexpectedly jumps out in a later process, it can be captured by the flange 49 of the tube 47. When the tube body 47 is attached in this way, the hose 41 and the head cock hose 42 connected to the test ball 40 are passed through the internal hole 47a of the tube body 47 and pulled out from the hole 48 of the flange 49. Keep it.

Next, the stopper 42 a of the head cock hose 42 is slightly opened, and the air in the test ball 40 is gradually discharged through the hose 41. Thereby, the test ball 41 is contracted. Then, the hose 41 (head cock hose 42) is pulled to allow the test ball 41 to pass through the hole of the ball valve 45 in the opened state and take it out (pulled out). At this time, even if the test ball 40 unexpectedly jumps out, it can be captured by the tubular body 47.
In this way, when the test ball 40 is taken out from the ball valve 45 and brought to the tube body 47 side, the ball valve 45 is immediately closed.

Next, a pearlite filling device (not shown) is mounted on the ball valve 45 in the same manner as before. Then, the ball valve 45 is opened, pearlite is filled into the pearlite filling tube 10 from the pearlite filling device, and the pearlite is increased and filled between the side wall portion 33 b of the inner tub 3 and the side wall portion 4 b of the outer tub 4.
When the additional filling operation is completed, the ball valve 45 is closed and the pearlite filling device is removed. The ball valve 45 may be removed again using the seal box 20, but may be left attached in preparation for the next additional filling operation.

  In such an additional filling method of pearlite, the opening of the pearlite filling tube 10 is closed with the test ball 40 in the seal box 20, and the seal box 20 is removed from the roof portion 4b of the outer tub 4 in this state, Since the ball valve 45 is attached to the opening of the pearlite filling tube 10 in that state, that is, at atmospheric pressure where there is no seal box 20, the ball valve 45 is attached in comparison with the conventional case where the ball valve 45 is attached in the seal box 20. It can be made much easier. Therefore, the pearlite additional filling operation itself can be made easier as compared with the prior art, and thereby the time required for the additional filling operation can be shortened and the cost can be reduced.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably. For example, after the ball valve 45 is attached to the pearlite filling tube 10, the test ball 40 may be directly taken out without attaching the tube body 47.
Moreover, about the structure of a seal box, the piping system attached to this, etc., it is not limited to the thing of the said embodiment, A suitable thing can be used.
Further, any test balls and hoses attached thereto can be used as long as they have the functions described above.

  DESCRIPTION OF SYMBOLS 1 ... Low temperature tank, 3 ... Inner tank, 3a ... Bottom plate part, 3b ... Side wall part, 4 ... Outer tank, 4a ... Bottom plate part, 4b ... Side wall part, 4c ... Roof part, 7 ... Cover body, 9 ... Perlite, 10 DESCRIPTION OF SYMBOLS ... Perlite filling pipe, 11 ... Opening flange, 12 ... Closing flange, 13 ... Fastening means, 14 ... Cavity, 15 ... Vise, 20 ... Seal box, 21 ... Viewing window, 22 ... Globe, 23 ... Piping system, 40 Test balls, 41 ... Hose, 42 ... Head cock hose, 45 ... Ball valve, 47 ... Tube, L ... Low temperature liquefied gas (LNG)

Claims (4)

An inner tub and an outer tub that covers the side wall and the roof of the inner tub, store the low-temperature liquefied gas in the inner tub, and between the side basin of the inner tub and the outer tub For a low-temperature tank in operation, which is filled with granular pearlite, and has a pearlite-filled pipe leading to the roof portion of the outer tub between the side wall portion of the inner tub and the side wall portion of the outer tub, When filling and increasing granular pearlite between the side wall of the inner tank and the side wall of the outer tank from the pearlite filling pipe,
A step of covering the pearlite filling tube and attaching a gloved seal box to the roof of the outer tub, and storing a test ball having a gas supply hose in the seal box;
Supplying and pressurizing an inert gas into the seal box, and removing a closing flange for closing the opening of the pearlite filling tube using the globe under the pressurized state;
The test ball is inflated by placing the test ball into the opening of the pearlite filling tube using the glove and subsequently filling the test ball with gas from the outside of the seal box through the hose. Closing the opening of the pearlite filling tube,
The seal box is removed from the roof of the outer tub, and then a ball valve is attached to the opening of the pearlite filling tube, and the ball valve is opened and the test ball hose is passed through the ball valve. Process,
Allowing the gas in the test ball to flow out through the hose, shrinking the test ball and taking it out of the ball valve, and subsequently closing the ball valve;
A pearlite filling device is mounted on the ball valve, and then the ball valve is opened and pearlite is filled into the pearlite filling pipe from the pearlite filling device, and between the side wall portion of the inner tank and the side wall portion of the outer tank. A process of increasing and filling pearlite;
A method for additionally filling pearlite for cold storage in a low-temperature tank. Prior to attaching the gloved seal box to the roof of the outer tub covering the pearlite filling tube,
A closing flange fixed to the opening flange of the pearlite filling tube by fastening means to close the opening of the pearlite filling pipe is fixed to the opening flange by a vise, and then the fastening means is removed and only the vise is removed. The method for additionally filling a pearlite for cold storage in a cryogenic tank according to claim 1, further comprising a step of fixing the closing flange to the opening flange.   In the step of attaching a gloved seal box to the roof of the outer tub so as to cover the pearlite filling tube, when storing a test ball having a gas supply hose in the seal box, 3. The method for additionally filling pearlite for cold storage in a low-temperature tank according to claim 1, wherein the hose is drawn out of the seal box.   In the step of shrinking the test ball and taking it out from the ball valve, and subsequently closing the ball valve, before shrinking the test ball, a tube having a smaller diameter hole than the test ball is attached to the ball valve. The method for additionally filling pearlite for cold insulation in a low-temperature tank according to any one of claims 1 to 3, wherein:

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