JPH11336986A - Structure of low temperature liquid transfer piping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the soundness of a piping system without requiring a large space and even in the case that excessive external force caused by a huge earthquake and the like is applied thereto, by connecting coaxially with a transfer pipe a thick bellows formed in the same thickness as the thickness of the transfer pipe. SOLUTION: When low temperature liquid such as LNG being low temperature liquid is passed through an empty low temperature liquid transfer piping system, a transfer pipe 2 lowers its temperature from room temperature to a temperature of the low temperature liquid such as LNG and thermally contracted. In this case, the bellows part 13 of a thick bellows 3 is so formed that crest parts 14 and trough parts 15 are respectively formed into a semicircular arc shape having the same diameter and are also connected zigzag to each other through connecting ring parts 16. The diameters of the crest parts 14 and the diameters of the trough parts 15 are respectively extended by the same pitch, thereby, when the thick bellows 3 is extended to absorb the thermal contraction of the transfer pipe 2, it can be extended without any trouble even though its thickness is formed thick. In contrast with this, when returning to room temperature, the transfer pipe 2 is returned to the length at the time of room temperature, and the thick bellows 3 can be contracted without any trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature liquid transfer piping structure for transferring a low-temperature liquid such as LNG and LPG.

[0002]

2. Description of the Related Art A low-temperature piping system for transferring a low-temperature liquid such as LNG and LPG is cooled to about -160 ° C. in an LNG pipe and to about -40 ° C. in an LPG pipe by flowing a low-temperature liquid through the pipe, and heat shrinks. Cause

For this reason, the low-temperature piping system is provided with heat shrinkage absorbing means for absorbing heat shrinkage at predetermined intervals.

As the heat shrinkage absorbing means, a loop-shaped pipe is usually used, and as shown in FIGS. 7, 9 and 11,
Generally, three types are known.

The heat shrinkage absorbing means 20 of the horizontal loop type shown in FIGS. 7 and 8 is for bending the low-temperature piping system 21 into a loop shape such as a U-shape so as to extend and detour in the lateral direction. The heat shrinkage of the transfer pipe 2 is absorbed by utilizing the flexibility of an elbow or the like that forms the transfer pipe 2.

The three-dimensional loop type heat shrinkage absorbing means 23 shown in FIGS. 9 and 10 first extends the low-temperature piping system 24 upward, and then bends into a U-shaped loop shape to extend in the lateral direction. It is a detour. The heat shrinkage of the transfer pipe 2 is absorbed by using the flexibility of an elbow or the like that forms the bent portion 25 in the same manner as the horizontal loop type heat shrinkage absorbing means 20.

The loop type heat shrinkage absorbing means 20 and 23 shown in FIGS. 7, 8, 9 and 10 have a loop shape and size determined in accordance with the heat shrinkage of the low-temperature piping systems 21 and 24. Therefore, the loop type heat shrinkage absorbing means 20, 2
3 is installed in a tunnel 30 or a culvert (not shown), the tunnel 30 or the culvert must be excavated according to the shape and size of the loop, and the floor surface 31 of the tunnel 30 must have a width. To use widely in the direction,
There is a problem that it is difficult to secure the passage 32, which requires enormous costly excavation, and that the use of four or more elbows in one loop increases the pressure loss of the fluid in the pipe.

Therefore, a bellows type heat shrinkage absorbing means 26 shown in FIGS. 11 and 12 is known.

The heat shrinkage absorbing means 26 is supported on a gantry 33 and connects the transfer pipes 2 with extendable bellows 27. The heat shrinkage of the transfer pipe 2 is utilized by utilizing the axial expansion of the bellows 27. It is designed to absorb.

Since the bellows 27 repeatedly expands and contracts, the bellows 27 is specifically designed to withstand fatigue (fatigue design).

Normally, the bellows 27 has a plate thickness of about 0.8 mm to 1.5 mm depending on the pipe diameter and the amount of expansion and contraction, and has a maximum thickness of about 3 mm (1/8 inch). Is used.

Although the heat shrinkage absorbing means 26 is designed to withstand expansion and contraction, it has a weak strength against the hydraulic pressure, and therefore, as shown in FIG. By loosely fitting the bellows 29, the expansion of the bellows 27 in the radial direction is restricted, and the bellows 2
7 is prevented from deforming radially outward.

This bellows type heat shrinkage absorbing means 26
Is easy to secure the passage 32 because it does not take up space.
The drilling cost does not increase, and the pressure loss is small due to the shape close to a straight pipe.

[0014]

However, since the bellows 27 of this bellows type heat shrinkage absorbing means 26 is designed to withstand repeated expansion and contraction, its thickness is very thin, and an excessive external force due to a huge earthquake or the like. When they act, there is a problem that damage and leakage are likely to occur.

Particularly, when the low-temperature liquid is transferred, if the bellows 27 is greatly stretched during an earthquake, the bellows 27 cannot withstand the internal pressure and may be damaged, and the low-temperature liquid may leak.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a low-temperature liquid transfer piping structure which does not take up space and can maintain the soundness of the piping system even when an excessive external force acts due to a large earthquake or the like. It is in.

[0017]

According to the present invention, there is provided a low-temperature liquid transfer pipe structure in which a low-temperature pipe for transferring a low-temperature liquid such as LNG is installed in a tunnel or the like. A thick bellows formed with the same thickness as the thickness of the pipe is connected coaxially.

By doing so, even if the bellows is completely stretched due to a large earthquake or the like, the bellows can withstand the internal pressure and does not leak the low-temperature liquid inside.

Further, the thick bellows preferably has a connecting pipe portion having the same diameter as the transfer pipe at both ends, and the end of the connecting pipe is preferably butt-welded to the end of the transfer pipe. High sealing performance can be maintained permanently.

The bellows portions at the center of the connection pipe portions at both ends have a semi-arc-shaped crest formed with the same thickness as the connection pipe portion, a semi-arc-shaped valley having the same diameter as the crest, and The ridge and the valley may be connected to each other by connecting ends thereof and extending radially.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a front sectional view of a thick bellows 3 for connecting the transfer pipes 2 and 2, and FIG.
FIG.

As shown in FIGS. 1 and 2, the thick-walled bellows 3 has straight tubular connecting pipes 12, 12 formed at both ends thereof with the same thickness t as the transfer pipe 2 and the same pipe. It is formed between the connection pipe parts 12 (center), and is formed between the connection pipe parts 12 and 12.
12 and a bellows portion 13 formed with the same thickness t.

The bellows portion 13 has a peak 14 having a semi-circular cross section which is convex in the radial direction, a valley 15 having a semi-circular cross section which is concave in the radial direction, and ends of the peak 14 and the valley 15. And a connection ring portion 16 connecting the portions to each other and extending in the radial direction.

The radius r of the peaks 14 and the valleys 15 is determined according to the thickness. For example, when the thickness is 6 mm, the radius r is 1
0 to 25 mm, the pitch P between the peaks 14 is
Four times the radius of the peak 14 and the valley 15 and the pitch P
And the width w of the connection ring portion 16 are set in accordance with the length of the transfer pipe 2 to be connected, and are connected in a zigzag manner. The minimum inner diameter d1 of the valley 15 is
The inner diameter d2 of the connecting pipe portion 12 is set to be the same as the inner diameter d2 so that the flow path resistance is small.

In the present embodiment, the bellows portion 13 is made of a stainless steel transfer pipe 2 (linear expansion coefficient: 15.0 m) having a length of about 5 m.
１６16.5 × 10 ⁻⁶ [mm / mm ° C.]). That is, the thick bellows 3
Are connected at intervals of about 5 m in the length of the transfer pipe 2, and L
Approximately 14mm of heat shrinkage when temperature drops to NG temperature
(The transfer pipe is 12m
Is designed to absorb the heat shrinkage of 32 mm).

More specifically, in the case of a 12-inch transfer pipe 2, the bellows portion 13 has a length l of 560 mm in the axial direction.
The thickness t = 6 mm, the pitch P between the valleys 15 and the peaks 14 is 70 mm, the diameter 2r of the valleys 15 and the peaks 14 is 35 mm, and the connection ring 16 is the width of the ring. (Length from the outer peripheral end to the inner peripheral end) w is formed to be 15 mm.

Then, the thick bellows 3 is
3 is formed to extend to about twice the length when completely extended.

The ratio of the product length of the thick bellows 3 (the length when no force is applied in the direction of expansion and contraction) to the total extension length is as follows:
Generally, the height and pitch of the peaks 14 of the thick bellows 3 depend on the design conditions and the connecting pipes 12,
Because it depends on the length of the sleeve tube part that does not form
This value depends on the design conditions. In determining this value, an upper limit, a lower limit, and an optimum value described later are considered.

The upper limit is about 3 to 5 times the product length. This value is a limit value at which the expansion and contraction can be stably absorbed without generating squarm.

The lower limit is about 1.5 times the product length. This value is a limit value at which the shapes of the peaks 14 and the valleys 15 can be formed.

The optimum value is about two to three times the product length. This value can be expected to operate the thick bellows most stably as a product.

The thick bellows 3 is formed from one stainless plate.

First, a stainless steel plate is formed into a tubular shape by a press or the like, and ends that abut in the circumferential direction are butt-welded by TIG welding or the like. In this case, in consideration of the weldability, as shown in FIG.
6 is provided with a groove 6a in advance, and is TIG-welded after being formed into a cylindrical shape.

A stainless steel plate formed into a tubular shape after the longitudinal welding (welding of the end portions that abut each other in the circumferential direction) is placed in a bellows forming mold, and hydraulic pressure is applied to the inner periphery. While being pressed from the longitudinal direction by a press or the like, the bellows 3 is formed into a thick bellows 3 shape.

As shown in FIG. 3, grooves 5a are provided at the ends 5, 5 of the connecting portions 12, 12 between the thick bellows formed and the transfer pipe 2 to form a butt weld with the transfer pipe 2 (see FIG. 3). TIG welding) to form a piping system.

The groove angle θ of the grooves 5a and 6a is 6
Although 0 ° is generally used, the angle may be set so that the best butt welding can be performed.

FIG. 5 shows an example in which the thick-walled bellows 3 described with reference to FIGS.

The transfer pipe 2 is made of stainless steel and has a thickness of 6 m so as to withstand the low pressure liquid pressure of 16 kg / cm ^2.
m and a length of 5 m.

A cooling material 4 made of urethane is wound around the outer periphery of the transfer pipe 2 in multiple layers, and a cooling means 7 is provided on the outer circumference of the thick bellows 3 connecting the transfer pipes 2 to each other.

The cooling means 7 includes ring-shaped partition plates 8 and 8 made of urethane provided on the outer periphery of the connection pipe portions 12 and 12 of the thick-walled bellows 3, and is packed between the partition plates 8 and 8. And glass wool 9 wound.

The partition plate 8 is provided with one surface 10 in close contact with the cold insulator 4 on the transfer pipe 2 side, and has an outer peripheral end protruding outward from the cold insulator 4 on the transfer pipe 2 side. .
The glass wool 9 is also packed in the valley 11 so as not to hinder the expansion and contraction of the thick bellows 3.

Next, the operation of the present invention will be described.

In the empty low-temperature liquid transfer pipe system 1, L
When a low-temperature liquid such as NG is allowed to flow, the transfer pipe 2 falls from room temperature to the temperature of the low-temperature liquid such as LNG and thermally contracts. At this time, assuming that the length of the transfer pipe 2 is 5 m, the thick bellows 3 extends about 14 mm and absorbs the contraction.

The bellows portion 13 of the thick bellows 3 has a peak portion 14 and a valley portion 15 each formed in a semicircular shape having the same diameter, and is further connected in a zigzag manner via a connection ring portion 16. Therefore, when the transfer pipe 2 is expanded to absorb the thermal shrinkage, the diameters of the peaks 14 and the valleys 15 of each pitch are expanded by the same amount, and the transfer pipe 2 is expanded without any trouble even if the wall is formed thick. It will be.

When the temperature returns to the normal temperature, the transfer pipe 2 returns to the normal temperature, and the thick bellows 3 contracts without any trouble.

The results of a fatigue life test on the thick bellows 3 will be described.

In the test, the stretching and shrinking were repeatedly performed 7000 times with a stroke of 14 mm, which is the length to be absorbed by the temperature difference between the normal temperature and the LNG temperature, and 500 times with the 32 mm stroke. It is a result of measuring the degree of fatigue when performing.

As a result, in any case, no breakage due to fatigue was observed in the number of times of design repetition, and it was confirmed that the material could sufficiently withstand actual use.

On the other hand, when a low-temperature liquid such as LNG is flowing through the low-temperature liquid transfer piping system 1, a large earthquake or the like occurs, and a large tensile force acts on the thick bellows 3 due to movement of the transfer pipe 2. In this case, the thick bellows 3
3 is stretched until it is almost in a straight pipe state.

At this time, the internal pressure of the low-temperature liquid such as LNG is applied also to the bellows portion 13 which has been completely extended, but each of the peak portion 14, the valley portion 15 and the connection ring portion 16 of the bellows portion 13 is connected to the transfer pipe 2. Since they are formed to have substantially the same plate thickness and have a sufficient thickness to withstand the internal pressure of the fluid in the pipe (the thickness of the transfer pipe 2 is designed to sufficiently withstand the internal pressure of the fluid in the pipe).
The thick bellows 3 is not damaged and does not leak a low-temperature liquid such as LNG as a fluid in the pipe.

A test was also conducted on such large displacement deformation of the thick bellows 3. The test was for thick bellows 3
By pulling the ends 5, 5 in the axial direction with a large force.

As a result, it was confirmed that the thick bellows 3 did not break even if it extended in a straight tube, and that the fluid inside the thick bellows 3 did not leak.

As described above, since the thickness of the bellows is formed to be 6 mm, which is the same as that of the transfer pipe 2, the bellows 13 can sufficiently withstand the fluid pressure of the fluid in the pipe even if the bellows 13 undergoes a large displacement deformation such that the bellows part 13 can be extended due to a large earthquake or the like. To prevent leakage of fluid in the pipe.

Further, since the thick-walled bellows 3 is butt-welded to the transfer pipe 2, a permanent high sealing property can be maintained at the seam, and complicated maintenance can be omitted.

Since the seam is formed by welding the same thicknesses to each other, the seam is excellent in strength.
Even if a large force that causes large displacement deformation of the thick bellows 3 is applied to the low-temperature liquid transfer piping system 1, breakage of the seam can be prevented, and leakage from the seam can be prevented.

Further, in the conventional heat shrink means of the thin bellows type, the fluid pressure of the fluid in the pipe has been dealt with by the reinforcing ring, but the bellows itself has strength enough to withstand the fluid pressure. The structure can be simplified, and the reliability can be improved.

Further, since the thickness of the bellows is made equal to that of the transfer pipe 2, the strength of the bellows against external force is also reduced.
Can be prevented, damage due to minute scratches at the time of manufacture can be prevented, and handling can be simplified.

The bellows portion 13 is formed into a semi-circular crest 14 having the same thickness, a semi-arc trough 15 having the same diameter as the crest 14, and an end of the crest 14 and the trough 15. The bellows portion 13 can be easily extended according to the heat shrinkage of the transfer pipe 2 because the connection ring portion 16 is connected to each other and extends in the radial direction.

Further, even if the transfer pipe 2 is largely moved by a large earthquake or the like, the movement of the transfer pipe 2 can be sufficiently absorbed by extending the bellows portion 13.

The low-temperature liquid to be transferred is LNG and LPG
The temperature is not limited to this, and any low-temperature liquid whose temperature is low enough to require the heat shrinkage absorbing means may be used.

Further, the number of peaks of the bellows portion 13,
The diameter of the valley portion 15 and the size of the connection ring portion 16 are appropriately changed depending on the absorption length.

Further, as shown in FIG. 6, an inner cylinder 18 may be provided inside the bellows portion 13 to be radially separated from the bellows portion 13 so as to reduce the resistance of the fluid in the pipe. In this case, it is preferable to fix only one end of the inner cylinder 18 to the inner surface of the thick bellows 19 and to float the other end in the air so as not to hinder the extension of the thick bellows 3.

The inner cylinder 18 comprises an upstream inner cylinder 18a disposed upstream of the bellows portion 13 and a downstream inner cylinder 18b disposed downstream.
Assume that the upstream end of 8a is fixed to the inner surface of the thick bellows 19, the downstream end is suspended in the air, the downstream end of the downstream inner cylinder 18b is fixed to the inner surface of the thick bellows 19, and the upstream end is suspended in the air. Good.

In this case, it is preferable that the downstream end of the upstream inner cylinder 18a facing each other while floating in the air and the upstream end of the downstream inner cylinder 18b be separated from each other at an appropriate interval.

[0066]

In summary, according to the present invention, the following excellent effects can be obtained.

(1) Even if the bellows portion undergoes a large displacement deformation such that it extends completely, it can sufficiently withstand the fluid pressure of the fluid in the pipe and can prevent leakage of the fluid in the pipe.

(2) Permanently high sealing performance can be maintained at the joint between the thick bellows and the transfer pipe, and complicated maintenance can be omitted.

(3) Since a straight piping layout is possible, the amount of excavation such as a tunnel diameter can be reduced and a limited space can be effectively used.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a thick bellows showing a preferred embodiment of the present invention.

FIG. 2 is a view taken along line II-II of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 1;

FIG. 4 is an enlarged view of a main part of FIG. 2;

FIG. 5 is an enlarged sectional view of a main part of a low-temperature liquid transfer piping system.

FIG. 6 is a side view of a thick bellows showing another embodiment.

FIG. 7 is a bird's-eye view of a conventional heat shrinkage absorbing unit.

FIG. 8 is a view taken along line VIII-VIII in FIG. 7;

FIG. 9 is a bird's-eye view of a conventional heat shrinkage absorbing means.

FIG. 10 is a view taken along line XX of FIG. 9;

FIG. 11 is a bird's-eye view of a conventional heat shrinkage absorbing unit.

FIG. 12 is a view taken along line XII-XII of FIG. 11;

FIG. 13 is an enlarged view of a main part of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low-temperature liquid transfer piping system 2 Transfer pipe 3 Thick bellows 12 Connection pipe part 13 Bellows part 14 Mountain part 15 Valley part 16 Connection ring part 30 Tunnel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinobu Togawa 3-2-16-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries, Ltd. Toyosu Sogo Office (72) Inventor Shinichi Takemura 6 Torishima Konohana-ku, Osaka-shi, Osaka No. 19-9, Osaka Gas Co., Ltd. (72) Inventor Susumu Hongo 6-19-9, Torishima, Konohana-ku, Osaka, Osaka Prefecture, Japan Inside (72) Inventor Norio Akayama 2--5 Sanno, Ota-ku, Tokyo No. 13 Tokyo Spiral Tube Works, Ltd. (72) Inventor Takeshi Hasebe 5-13, Sanno, Ota-ku, Tokyo, Japan

Claims (3)

[Claims] 1. A low-temperature liquid transfer pipe structure in which a low-temperature pipe for transferring a low-temperature liquid such as LNG is installed in a tunnel or the like.
A low-temperature liquid transfer pipe structure, wherein a thick bellows formed to have the same thickness as the transfer pipe is coaxially connected to the transfer pipe. 2. The thick-walled bellows according to claim 1, wherein the thick-walled bellows has a connecting pipe portion having the same diameter as the transfer pipe at both ends, and the end of the connecting pipe is butt-welded to the end of the transfer pipe. Low temperature liquid transfer piping structure. 3. The bellows part at the center of the connecting pipe part at both ends,
A semi-arc-shaped crest formed with the same thickness as the connecting pipe portion, a semi-arc-shaped valley having the same diameter as the crest, and connecting the ends of the crest and the valley to each other in the radial direction. The low-temperature liquid transfer piping structure according to claim 2, comprising a connection ring portion extending.