JPS63159193A - Spherical tank device with elastic tank cover for marine use - Google Patents

Abstract

PURPOSE:To prevent a tank cover from cracking on its junction to the upper deck by providing elastic members arranged along the tank cover so as to reach to the upper deck on both ends. CONSTITUTION:A semi-spherical tank cover 9 covering the upper part of a spherical tank 6 over the upper deck is provided. A disc plate like top plate 10 is arranged on the top of this tank cover 9 while said cover 9 is fixed at the bottom edge to the upper deck 7 surface through welding. In a circle viewing this semispherical tank cover 9 from the above, elastic members 11, 12 stretching to lateral direction are arranged along the tank cover 9 on positions in front and rear of the center of said circle by a half of the radius of this circle that is R/2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a spherical tank device used in ships such as tankers, and in particular to a marine spherical tank with a retractable tank cover, in which the spherical tank is covered with a cover. Regarding equipment.

[Conventional technology]

As tankers for transporting low-temperature liquids such as liquefied natural gas (LNG), tankers equipped with spherical tanks installed in the hull and partially protruding above the upper deck are widely used.

In addition, in such tankers, in order to protect the upper deck part of the spherical tank from external electricity such as scattered salt at sea, the upper deck part of the spherical tank is covered and its lower edge is attached to the upper deck surface. Spherical tank devices have previously been developed with a hemispherical tank cover that is welded in place.

In such a spherical tank device with a tank cover, when the hull is subjected to repeated hogging and sagging, the upper deck of the hull expands and contracts as the hull bends vertically, causing a very large force to act on the tank cover. .

Therefore, in order to solve this problem, we created a marine spherical tank VCFI with a retractable tank cover, in which a retractable member is arranged in the meridian direction of the hemispherical tank cover! I is special public official 1986-218
It was proposed and put into practical use in Publication No. 72. In other words, such a marine spherical tank device with a retractable tank cover is constructed as shown in FIGS. Tank 6 is provided.

This spherical tank 6 is connected to the hull longitudinal bulkhead 2. It is stored in a space 5 surrounded by the hull side [3] and the double bottom and top plate 4.

Further, a hemispherical tank cover 9 is provided to cover the upper part of the upper deck of the spherical tank 6, and a disk-shaped top plate 10 is disposed on the top of the tank cover 9, and the lower edge of the tank cover 9 is It is welded and fixed to the 7 sides of the upper deck.

Further, the tank cover 9 is provided with a telescopic member 21.22°23.24 extending in the meridian direction along the tank cover 9 between the top plate 10 and the lower raAi of the tank cover 9.

These elastic members 21, 22, 23, 24 exhibit high rigidity against elastic forces in the longitudinal direction, but become flexible when exposed to elastic forces in the lateral direction (vA force direction). ing.

Then, a telescopic member 21 is provided at the lower edge of the tank cover 9.
, 22, 23, and 24 are point A and point B, respectively.

At point 0 and point D, hull longitudinal bulkhead 2 or hull transverse!
! Connected to 3.

As a result, even if the upper deck 7 expands and contracts due to vertical bending of the hull, the deformation that occurs in the hemispherical tank cover 9 is absorbed by the expansion and contraction of the expandable members 21, 22, 23, and 24.
Large stress is prevented from being generated on the tank cover 9 and the upper deck 7.

[Problem that the invention seeks to solve]

However, in many ships equipped with the above-mentioned marine spherical tank device with a retractable tank cover, the tank cover 9
Numerous cracks were formed in a short period of time at the weld between the lower edge of the deck and the upper deck 7.

The reason why cracks occur in such a short period of time is explained as follows. In other words, an interaction force is generated at the joint between the flat upper deck 7 and the hemispherical tank cover 9 due to the difference in deformation between the two.
rce) occurs.

When hogging the hull, the tank cover 9 is
When the hull is sagged, it deforms as shown by the broken line in the figure.
The tank cover 9 is deformed as shown by the dotted line tn in Fig. 12.

As a result, the front end (B, 1.'
1. ), rear E (AQ) O, and both 111 ends (points C and D)
Cyclic stress occurs in the vertical direction, which is the maximum.

In addition, in Fig. 13, the broken MSI indicates the stress during hogging of the ship's hull by one point multiplication r (line S2 indicates the stress during sagging,
The upward direction is compressive stress, and the downward direction is tensile stress.

In this way, when vertical bending of the hull occurs, the elastic member 21.
22, 23, and 24 are connected, but since these elastic members 21, 22, 23, and 24 exhibit high rigidity against expansion and contraction in the length direction, as a result, excessive expansion and contraction occurs at the bases. A force F^ is generated, which causes cracks to occur.

Also, A, I:!, to which the bases of the telescopic members 21, 22, 23, and 24 are connected! Immediately below points i, lB, C, and D are the hull longitudinal bulkhead 2 or the hull transverse I! lt3 are provided C), and these parts have higher rigidity than other parts on the upper deck 7, and the second thing further increases the expansion and contraction force FA generated at the base, making cracks more likely to occur. are doing.

Furthermore, since each of the telescopic members 21, 22, 23, and 24 is joined to the highly rigid top plate 10, these telescopic members 2
1, 22, 23, and 24 is large, and this is also one of the causes of crack occurrence.

Also, among the expandable members 21, 22° 23.24 arranged radially around the top plate 10 of the tank cover 9 when viewed from above, the expansion and contraction directions of the expandable portions 21 and 22 correspond to the direction of expansion and contraction of the tank cover as the hull deforms. It does not match the direction of deformation in 9,
The telescoping members 21, 22 do not perform their telescoping function adequately.

The present invention was proposed in view of the above-mentioned situation, and is a retractable tank cover that reduces the stress generated at the joint between the tank cover and the upper deck and prevents cracks from forming at the joint. The purpose of the present invention is to provide a marine spherical tank device with a spherical tank.

[Means for solving problems]

For this reason, the marine spherical tank device with a retractable tank cover of the present invention is installed in the hull of the ship. a spherical tank with a part protruding above the upper deck, and a spherical tank cover which covers the upper part of the upper deck of the spherical tank and whose lower end edge is welded and fixed to the upper deck surface; The tank cover has an elastic part extending in a substantially horizontal direction between the center of the circle and each of the 1111 end and the rear end of the circle when viewed from above. The i part is arranged along the tank cover, and both ends of the extendable part are provided so as to reach the upper deck.

[For production]

In the above-mentioned marine spherical tank device with a telescoping tank cover of the present invention, both ends of the telescoping portion reach the upper deck at the lower edge of the tank cover where the stress generated due to vertical bending of the hull is small. Excessive stress is prevented from being generated at the joint between the and the elastic part, and
Since the extensible portion extends substantially laterally, deformation of the tank cover is reliably absorbed by the expansion and contraction of the extensible portion.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Figures 1 to 5 show a marine spherical tank device with a retractable tank cover as a PISi embodiment of the present invention.
The figure is a plan view, FIG. 2 is a side view, FIG. 3 is a sectional view taken along arrows -■ in FIG. 2, and FIGS. 4(a) is a sectional view showing an example of ttSl, FIG. 4(1)) is a sectional view showing a second example of ttSl, and FIG. Figure 4(e) is a cross-sectional view showing an example of PttJ3,
FIG. 5 is a schematic diagram for explaining the stress generated at the joint between the tank cover and the upper deck.

As shown in FIGS. 1 to 3, a spherical tank 6 is disposed within the hull surrounded by the outer skin 1 and has a portion thereof protruding above the upper deck 7.
This spherical tank 6 has a hull longitudinal spacing of J! !
2. It is housed in a space 5 surrounded by a hull transverse bulkhead 3 and a double bottom top plate 4.

Further, a hemispherical tank cover 9 is provided to cover the upper part of the upper deck of the spherical tank 6, and a disk-shaped top plate 10 is disposed at the top of the tank cover 9, and the lower edge of the tank cover 9 is It is welded and fixed to the 7 sides of the upper deck.

This hemispherical tank cover 9 has a circular shape when viewed from above, and from the center of the circle there are sections extending in the lateral direction from the center of the circle to the front and rear positions by one-half of the diameter R of the circle, that is, R/2. A telescoping member 11 , 12 is arranged along the tank cover 9 .

In addition, the position setting of such extensible members 11 and 12 is based on the following reasons.

In other words, when vertical bending due to hogging or sagging occurs in the hull, the interacuntan 7 os at each joint between the tank cover 9 and the upper deck 7 is distributed as shown in Figure 'tx5. Therefore, the minimum point of the interaction 7↑-s is at a position r! slightly outward from the point 1/2 of the radius R from the center of the tank cover 9. IM, M'.

As the base of the elastic member 11.12, the smaller the ink force is, the more advantageous it is, so M in FIG.
, M' point, that is, 1 radius R from the center of the tank cover 9
A location slightly outside of point /2 is optimal.

On the other hand, in general, when a structure is provided with expandable members, it is ideal to provide them at equal positions along the entire length of the structure in order to ensure uniform expansion and contraction as a whole.

Therefore, the tank cover has two elastic members 11°12
In the case of providing a diaphragm, it is most effective to provide it at positions N and N' which divide the diameter into three equal parts. So, rank r! 1M.

The extensible members 11 and 12 are provided at a point approximately 1/2 of the tank radius, which is close to both M', N, and N'.

The proximal ends 11', 12' of these telescoping members 11.12 are
It reaches the joint between the upper deck 7 and the tank cover 9, and is connected to the upper deck 7.

Further, in this embodiment, the expandable member 11.12 is configured to have an open cross-sectional shape as shown in FIG. 4(a), FIG. 4(b), or FIG. 4(c). It exhibits high rigidity against stretching forces in the vertical direction, and flexibly expands and contracts against stretching forces in the lateral direction.

Note that in FIG. 1, reference numeral 8 indicates the hull centerline.

Since the marine spherical tank device with a retractable tank cover as the first embodiment of the present invention is constructed as described above,
Even if the upper deck 7 expands and contracts due to vertical bending of the hull, the expansion and contraction of the expansion and contraction members 11.12 will absorb the expansion and contraction of the expansion and contraction members 11.12, since the deformation that occurs in the tank cover 9 and the expansion and contraction directions of the expansion and contraction members 11. Excessive stress is reliably prevented from being generated at the joint between the cover 9 and the upper deck 7.

Furthermore, when the hull is subjected to hogging or sagging, an interaction force as shown in figure m5 occurs at the joint between the tank cover 9 and the upper deck 7, but the base j! 11°112゛ is a high part of the interaction 1 interface (points A, B, 0, and D shown in Figures 1, 2, and 5) at the joint between the tank cover 9 and the upper deck 7. ), but not interaction.”
The elastic members 11 and 12 are connected to relatively low stress areas near the minimum points M and M' of the
The stretching force in the longitudinal direction generated in this case is reduced to about 115 compared to the conventional one.

In addition, in Figure 5, 4QS1 is the stress during hull hogging,
A single point frequency @82 indicates the stress during sagging, with the upward direction being the compressive stress and the downward direction being the tensile stress.

Furthermore, the proximal ends 11', 12' of the telescoping members 11.12 are
It is joined to the upper deck 7 while avoiding the hull longitudinal bulkhead 2 and the hull transverse bulkhead 3, thereby further suppressing the stress generated at any joint between the tank cover 9 and the upper deck 7.

In addition, since the top portions 11'' and 12'' of the telescopic member 11.12 are not joined to the highly rigid top plate 10, and there is no reaction force acting on the telescopic member 11.12 from the top plate 10, the tank cover 9 The stress generated at the joint between the upper deck 7 and the upper deck 7 can be further suppressed.

The telescopic members 11.12 are shown in FIGS.
), the stress generated within the member due to lateral expansion and contraction is reduced to approximately 1/2 compared to the case where the member has a closed cross-sectional shape.
The reliability of the fatigue strength of the telescopic members 11, 12 is improved, and the labor required for their construction and maintenance is also reduced.

Furthermore, since the positions of the elastic members 11 and 12 are set close to rlIN,N' where they can easily exhibit elasticity,
This position setting is based on the effect of reducing stress due to expansion and contraction.

In this way, it is possible to reliably prevent cracks from forming at the joint between the tank cover 9 and the upper deck 7 and at various parts of the tank cover 9.

To explain the marine spherical tank device with a retractable tank cover as the 12th embodiment of the present invention, fjS
Figure a is its plan view, and figure fjST is its side view.

In the second embodiment of the present invention, in almost the same configuration as the first embodiment described above, as shown in FIG. 6.7, the rear end (point A) and the right end (point 0) of the tank cover 9 are The telescopic member 31 is extended along the tank cover 9 so that the midpoint of the arc connecting them and the midpoint of the arc connecting the rear end (point A) and left end (point D) are connected. Along with being placed,
The midpoint of the arc connecting the front end (point B) and the right end (point 0) of the tank cover 9, and the midpoint of the arc connecting the front end (point B) and the left end (point D) of the tank cover 9. A telescopic member 32 is disposed along the tank cover 9 so as to connect the tank cover 9.

As shown in FIG. 7, these telescopic members 31 and 32 are arranged along the tank cover 9 so as to have a slight inclination when viewed from the side.

In addition, in FIGS. 6 and 7, the reference numerals already described indicate almost the same parts.

This second embodiment of the present invention also provides substantially the same functions and effects as the first embodiment described above, but in particular, in the second embodiment,
The proximal ends 31', 32' of the expandable members 31, 32 are located at positions M, M' (see Fig. 5), where the stress generated at the joint between the tank cover 9 and the upper deck 7 is minimum, that is, as shown in Fig. 6. Since they are arranged at the intermediate point between point A, point B, point C1, and point D, the lengthwise stretching force applied to the stretchable members 31 and 32 is minimized.

Therefore, the vertical stress generated at the bases j131° and 32° of the extensible members 31 and 32 is further reduced,
This ensures that cracks are prevented from forming at the joint between the tank cover 9 and the upper deck 7.

〔Effect of the invention〕

As described in detail above, according to the marine spherical tank device with a retractable tank cover of the present invention, a spherical tank installed in the hull and partially protruding above the upper deck, and a spherical tank installed in the hull and partially protruding above the upper deck A hemispherical tank cover covers the upper part and has a lower edge welded and fixed to the upper deck surface, and when the tank cover is viewed from above, the center of the circle and the front and rear areas of the circle are connected to each other. It has a telescopic part extending substantially laterally between each of the ends, and the telescopic part is arranged along the tank cover, and both ends of the telescopic part reach the upper deck. With this simple configuration, it is possible to reliably prevent cracks from occurring due to excessive stress occurring at the joint between the tank cover and the upper deck due to vertical bending of the ship's hull, which in turn improves the safety of the ship. In addition, the labor and cost required for maintenance can be greatly reduced.

[Brief explanation of the drawing]

Figures 1 to 5 show a marine spherical tank device with an extendable tank cover as a first embodiment of the present invention. Figure 1 is a plan view thereof, Figure f52 is a side view thereof, and Figure 3 is a Pt52 tank device.
The cross-sectional views taken along the line ■-■ in the figure and FIGS. ) is a sectional view showing the first example,
FIG. 4(b) is a sectional view showing the second example, FIG. 4(c)
) is a cross-sectional view showing the third example, FIG. 5 is a schematic diagram for explaining the stress generated at the joint between the tank cover and the upper deck, and FIG. 6.7 is a cross-sectional view showing the third example. Fig. 6 is a plan view thereof, Fig. 7 is a side view thereof, and Figs. Marine spherical tank g! CR! i, rjS
Figure 8 is a plan view thereof, Figure Pt59 is a side view thereof, Figure 10 is a sectional view taken along the line X-X of Figure fjS9, Figure tjS11 is a side view showing deformation of the tank cover due to vertical bending of the hull, Pt5.
FIG. 12 is a plan view showing the deformation of the tank cover due to vertical bending of the hull, and FIG. 13 is a schematic diagram illustrating the stress generated at the joint between the tank cover and the upper deck. 1. Outer plate, 2. Hull longitudinal bulkhead, 3. Hull transverse bulkhead,
4. Double floor top plate, 5. Space, 6. Spherical tank, 7. Upper deck, 8. Hull center line, 9. Tank cover, 10. Top plate, 11.12. Expandable member. , 11°,
12″... Base end of the telescopic member, 11″, 12″… Top of the telescopic member, 31.32… Telescopic member, 31°, 32°.
・Proximal end of expandable member. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 Figure 2, 4 ■'' Figure 3 Figure 4 (a) (b) (c) Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13

Claims (1)

[Claims] A spherical tank installed in the hull with a part protruding above the upper deck, and a hemispherical tank cover that covers the upper part of the upper deck of the spherical tank and whose lower edge is welded and fixed to the upper deck surface. Preferably, the tank cover has an expandable portion extending substantially laterally between the center of the circle and each of the front and rear ends of the circle when viewed from above. A marine spherical tank device with an extendable tank cover, characterized in that a part is arranged along the tank cover, and both ends of the extendable part are provided so as to reach the upper deck.