US 3782053 A
A construction for a liquid-tight joint between adjacent edges of panels forming the inner wall of a low temperature liquid storage tank, each being of multi-layer construction and having a liquid-tight membrane as an interior layer. A patch member covers the adjacent edge portions of a pair of panels at the joint and is secured to the panels and to a supporting joist. Each panel is relieved to expose a portion of the surface of the liquid-tight membrane adjacent each side of the patch member, and a low temperature resistant adhesive is applied to the joint area, covering the exposed membrane surfaces and the patch member.
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Description (OCR text may contain errors)
United States Patent Nakano et al. Jan. 1, 1974 [5 1 JOINT CONSTRUCTION FOR LOW 1,656,682 1/1928 Slater 52/463 x E RATU PURPOSE LIQUID-TIGHT 3,055,532 9/1962 Morrison 220/9 LG X PANELS 3,093,260 6/1963 Macormack et a1 220/15 X 3,138,132 6/1964 Neimann 220/9 A X  Inventors; Kenji Nakano; lchizo Okano; Ryuzo 3,477,606 11/1969 Schwendtner 220/9 A Teramoto; Hayakawa all of Passovoy t X Osaka Japan 3,605,368 9/1971 Lalouche .1 52/460  Assignee: Hitachi Shipbuilding and Engineering Company Ltd., Osaka, Primary Examiner-James R. Boler Japan Assistant Examiner-Wayne L. Shedd  Filed: July 6, 1972  Appl. No.: 269,447
 ABSTRACT  Forelgn Apphcanon Pnomy Data A construction for a liquid-tight joint between adja- July 9, 1971 Japan 46/50831 cent edges of panels forming the inner wall of a low July 9, 1971 Japan 46/50832 temperature torage tank each being of multilayer construction and having a liquid-tight membrane --52/753 J, 52/463, 220/9 LG, as an interior layer. A patch member covers the adja- 220/9 T, 2 0/9 F, 2 cent edge portions of a pair of panels at the joint and [51 1 Int- Cl. i e ured t the panels and to a supporting joigL Each 1 Field of Search 287/2092 L 20-92 R, panel is relieved to expose a portion of the surface of /l 22 9 F, 9 LG, 9 the liquid-tight membrane adjacent each side of the 52/460, 461, 463 patch member, and a low temperature resistant adhesive is applied to the joint area, covering the exposed 1 1 Referencils Cited membrane surfaces and the patch member.
3 Claims, 4 Drawing Figures 1 JOINT CONSTRUCTION FOR LOW TEMPERATURE PURPOSE LIQUID-TIGHT PANELS SUMMARY OF THE INVENTION The present invention relates to a junction construction for low temperature purpose liquid-tight panels used to form a liquid-tight inner wall for low temperature liquified gas storage tanks.
In general, since plywood has a low coefficient of expansion or contraction in connection with temperature change, it is used as a wall material for low temperature liquified gas storage tanks. However, since plywood is lacking in liquid-tightness, it is necessary to make it liquid-tight when it is used as an inner wall material for such a tank. Plywood constructions made liquid-tight have heretofore been known, including those having a low temperature resistant metal sheet, such as of aluminum or stainless steel, bonded to the surface of the plywood, and those having a low temperature resistant synthetic resin film bonded to the surface of the plywood.
When such a plywood construction, having a liquidtight membrane bonded to the plywood surface, is subjected to a sudden temperature change, there will be a violent shearing force acting on the interface between the membrane and the plywood. This is because the thermal expansion coefficient of the metal sheet or synthetic resin film is much greater than that of plywood, resulting in a high heat shock being produced. In the case of aluminum, for example, the thermal stress is of the order of 50-60 times that of plywood. Therefore, a construction comprising a metal sheet bonded directly to a plywood surface has the danger of the metal sheet separating and cracking or of the plywood warping as a result of the shearing force acting in the described manner. Further, since the metal sheet or synthetic resin film is intended for providing liquidtightness, not for supporting liquid pressure, the thickness thereof may be of the order of 0.3-0.1mm. There fore, when plywood having such a thin, film-like membrane exposed on the plywood surface is used to form a tank wall, the membrane is liable to be damaged by contact with other objects.
In order to'eliminate these drawbacks due to thermal factors and mechanical damage, an improved liquidtight multi-ply panel has been devised. One or more metal sheets or synthetic resin films serving as liquidtight membranes are arranged at suitable intervals within a panel consisting of a plurality of wood veneers, or such a liquid-tight membrane is bonded to the surface of a plywood panel and is then topped with a soft fibrous material bonded thereto. These constructions prevent heat shock due to direct contact between a low temperature liquid and the liquid-tight membrane, thereby preventing the separation and cracking of the membrane, permitting the whole low temperature purpose liquid-tight panel to expand and contract ideally, and precluding the possibility of the membrane being damaged during operation.
When liquid-tight panels of such construction are used to constitute the inner tank wall, it is necessary to maintain liquid-tightness between the adjacent edges thereof. However, as an arrangement for this liquidtightness, the mere bonding of a seal sheet between the adjacent abutting edges would not provide sufficient liquid-tightness because the low temperature liquid side of the panels is formed of a veneer or fibrous layer, permitting the liquid to permeate the layer and leak to the outside from between the adjacent edges.
With the above problems in mind, the object of the present invention is to completely prevent the leakage of liquid through a joint between low temperature purpose liquid-tight panels having no liquid-tight membrane exposed on the surfaces thereof.
The present invention provides a junction construction for use at a joint between the edges of a pair of multi-ply panels supported on joists to form a portion of the inner wall of a low temperature liquid storage tank, each panel having an interior ply formed by a low temperature resistant liquid-tight membrane; wherein, a patch member covers the joint and is secured by suitable fastening means to each of the panels and to a joist, a relieved portion is formed on the inner wall surface of each of the panels exposing the surface of the membrane thereof adjacent the sides of the patch member, and a low temperature resistant adhesive covers the patch member and the exposed surfaces of the membranes of the panels.
According to the above-described construction of the present invention, the liquid-tight membranes of the panels are continuously interconnected at the junction by the low temperature resistant adhesive to constitute a perfect liquid-tight barrier, with the result that the danger of liquid leaking through the junction is eliminated. Moreover, the liquid-tight membranes are prevented from contacting low temperature liquid even at the junction, so that it is possible to completely eliminate the drawbacks due to thermal factors and mechanical damage.
Other features and merits of the invention will be understood from the description to follow of the embodiments shown by way of example in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view in transverse section through the wall of a tank showing ajunction construction of the invention employing one type of multi-ply liquid-tight panel;
FIG. 2 is a transverse section of an embodiment of the invention using another type of liquid-tight panel; and,
FIGS. 3 and 4 are perspective sectional views showing other types of liquid-tight panels.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Multi-ply liquid-tight panels 1 shown in FIG. 1 are each constructed by bonding liquid-tight membranes 4a and 4b of low temperature resistant metal to both sides of a plywood unit 3 consisting of a plurality of veneers 2, and then bonding veneers 5a and 5b to the surfaces of said liquid-tight membranes 4a and 4b to serve as heat shock absorbing members. The veneer 5a of the panel 1 which will be in direct contact with low temperature liquid is cut away in advance over a predetermined width from the edge thereof to form a relieved portion exposing a band 6 of the surface of the membrane 4a. Connector joists 8 are disposed in a latticelike pattern within an ordinary steel plate outer wall 7 of a low temperature liquified gas storage tank so as to be in conformity with the size of the liquid-tight panels 1 and the joists 8 are secured to the outer wall through stay plates 9. The adjacent edge portions of such liquid-tight panels 1 are placed on one of the joists 8, and a connector patch member 12 is bonded to the outer side of said adjacent edge portions 10 over the bandlike exposed membrane surfaces 6 by means of an adhesive 11. The width of the patch member 12 is such that some areas of the band-like exposed membrane portions 6 are left uncovered on both sides of the patch member 12. Fastening means 13, such as nails, are driven through the patch member 12 into the joist 8 through both panels 1, thereby securing the adjacent edge portions 10 to the joist 8. Finally, a coating layer 14 of low temperature resistant adhesive is applied over the patch member 12 and the band-like exposed membrane surfaces 6 left uncovered on both sides of the patch member.
In FIG. 1, the numeral 15 designates a heat insulator, which is prepared either by injecting a foamable material into a space surrounded with a lattice-like enclosure defined by the connector joists 8 and stay plates 9, the outer wall 7 and the low temperature resistant liquid-tight panels 1 through openings in said latticelike enclosure, and allowing the material to foam in said space; or, by filling the lattice-like enclosure with a preformed heat insulator before the low temperature resistant panel 1 is secured in position.
As a result of the above construction, there is no exposed portion of the liquid-tight membranes 4a; direct contact of a low temperature liquified gas contained in the tank with the liquid-tight membranes 4a is positively prevented by the veneers 5a and the coating layers l4; and, the liquid-tight membranes 4a of adjacent panels 1 are liquid-tightly interconnected by the coating layers 14, so that there is no possibility that any liquid which has permeated the veneers 5a will leak through the junctions of the panels.
Further, when the liquid-tight panel 1 shown in the above embodiment is used, it is, of course, possible to prevent the separation and cracking of the membranes by absorbing the heat shock caused by direct contact between the inner wall of the tank and the low temperature liquid, and since the membranes 4a and 4b are symmetrically arranged with respect to the center of the panel and expand and contract approximately equally, such expansion and contraction of the membranes 4a and 4b will not result in warping the panel 1. Thus, the entire liquid-tight panel can ideally expand and contract.
In FIG. 1, single ply veneers 5a and 5b are bonded to the surfaces of the liquid-tight membranes 4a and 4b, but a laminate formed by a plurality of veneers may be bonded thereto as a heat shock absorbing material.
As for the method of interposing a membrane of low temperature resistant metal between veneers of plywood, a method may be employed wherein hot pressing is carried out with a resin-impregnated paper sheet interposed between the membrane and a veneer on each side thereof.
FIG. 2 shows a different embodiment of the invention. A liquid-tight panel used in this embodiment consists of two plywood layers 21a and 21b of approximately the same thickness with a liquid-tight membrane 22 of low temperature resistant metal interposed therebetween. If such a panel 20 were applied to the embodiment shown in FIG. 1, since the thickness of the plywood 21a working as a heat shock absorbing material with respect to the liquid-tight membrane amounts to about half the thickness of the panel 20, a bandwise cutting away of the plywood 21a for placing a connector patch member on the cut away area would result in the adjacent edge portions of the panels being too thin, thus presenting a problem of strength. Therefore, as shown in FIG. 2, a connector patch member 23 is bonded directly to the surfaces of adjacent panels 20 by an adhesive, and the adjacent edge portions 25 of the panels 20 are secured to a connector joist 26 by fasteners 24. on both sides of said patch member 23, grooves 27 reaching the liquid-tight membranes 22 are provided in the plywood 21a parallel to the patch member 23. Each groove 27 is filled with a low temperature resistant adhesive 28 so as to be in contact with the liquid-tight membrane 22, and a coating layer 29 of low temperature resistant adhesive covering the patch member 23 is united with said low temperature resistant adhesive 28, thereby interconnecting the panels 20 in a liquid-tight manner without involving any problem of strength.
Further, as in the embodiment shown in FIG. 2, by placing the liquid-tight membrane centrally of the panel, it is possible to avoid heat shock caused by direct contact of the membrane with low temperature liquid, and, moreover, in spite of the use of a single membrane there is no possibility that warping of the panel will take place due to the expansion and contraction of said membrane.
FIGS. 3 and 4 show other embodiments of liquidtight panels useable in the present invention. In FIG. 3, a liquid-tight panel 30 is constructed by bonding liquidtight membranes 33a and 33b of low temperature resistant metal or synthetic resin to both sides of plywood 32 consisting of a plurality of layers of veneers 31 and then bonding a soft fibrous material 34 of suitable thickness serving as a heat shock absorbing material to the outer side of one membrane 33a. The fibrous material may be a wood fiber plate, a thick fabric, a laminated thin fabric, a rug or the like.
Although the low temperature liquid permeates the fibrous material 34 when the fibrous material 34 forms the inner side of the tank, permeation beyond the same is prevented by the liquid-tight membrane 33a. Therefore, heat shock caused by direct contact between the liquid-tight membrane 33a and the low temperature liquid can be avoided by the fibrous material 34, so that there is no possibility of the membrane 33a coming off or cracking. Further, since the liquid-tight membranes 33a and 33b are positioned on both sides of the plywood 32 and expand and contract approximately equally, there will be no possibility that the plywood will warp as a result of the expansion and contraction of the membranes 33a and 33b.
A liquid-tight panel 40 shown in FIG. 4 is constructed by interposing two or more layers of low temperature resistant resin-impregnated paper sheets 43 between plywood veneers 41 and 42 and subjecting the assembly to a hot press process. In this liquid-tight panel, the thermal stresses produced in the liquid-tight membranes are very small as compared with the case of using a low temperature resistant metal sheet, so that the plywood will not warp. Further, the low temperature resistant resin-impregnated paper sheets 43 are easy to bring into close contact with the plywood veneers, so that the production of the liquid-tight panel is facilitated.
l. A junction construction for use at a joint between the edges of a pair of multi-layer panels supported on joists to form a portion of the inner wall of a low temperature liquid storage tank, each panel having an interior layer formed by a low temperature resistant liquid-tight membrane, said junction construction comprising:
a patch member covering the joint, and fastening means securing the patch members to each of the panels and to the joist;
a relieved portion formed on the inner wall surface of each of the panels exposing the surface of the membrane thereof adjacent the sides of the patch member; and
a low temperature resistant adhesive covering the patch member and the exposed surfaces of the membranes of the panels.
2. A junction construction as set forth in claim 1 wherein said relieved portion comprises a band of exposed membrane surface extending inwardly from the adjacent edges of each of the panels, each band being partially covered by the patch member and the remainder of the exposed membrane surface of each band being covered by the low temperature resistant adhesive.
3. A junction construction as set forth in claim 1 wherein said relieved portion comprises a groove cut in the inner wall surface of each of the panels a distance from the adjacent edges thereof such that the patch member extends parallel to the grooves and within the area bounded thereby.