US3137044A - Insulation structure - Google Patents

Description

June 16, 1964 Filed June 23, 1958 c. D. DOSKER 3,137,044

INSULATION STRUCTURE 2 Sheets-Sheet l w L W WI INVENTOR. Cornehus D. (Dosker WLMYW ATTorneqs June 16, 1964 c. D. DOSKER INSULATION STRUCTURE 2 Sheets-Sheet 2 Filed June 25, 1958 INVEN TOR. Cornehus D.Dosker- BY @MWAWM z wmym Afforneqs United States Patent 3,137,044 INSULATHON STRUCTURE Cornelius D. Dosker, Louisvilie, Ky,, assignor, by mesne assignments, to Conch'lnternational Methane Limited, Nassau, Bahamas, a corporation of the Bahamas Filed June 23, 1958, Ser. No. 743,539 1 Claim. (Cl. .2092) This invention relates to the fabrication of an insulated space of substantial dimension for receiving tanks of large capacity housing liquids which need to be maintained at extremely low temperature, and it relates more particularly to elements employed in combination with prefabricated panels ofinsulation material to build up an insulation which is continuous in its coverage of a sup porting walldefining the space, and which, in combination with the insulation panels, provides a continuous liquid impervious surface to prevent the escape or penetration of liquid in the event such cold liquid comes in contact therewith.

The concepts of this invention will be described with reference to operation with a liquefied natural gas housed in large volume at or slightly above atmospheric pressure in large tanks of aluminum, alloys of aluminum,

copper, stainless steel, or other austenitic steels or metals capable of retainingstrength and ductility at the low temperatures of the liquefied natural gas housed therein. It. will be understood that the same concepts can apply regardless of the character of the liquid as long as it is necessary to insulate the space in which the storage tanks are located to minimize heat loss into the liquid which otherwise would cause excessive vaporization thereof.

Liquefied natural gas is formed mostly of methane which boils at 258 F. at atmospheric pressure. However, liquefied natural gas will usually boil at a somewhat higher temperature because of the presence of heavier hydrocarbons, the increase in boiling point depending upon the type and amount of such heavier hydrocarbons, but the boiling point will usually lie within the range of about 240 F. to 258 F. It is desirable to transport the gas in a liquefied state because the liquid phase occupies about ,4 of the volume of the corresponding amount of gas in the gaseous phase thereby to make it practical to transport the gas from a source of plentiful supply to an area Where a deficiency exists, especially where such areas are separated by a large body of 'water 'to require ship transportation.

It' will be apparent that, because of the large tempera ture differential between the liquefied gas and the ambient atmosphere, some heat loss into the liquid will naturally take place, and it is desirable to minimize the heat loss as much as possible to prevent excessive loss of the gas by vaporization or to reduce the cost and size of equipment for reliquefaction. Thus, it is essential to insulate the space in which the liquid carrying tanksare housed for storage or transportation.

Where the space to be insulated is of substantial dimension, as in the hold of an ocean-going vessel, for transportation of the gas from a source of plentiful supply, Where it is liquefied, to an areawhere a deficiency exists, where the liquid is revaporized, it has been established that the most practical way to insulate the space is to prefabricate panels of substantial dimension of the insulating material, such as panels of 4 x 8' x 1.5, or

t 8' x 8' x 2', and to mount the prefabricated panels on a supporting wall which defines the storage space.

Reference may be made to my co-pending application filed concurrently herewith and now abandoned entitled, Insulation Panels for Thermally Insulating a Storage Space, Serial No. 743,541, filed June 23, 1958, for a description of a panel of the type contemplated for mounting upon the wall and the means for mounting such panels 3,137,044 Patented June 16, 1964 thereon. Reference can also be made to my copending application, Serial No. 646,001, filed March 14, 1957, entitled, Heat-Insulated Wall and Tank Construction, of which this application is va continuation-impart.

Briefly described, such prefabricated insulation panel comprises an insulation section of substantial thickness sandwiched between inner and outer face plys preferably formed of structurally strong plywood panels. The inner face ply may instead be formed of a metallic sheet or foil, or it may be fabricated to embody a continuous sheet of metal as one of the plys of the plywood panel. The outer face ply is adapted to be structurally strong for positioning onto the supporting wall, as described in the aforementioned co-pending applications. The insulation section may be formed of a low density wood, such as balsa wood, quippo, or the like, or of a honeycombed structure formed of paper, veneer or the like, or of a foamed or molded glass or ceramic which is capable of standing up under the extreme temperature conditions existing.

Although the panels may be mounted on the wall so that the edges of one are in contacting relation with the edges of the adjacent panels to obviate the formation of a space relationship therebetween, it will be apparent that when the cold boiling liquid or other material which needs to be maintained at extremely low temperature is introduced into the insulated space, as upon filling the tanks, contraction will naturally occur in the panels as they are reduced in temperature-the amount of contraction being somewhat proportionate to the temperature drop through the cross section thereof. Such contraction will naturally cause a space relationship to develop between the panels through which heat can flow from the ambient atmosphere to the tanks, and through which liquid coming in contact with the insulation may flow to the supporting wall to cause possible breakdown thereof, or to cause a development of other extremely dangerous conditions.

Thus, it is an object of this invention to produce and to provide a method for producing and mounting and maintaining a sealing relationship between the insulation panels mounted upon the supporting wall, which sealing relationship can be maintained through limitless cycles of filling and emptying of the tanks with the cold boiling liquid.

These and other objects'and advantages of this invention will hereinafter appear, and for purposes of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawings in which FIGURE 1 is a vertical view in cross section of adjacent portions of panels as assembled on a supporting wall;

FIGURE 2 is a sectional view similar to that of FIG- URE 1 illustrating the preparation of the panels for receiving a sealing member therebetween;

FIGURE 3 is a perspective view of the wedge insert employed in the practice of this invention;

FIGURE 4 is a perspective view of a modification of the wedge member shown in FIGURE 3;

FIGURE 5 is a sectional view similar to that of FIG- URES 1 and 2 showing the wedge inposition of use between the panels;

FIGURE 6 is a perspective view of an expansion joint employed in the practice ofthis invention; and

FIGURE 7 is a sectional view similar to that of FIG- URES 1, 2 and 5, showing the expansion joint in the position of use in the assembly. 7

In the drawings illustrating the practice of this invention, the numeral 10 represents a supporting Wall which may be the hull of a ship, or inner hull of a double-walled ship defining the hold space, or it may be the wall of a large housing for a land storage tank or the like. The prefabricated insulation panels, which are indicated by the numeral 12, are shown as 4' x 8 panels of rectangular shape. Instead, the panels may be of other interfitting polygonal shape and they may be flat or angled, depending upon the contour of the wall to becovered. The panels are of substantial thickness, usually formed of an outer face 14 and an inner face 16 of plywood, plastic or metal laminate as previously described, with a thick layer 18 of a low density wood or other insulating material in between. The panels 12 are secured, by the supporting wall in side by side and end to'end relation substantially completely to cover thesurface to insulate the space that is defined thereby. Attachment may be efiected by bolt and nut means as described in the aforementioned copending applications.

In effecting a sealing relation between the panels which will permit relative movement of the panels in a planar direction with the face responsive to expansion or contraction, it is desirable to make use of a joint which is capable of attachment to adjacent surfaces of the panel and which is also capable of movement with the adjacent surfaces under the cold temperature conditions existing at the inner face without breakdown and without separation. i

For this purpose, use is made of a length 20 of thermal insulating material or other rather flexible or resilient, heat insulating material. The length is formed to wedge shape in cross-section with a central slot 22 cut into the wedge from the outer edge of larger dimension to a distance just short of the apex to subdivide the wedge lengthwise into a pair of laterally spaced legs 24 and 26. This enables the leg sections to be flexed in a direction toward and away from each other while remaining joined in sealing relation at their outer ends. The wedge 20 can be formed of a low density wood, such as balsa wood, quippo, foamed plastics and the like materials, which are capable of retaining sufficient resiliency and flexibility under the temperature conditions existing to enable flexure of the sections 24 and 26 without causing separation through the remainder of the wedge. To improve the mass integrity of the wedge and its strength and resiliency, it is desirable to fix a ply of a high strength material to the outer surface of the wedge, such, for example, as a wooden veneer 28, as illustrated in FIGURE 3, or preferably a coating 39 of a polyester or the like resin reinforced with one or more plys 32 of glass fibres or other high strength fibre in fabric form.

After the insulation panels 12 are assembled in the desired relation on the supporting wall It), the outer edges of the panels are routed out or otherwise formed to provide a groove 34 therebetween which corresponds in cross section with the cross section of the wedge 20 but is preferably formed to have a width which is slightly less than the normal width of the wedge so as to require the wedge to' be rammed into the groove with sufiicient force to squeeze the wedge and substantially close the slot 22, as indicated in FIGURE of the drawing.

Adhesive 36 is applied to the outer side walls of the wedge 20 with the adhesive preferably limited to the area inwardly of the endof the slot 22, or adhesive can be applied to the surface of the panels adapted to be engaged by the corresponding portions of the side walls of the wedge, or adhesive can be applied to both of the surfaces to bond the lateral surfaces of the wedge to the adjacent surfaces of the panels whereby one side of the wedge becomes secured in sealing relation to one of the panels while the other side of the wedge becomes secured in sealing relation to the other panel throughout the lengths therebetween. Thus, as one panel contracts in the direction away from the other, the respective sides of the wedge move with the panels resulting in a spread between the sections 24 and 26 about the joining base 38 as the pivot. It is for this reason that it is desirable to bond the side walls of the wedge to the panelsin areas limited to be outwardly from the base of the wedge, otherwise the spreading forces would extend through the entire depth of the wedge to cause separation therein. The reinforcing and flexibilizing ply 28 or 32 helps greatly in providing flexibility in the sections to enable the legs 24 and 26 to be spread without separation to destroy the sealing connection between the panels.

While the wedge provides a sealing relation between the adjacent panels, the necessity to enable relative movement between the sections24 and 26 of the Wedge makes it diflicult to embody a barrier to the penetration of liquid which might come in contact with the inner surfaces of the insulation. Thus, another concept of this invention resides in the combination with the wedge of a vapor and fluid impervious expansion joint which does not interfere with the operation of the wedge yet provides a liquid seal between the panels. 7 7

It would not be expected that a material stretchable at ordinary temperature could be used for this purpose because very few materials would remain stretchable at the extremely low temperature of about 200 F. or less. In accordance with the practice of this invention, the desirable results are achieved by the use of an elongated strip 40, of a fluid impervious sheet of material formed to have a bulbous portion 42 extending lengthwise throughout the central portion thereof with flat flaps 44 and 46 extending outwardly fromthe bulbous portion for a distance greater than the space relationship between the panels. The strip can be formed of a plastic material which is fluid, andpreferably also vapor impervious, and which is capable of standing up under the cold temperatures existing. It can be formed of a Wood, veneer, or of metal formed to the desired shape, but it is desirable to mold the expansion strip of a curable resin ous material, such as a polyester resin or a polyurethene, or a polyisocyonate resin or the like, reinforced and flexibilized with glass fibres or other high strength fibres in fabric form.

The expansion strip 49 can be mounted on the panels with the bulbous portion 42 extending inwardly in the direction away from the surface of the panels but this might be undesirable because the bulbous portion would extend into the storage space to be occupied by the tanks. Thus, it is preferred to arrange the strip 4t? in a position of usewith the bulbous portion 42 extending outwardly into an area between the insulation. For this purpose, a groove 48 is. provided Within the inner face of the wedge 20 dimension to receive the bulbous portion in a substantially fitting relation therein. In assembly, adhesive 50 is applied to the outer surfaces of the flaps 44 and 46 inthe areas adapted to abut against the inner faces of the adjacent panels to efiect a sealing relation therebetween. The length of the strip overlying the wedge is kept free of adhesive so that the expansion strip will be free to move independently of the wedge.

Thus, as the panels contract and increase the space relation therebetween, the bulbous portion 42 will be shallowed by an amount to provide the additional width to the strip to enable movement of the bonded sections of the strip with the panels to maintain the fluid tight seal therebetween. At the same time, the sections 24 and 26 of the Wedge will be able to spread with the panel walls to maintain joinder therebetween. Upon expansion of the panels, the decreased width of the expansion strip can be compensated by outward flexure of the bulbous portion, while at the same time, the sections 24 and 26 of thke1 wedge can be flexed in the direction toward each 0t er.

It will be apparent from the foregoing that I have provided a simple and efficient means for maintaining a blocking relation and a fluid-tight sealing relationship between the adjacent prefabricated panels when mounted in their assembled relationship on a supporting wall. It will be understood that various changes may be made with respectto the materials employed in the practice of 5 this invention and in the construction and operation of the elements, without departing from the spirit of the invention especially as defined in the following claim.

I claim:

Means for maintaining a continuous seal between prefabricated insulation panels of large dimension mounted in side-by-side relation on a supporting wall and which are subject to substantial reduction in temperature from the temperature of installation to the temperature of use with corresponding reduction in dimension due to contraction, comprising a groove in the adjacent outer edges of adjacent panels defining a continuous recess therebetween, a spline having a cross-section corresponding to the cross-section of the recess and filling the recess formed between the panels, said spline being formed with a recess in the upper surface thereof and a slot extending from the lower portion of the recess and extending centrally of the spline for a distance short of the bottom of the spline whereby the connecting portion at the bottom of the spline resiliently connects the portions of the spline separated by the slot, the side walls of the spline being bonded to the adjacent walls of the panel in an area corresponding to the slotted sections, an expansion joint in the form of an elongate strip of fluid impervious material having a central bulbous portion and being dimensioned to have a width bonding the portion overlying the panels to the underlying surfaces of the panels.

References Cited in the file of this patent UNITED STATES PATENTS 1,009,987 Murray Nov. 28, 1911 1,622,311 Fischer Mar. 29, 1927 1,890,954 Snyder Dec. 13, 1932 1,965,403 Alvey July 3, 1934 2,073,665 Welch Mar. 16, 1937 2,091,061 Waugh Aug. 24, 1937 2,100,238 Burgess Nov. 23, 1937 2,220,628 Stedman Nov.-5, 1940 2,731,374 De Reus Ian. 17, 1956 2,835,938 McElroy May 27, 1958 2,855,636 Donnelly Oct. 14, 1958 2,863,180 Birdwell Dec. 9, 1958 2,863,185 Ried Dec. 9, 1958 FOREIGN PATENTS 17,164 Great Britain Dec. 31, 1914

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