US3167412A - Dry-seal pressure-type gasholders - Google Patents

Description

Jan. 26, 1965 F. w. HORNER, JR 3,167,412

DRY-SEAL PRESSURE-TYPE GASHOLDERS Filed Feb. 16, 1962 2 Sheets-Sheet 1 ,1; INVEIJTOR WALTER HORNE/i, JR.

& ATTYS.

Jan. 26, 1965 F. w. HORNER, JR

DRY-SEAL PRESSURE-TYPE GASHOLDERS 2 Sheets-Sheet 2 Filed Febl6, 1962 ili vvliilltil'flililiilli INVENTOR.

E WALTER HORN/FR, JR.

,5 p & ATTYS.

United States Patent Ofiice 3,167,412 Patented Jan. 26, 1965 3,167,412 DRY-SEAL PRESSURE-TYPE GASHOLDERS Frank Walter Horner, Jr., Park Ridge, 111., assignor to General American Transportation Corporation, Chicago, 111., a corporation of New York Filed Feb. 16, 1962, Ser. No. 173,696 14 Claims. (Cl. 48-174) The present invention relates to dry-seal pressure type gasholders, and more particularly to improved diaphragms for such gasholders.

A dry-seal pressure-type gasholder conventionally comprises a container including an upstanding substantially cylindrical shell or side Wall, a substantially disk-shaped piston arranged in the container and movable in the vertical direction, an upstanding substantially cylindrical fender carried by the piston adjacent to the circumference thereof and spaced radially inwardly with respect to the shell to provide an annular space therebetween, and an annular curtain-like gas-impervious flexible diaphragm arranged in an upwardly directed annular loop in the annular space. In the arrangement, the diaphragm includes an annular outer wall sealed adjacent to the bottom thereof to an annular portion of the shell, an annular inner wall sealed adjacent to the bottom thereof to an annular portion of the piston, and an annular connecting wall extending between the top of the outer wall and the top of the inner Wall, whereby the gas pressure in the container presses the outer wall into firm engagement with the inner surface of the shell and presses the inner wall into firm engagement with the outer surface of the fender. When the piston rises in the container, the material in the diaphragm is fed from the inner wall through the connecting wall into the outer wall; and conversely, when the piston falls in the container, the material in the diaphragm is fed from the outer wall through the connecting wall into the inner wall. Since the circumferential length of the inner surface of the shell is necessarily greater than the circumferential length of the outer surface oflthe fender, the outer wall of the diaphragm has a tendency to have a circumferential length that is greater than thatof the inner wall of thediaphragm; with the result that folds, wrinkles and creases tend to form across the looped part of the diaphragm. This condition of the diaphragm is most objectionable as it leads to early puncture and mechanical failure of the diaphragm in the normal operating cycle of the piston. In order to prevent such wrinkling of the material in the diaphragm as it is fed between the outer and inner walls thereof, many elaborate constructions of the diaphragm and of the associated fender have been employed heretofore, as disclosed in US. Patent No. 2,723,908, granted on November 15, 1955, to John H. Wiggins, John W. Allen and F. Walter Homer, and in US. Patent No. 2,756,132, granted on July 24, 1956, to John H. Wiggins. While these arrangements are reasonably satisfactory in the operation of the gasholder, they are entirely too expensive to manufacture and to maintain in service.

Accordingly, it is the general object of the present invention to provide in a gasholder of the type described, an improved and simplified diaphragm that is economical to manufacture and that requires no external devices or appliances to prevent wrinkling of the material therein incident to the feed of the material in the diaphragm between the outer and inner walls thereof.

Another object of the invention is to provide in a gasholder of thetype described, an annular flexible diaphragm arranged in an upwardly directed annular loop in the annular space between the shell of the container and the fender carried by the piston arranged therein,

wherein the diaphragm has an unstrained circumferential length Cd that is less than the inner circumferential length Cs of the shell and that is greater than the outer circumferential length Cf of the fender, whereby the gas under pressure in the container produces circumferential tension strains in the material in the outer wall of the diaphragm so as to stretch the same to a circumferential length substantially equal to Cs without effecting wrinkling thereof and so as to press the thus stretched outer wall into firm engagement with the inner surface of the shell, and whereby the gas under pressure in the container produces circumferential compression strains in the material in the inner wall of the diaphragm so as to compress the same to a circumferential length substantially equal to C without effecting wrinkling thereof and so as to press the thus compressed inner wall into firm engagement with the outer surface of the fender, with the result that the vertical movement of the piston elfeets the feed of the material of the diaphragm between the outer wall and the inner wall through the connecting wall and the consequent reversal of the circumferential strains in the material thus fed.

' A further object of the invention is to provide in a gasholder of the type described, a diaphragm of improved composite construction, whereby the same possesses as inherent characteristics thereof the previously described elastomeric qualities.

A still further object of the invention is to provide a diaphragm for a, gasholder, wherein the diaphragm is of composite sandwich construction including an inner layer of material in contact with the gas stored in the container and an outer layer of material in contact with the atmosphere, wherein the materials of the two layers mentioned are especially selected for the special properties thereof that render them substantially ideally. suited to the environmental operating conditions respectively encountered thereby, and wherein the materials of the,

two layers mentioned are so coordinated that the diaphragm as a whole possesses the previously described elastomeric qualities. 1

A further object of the invention is to provide a diaphragm of the type described that essentially comprises a gas-impervious inner layer and a resilient outer layer intimately bonded together, wherein the inner layer is formed of elastomeric organic material that is chemically inert to the gas stored in the container and that is char.- acterized by substantial stretchability in the circumferential direction of the diaphragm, and wherein the outer layer is formed of elastomeric organic material that is resistant to atmospheric gases and to water vapor and that is characterized by both substantial stretch-ability and substantial compressibility in the circumferential direction of the diaphragm.

A further object of the invention is to provide a diaphragm of the type described that further comprises an intermediate layer of adhesive firmly securing together the inner and outer layers noted, wherein the intermediate layer is formed of organic material that is characterized by substantial flexibility after setting thereof. 7

Yet another object of the invention is to provide a diaphragm of the type described, wherein each of the layers noted essentially comprises an elastomeric material that is in the form of a synthetic rubber or a synthetic organic resin having the general properties of a synthetic rubber.

A further object of the invention is to provide in a gasholder, a diaphragm of the type described that incorporates a textile fabric that is elastic and that is characterized by exceedingly great tensile strength in the radial direction between the outer and inner perimeters thereof that are respectively sealed to the shell and to the piston in the gasholder.

A still further object of the invention is to provide a gaspiston type including a number of nested pistons movable in the vertical direction and also including a corresponding numberof flexible diaphra'gms of the type specified.

Further features of the invention pertain to the particular arrangement of the elements of the gasholder and of the diaphragm incorporated therein, whereby the above-outlined and additional operating features thereof are attained. p I

The invention, both as it is organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the follow ing specification, taken in connection with the accompanying drawings, in which: 7

FIGURE 1 is a fragmentary plan view, partly in horizontal section, of a dry-seal pressure-type gasholder incorporating a diaphragm embodying the present invention;

FIG. 2 is a fragmentary vertical sectional view of the gasholder, this view being taken in the direction ofthe arrows along the line 2-2 in FIG. 1;

FIG. 3 isa fragmentary vertical sectional view, similar to FIG. 2, of a modified form of the gasholder that is provided with the two nested pistons and incorporating FIG. 6 is a greatly enlarged sectional view, similar to gasholder 10 there illustrated and embodying the features of the present invention comprises a container 11 that includes an upstanding substantially cylindrical outer wall or shell 12, a substantially disk-shaped bottom wall or .floor 13 and av substantially cone-shaped top wall or roof 14; which container 11 is adapted to contain and to store under pressure such gases as natural gas, light petroleum gases,.coke oven gas, etc. The stored gases have a wide variety of compositions; for instance, coke oven gas essentially comprises methane','hydrogen, carbon dioxide, carbon monoxide, hydrogen sulfide, oxygen, nitrogen and aromatic compounds including benzene, toluene and pyridine, and adulterant compounds such as carbon disulfide and mercaptan sulphur. Also, the gasholder 10 comprises a substantially disk-shaped piston 15 arranged in the container 11 and movable in the vertical direction; which piston 15 carries adjacent to the circumference thereof an upstanding substantially cylindrical fender 16 that is spaced radially inwardly with respect to the shell 12 to provide an annularspace 17 therebetween.

An annular curtain-like gas-impervious flexible diaphragm 20 is arranged in an upwardly directed annular loop in the annular space 17; andthe diaphragm 20 essentially comprises an annular outer Wall 21 and an annular inner wall 22 and an annular connecting wall 23. The bottom of the outer wall 21 is sealed to an annular portion of the shell 12 by an associated annular sealing bar 31; and the bottom of the inner wall 22 is suitably sealed to an annular portion of the piston 15 adjacent to the bottom of the fender 16. The top of the outer wall 21 integrally joins the outer looped portion of the connecting wall 23; and the top of the inner Wall 22 interally joins the inner looped portion of the connecting wall 23. The gas contained in the gasholder 10 is stored under pressure in the lower portion of the container 11 below the piston 15 and the diaphragm 20; whereby the lower or inner side of the diaphragm 20 is in cont-act with the stored gas. The upper portion of the container 11 above the piston 15 and the diaphragm 20 is vented to the atmosphere, usually through a series of vent devices, not shown;

whereby the upper or outer side of the diaphragm 20 isin contact With the atmosphere.

When the container 11 is empty of stored gas, the piston 15 occupies its lower portion, as illustrated in full lines in FIG. 2; when the container 11 is full of stored gas, the piston 15 occupies its upper position, as illustrated in broken lines in FIG. 2; and when the container 11 is partially full of stored gas, the piston 15 occupies an appropriate intermediate position with respect to its lower and upper positions noted. The piston. 15 in its lower position is supported on the floor 13; and the piston 15 in its upper position is disposed near the roof 14, the upper position of the piston 15 being established by a volume control safety vent, not shown. In the operation of the piston 15 in thevertical direction between its lower and upper positions, a substantially constant pressure is maintained upon the stored gas in the container 11; which pressure of the stored gas is normally held or maintained at about 20 water gauge. Also the gas under pressure stored in the container 11 forces the diaphragm 20 into its upwardly directed annular loop-like configuration, so as to press the outer wall 21 of the diaphragm 20 into firm engagement with the adjacent portion of the inner surface of the shell 11 and so as to press the inner wall 22 of the diaphragm 20 into firm engagement with the adjacent portion of the outer surface of the fender 16. As the piston 15 falls in the container 11, the material in the outer Wall 21 of the diaphragm 20 is fed-off of the inner surface of the shell 12 through the connecting wall 23 into the inner wall 22 and is thus pressed into firm engagement with the outer surface of the fender 16. Conversely, as the piston 15 rises in the container 11, the material in the inner wall 22 of the diaphragm 20 is fedoff of the outer surface of the fender 16 through the connected wall 23 into the inner wall 21 and is thus pressed into firm engagement with the inner surface of the she1l12. In the gasholder 10, the shell 12 has an inner radius Rs, 'as illustrated in FIG. 2, and a corresponding inner circumferential length Cs. Similarly, the fender 16 has an outer radius Rf, as illustrated in FIG. 2, and a corresponding outer circumferential length C The diaphragm 20 has an unstrained radius Rd, as illustrated in FIG. 2, anda corresponding unstrained circumferential length Cd. In the arrangement, the relationship exists: 1

Cs Cd Cf the container 11 produces circumferential tension aSCl compression strains in the material in the walls of the diaphragm 20 as the verticalmove'ment of the piston 15 effects the feed of the material of the diaphragm 20 between the outer wall 21 and the inner wall 22 thereof through the connecting wall 23 thereof and the consequent reversal of the circumferential strains in the material of the diaphragm '20 thus fed.

In a very small gasholder 10 of about 50 cu. ft. Cs is equal to about 104% of Cf, whereas in a relatively large gasholder 10 of about 5,000,000 cu. ft. Cs is equal to about IOU/4% of C The unstrained circumferential,

length Cd of the diaphragm 20 is equal to about /2 (Cs-f-Cf); whereby the material of the diaphragm 20 is.

' stretched circumferentially by about 0.6% to about 2% of Cd and is compressed circumferentiallytby the same percentages all without inducing wri kles aC looped portion of the diaphragm 20. v I

In constructing the gasholder 10, the diaphragm 20 is fabricated from a plurality of straight runs of material into a composite ring having a total internal circumferential length and a total external circumferential length of approximately Cd in unstrained condition of the material. The thus fabricated diaphragm 20 has an inner side and an outer side that are different from each other, as explained more fully hereinafter; whereby the composite diaphragm 20 is then placed in the annular space 17 between the shell 12 and the fender 16 and with the inner side in downward position so that ultimately it will be in contact with the gas stored in the container 11. The bottom of the outer wall 21 of the diaphragm 20 is suitably stretched to the circumferential length Cs and is suitably secured to the shell 12 appropriately above the floor 13, utilizing the sealing bar 31. The bottom of the inner wall 22 of the diaphragm 20 is then suitably compressed to the circumferential length Cf without inducing wrinkles across the looped portion of the diaphragm 20 and is suitably secured to the piston 15 adjacent to the bottom of the fender 16. Accordingly, at this time, the bottom of the inner wall 22 is compressed with respect to the unstrained circumferential length Cd thereof and into the circumferential length Cf, while the bottom of the outer wall 21 is stretched with respect to the unstrained circumferential length Cd thereof and into the circumferential length. Cs, without inducing wrinkles in the diaphragm 20. Subsequently, when the gas to be stored in the container 11 is introduced thereinto below the piston 15 and the diaphragm 20, the diaphragm 20 is blown into its normally upwardly directed annular looplike configuration, as shown in FIG. 2. At this time, the remainder of the outer wall 21 of the diaphragm 20 is stretched to the circumferential length Cs and is pressed into firm engagement with the inner surface of the shell 12, and the remainder of the inner wall 22 of the diaphragml-U is compressed to the circumferential length Cf and is pressed into firm engagement with the outer surface of the fender 16, all without inducing wrinkles in the diaphragm 20.

Referring now to FIG. 3, the modified form of the gasholder 110 there illustrated is basically the same as the gasholder 10, as described above in conjunction with FIGS. 1 and 2 except that in this case, the piston is of composite construction including two piston sections 115A and 115B arranged in nested relation. More particularly, the outer piston section 115A is spacedradially inwardly with respect to the shell 112 of the container 111 and the inner piston section 11513 is spaced radially inwardly with respect to the outer piston section 115A. The outer piston section 115A carries an upstanding substantially cylindrical fender 116A, and theinner piston section 115B carries-an upstanding substantially cylindrical fender 116B. Also, the diaphragm is of composite construe:

tionincluding two diaphragm sections 126A and 120B arranged in nested relation. Specifically, the outer diaphragm section 120A is arranged betweenthe inner surface of the shell 112 of the container 111 and the outer surface of the outer fender 116A; while the inner diaphragm section 12013 is arranged between the inner surface of the outer fender 116A and the outer surface of the inner fender 1163. Accordingly, the outer diaphragm section 12tlA includes an annular outer wall 121A that is sealed adjacent to the bottom thereof to an annular portionof the shell 112, an annular inner wall 122A that is sealed adjacent to the bottom thereof to an annular portion of the outer piston 115A, and an annular connecting wall 123A extending between the top of the outer wall nular inner wall 122B that is sealed adjacent to the bottom thereof to an annular portion of the inner piston B,

and an annular conecting wall 123B extending between the top of the outer wall 121B and the top of the inner wall 122B.

The inner piston 11513 has a lower position, illustrated in full lines in FIG. 3, wherein it is supported upon the floor 113 of the container 111; and the outer piston 115A has a lower position illustrated in full lines in FIG. 3, wherein it is supported upon associated structure 134 carried jointly by the floor 113 and by the shell 112 of the container 111. Also the inner piston 115B has an upper position shown in broken lines in FIG. 3, wherein it is disposed entirely within the upper portion of the outer piston 115A; and the outer piston 115A has an upper position shown in broken lines in FIG. 3, wherein it is disposed adjacent to the roof 114 of the container 111 as established by the volume control safety valve, not shown.

In the operation of the gasholder 110,, when the gas to be stored is first admitted into the container 111 below the piston sections 115A and 115B and below the diaphragm sections 12A and B, the inner piston section 115B first rises within the outer piston section 115A and into its upper position, as shown in broken lines in the middle of FIG. 3. At this time, further upward move- 1 ment of the inner piston section 115B relative to the outer the container 111. When the lower portion of the container 111 is completely full of the gas to be stored, the outer piston section 1115A is moved into its upper'position carrying the inner piston section 115B therewith and into the positions as shown in broken lines at the top of FIG. 3. i

In the gasholder 110, the shell 112 has an inner radius of Rs and a corresponding inner circumferential length of Cs; the outer fender 116A has an outer radius of Rlfo and a corresponding outer circumferential length of Clyo; the outer fender 116A has an inner radius of Rlfi and a corresponding inner circumferential length of Clfi, the inner fender 11613 has an outer radius of R2f0 and a corresponding outer circumferential length of CZfo; the outer diaphragm section 1253A has an unstrained radius Rld and a corresponding unstrained circumferential length Cld; and the inner diaphragm section 126B has an unstrained radius RZd and a corresponding unstrained circumferential length C2d. In the gasholder 116, Cs is equal to about 101% to about 104% to Clfo, and Clfi is equal to about 101% to about 104% of C2fo. Cld is equal to about /z(Cs-}-Cl 0) and C2d is equal to about The mode of constructing the gasholder lltl is substantially the same as that employed in constructing the gasholder 1% as previously described Specifically, the bottom of the outer wall 121A of the outer diaphragm section 120A is stretched circumferentially from about 0.6% to about 2% of the unstrained circumferential length Cld and is sealed to the adjacent annular portion of the shell 112; and similarly, the bottom of the inner wall 122A of the outer diaphragm section 120A is compressed circumferentially by about 0.6% to about 2% of the unstrained circumferential length Cld thereof, without inducing wrinkles across the loop of the material and is sealed to the adjacent annular portion of the outer piston section 115A. Specifically, the bottom of the outer wall 121B of the inner diaphragm section 120B is stretched circumferentially by about 0.6% to about 2% of the unstrained circumferential length C2d thereof and is sealed to the adjacent annular portion of the outer piston 115A; and similarly, the bottom of the inner Wall 1228 of the inner diaphragm section 12913 is compressed circumferentially by about 0.6% to about 2% of the unstrained circumferential length C2d thereof, without inducing wrinkles across the loop of the material and is sealed plasticity, after setting thereof.

2 to the adjacent annular portion of the inner piston section 115B.

' Referring now to FIG. 4, there is shown a cross section of a body of diaphragm material 420 that is particularly suitable for the fabrication of the diaphragm 2% in the gas holder of FIGS. 1 and 2, and for the fabrication of the diaphragm sectionslZtlA and 1203 in the gasholder 110 of FIG. 3; which body of diaphragm material 420 is of composite sandwich construction including a gas-impervious inner layer 425 and a resilient outer layer 426 intimately bonded together by an intermediate layer of adhesive 427. The inner layer 425 is formed of a sheet of elastomeric organic material that is chemically inert to the gas that is stored in the container of the gasholder and that is characterized by substantial stretchability in the circumferential direction of thc ultimately fabricated diaphragm; the outer layer 426 is formed of a body of elastomeric organic material of cellular structure that is resistant to atmospheric gases and to Water vapor and that is characterized by both substantial stretchability and substantial compressibility in the circumferential direction of the ultimately fabricated diaphragm; and the intermediate layer 427 is formed of a film of any suitable adhesive material that is characterized by substantial elasticity and flexibility after setting thereof. More particularly, the inner layer 425 essentially comprises a textile-reinforcing fabric 425a that issuitably embedded in a'body 425b of synthetic rubber or synthetic organic resinhaving the general properties of rubber; while the outer layer 426 essentially comprises a cushion or mattress of foamed synthetic rubber or synthetic organic resin having the general properties of foamed rubber; and the intermediate layer essentially comprises a synthetic rubber adhesive or asynthetic organic resin adhesive having' the general properties of a rubber adhesive.' Preferably, the textile fabric 425a comprises cords that extend between the inner and outer perimeters of the ultimately fabricated diaphragm and that lend'great tensile strength thereto that is in the general range 180# to 600# per inch of circumferential length of the ultimately fabricated diaphragm; which cords may be formed of nylon, rayon, etc.,

in the usual manner of the cords incorporated in the textile fabrics normally utilized in the production of heavyduty tires for trucks, road-working machines, etc.

In a constructional example of the diaphragm mate- 7 rial 420, the inner layer 425 has a thickness in the gen- I ferential direction of the ultimately fabricated diaphragm by at least 10% of the unstrained circumferential length thereof and is compressible in the circumferential direction when put in the loop form of the ultimately fabricated diaphragm by at least 4% of the unstrained circumfe rential length thereof without inducing wrinkles therein. In the diaphragm material 420, the inner layer 425 constitutes a primary membrane having a low permeability to the gas stored in the container, the intermediate layer 427 constitutes a flexible bonding agent that may also have a low permeability to the gas stored in the container and also to atmospheric gases and to Water vapor, and the outer layer 426 serves fundamentally as a cushion or mattress, so that this foamed material may be of either the open-cell type or the closed-cell type, depending upon the particular constituents thereof. More particularly, the intermediate adhesive layer 427 retains substantial Since the outer layer 426 is resilient, it is capable of readily peeling off from the adjacent inner surface of the associated shell and upon the adjacent outer surface of the associated fender and back again in the normal operation of the ultimately fabricated diaphragm, as previously explained.

. In the diaphragm material 420, the outer layer 426 contributes suflicient body and mass thereto that short forced nitrile rubber, polysulfide rubber, polychloroprene, Chemigum SL, Ensolite, or polyurethane resin; the

outer layer 426 is formed of foamed nitrile rubber, polysulfide rubber, chloroprene, Chemigum SL, Ensolite or polyurethane resin; and the intermediate adhesive layer 427 is formed of Hycar rubber cement, Pliobond rubber cement, Chemigum SL resin cement or polyurethane resin cement.

A particularly advantageous construction of phragm material 426 comprises the inner' layer 425 formed of textile fabric reinforced nitrile rubber, the

outer layer 426 formed of foamed polyurethane and the intermediate adhesive layer 427 formed of Hycar rubber cement.

Referring now to FIG. 5, the modified form of the diaphragm material 520 there illustrated is fundamentally of the same construction as that of the diaphragm ma? terial 420 as described in conjunction with FIG. 4; which diaphragm material 520 comprises the gas-impervious inner layer 525 and the resilient outer layer'526 intimately bonded together by the intermediate layer of adhesive 527. In this case, the inner layer 525 comprises a simple sheet of elastomeric organic material that is chemically inert to the gas that is stored in the container of the gasholder and that is characterized by substantial stretchability in the circumferential direction of the ultimately fabricated diaphragm, whereby the inner layer 525 constitutes a primary membrane having a low permeability to the gas stored in the container. Specifically, the inner layer 525 may be formed of a sheet of nitrile Iubber, polysulfide rubber, polychloroprene, Chemigum SL, Ensolite, Mylar or polyurethane resin, whereas the outer layer 526 and the intermediate layer 527 may be formed of the materials as previously explained in conjunction With the corresponding layers 426 and 427.

In a constructional example of the diaphragm mate rial 520, the inner layer 525 has a thickness in the general range 0.010" to 0.060" and is preferably formed of Mylar, the outer layer 526 has a thickness in the general range A" to /2" and is preferably formed of foamed polyurethane resin, and the intermediate layer 527 has 7 a thickness in the general range one to several mils and;

is preferably formed of Hycar rubber cement; whereby the composite diaphragm material 520 is elastomeric and is stretchable in the circumferential direction of the 'loop form of the ultimately fabricated diaphragm by at least 4% of the unstrained circumferential length there'- ofwithout inducing wrinkles therein.

Referring now to FIG. 6, the modified'form of the diaphragm material 620 there illustratedcomprises a combination of the constructions of the diaphragm materials 420 and 520 as described in conjunction with FIGS. 4 and 5; which diaphragm material 620 comprises the gasirnpervious inner layer 625, the resilient outer layer 626, the gas-impervious intermediate layer 627, the intermediate layer of adhesive 627a bonding together the layers 625 and 627, and the intermediate layer of adhesive 6271) bonding together the layers 626 and 627. In this case, the inner layer 625 comprises a simplesheet of elastorneric organic material corresponding to the inner layer 525, the

These characthe dia-.

- 620, the inner layer 625 has a thickness in the general range 0005" to 0.030" and is preferably formed of Mylar, the intermediate layer 627 has a thickness in the general range 0.005" to 0.030" and is preferably formed of textile fabric reinforced nitrile rubber, the outer layer 626 has a thickness in the general range A" to /2" and is preferably formed of foamed polyurethane resin,and each of the intermediate layers 627a and 627]) has a thickness in the general range one to several mils and is preferably formed of Hycar rubber cement; whereby the composite diaphragm material 620 is elastomeric and is stretchable in the circumferential direction of the ultimately fabricated diaphragm by at least of the unstrained circumferential length thereof and is compressible in the circumferential direction when put in the loop form of the ultimately fabricated diaphragm by at least 4% of the unstrained circumferential length thereof without inducing wrinkles therein.

Consider now the chemical definitions of the foregoing named compositions.

Nitrile rubber (GR-A) essentially comprises copolymers of butadiene and acrylonitrile and has the generalized formula:

[('CH2 CH=CH OH2 r-CHCH1] N Polysulfide rubber has the generalized formula:

['"CII2CH2fi|SI ]n s s Polychloroprene (GR-M) has the generalized formula:

or+n o=orr-o11 n ChemigumSL comprises a polyester of ethylene glycol and propylene glycol and adipic acid (to produce a linear polymer) that has been reacted with a diisocyanate (to produce urethane cross linkages).

Ensolite comprises a nitrile rubber (copolymers of butadiene and acrylonitrile) modified by a content 0 about 25% by weight of polyvinyl chloride resin.

4 Mylar comprises a polyester of ethylene glycol and terephthalic acid.

A typical polyurethane comprises polymers produced by the addition reaction between a polyisocyanate and a hydroxl-rich compound (at least 2 hydroxl groups per molecule); such as glycols', polyesters, polyethers, etc.

Hycar rubber cement comprises a nitrile rubber (copolymers of butadiene and acrylonitrile) modified by a content of a few percent by weight of phenolic resin, as

well as a plasticizer (normally dioctylphthalate).

Pliobond rubber cement comprises a nitrile rubber (copolymers of butadiene and acrylonitrile) modified by a few percent by weight of a reinforcing resin (such as polyvinyl chloride) and a suitable plasticizer.

Chemigum SL resin cement comprises Chemigurn SL resin modified by a few percent by weight of a rein: forcing resin and a suitable plasticizer.

Polyurethane resin cement comprises polyurethane resin modified by a few percent by weight of a reinforcing resin and a suitable plasticizer.

The foregoing compositions are vastly superior to natural rubber with respect to resistance to swelling and to deterioration in the presence of petroleum products, with respect to chemical inertness in the presence of a wide variety of gases that may be stored in the container of the gasholder, with respect to resistance to atmospheric gases, water vapor, ozone and aging, and with respect to a low permeability to a wide variety of gases that may be stored in the container of the gasholder and to atmospheric gases and to water vapor; whereby the diaphragm materials 420, 520 and 620 have an exceedingly long useful life in the ultimately fabricated diaphragms of the gasholders.

In the diaphragm constructions 420, 520 and 620, as respectively shown in FIGS. 4 to 6, inclusive, the inner and outer layers of material are separate and distinct with respect to each other, either being chemically identical or totally dissimilar, and bonded together by a separate and distinct intermediate layer. However, it should be readily understood that a suitable diaphragm of the character described may also be constructed by foaming-the rubber or other plastic material directly onto the inner gas-impervious film or fabric layer, thus obviating any distinct intermediate layer of bonding material. Also, it is possible to form a surface on a body of foamed rubber or plastic material that is inert and impervious to gas to be stored, by sealingsuch surface, employing either a heat treatment or a chemical treatment. f g

In view of the foregoing, it is apparent that there has been provided in a dry-seal puressure-type gasholder, an

improved diaphragmof composite construction that is capable of feeding in either direction between the inner surface of the shell of the container and the outer surface of the fender carried by the piston, without inducing wrinkles, folds or creases therein, whereby the diaphragm has an exceedingly long useful life in the gasholder. Furthermore, the composite diaphragm is fabricated of a plurality of layers of componentmaterialsthat are especially selected to impart to the diaphragm the required elastomeric properties, to resist chemical attack by a wide variety of gases stored in the gasholder, to resist oxidation and aging in the presence of such stored gases, atmospheric gases and water vapor andto provide a composite diaphragm that has an exceedingly low permeability to the stored gases and to atmospheric gases and to water vapor. r

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to. cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

.1. In a dry-seal pressure-type: gasholder, a containerincluding an upstanding substantially cylindrical shell, a

substantially disk-shaped piston arranged in said container and movable in the vertical direction, an upstanding substantially cylindrical fender carried by said piston adjacent to the circumference thereof and spaced radially inwardly with respect to said shell to provide an annular space therebetween, and :an annular curtain-like gas-impervious flexible diaphragm arranged in an upwardly directed annular loop in said annular space, said diaphragm including an annular outer wall sealed adjacent to the bottom thereof to an annular portion of said shell and an annular inner wall sealed adjacent to the bottom thereof to an annular portion of said piston and an annular connecting wall extending between the top of said outer wall and the top of said inner wall, said diaphragm being formed of elastomeric material and having a thickness of at least about A", the circumferential length of said diferential length Cd, said fender having an outer circumferential length Cf, wherein Cs Cd Cf, the material in said outer wall being constantly stretched and the material in said inner wall being constantly compressed when said diaphragm is put in place, the gas under pressure in said container producing constant circumferential strains in the material in said diaphragm so as to stretch the material in said outer wall into firm engagement with the inner surface of said shell and to compress the material in said inner wall into firm engagement with the outer surface of said fender, whereby vertical movement of said piston effects the feed of the material in said diaphragm between said outer wall and said inner wall through said connecting wall and the consequent reversal of the cir cumferential strains in the material thus fed, all without inducing wrinkles in said diaphragm.

2. The gasholder set forth in claim 1, wherein Cs is equal to about 101% to about 104% of C and Cd is equal to about /z(Cs+Cf).

3; In a dry-seal pressure-type gasholder, a container including an upstanding substantially cylindrical shell, a first substantially annular piston arranged in said container and movable in the vertical direction, a first upstanding substantially cylindrical fender carried by said first piston and spaced radially inwardly with respect to said shell to provide a first annular space therebetween, a first annular curtain-like gas-impervious flexible diaphragm arranged in an upwardly directed annular loop in said first annular space, said first diaphragm including a first annular outer wall sealed adjacent to the bottom thereof to anannular portion of said shell and a first annular inner wall sealed adjacent to the bottom thereof to an annular portion of said first piston and a first annular connecting wall extending between the top of said first outer wall and top of said first inner wall, a second substantially diskshaped piston arranged in said container and movable in the vertical direction, asecond upstanding substantially cylindrical fender carried by said second piston and spaced radially inwardly with respect to said first fender to provide a second annular space therebetween, and a second annular curtain-like gas-impervious flexible diaphragm arranged in an upwardly directed annular loop insaid second annular space, said second diaphragm including a second annular outer wall sealed adjacent to the bottom thereof to an annular portion of said first piston and a second annular inner wall sealed adjacent to the bottom thereof to an annular portion of said second piston and a second annular connecting wall extending between the top of said second outer wall and the top of said second 'inner wall, each ofsaid diaphragms being formed of the material in said first outer wall being constantly stretched and the material in said first inner wall being constantly compressed when said first diaphragm is put in place, the gas under pressure in said container producing constant circumferential strains in the material in said first diaphragm so as to stretch the material in said first outer wall into firm engagement with the inner surface of said shell and to compress the material in said first inner wall into firm engagement with the outer surface of said first fender, whereby vertical movement of said first piston effects the feed of the material in said first diaphragm between said first outer wall and said first inner wall through said first connecting wall and the consequent reversal of the circumferential strains in.the material thus fed, all without inducing wrinkles in said first diaphragm, the-material in said'secondrouter Wall being constantly stretchedand thematerial in said second inner wall being outer wall and said second inner wall through said second connecting wall and the consequent reversal of the circumferential strains in the material thus fed, all without inducing Wrinkles in said second diaphragm.

4. The gasholder set forth in claim 3, wherein Cs is equal to about 101% to about 104% of Clfo, Cdlis equal to about /2(Cs+Clf0), Clfi is equal to about 101% to about 104% of C2f0, and Cd2 is equal to about /2(Clfi-{C2f0).

5. In a dry-sealpressure-type gasholder, a container ineluding an upstanding substantially cylindrical shell, a

substantially cylindrical piston arranged in said container and movable in the vertical direction, said piston being spaced radially inwardly with respect to said shell to provide an annular space therebetween, and an annular curtain-like gas-impervious flexible diaphragm arranged in an upwardly directed annular loop in saidannular space, said diaphragm including an annular outer wall sealed adjacent to the bottom thereof to an annular portion of said shell and an annular inner wall sealed adjacent to the bottom thereof to an annular portion of said piston and an annular connecting wall extending between the top of said outer wall and the top of said inner wall, whereby vertical movement of said piston in saidshell effects the feed of the material in said diaphragm between said outer and inner walls .via said connecting wall and the consequent reversal of the circumferential strains in the material thus fed, said diaphragm being formed of elastomeric material and having a thickness of at least about A", the circumferential length of said diaphragm being both stretchable and compressible by about 0.6% to about 2% of the unstrainedcircumferential length thereof without inducingwrinkles in the material therein.

6. In a dry-seal. pressure-type gasholder including a substantially cylindrical container and a substantially cylindrical piston axially movably arranged in said container, said piston being spaced radially inwardly with re,- spect to said container to provide an annular space therebetween, a substantially ring-like flexible diaphragm arranged in said annular space and sealed adjacent to the outer perimeter thereof to said container and sealed adjacent to the inner perimeter thereofto said piston, wherein said diaphragm has an inner side in contactwith the gas in said container and an outer side-in contact with the at-' mosphere, whereby axial movement of said piston in said container effects the feed of the material in said diaphragm between the outer portion thereofdisposed adjacent to, said container and the inner portion thereof disposed adja-,

cent to said piston and the consequent reversal of the circumferential strains in the material thus fed; said diaphragm being of composite construction including a gasimpervious inner layer'and a resilient outer layer intimately bonded together, said inner layer being relatively thin and formed of elastomeric organic material that is chemically inert to the gas stored in said container and that is characterized by substantial stretchability in the circumferential direction of said diaphragm, said outer layer being relatively thick and formed of elastomeric organic material that is resistant to atmospheric gases and to about 2% of the unstrained circumferential length thereof without inducing Wrinkles in the material therein.

7. The gasholder set forth in claim 6, wherein said composite diaphragm has a tensile strength between the inner and outer perimeters thereof in the range 180 pounds to 600 pounds per inch of circumferential length thereof.

8. The gasholder set forth in claim 6, wherein said inner layer has a thickness in the range 0.010" to 0.060 and said outer layer has a thickness in the range A" to /2".

9. The gasholder set forth in claim 6, wherein said outer layer essentially comprises a closed-cell synthetic organic resin.

10. The gasholder set forth in claim 6, wherein said outer layer essentially comprises an open-cell synthetic organic resin.

11. In a dry-seal pressure-type gasholder including a substantially cylindrical container and a substantially cylindrical piston axially movably arranged in said container, said piston being spaced radially inwardly with respect to said container to provide an annular space therebetween, a substantially ring-like flexible diaphragm arranged in said annular space and sealed adjacent to the outer perimeter thereof to said container and sealed adjacent to the inner perimeter thereof to said piston, wherein said diaphragm has an inner side in contact with the gas in said container and an outer side in contact with the at mosphere, whereby axial movement of said piston in said container eflects the feed of the material in said diaphragm between the outer portion thereof disposed adjacent to said container and the inner portion thereof disposed adjacent to said piston and the consequent reversal of the circumferential strains in the material thus fed; said diaphragm being of composite sandwich construction including a gas-impervious inner layer, a resilient outer layer, and an intermediate layer of adhesive firmly securing together said inner and outer layers, said inner layer being relatively thin and formed of elastomeric organic material that is chemically inert to the gas stored in said container and that is characterized by substantial stretchability in the circumferential direction of said diaphragm, said outer layer being relatively thick and formed of elastomeric organic material that is resistant to atmospheric gases and to Water vapor and that is characterized by both substantial stretchability and substantial compressibility in the circumferential direction of said diaphragm, said intermediate layer being relatively thin and formed of organic material that is characterized by substantial elasticity and flexibility after setting thereof, said composite diaphragm having a thickness of at least about A", the circumferential length of said composite diaphragm being both stretchable and compressible by about 0.6% to about 2% of the unstrained circumferential length thereof without inducing wrinkles in the material therein.

12. In a dry-seal pressure-type gasholder including a substantially cylindrical container and a substantially cylindrical piston axially movably'arranged in said container, said piston being spaced radially inwardly with respect to said container to provide an annular space therebetween, a substantially ring-like flexible diaphragm arranged in said annular space and sealed adjacent to the outer perimeter thereof to said container and sealed adjacent to the inner perimeter thereof to said piston, wherein said diaphragm has an inner side in contact with the gas in said container and an outer side in contact with the atmosphere, whereby axial movement of said piston in said container effects the feed of the material in said diaphragm between the outer portion thereof disposed adjacent to said container and the inner portion thereof disposed adjacent to said piston and the consequent reversal of the circumferential strains of the material thus fed; said diaphragm being of composite construction including a gas-impervious inner layer and a resilient outer layer intimately bonded together, said inner layer being formed of a relatively thin sheet of elastomeric synthetic organic resin that is chemically inert'to the gas stored in said container and that is characterized by substantial stretchability in the circumferential direction of said diaphragm, said outer layer being formed of a relatively thick mattress of foamed elastomeric synthetic organic material that is resistant to atmospheric gases and to water vapor and that is characterized by both substantial stretchability and substantial compressibility in the circumferential direction of said diaphragm, said composite diaphragm having a thickness of at least about A", the circumferential length of said composite diaphragm being both stretchable and compressible by about 0.6% to about 2% of the unstrained circumferential length thereof without inducing wrinkles in the material therein. p

13. In a dry-seal pressure-type gasholder including a substantially cylindrical container and a substantially cylindrical piston axially movably arranged in said container, said piston being spaced radially inwardly with respect to said container to provide an annular space therebetween, a substantially ring-like flexible diaphragm arranged in said annular space and sealed adjacent to the outer perimeter thereof to said container and sealed adjacent to the inner perimeter thereof to said piston, wherein said diaphragm has an inner side in contact with the gas in said container and an outer side in contact with the atmosphere, whereby axial movement of said piston in said container efliects the feed of the material in said diaphragm between the outer portion thereof disposed adjacent to said container and the inner portion thereof disposed adjacent to said piston and the consequent reversal of the circumferential strains in the material thus fed; said diaphragm being of composite sandwich construction including a gas-impervious inner layer of organic material, 7

a resilient outer layer of organic material, an intermediate layer of textile fabric, a first layer of adhesive bonding said inner layer to said intermediate layer, and a second layer of adhesive bonding said outer layer to said intermediate layer, said inner layer being relatively thin and elastomeric and characterized by substantial stretchability in the circumferential direction of said diapragm, said outer layer being relatively thick and elastomeric and characterized by both substantial stretchability and substantial compressibility in the circumferential direction of said diapragm, said intermediate layer being relatively thin and elastic and characterized by great tensile strength in the radial direction between the inner and outer perimeters of said diaphragm and by both substantial stretchability and substantial compressibility in the circumferential direction of said diaphragm, each of said adhesive layers being relatively thin and characterized by substantial elasticity and flexibility after setting thereof, said composite diaphragm having a thickness of at least about A, the circumferential length of said composite diaphragm being both stretchable and compressible by about 0.6% to about 2% of the unstrained circumferential length thereof without inducing Wrinkles in the material therein.

14. In a dry-seal pressure-type gasholder including a substantially cylindrical container and a substantially cylindrical piston axially movably arranged in said container, said piston being spaced radially inwardly with respect to said container to provide an annular space therebetween, a substantially ring-like flexible diaphragm arranged in said annular space and sealed adjacent to the outer perimeter thereof to said container and sealed adjacent to the inner perimeter thereof to said piston, wherein said diaphragm has an inner side in contact with the gas in said container and an outer side in contact with the atmosphere, whereby axial movement of said piston in said container elfects the feed of the material in said diaphragm between the outer portion thereof disposed adjacent to said container and the inner portion thereof disposed adjacent to said piston and the consequent reversal of the circumferential strains in the material thus fed; said diaphragm being formed essentially of foamed elastomeric material that is characterized by resiliency and by both 15 circumferential stretchability and circumferential compressibility, said material also being resistant to atmospheric gases and to Water vapor, said material of the inner side of said diaphragm also being both inert and highly impervious to the gas stored in said container, said diaphragm having a thickness in the general range A" to /2", the circumferential length of said diaphragm being both stretchable and compressible by about 0.6% to about 2% of the unstrained circumferential length thereof without inducing wrinkles in the material therein.

References Cited in the file of this patent UNITED STATES PATENTS I Wiggins Aug. 9, 1949 Byrd et a1. Jan. 31, 1950 Breit Nov. 28, 1950 'Allen Aug. '12, 1952 7 Allen Mar' 10, 1953 Wiggins et a1. Nov. 15, 1955 Wiggins July 24, 1956 Woodard et a1. Apr. 3, 1962

Claims (1)

1. 5. IN A DRY-SEAL PRESSURE-TYPE GASHOLDER, A CONTAINER INCLUDING AN UPSTANDING SUBSTANTIALLY CYLINDRICAL SHELL, A SUBSTANTIALLY CYLINDRICAL PISTON ARRANGED IN SAID CONTAINER AND MOVABLE IN THE VERTICAL DIRECTION, SAID PISTON BEING SPACED RADIALLY INWARDLY WITH RESPECT TO SAID SHELL TO PROVIDE AN ANNULAR SPACE THEREBETWEEN, AND AN ANNULAR CURTAIN-LIKE GAS-IMPERVIOUS FLEXIBLE DIAPHRAGM ARRANGED IN AN UPWARDLY DIRECTED ANNULAR LOOP IN SAID ANNULAR SPACE, SAID DIAPHRAGM INCLUDING AN ANNULAR OUTER WALL SEALED ADJACENT TO THE BOTTOM THEREOF OF AN ANNULAR PORTION OF SAID SHELL AND AN ANNULAR INNER WALL SEALED ADJACENT TO THE BOTTOM THEREOF TO AN ANNULAR PORTION OF SAID PISTON AND AN ANNULAR CONNECTING WALL EXTENDING BETWEEN THE TOP OF SAID OUTER WALL AND THE TOP OF SAID INNER WALL, WHEREBY VERTICAL MOVEMENT OF SAID PISTON IN SAID SHELL EFFECTS THE FEED OF THE MATERIAL IN SAID DIAPHRAGM BETWEEN SAID OUTER AND INNER WALLS VIA SAID CONNECTING WALL AND THE CONSEQUENT REVERSAL OF THE CIRCUMFERENTIAL STRAINS IN THE MATERIAL THUS FED, SAID DIAPHRAGM BEING FORMED OF ELASTOMERIC MATERIAL AND HAVING A THICKNESS OF AT LEAST ABOUT 1/4", THE CIRCUMFERENTIAL LENGTH OF SAID DIAPHRAGM BEING BOTH STRETCHABLE AND COMPRESSIBLE BY ABOUT 0.6% TO ABOUT 2% OF THE UNSTRAINED CIRCUMFERENTIAL LENGTH THEREOF WITHOUT INDUCING WRINKLES IN THE MATERIAL THEREIN.

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