|Publication number||US2280501 A|
|Publication date||Apr 21, 1942|
|Filing date||Aug 15, 1939|
|Priority date||Aug 25, 1938|
|Publication number||US 2280501 A, US 2280501A, US-A-2280501, US2280501 A, US2280501A|
|Original Assignee||British Oxygen Co Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (31), Classifications (33)|
|External Links: USPTO, USPTO Assignment, Espacenet|
April 1942- A. STEPHENSON 80,501:
CONTAINER FOR FLUIDS UNDER'PRESS'URE Filed Aug. 15, 1939 Sheets-Sheet April 21, 1942. A. STEPHENSON 12 5 CONTAINER FOR mums .UNDER PRESSURE Filed Aug. 15,' 1939 4 Sheets-Sheet 2 Fig 3.
,,"1111I/lII/II/ //////////A 'I//IIIIIIIIIIIIIIIIIIIIII... a
Moe/Mar.- Agyl'bur Stephenson 1 April 21,1942. AQSTEPHENSON Y I 2,280,501
- CONTAINER FOR FLUIDS UNDER PRESSURE Filed Aug. 15, 1959 4 Sheets-Sheet 5 'Fig. 9.
. [Carney p 21, 1942- I I A. STEPHENSON 28 CONTAINER FOR FLUIDS UNDER PRESSURE Filed Aug. 15, 1939 4 Sheets-Sheet 4 Fig. 17,
' lm entor: Arthur (Stephenson hgqm 4 Aktomey Patented Apr. 21, 1942 UNITED STATES PAT-E NT ,OFFICE oon'mmnn ron FLUIDS UNDER.
rnnssunn Arthur Stephenson, London, England, assignor to The British Oxygen Company England Limited,'London,
Application August 15, 1939, Serial No. 290,162
In Great Britain August 25, 1938 r 2 Claims.
sistance to stress of the weakest portion of the walls and, for any given internal fluid pressure, the weight of a container in relation to its internal volume is a minimum when the resistance of its walls to fluid pressure is uniform throughout the materials of which the walls are constructed and the container is designed so that it may just withstand the pressure to which it is subjected in use with the desired or statutory margin for safety.
It is well known that for any given material of construction the weight of a containenin relation to its internal volume is a minimum when the container is in the form of a hollow sphere and that fluid pressure acting on the internal surface of a'spherical container will produce a .material, or each of these in relation to the others, and although the computed values for these may vary slightly according to the formula adopted in practice, it is conventionally accepted that the values of these factors in the case of a spherical container conform substantially to the law of the following equations:
nu f 42! wherein p=pressure t=thickness d=diameter f=stress It is also well known that if the container be in the form of a hollow cylinder with closed endsthis being the more usual form of container employed in practice for the storage and transport of fluids under pressurethe degree of stress in the material of the walls resulting from internal fluid pressure is not uniform as in the case of a spherical container butis greater in the circumferential direction than in the longitudinal direction; for example, by simple conventional formula, the degree of circumferential stress or hoop tension is computable as:
and the degree of longitudinal or endwise stress is similarly computable as:
n! f 4t from which it is to be seen that whereas the longitudinal stress is of the same order as that which prevails under similar conditions in the walls of a spherical container, the degree of circumferential stress in the cylindrical wall is computed to be twice as great. Consequently, in
order that the resistance to stress imparted by portion should be twice that of the part spherical ,portions.
Similarly, in order that, for any given internal pressure, the resistance to longitudinal stress along the line of junction of an end-piece to the cylindrical body portion may be of the same order as the resistance to circumferential stress, the minimum thickness of material required to connect the end pieces to the cylindrical portion is indicated to be half the calculated thickness of the cylindrical wall.
Therefore, in designing and constructing a cylindrical container so that the stresses in its walls may be uniform according to accepted method of computation, the entire length of the body portion should have a wall thickness twice that of the part-spherical end pieces, and if so constructed, the weight of the container in relation to internal volume is to be regarded as a minimum for any given conditions of fluid pres-' sure and for the material employed in its construction.
Obviously, the weight of such a container in It is however, usual in the manufacture of cylindrical containers to form the body portion sufficient closure is produced. The concentration of material as the terminal portion of the tube is progressively reduced in diameter results generally in a thickness of end piece appreciably greater than the wall thickness of the body portion of the container whereas, according to the above-mentioned formulae, it may be half the thickness. Where limitation in weight is an important consideration in the use of a container, the excess thickness of material in end pieces so formed is, insofar as is possibleand practicable, subsequently, removed, but the operations mvolved are inconvenient and costly. The expense and difliculties attaching to these operations are obviously increased and frequently they become impracticable at the end which is entirely sealed;
in consequence, the weight .of the finished container remains excessive, and the stress in the material of the end piece is not uniform with that of the body portion. I
Various methods of producing cylindrical containers of reduced weight in relation to their internalvolume have been proposed, such prior proposals falling broadly into three groups. One proposal is to construct a container in which the thickness throughout is substantially equal to that required or computed for the end pieces and thereafter to reinforce the body port1on by applying to its external surface strengthemng material in the form of a sheath, windings of wire or series of equally spaced or equal sized hoops.
Another proposal is to form deep corrugations in the container so that it is comprised of a series of partial spheres or globular portions joined to-' gether by thickened necks of reduced diameters, or first to form a cylindrical container of nor- .mal thickness and then to subject it to an exmined intervals, thereby forming a series of partial spheres or globular portions joined by necks of materials which remain at the original thickness. D
A third proposal is to reduce the th ckness of the terminal portions of the tube so that it is less than that of the cylindrical portion before forming the contiguous end pieces.
None of the containers constructed in accord ance with such prior proposals possess a resistance to stress per unit area of the container walls including the reinforcing elements which would even approximate to uniformity.
It is an object of the present invention to pro.- vide a substantially cylindrical container for fluids under pressure in which the mass of material and/or weight thereof in relation to its internal volume is a minimum for any material or combination of materials of given or desired degree of permissible working stresses.
It is another object of the invention to provide a cylindrical container in which the reinforcement naturally resulting from the' end pieces, and which is transmitted for an appreciable distance along the body portion, is advantageously employed to reduce the amount of material required to impart to the.body portion to provide a metal container of a novel and improved character for the transportation and storage of fluids under pressure having a minimum of weight for a given volumeand a wall thickness which is different at different portions thereof in accordance with the distribution of stresses.
The invention also contemplates an improved metal container for fluids under pressure having a minimum of weight for a given volume and having reinforcing members incorporated therethe invention will become apparent from the present description taken in conjunction with the accompanying drawings, in which:
Fig. l is a central longitudinal section of a cylindrical container constructed in accordance with the invention on which is superimposed, for the purpose of comparison, a similar section of a standard type of cylindrical container of equal internal volume as used heretofore;
Fig. 2 is a central longitudinal section of a cylindrical container having reduced weight in accordance with the invention, the figure also showing in dotted lines the extension of the body portion prior to formation of the end pieces therefrom;
Figs. 3, 4, 5 and 6 are central longitudinal part sections of modified forms of the container;
Fig. '7 is a central longitudinal section of a further modification;
Fig. 8 is a plan view partly in section of another modification; 1
Fig. 9 shows a part section of a cylindrical container strengthened by the application of a reinforcing member;
Fig. 10 shows a constructional modification of the reinforcing member shown in Fig. 9;
Figs. 11 to 14 similarly show various modifications of reinforcing members as applied to the container;
Fig. 15 is a central longitudinal part section of another modified form of container;
Figs. 16 to 27 are part sectional views and end elevations of various modified forms of end portions of containers;
According to this invention there is provided for -fluids under. pressure a container comprising a substantially cylindrical body portion and an end piece constituting a closure member at each extremity thereof, the mass per unit area of the material constituting the body portion decreasing towards each extremity preferably in direct or approximate proportion to the degree of reinforcement for stress resistance imparted to and transmitted along the body portion by and from the end pieces, the construction being such that the resistance to stress and dilation due to internal fluid pressure is substantially uniform throughout the body portion.
According to a furtherfeature of this invention, in a container for fluids under pressurecomprising a substantially cylindrical body portion and an end piece at each extremity thereof, the mass per unit area of the body portion decreasing towards each extremity, at least one end piece is 2,280,561 I of a thickness less than that conventionally computed as required to withstand the fluid pressure to which the container is subject in use and is provided with reinforcing means whereby the requisite resistance to stress due to internal pressure is achieved with minimum mass of material. By employing a container constructed in accordweight, the storage and transportation costs of fluids stored therein may be substantially reduced.
In the design and construction of. containers according to the invention, the -wall thickness at or about the longitudinal centre of the body porance with the invention so as to have reduced tion and the thickness of the'end pieces may be .determined empirically or computed in accordance with any convenient or accepted formula utilising appropriate values for the allowable degree of stress in the material to be used for construction of these as may be determined in an empirical manner from typical test containers subjected to appropriate internal fluid pressures.
Reinforcing members capable of acting also' as rolling hoops or impact and wear resisting memhers may be applied to the container and these may be formed either integrally with'the material of the container or as separate members and subsequently applied or attached to the preformed container.
The diminution in thickness may be produced.
on the internal or external surface, or conjointly on both internal and external surfaces, and may be produced before or after attachment of the end pieces to or their formation from the bodyportion.
If the diminution is carried out before forming the end pieces, the decrease in thickness may be extended either. progressively or in modified degree to the extremities of the tubular or cylindrical body piece from which the contiguous end pieces are to be formed so as to avoid or limit excess of metal in the formed end pieces.
If the length of the body portion be short in relation to its diameter, for certain materials the normal calculated wall thickness of the body porsired shape, and may be convex, concave 01 convex-concave, and of either uniform or varying thickness, according to the shape of the end piece preferred or required.
Inlet or outlet ports or connections, manholes,- and lifting or other requisite attachments may be arranged either in or on the end pieces or on the body portion.
The weight of the end pieces may be reduced by diminishing their thickness from the outer diameter at or near the point of junction between the and pieces and the body portion and towards the centre of the end piece either in steps as, for example-by a series of concentri S recesses, or progressively, and the centre part may be left thicker for convenient attachment of valve, or inlet and outlet connection or other attachments.
Alternatively, the grooves or recesses may be formed to extend radially from the centre of an end piece to the periphery, in which case the grooves may be formed by pressing or by addition to or removal ofsome of the material from the end piece during or after-manufacture thereof so that spaced radial ribs or ridges of thicker metal capable of reinforcing the end pieces remain be-' tween the recesses or grooves. Combinations of such radial and concentric reinforcing grooves or ribs may be, of course, employed.
As a further alternative, the metal of the end piece maybe first made of progressively diminishing thickness from the periphery towards the centre thereof, and' the radial grooves or recesses may be subsequentlvformed. For this pur-' pose, moulds may be applied to the end pieces acting against internal fluid or mechanical pressure, so'that the material is made to conform the shape provided in the mould. o
The provision of radial ribs and grooves or recesses can be advantageously adopted in cases where the end pieces are of theconcave type, which, in view of their shape, are partly housed within the body portion and which, unless of excessive weight as compared with the convex type. have a normal tendency to invert and assume a convex hemispherical shape when subjected to internal fluid pressure.
The material of the finished container may, after completion, be subjected to suitable heat treatment for normalising, or hardening or tempering such as sorbitising, or certain parts, such as the outer surface of the body portion and/or the reinforcing or stiffening members only may be hardened or tempered to increase the stress hearing qualities I Alternatively, the heat treatments necessary to produce tempering or hardening orconditioning of the material may be applied only to the portions which are of diminished or diminishing thickness, so that the material of the container may have greater ductility in its thicker portions and/or in the reinforcing orstiflening members. In another method of carrying the improvements into effect in accordance with the. invention, the bodyportion is formed with thinner walls, e. g. is only of suflicient thickness to withstand the longitudinal stress and is provided Preferably, the reinforcing sheath has maximum thickness about its central portion and tapers towards each extremity. For example, it
may be formed externally as a convex catena and internally as a tube of parallel bore to conform 'to the external surface of the preformed body portion, so that when the sheath is fitted over the container, the greatest thickness and strength is provided for a limited distance on each side of the longitudinal centre. The sheath may be so used,-each super-imposed sheath being of shorter length than the inside one it envelopes so that greatest thickness results at or near the longitudinal centre.
The sheath or sheaths may be fitted to the con tainer either by mechanical pressure or- "by shrinking on. If shrunk on, the sheath or sheaths may be heated for enlargement before passing over the thin-walled container, or the thin-walled container may be intensely cooled before insertin: it into the sheath.
In the case where wire winding is used instead of a'single or multiple sheath to provide the progressively increasing reinforcement in accordance with the invention, the diameter of the wire may be greater for the winding at the centre and may diminish in stages as it extends towards the end pieces. 'For this purpose wires of different cross-sectional diameter and/or strengths may be either joined at intervals or left discontinuous and the windings may be made in separate sections with spacings therebetween or abut each other closely. Alternatively, th increase in strength of reinforcing material towards the longitudinal centre may be obtained b superimposing one or more layers of wire winding of diminished or diminishing length so that the greatest thickness of superimposed wire is disposed at or about the longitudinal centre.
The windings may be held in position in rela tion to each other and lateral movement along the cylinder or turning movement about thecylinder prevented by any convenient means, such as by applying a metal or other suitable material of low melting temperature either'as a. brazing, solder, paint or cement-like filler of any sprayed on metal, and the material used for this purpose may be so selected and applied that it will serve as a protection against corrosion or like surface attack.
In order to ensure close fitting of the wire winding, the initial containermay be intensively cooled before the winding is applied, or prior to the application of each successive layer.
It is, however, not essential that the wire windings or the reinforcing sheath or sheaths apply pressure to any appreciable degree before the container is subjected to internal pressure. For certain purposes. it is preferable that the initial container be capable of expanding before the reinforcing members operate, provided that the exf pansion of the initial container shall reasonably be within the elastic range of the material from which it is constructed.
In an alternative method of carrying out the invention the body portion of the container may be corrugated, the corrugations being so constructed and arranged as to produce a progressively increased strengthening effect from the junction of the end portions with the body portion towards the longitudinal centre. The corrugations may be continuous or separated by non-corrugated portions and may be parallel or helical, being preferably deeper and more steeply curbed towards the longitudinal centre of the body portion.
It will be clearly understood that these various and alternative methods of producing a container of the-cylindrical type. in which the re sistance of the cylindrical portion to circumferential stress increasestowards the longitudinal centre, lend themselves conveniently to combinasuch a globular extension affords a reinforcing eifect which can be applied to reduce still fur-- ther the thickness of the tapering portion disposed between the end pieces and the globular extension.
Referring to Fig. 1, the usual known type of cylindrical container is formed from a tube having a central portion which constitutes the body portion l of the finished container and contiguous end pieces 5, I which are produced by bending over and progressively reducing the diameter of the terminal portions of the tube. As shown inFig. 1, the concentration of material at. for example, the end piece 8 due to the shaping operation results in the thickness of the end piece 8 being considerably morp than that of the body portion I from which it is formed; whereas, in accordance with the foregoing formulae, the end piece may be half the thickness of the body portion. The amount of material which may be dispensed with is shown in the dotted portion and the residual material which constitutes a cylindrical container shaped in accordance with the invention is shown by the hatched parts in Fig. 1.
From empirical determinations of containers of the two forms of construction, it has been-ascertained that the saving in weight which may be effected by proceeding in accordance with the invention is of the order of 36 to 0 per centum for containers of equal strength and internal capacity.
. Referring to Fig. -2 of the drawings, a simple form of container constructed in accordance with the invention and having a weight in relation to its contained volume which is less than that of containers of similar volume used hitherto, is formed from a hollow, and substantially cylindrical, body portion I. At its longitudinal centre 2, the body portion has a wall thickness either calculated according to the usual formulae or determined empirically for the degree of permissible stress and dilation due to circumferential tension, and sections 3 and 4 disposed between the centre section 2 and the end pieces which progressively diminish in thickness towards each extremity, so that when the end pieces 5 and 6 are formed from the thinner extremities of the body portion, the thickness of wall at and/or adjacent tothe line of junction between the parts 1 and 5 at one end, and the parts 4 and t at the further end, is substantially equal or approximates to the requisite wall thickness of the end pieces when calculated according to the usual formulae. If the end pieces 5 and 0 be hemispherical, they can be substantially half the thickness of the centre section 2. In the preferred design of the simple form of improved container, the progressive diminution in thickness of the walls of the bodypiece I from its longitudinal-centre 2 towards the end pieces results in the external of the body piece having the shape of a convex catena as shown in Fig. 6.
the precise form of which is preferably determined empirically from typical test cylinders subjected to appropriate pressures.
The end pieces which arepreferably of reduced thickness as compared with the body portion may be varied in thickness to provide a suflicient each side of the longitudinal centre.
- The amount of metal that can be so displaced ordispensed with without impairing the effective strength of the body portion of the container is dependent upon its length in relation to its diameter; for example, if when constructed of material normally employed for such containers the length of the body portion be less than approximately diameters, it is possible to reduce its weight to a further extent by reducing the thickness of wall at the longitudinal centre, in addition to the progressive reduction in thickness towards the and pieces, because of the distance to which the reinforcing eifect of the end pieces is transmitted along the bod) portion. It has been found in practice that the approximate distance of 10 diameters varies also with the physlcalproperties of the material.
In practice, however, it is necessaryto provide for variations in thickness of wall in consequence of the variations in thickness required for normal tolerances on dimensions during manufacture. Unless the conditions of use merit the cost lb is accordingly caused to taper from 2b towards lib. For the same reason, the portion 36 tapers towards the further extremity of'the container. Both ends may be globular or/hemispherical.
Instead of shaping the wall of the body portion so that it tapers from the central section towards the extremities, a cylindrical body portlon having a thickness no greater than is required for the end pieces may be used, and the body portion strengthened by a reinforcing member or members. I
As shown in Fig. 9, the reinforcing member may comprise a separate sheath I which tapers from the centre section'towards' each extremity. The form of taper may be that shown in any of Figs. 2, 3, 4, 5 and 6. Alternatively, a compound sheathing as illustrated in Fig. 10 may be employed. V
In place of the sheathing 7, the reinforcing member may comprise windings of wire lb arranged in superimposed layers. The windings may be continuous as shown in Fig. 11, the number of layers being greatest about the central section of the body portion and progressively decreasing towards each extremity. Alternatively, groups of multi-layer windings lb may be provided as illustrated in Fig. 12, the number of layers in each group decreasing from the centre sections towards each extremity. Bands or collars 'lc, which may be shrunk-on, welded or otherwise secured to the body of the container, may
of manufacture to extremely small tolerance 1imitsfin thickness and concentricity, it is necessary, and less costly, to allow reasonable tolerances on the limits of accuracy, and to reduce to a proportionate amount, for. example, 5 diameters, the length of body portion to which any reduction in wall thickness at the longitudinal centre is eifected. In cases where the length of the body portion is considerable in relation to diameter no metal is removed from the body portion for some distance either side of the centre section 2, the wall of the central zone 2a remaining parallel to the central longitudinal axis of the body piece asshown in Figs. 3, 4 and 5. The portions 3, 8 between the zone 2a and the end pieces may taper in a. straight line as shown in Fig.3, or in' steps as shown in of course, be used so long as the reinforcing ef- Fig. 4, or in acatenary curve as shown in Fig. 5.
If, in order to facilitate transport or for any other reason, it is desirable that the exterior surface of the container be substantially cylindrical, the inner wall may be made to taper towards the extremities as shown in Fig. 7. This may be accomplished either by removing material from the internal surface or removing it from' the external surface and then by well known means forcing the material inwards so that the external surface is made parallel.
In the modification shown in Fig. 8, the central section 2b is extended into a globular shape.
By reason of it possessing this shape, the thickness of the section 2b need not be greater than that of the end piece 612, which may also be globular. As thesphericity of the end piece 6b is greater than that of the section 2b, it is capable of imparting to the intermediate portion lb a larger reinforcing eifect and the portion be employefd as reinforcing members instead of wire windings. Fig. 13 shows one arrangement of collars 'Ic which vary in width, the widest being located about the central section of the body portion and successively narrower collars being disposed at progressively wider intervals towards each extremity of the body portion. Fig. 14 shows an arrangement of reinforcing members 7c similar to that shown in Fig. 13, but the collars in this case decrease progressively in thickness towards each extremity.
The reinforcing members may be made of materials differing in tensile strength, the material with the highest tensile strength preferably be ing disposed about the central section of the body portion, members having progressively lower and lower tensile strength being disposed between the central section and the terminal portions. .Any combination of reinforcing members differing in dimensions and tensile strength may,
fect imported to the body portion is greatest about the central section and diminishes towards the end pieces.
In an alternative construction shown in Fig. 15, the thickness of the central portion may be reduced as compared with that shown in Figs. 1 to 6 and without the necessity of providing any reinforcing members, by forming a central corrugation 2c and complementary corrugations 8, 9 at the junctions of the end pieces with the body portion, the intermediate portions 30 and 4c tapering from the corrugation 2c towards each extremity. It will, of course, be understood that the number of corrugations is not limited to that shown.
Containers having a body portion which tapers in thickness towards the end 'pieces as hereinbefore described may also be corrugated to provide any desired reinforcement. These corrugations may be of uniform pitch and depth'or they may vary in pitch and/or depth to impart a varying. A
degree of reinforcement to different parts of the body portion so as to maintain uniformity in the resistance to stress and dilation due to internal fluid pressure.
, Similarly, the reduction in weight of the end pieces is dependent upon/or corresponds to the amount of metal displaced or dispensed with either before or after forming the end pieces. The amount of metal that can be displaced or dispensed with is'dependent upon the form of end piece to be employed. The hemispherical form made from extremities of the body portions which have been previously reduced in thickness is most convenient to'manufacture and affords the greatest volume in relation to weight more especially if its thickness is further diminished towards the centre, but circumstances or conditions of use requently require that the shape of the end piece shall be concave or convex-concave, ellipsoidal, flat or other convenient shape. In this case concentric or radial grooving or the formation of radial ribs or fins permits of part of the end piece to be of reduced thickness to effect closure and disposes the metal of the reinforcing elements in such a position that maximum reinforcement is afforded with minimum weight.
Various forms of end pieces shaped in accordance with the invention are illustrated in Figs. 16 to 27.
As shown in Fig. 16, the end piece 6 is hemispherical and of uniform thickness less than that of the terminal portion 4 of the body por-- tion. Where the end piece 8 is less than hemispherical the thickness thereof may progressively decrease towards the centre as shown in Fig.
When the end piece 6 is fiat as shown in Figs. 18 and 19, it may be reinforced by a plurality of substantially hemispherical or other conveniently shaped radial buttress ribs l extending diametrically across the base of the container,
the ribs having the greatest depth at the middle. When the end piece 8 is concave, it may be reinforced by a plurality of radial buttress ribs lilalextending diametrically across the concave portion as shown in Figs. 20 and 21. Figs. 22 and 23 show similar reinforcement achieved by providing radial ribs [0b with a centre boss H to permit either of the formation of an inlet or outlet connection or the attachment of lifting or other means.
Where the end piece 6 is convex, radial ribs [0c may be provided as shown in Figs. 24 and 25,
the ribs increasing in depth to a maximum at the middle. If a convex end piece has initially a greater thickness than is necessary to withstand the iuternal fluid pressure to which the container is subject in use, annular grooves may be formed in the-end piece, the depth and/or width of the grooves increasing towards the centre of the end piece. As shown in Figs. 26 and 27, the grooves may be V-shaped as shown at llld, and these may be supplemented by radial ribs such as illustrated in the preceding Figs. 18 to 25.
It will be clear that containers constructedv from metallic materials of comparatively low tensile strength and which, to provide adequate strength in the central part of the cylindrical Such materials, for example, mild steels, usually have greater shock resistance and a higher de-- gree of ductility than high carbon or alloy steels; moreover, they are less costly and have the added advantage that they are usually less diiilcult to manipulate in the processes of manufacture and heat treatment.
It will, of course, be understood that, whereas, the improvements may show greater advantage in materials of lower degrees of stress resistance, they are equally applicable tomaterials of; high degree of stress resistance. Further, the improvements hereinbefore proposed may be applied for the same purpose and advantage to containers designed and constructed according to present practice and which may even have already been in service for the storage and/or transport of fluids under pressure.
1. A container adapted for the storage of fluids under pressure comprising a substantially cylindrical body portion formed from a single homogeneous tubular member, and an end piece at each extermity of the body portion constituting a closure member, said end pieces being formed integrally with the'body portion by progressive reduction in diameter of the material of the body portion, the mass per unit area of the material constituting the body portion decreasing towards each extremity substantially in proportion to the degree of reinforcement for resistance to stress and dilation imparted to and transmitted along the body portion by the end pieces, said decrease in mass being effected by a progressive reduction in thickness of the body portion whereby the resistance to stress and dilation due to internal fluid pressure is substantially uniform throughout said body portion, and wherein the progressive reduction in thickness of the body portion is stepped at appropriate intervals. v v
2. A container adapted for the storage of fluids under pressure comprising a substantially cylindrical body portion formed from a single homogeneous tubular member, and an end piece at each extremity of the body portion constituting 'a closure member, said end pieces being formed integrally with the body portion by progressive reduction in diameter of the material of the body portion, the mass per unit area of the material 4 constituting the body portion decreasing towards each extremity substantially in proportion to the degree of reinforcement for resistance to stress and dilation imparted to and transmitted alon the body portion by the end pieces, said decrease in mass being effected by a progressive reduction in thickness of the body portion whereby the resistance to stress and dilation due to internal fluid pressure is substantially uniform throughout said body portion, and wherein the body portion has a substantially cylindrical internal surface, and wherein the progressive reduction in thickness of the body'portion is effected externally.
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|U.S. Classification||220/586, 220/600|
|International Classification||F17C1/02, F17C1/00|
|Cooperative Classification||F17C2209/224, F17C2203/012, F17C2203/0636, F17C2223/035, F17C2223/033, F17C2201/0114, F17C2201/0119, F17C2223/0123, F17C2201/0147, F17C1/02, F17C2203/0619, F17C2203/0607, F17C2205/0379, F17C2201/0123, F17C2260/053, F17C2201/0109, F17C2260/012, F17C2209/232, F17C2209/2154, F17C2205/0323, F17C2203/0617, F17C2260/011, F17C2209/221, F17C2260/017, F17C2223/0153, F17C1/00, F17C2203/0639|
|European Classification||F17C1/02, F17C1/00|