US2370677A

US2370677A - Container for high-pressure fluids

Info

Publication number: US2370677A
Application number: US379037A
Authority: US
Inventors: Mapes Daniel
Original assignee: Specialties Development Corp
Current assignee: Specialties Development Corp
Priority date: 1941-02-15
Filing date: 1941-02-15
Publication date: 1945-03-06
Anticipated expiration: 1962-03-06
Also published as: GB556801A

Description

D. MAPES CONTAINER FOR HIGH PRESSURE FLUIDS March 6, 1945,

Fil ed Feb. 15,

INVENTOR mil/WEI. M PES,

ATTORNEY Patented Mar. 6, 1945 UNITED STATES PATENT OFFICE CONTAINER FOR HIGH-PRESSURE FLUIDS Daniel Mapes, Rutherford, N. J., assignor to Specialties Development Corporation, Bloomfield, N. J a corporation of New Jersey Application February 15, 1941, Serial No. 379,037

7 3 Claims.

This invention broadly relates to cylinders or containers for'gaseous fluid media, and more speciflcally to cylinders or containers adapted to hold fluid media under high pressures.

The high pressure media most commonly used are carbon dioxide, oxygen, nitrogen and hydrogen, and, while their individual practical applications are quite numerous, the best known uses are for the carbonation of fluids, fire extinguishing, inflation of inflatable devices, power actuation and welding.

An increasingly important application of high pressure fluid media is that to aircraft, and particularly to combat planes where the use of carbon dioxide fire extinguishing, flotation, emergency raft inflation, and the emergency operation of hydraulic equipment, the use of oxygen for high altitude breathing, and various other uses of high pressure fluid media have made the high Pressure gas container an indispensable accessory.

Containers for high pressure fluid media have been made in a number of ways, but are usually of seamless construction, and where such containers are to be shipped by common carriers in interstate commerce, they are required to meet regulations issued by the Interstate Commerce Commission. While such containers intended for use on aircraft are usually of lighter weight than those for other uses, as for example containers made in accordance with Letters Patent of the United States No. 2,026,133, containers meeting the requirements of the Interstate Commerce Commission are made with a consider-able factor of safety, and can withstand pressures of two to three or more times the normal working pressure of the contained fluid medium.

Up until the relatively recent past, it was not thought necessary to give any special consideration to the construction of these containers for use on combat planes. However, in view of the practically universal military acceptance of highpowered, high-caliber machine gun ammunition, or, to be more precise, the supplanting of 0.30 by 0.50 caliber bullet on military aircraft, new hazards have arisen, not heretofore present. Thus, cylinders containing high pressure fluids, struck by 0.50 caliber bullets, in contrast to the effect of a 0.30 bullet, generally burst with a violent explosion, naturally dam-aging the airplane and endangering its occupants.

It has been observed in the course of numerous tests, which were undertaken to determine the exact nature of the behavior of such containers when struck by bullets, flying shrapnel or the like, that a cylindrical container of the type referred to, when squarely hit on its cylindrical portion, will permit the bullet to enter, usually leaving a round opening, but will literally rip wide open longitudinally at the point of exit of the bullet, the internal pressure being efl'ectual in completing the failure of the cylinder wall begun by the bullet. This is in consonance with the known fact that once a piece of material, such as steel, has been partially deformed Or has suffered an initial local rupture, such piece will require a much smaller force to be completely ruptured than if no such initial rupture had been sustained. 'An

analysis of the performance of the tested cylinders I disclosed that the effect of the bullet on the container wall was most pronounced at the point of the bullet exit, as in that case the bullet was assisted by the action of the internal fluid pressure.

Since the strengthening of the cylinder walls by an increase in their thickness, although possibly effective in stopping or slowing the bullet, would render such containers too heavy for practical use, and especially for aircraft application, it occurred to me to provide supporting means for the cylinder wall, which, while it might be injured or locally destroyed by the bullet, would support the uninjured portions of the wall adjacent to the bullet hole, thus, effectively preventing the further tearing of the cylinder. The supporting means, therefore, would preferably be in the nature of a form of jacket means with a high strength-to-weight ratio as one of its prerequisites. After lengthy experimentation with various methods of protection, it was found that the method of winding the cylinders externally with high tensile piano steel wire, properly secured, afforded a really positive protection, while its comparative light weight, its adaptability for production purposes, and its cheapness pointed to its being a solution well adapted to the requirements of these cylinders and their application.

It is therefore an object of this invention to provide means which will lend strength against bursting to the walls of high pressure fluid medium containers at a time only when said walls have been deformedly weakened.

It is also an object of this invention to provide a means for minimizing the destructive effects on high pressure fluid medium containers produced thereon when they are struck by bullets, flying shrapnel or other projectiles propelled at a high velocity.

' It is a further object to provide high pressure fluid medium containers with gun flre protection jacket means of the type referred to without appreciably adding to the weight of the containers.

These and other objects will become apparent as the description proceeds with reference to the accompanying drawing, in which:

Figure 1 is an elevational view, partly in section, illustrating a container for high pressure fluid media, protected in accordance with the present invention.

Figure 2 is a perspective view of a portion of the container, illustrating one of the wire winding retaining rings.

Figure 3 is a fragmentary view of a wire retaining ring, showing a method of anchoring the ends of the wire.

Figure 4 is a fragmentary sectional view of the retaining ring showing its arrangement with respect to the cylinder and the layers of wire.

Figure 5 is a fragmentary elevational view, illustrating another method of protecting containers by layers of wire.

Referring now to the drawing, wherein the same references are used for the same elements, i refers to a conventional metallic high pressure fluid container having a generally cylindrical form and a hemispherical shoulder and closed end, and initially strong enough to withstand a pressure higher than the normal operating pressure and in accordance with the acceptance tests of the Interstate Commerce Commission. The shoulder is provided with an opening terminating in a necked-in portion 2, into which is threadedly secured a fiuid control device 3, and which may take a y one of numerous valve forms in accordance with the application desired.

At 4 is indicated a jacket for the cylindrical portion of the container, which is formed in this case of a double layer winding of high tensile strength steel wire, commonly known as piano wire," and which is applied under varying degrees of tension. The relation between the cylinder wall and the double layer winding is clearly seen at 5, where the container is broken away to reveal the wall and the jacket in section. The wire winding may be secured by various methods, and is here shown, by way of illustration, as being held in place at its ends by means of retaining rings 6. In Figure 2, such a ring may be seen to have a flange '1 and to be split as at 8. Apertures 9 in the flange provide anchorage for the free wire ends, as more clearly shown in Figure 3, where an elevational view of a section of a retaining ring 6 indicates how the beginning ID of the wire winding is looped into one of the apertures, and the end of the winding H is anchored in the other opening. The double layer winding is continuous and comprises, in this instance, one forward and one return winding.

.When the wire is completely in place, the flange I is bent inwardly, as is apparent from Figure 4, which illustrates a section of the cylinder wall, the retaining ring and the wire jacket. In order to assure the stability of the entire jacket, its surface is solder-licked, that is, covered with a relatively thin though coherent coat of solder, indicated by reference numeral 13.

Figure 5 illustrates a variation of the winding of Figure 1, insofar as the layers are wound so as to form an angle with respect to each other.

Under operating conditions, it has been the experience that an unprotected cylinder, charged with a high pressure fluid medium, when hit by a bullet, will be pierced, if fired on at fairly close range, both through the front and rear walls. With 0.50 caliber fire, for instance, the entrance hole is generally round, taking the shape of the entering bullet. Seldom, if ever, do splits or fractures occur at the entrance hole. However, at tht exit hole, the cylinder, due to the fact that the metal of the wall is pushed outwardly by the impact of the outgoing bullet, will, in practically all cases, develop cracks radiating from the hole. These local cracks are sufllcient to permit the high pressure medium to rip the cylinder wide open, producing the equivalent of a violet explosion. These cracks about the bullet exit hole apparently so weaken the cylinder that the hoop stress generated by the pressure in the cylinder far exceeds the resistance of the steel. The mere fact that the homogeneity of the steel is impaired by the hole and the fissures radiating therefrom, renders adjacent sections of the metal much less stressresistant than they would be normally, even though they might be thicker there than at an uninjured place. This is in accord with the wellknown theory of elasticity that the unit stresses in the section of a member under load immediately adjacent a hole or groove are a multiple of what they are in the member as a whole. By wrapping high tensile piano wire, which has, say, a tensile strength of about 400,000 pounds per square inch in the sizes used, around the cylindrical portion of the cylinder, preferably with each coil touching the next, and extending the wrapping or winding substantially from the junction of the hemispherical bottom or closed end to the junction of the hemispherical shoulder, as shown in the illustrative embodiment of the invention, additional strength is lent to the cylindrical wall section at the time of a sudden tress due to piercing of the containers by a bullet or other projectile. A hole or crack in the cylinder wall, therefore, once started by a bullet or other projectile on its way out through the container, is effectively prevented from developing into a destructive tear by the reenforcement given to the metal adjacent the tear by the coils of piano wire or other suitable reenforcement, since the undamaged turns are able to exert their full and undiminished strength. In this, they may be aided by the manner in which the wire is wound, as for example shown in Figure 6, where the angularity of one layer of the winding with respect to the other indicated here, has the effect that the bullet in passing through breaks any single coil in one place only, assuming, of course that the cylinder'is hit squarely, unless it be in a certain range adjacent the short axis of the now elliptical coil. This is in contrast to the double break which the coils in the line of the passing bullet sustain, when wound in accordance with igure 1.

In the matter of securement of the winding, it has been found desirable to give adjacent coils of the wire a certain amount of cohesion, as well as a preset, that is, coil the wire with a radius somewhat smaller than that of the container so that the wire, even if severed locally, will resist any tendency to unravel, and, by being made to grip the cylinder, will properly function to reenforce the cylinder wall at the time of greatest stress. Thin, adherent coatings of various materials, applied over the winding, are capable of achieving such coherence, the illustrated method of "solderlicking being a practical and satisfactory example.

The' cylindrical portion of the container is about half as strong in bursting as the hemispherical dome and bottom, since the container as a whole is of uniform wall thickness because of regulations and for manufacturing reasons. It is primarily, therefore, this cylindrical section which needs reenforcement. This has been proven in numerous tests, which showed, when the bottom or dome of the container is hit by representative caliber machine gun bullets, that the container will not rupture. The preferred method, therefore, is to apply such protection to the cylindrical section of the container, starting and ending approximately at the junctions of the spherical with the cylindrical surfaces, a. procedure which has proven quite satisfactory.

The invention, however, contemplates the use also of other types of jacket means varying in their structure and composition, in accordance with requirements and circumstances. Similarly, the invention may be applied to various types of high pressure fluid containers, which differ in their method of fabrication, structure, material or wall thickness. While such other jacket means variations are possibly not as effective as the methods specifically described, their use is determined by preference and they clearly fall within the scope of the present invention. It is, therefore, as an exemplifying embodiment of the invention, for a clearer emphasis of the purpose and scope thereof, that containers normally capable of withstanding the stresses produced by the internal pressure, and constructed substantially in accord with the rules of the Interstate Commerce Commission, and their protection by the preferred methods mentioned above, have been adduced here.

It has of course been proposed to construct containers for fluid media out of relatively thinwalled containers wrapped with wire to strengthen the containers against bursting under only normal operating pressures; but my invention difiers therefrom in that it is concerned with protecting containers, which are normally sumciently strong to safely withstand normal operating pressures, against unusual bursting stresses developed when such containers are struck or pierced by machine gun fire, flying shrapnel or other projectiles propelled at a high velocity. Actually, the problem of protecting high pressure fluid media containers against gunfire and the like is a problem more particularly occasioned by present-day warfare, not only because of the greater destructive power of modern weapons, but also because of the relatively recent but widespread use of high pressure fluid media containers on warplanes with the attendant danger of violent bomb-like explosions of such containers when struck or pierced by high velocity projectiles. This problem the present invention solves in a way not previously contemplated, by reenforcing containers which are otherwise normally sufficiently strong to safely withstand desired p. erating pressures against the destructive forces which arise only when such containers are struck or pierced by high velocity projectiles. It must therefore be constantly kept in mind that the containers for which jacketing means in accordance with the present invention are provided, are quite capable by themselves of resisting normal internal fluid pressures, and that the jacketing means as such acquires significance and comes into action only when abnormal stresses are developed upon striking or piercing of the containers.

The present invention may also be utilized not only to provide reenforcement to the cylinder wall immediately adjacent any weakened portion thereof and to counteractthe incidentally increased local stresses, but also at the same time to hold such incidental stresses to a minimum by conditioning the initial state of stress in the cylinder wall. Thus, by increasing the tension under which the reeni'orcing wire or other type of jacketing means is secured over the cylinder, the cylindrical wall may be put under pre-compression, so that both the normal stress in the cylindrical wall due to the normal pressure'of the contained medium and the abnormal stress developed when the wall is struck or pierced, may be counteracted and reduced.

From the foregoing description, it will be seen that I have provided gun fire protective means for containers for high pressure fluid media in accordance with the objects enumerated above, and that while the invention has been described with reference to specific embodiments of the invention, it will be evident to one skilled in the art that the objects of the invention may be achieved through other forms without departure from the spirit and the scope thereof, and for this reason I-do not wish to be strictly limited to the forms of this disclosure but rather to the scope of the appended claims.

I claim:

1. A container for storing a high pressure fluid medium comprising a one-piece substantially rigid seamlessly formed metallic cylinder inherently subject to ripping apart when pierced by a projectile, said cylinder havinga cylindrical wall of substantially uniform shape and thickness provided with substantially smooth inner and outer surfaces, and being of a thickness to withstand the highest working pressures at which the fluid medium may be confined in said cylinder under normal conditions of use without further reenforcement; a continuous winding of only two layers of contiguous convolutions of steel pianowire of high tensile strength woundunder tension on said cylindrical wall, said wire having been given a preset prior to being wound on said cylindrical wall, said preset establishing convolutions of slightly smaller inner diameter than the outer diameter of said cylindrical wall whereby said convolutions tend to embrace said cylindrical wall in clasping relation to minimize and localize the area of rupture of said cylinder and to prevent ripping apart of said cylinder when said cylindrical wall is pierced by a projectile; a split ring at each end of said cylindrical wall, said split rings having a flange extending under the end convolutions of said windings and having a second flange folded over the end convolutions of said winding to secure the end convolutions, one of said rings securing both free ends of said winding; and a coating of solder applied to said winding serving to secure adjacent convolutions and aiding the preset condition of the coils in resisting the tendency for the wire to unravel when severed by a projectile.

2. A container for storing a high pressure fluid medium comprising a one-piece substantially rigid seamlessly formed metallic cylinder inherently subject to ripping apart when pierced by a projectile, said cylinder having a cylindrical wall of substantially uniform shape and thickness provided with substantially smooth inner and outer surfaces, and being of a thickness to withstand the highest working pressures at which the fluid medium may be confined in said cylinder under normal conditions of use without further reinforcement; a continuous winding of no more than two layers of contiguous convolutions of steel piano-wire of high tensile strength wound under tension on said cylindrical wall, said wire having been given a preset prior to being wound on said cylindrical well, said preset establishing convolutions of slightly smaller inner diameter than the outer diameter of said cylindrical wall whereby said convolutions tend to embrace said cylindrical wall in clasping relation to minimize and localize the area of rupture of said cylinder and to prevent ripping apart of said cylinder when said cylindrical wall is pierced by a projectile; a split ring at each end of said cylindrical wall, said split rings having a flange extending under the end convolutions of said windings and having a second flange folded over the end convolutions of said winding to secure the end convolutions; and a coating of adherent material applied to said winding adhering thereto and serving to secure adjacent convolutions and aiding the preset condition of the coils in resisting the tendency for the wire to unravel when severed by a projectile.

3. A container for storing a high pressure fluid medium comprising a one-piece substantially rigid seamlessly formed metallic cylinder inner-- ently subject to ripping apart when pierced by a projectile, said cylinder having a cylindrical wall of substantially uniform shape and thickness provided with substantially smooth inner and outer surfaces, and being of a thickness to withstand the highest working pressures at which the fluid medium may be confined in said cylinder under normal conditions of use without further reenforcement; a continuous winding of no more than two layers of contiguous convolutions of steel piano-wire of high tensile strength wound under tension on said cylindrical wall, said wire having been given a preset prior to being wound on said cylindrical wall, said preset establishing convolutions of slightly smaller inner diameter than the outer diameter of said cylindrical wall whereby said convolutions tend to embrace said cylindrical wall in clasping relation to minimize and localize the area of rupture of said cylinder and to prevent ripping apart of said cylinder when said cylindrical wall is pierced by a projectile; means for retaining said winding on said cylinder; and a coating of adherent material applied to said winding adhering thereto and serving to secure adjacent convolutions and aiding the preset condition of the coils in resisting the tendency for the wire to unravel when severed by a projectile.

DANIEL MAPES.