US2554499A - High-pressure apparatus - Google Patents

Description

May 29, 1951 T. c. POULTER 2,554,499

HIGH-PRESSURE APPARATUS Filed Sept. 8, 1947 2 Sheets-Sheet 2 l-.EU

20.4 8. 36 jf f3 4a 49 /f l 47 @1 //.r

Patented May 29, 1951 HIGH-PRESSURE APPARATUS Thomas C. Poulter, La Grange, Ill., assigner to Armour Research Foundation of Illinois Institute of Technology, Chicago, Ill., a corporation of Illinois Application September 8, 1947, Serial No. 772,645

12 Claims. l

This invention relates to a high pressure apparatus for the obtaining of very high pressures, such as those of the order of one million pounds per square inch and over. Such apparatus is frequently referred to as a pressure bomb.

Heretofore, for eXtra high pressure work, pressure bombs have often been constructed as a tube, simple or composite, open at both ends and defining a cylindrical bore running axially for the full length of the tube. Cylindrical pistons, one of which may be stationary and the other movable with respect to the bomb, are arranged for introduction into the open ends of the bore in opposed position. Pressure is applied eX- ternally and axially to the two pistons as by means of a hydraulic press or other suitable means, to create the desired pressure within the bomb bore between the adjacent ends of the two pistons.

The pistons, as heretofore employed, are usually made of high grade steel or sintered carbide, tempered glass-hard, and are generally capable of withstanding pressures greater than those which can be sustained by the bomb. The piston strength increases as the unsupported length decreases and as the diameter decreases. Values of one-half million pounds per square inch are obtainable with pistons of one-half inch in diameter and pressures of even a few million pounds per square inch are attainable with one-eigth to one thirty-second inch diameter pistons. n

In the past, bombs have often been constructed as single thick-walled tubes or a nest of two or more such tubes shrunk or taper-fitted and pressed together. Calculation and control of stresses in such bombs are difcult. Usually creep is involved, and the permissible pressures which can be utilized are empirically determined by the length of time and number of repetitions of applied pressure, and by the temperature and nature of contents compressed in the bomb. If the bomb does not burst, often the central bore is stretched and deformed, requiring reboring, grinding, and lapping to a new truly cylindrical form. This is a time-consuming and expensive process. Other limitations and .disadvantages of heretofore constructed bombs are well known to those skilled in the art and efforts to overcome them have only been partially successful.

I have devised an entirely novel and improved bomb construction which avoids the above mentioned difculties and which has additional advantages not heretofore realized. In general, the bomb of my present invention comprises a relatively thin-walled inner tubular member dening a working volume to be subjected to high pressure, an outer ring-like member, and a plurality of sector-shaped blocks in mutual laterally supporting relationship compressively confined between the inner tubular member and the outer ring-like member. In the bomb of my invention, extremely high stresses produced near the center are transmitted radially outwardly by essentially pure compression to outer members, including the outer annular ring and the sector-shaped blocks, which serve to restrain these extremely high stresses with the imposition of relatively moderateV stresses upon the outer ring-like member. The intermediate sector-shaped block elements cannot fail since they are subjected to practically pure compression with lateral and mutual support.

Furthermore, the bomb of my invention can be readily assembled and disassembled so that the central tubular liner can be removed and replaced and any other parts readily interchanged. This feature of construction is of particular convenience not only in the replacing of liners with corroded or worn out bores but also in the accommodation of liners with different bore diameters and correspondingly sized pistons as desired. The major components of my bomb seldom or never require renewal, a factor which is an obvious advantage.

The construction of my bomb also makes it feasible and convenient to introduce electrical inlar liner denes the working volume of the bomb and such liner can be placed under a predetermined initial radial pressure to absorb a portion of the pressure developed within such working volume yof the bomb.

It is a further important object of this invention to provide a high pressure bomb capable of withstanding pressures of the order of over a million pounds per square inch, and wherein the stresses therein set up near the center of the bomb are properly controlled and restrained by the outer members of the bomb construction at relatively moderate stresses.

It is a still further important object of this invention to provide a high pressure bomb in which a relatively thin-walled tubular liner is confined within an outer annular member by means of sector-shaped blocks initially placed under corn'- pressive stress by said outer annular member to withstand the pressures radially transmitted out- Wardly.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings. l

On the drawings: v

Figure 1 is a vertical cross-sectional View, with parts shown in elevation, Aof a high pressure apparatus. made in accordance with Amy present invention, the apparatus being shown as positioned upon the floor or bed of a hydraulic press between a lower stationary bed and an upper movable ram of the press.

Figure 2 is a partial sectional View taken substantially along the line II-II of Figure 1.

Figure 3 is a vertical sectional View of a modied form of the inner bom-b construction,

Figure 4 is a broken, vertical sectional view, with parts shown in elevation, of a modified construction of the bomb shown in Figure 1, the modified bomb being adapted for electrical heating of the pressure chamber.

As shown on the drawings: v

The reference numeral I@ (Figs. 1 and 2) indicates generally a high pressure apparatus, or pressure bomb, embodying the principles of my invention. Said apparatus I includes an inner tubular member, or liner I I, which is of relatively thin-walled construction and which is open at both of its ends for the reception of relatively movable pistons I2 and I3 to be described in greater detail later on. Said pistons I2 and I3 serve to produce the desired high pressure in working volume A within the bore I4 of the tubular liner II.

A plurality of sector-shaped blocks l5 conne and laterally support the tubular liner I I. When assembled in place about said tubular liner I I, the assembled blocks I5 define an inner cylindrical surface it for conforming contact with the outer cylindrical surface of the tubular liner II. As will be later explained, the outer diameter of the tubular liner II may be of the exact size of the diameter of the inner cylindrical surface I6, or it may be undersized or oversized, depending upon the results desired.

The outer surface of the assembled blocks I5 is preferably slightly tapered, as indicated by the surface Il, to facilitate the mounting of said assembled blocks within an outer, annular retaining member IS having a similarly tapered inner surface i5. The outer annular retaining member i8 may be of a solid piece of metal, or alloy, or may be of composite construction. The tapered surfaces I1 and I9 are preferably conical surfaces of the same small axial taper so as to permit a press t. The sector-shaped blocks I5 are rst assembled about the tubular liner II 4 and the outer annular retaining member I8 then pressed axially onto the liner-block assembly. In the final assembled relationship, as shown in Figure 1, the blocks I5 are under predetermined circumferential-radial compression, as in the case of very thick staves of a barrel bound together by hoops. With a definitely undersized tubular liner Il, the sector-shaped blocks I5 alone, by virtue of the keystone or barrel stave action that results, would support the entire compressive forces exerted by the outer annular retaining member I8 and no radially compressive force would be exerted on the outer surface 20 of the tubular liner II.

On the other hand, if the tubular liner Il were definitely oversized, the entire compressive forces exerted by the outer annular retaining member I8 would be transmitted to the outer surface 2U of the tubular liner II. Therefore, by a proper 'selection of the outer diameter of the tubular liner Il with respect to the inside diameter vof the cylindrical surface It defined by the inside ends of the sector-shaped blocks I5, it is possible to control the initial radial compression on the liner II across the surface 2S thereof to any 'desired fraction of the total initial radial compression'exerted by the outer ring I8.

This is a great advantage since it permits the use of an inner tubular liner I I of a comparatively thin-walled section without crushing of the liner by initial external radial pressure set up upon assembly of the apparatus. The large initial compression produced by the outer restraining annular member I8 is initially carried largely `by a circumferential pressure between the contacting lateral surfaces 2| `of the sector-shaped blocks. As hydrostatic pressure is built up within the working volume A within the bore I4 of the tubular liner II under the action of the pistons I2 and I3, this pressure is transmitted radially outwardly, first through the sector-shaped blocks I5 and then to the outer annular retaining member I8. The sector-shaped blocks I5 themselves provide mutual lateral support circumferencewise and have longitudinal and radial dimensions 'both large compared to the corresponding dimensions cf the high pressure working face Ill. lI "herefore, at 4all times the sector-shaped blocks I5 are stressed in virtually pure compression with adequate lateral support so that their failure is virtually impossible. Moreover, the outer annular retaining member I8 is of a size and accessibility that, without overstressing, it will readily support any pressure which it is feasible to develop yin the space A. Consequently, the major outer parts of the bomb such as the sector-shaped blocks I5 and the annular retaining member I8, have indefinitely Vlong life.

The end faces of `the assembled blocks I5 provide `an outer annular plane surface 22 (Fig. l) and an inwardly directed conical recess 23. The tubular Yliner II 4isof such length as to terminate at the bottoms of said conical recesses 23. A stationary base block '254, supported upon the floor or bed 25 of a hydraulic press (not shown), extends into one of said vrecesses 23 and is provided with a conformingly tapered conical end portion 26. Thepiston I3 projects from the end of said base block v2d to leave an annular plane shoulder 21 for supporting the adjacent end of the tubular liner lI l. The movable ram, indicated by the reference'numeral 28 is similarly provided with a conically shaped block 2e which extends into the corresponding conical recess 23. The piston I2 projects from the conical end of block.

29 into the tubular liner IIy in opposed relationship to the piston I3. The end portions of said pistons I2 and I3 are preferably carefully lapped to t exactly the bore I4 of the tubular liner Il.

For some applications, a pressure tight fit between the pistons I2 and I3 and the wall of the bore I4 may be insured by providing seals 30 and 3l, respectively, on the ends of said pistons. Said seals may be formed of any suitable plastic or resilient material, such as a soft vulcanized rubber, either natural or synthetic, a silicone resin, or the like, capable of withstanding the temperatures employed. Said seals 30 and 3| may initially be somewhat oversize to effect a tight seal, and need not be secured in any manner to the ends of said pistons. These seals 3D and 3| are more conveniently merely pushed ahead of the active ends of the pistons I2 and I3.

ln assembling the apparatus, the sector-shaped blocks I5 are first assembled in place around the tubular liner I I, and the outer annular retaining member I8 is then pressed or shrunk in place about the assembled blocks to clamp the blocks together by virtue of the conical surface of contact between the outer surfaces I'i of the blocks I5 and the inner surface I9 of the member I8. The pistons I2 and I3 are inserted into the ends of the upper block 29 and the lower base block 2li, which may be of hard steel or sintered carbide. The lower, stationary piston I3 is inserted into the lower end of the tubular liner I I, and the entire bomb and lower piston assembly placed on the floor 25 of a hydraulic press. The desired charge is then placed in the cavity A, the upper piston I2 inserted, and pressure applied by the ram 28 to the upper block 2S and piston I2.

In the specic form of my apparatus illustrated in Figures 1 and 2, the sector-shaped blocks I5 are shown provided with plane lateral faces and the dihedral angle between these plane faces exactly S60/n", where n is the number of sectors around the liner. For optimum control of the extremely high stresses which may be produced in the' central regions 0f the bomb, it may be desirable to depart from such geometric accuracy and the opportunity to do so in the bomb of my invention is one of the major advantages of the design. It may not be desirable that the lateral faces of the blocks be exactly plane or that the dihedral angles between the lateral faces of the sector blocks be exactly S60/n". Instead of the lateral faces being at, they may be slightly convex, or in general, of compound curvature. In such case, after the outer annular member I8 has been pressed over the slightly tapered outer conical surface I9 of the blocks I5, a predetermined circumferential compressive stress can be established throughout the sector-shaped blocks, with initial radial and longitudinal gradation of this circumferential stress pre-controlled as desired.

Alternatively, the sector-shaped blocks may be machined or ground as geometrically perfect as feasible, both with respect to dihedral angles and the flatness of the lateral faces. Before assembly,

however, thin shims of metal foil, ake mica, or

the like, of desired thickness and contour may be inserted between the sector-shaped blocks, and the blocks then assembled and the outer annular member pressed into place. The additional thickness, when compressed between the blocks, creates additional circumferential pressure, with kresultant radial and circumferential pressure profiles accurately predetermined at will. Shims of different thickness and thickness profiles can be ineluded for different bombs or for different pressure runs of the same bomb, thus making the initial pressure distribution different, as desired, for different internal liners, operating pressures, and different temperature profiles (with resultant different thermal dilation and distortion which will exist under the different temperature gradients) for particular heating and external cooling conditions of various tests. Such graded shims, therefore, make possible the grading of circumferential pressure over the faces of the sector-shaped blocks adjustable at will to compensate for the conditions of any given pressure run of any bomb.

As a still further essential refinement in the control of stresses in the crucial central highstress region made possible by the bomb of my invention, a controlled longitudinal beam action can be introduced into the block sectors I5. This may be accomplished in either or both of two ways. First, when internal pressure is developed in the working space A (Fig. l), as pressure is applied to the pistons I2 and I3, then, due to the fact that the axial length of A is much shorter than the length of the sectors I5 and outer ring I I3, the stretching or radial dilation lwill be greatest at and near the central plane II-ll. This action may be accentuated by purposely reducing the thickness of the outer ring I8 .at its central section by making its outer surface 52 spool or capstan shaped. Secondly, instead of making the inner surface IS of outer ring I8 and outer surface Il of assembled sectors I5 both truly straight mating conical surfaces, either or both of these surfaces may be intentionally ground with an axially extending concavity to fit tighter at the ends than at the center. ractically, it is convenient to make the inner surface I9 of the outer ring I 8 truly conical and to grind the cuter conical surface Il of the assembled sectors I5 slightly more at the center than is represented by a true cone.

Using either or both of these expedients in combination, hydrostatic pressure applied in the working volume A will cause the sectors I 5 to dilate or bulge radially outward more at their centers than at their ends, i. e., to bend slightly along their length like the lengthwise bend in wooden barrel staves. This will produce nominal tensile stresses axialwise in the outer wide sections of the blocks I5 where areas are large and other stresses comparatively small. However, more important, it will create large axial cornpressive stresses in the narrow inner portions of the block sectors I5 adjacent to liner II, these axial stresses being greatest, in a lengthwise direction, in the region surrounding working velume A.

In the preceding exposition, descriptive terms have been used such as blending like barrel staves, etc. It must be realized, however, that all dilations, bending, intended departures from true geometric at surfaces and angles or conical surfaces actually are matters of a few mils at most either initially or during pressure application and are, therefore, far too small to indicate in the figures.

It is well known that with equal triaxial compressive stresses, i. e., three equal compressive stresses in mutually orthogonal directions which is equivalent to hydrostatic pressure, any homogeneous metal can withstand any hydrostatic pressure whatever, no matter how large, without plastic distortion. Now, although it is not possible to design my bomb so that/(a) the circumferasl-strot -ential pressure stresses produced in blocks I by Inon-flat or :slightly off-angled faces or shims between `vfaces, and (b) axial stresses in the inner portions of the sectors I5 due to lengthwise bending Awill, at all times of a pressure cycle from zero to full hydrostatic pressure in space A, both be equal to each other and to (c) the radial pressure exerted by liner II itself, plus the hydrostatic pressure internal to A, yet in the crucial central region of the sectors, these three triaxial compressive stresses can be controlled in my bomb, never to become unequal to a sufficiently large amount to cause permanent distortion of the sectors I5 or outer ring I8.

As 'internal pressure Vis created in the bomb, the additional radial compression combines 'With and alters the initial circumferential and axial bendlingst'resses in such a manner that at 'no time 'and at no place in the sector-shaped blocks do the resultant combined triaxial stresses cause plastic deformation of the sector blocks I5. This is a distinctly `superior result, made possible by my invention, unobtainable heretofore with the use of the ordinary, thick-Walled tube bomb construction Where the metal immediately surrounding -the pressure cavity is plastically deformed in Atension each time the tube is loaded and in compression each time the tube is unloaded. Under those conditions, a feW repetitions of such cyclic plastic deformations causes failure after a limited number of times of use. While the thin-Walled inner 'tubular liner I I of my bomb may, of course, be plastically ldeformed upon application and release of pressure, it can be made of a softer alloy which is capable of appreciable deformation, since the stresses which it is called upon to With- Stand are nominal, just like an inner tube in a tire casing. Indeed, for some applications, I nd it desirable to replace liner II by a soft rubber tube (or the like) closed at both ends and containing the charge to be compressed. In this case, pistons l2 and I3 (Fig. l), are made to ac'- 'curately nt the inner cylindrical surface i3 ofthe sector blocks I5, which pistons then longitudinally compress such soft rubber or metal capsule together With its contents.

Moreover, the high unit radial stresses at the central ends of the sector-shaped blocks are fanned out and become nominal pressures at the inside surface I8 of the outer annular member I8. Since the annular member I8 is of comparatively large inside diameter, the ratio of its outer to inner radii is not far from unity. Therefore, the metal inthe outer annular member I3 is nearly uniformly stressed over its cross-section in hoop tension, so that the required cross-section need not be excessive, nor the alloy used in making the member I3 so critical as with usual high pressure bomb constructions.

External radial support for the tubular liner I in the construction of Figures l and 2 is adequate under all circumstances. Because of the thin-walled section of the liner and the friction along the Surface 28, axial support of the liner may not be required under ordinary circumstances. However, should the liner Wall be comparatively thick andthe temperature and pressure of operation extreme, there is a possibility that the tubular liner I I may be squeezed in two parts near its center by internal hydrostatic pressure and the two parts extruded axially endwise out of the bomb.

lIn order to prevent this possibility, the alternative constructionV illustrated in Figure 3 -maybe employed. As there shown, the inner tubular liner IIav is .provided with an outer circumferentially -uted surface 32. The uting may be helically arranged, in a manner similar to threads on a screw, or may be arranged annularly. The inner surfaces of the blocks I5 are similarly contoured as at 33. This arrangement eiectively prevents failure `of the liner by extrusion. There -is adequate axial strength in the sector-shaped blocks I5 to rprovide this `additional function of longitudinal-or axial support Vfor the tubular liner vIlor IIa.

One great advantage of the bomb of my ing vention is the convenience with which it .may be modified v'for electrical heating of the'charge wlhile such charge is under extreme pressure. vA vpreferred embodiment of this modication is shown in Figure 4.

InvFgure 4, similar reference numerals are used to indicate the tubular liner II, the sectorshaped blocks I5 and the outer annular retaining membernl'. The upper piston I2 is mounted as previously described in a block 28, but an electrically conductive plate 35 is positioned in place against the top of said yblock 29 and a layer of insulation 36 inserted between said plate 35 and the upper movable ram 28.

The lower piston 3l is made of slightly less diameter than the inside of the tubular liner II to permit a thin tube, or .sleeve 38, formed of mica or other suitable insulating material, vto fit snugly around the piston 31 and extend upward- 4ly from the block I39 'into the tubular liner II. Said insulating sleeve 38 extends from the end surface of the block 39 to a point somewhat short of the Working end o'f the piston I2 in its initial position.

An Vinsulating washer M! lies against the end of said block 39 about the ,piston 3l and insulating sleeve 38.Y This insulating Washer i6 prevents the conical face of block 39 from completely seating in the conical recess 23 in the ends of segments I5, the conical air gap so formed electrically insulating Athe respective members from each other, Aplate 4I of electrically conductive material is inserted lbetween the block 33 and a yplate 42 of insulating material that rests upon the filoor -2'5 of the hydraulic press. The electricallyconductive plates 35 and il are provided with contacts 4'3 .and M, respectively, for connecton vvithal source of electrical current including Wires 45 and 4,5. In addition, an electrical contact, including an electrically conductive plate 'II-'l andi-a contact post 48, may be provided for the outer annular ring I8, with a Wire 49 forconnection to the source of electrical current in parallel With or as an .alternative to wire 45.

In assembling .the apparatus illustrated .in Figures, thepiston 31 is secured in the end ofthe block A39 andthe insulating sleeve 38 slipped over the projecting end of the piston. The insulating Washer 40 is then inserted `in vplace against the endof .the block 39. The entire sub-assembly including the `piston 3l, block 39, insulating sleeve 38 and insulating vWasher d0 may then be chilled, if desired, and the insulating sleeve 38 and piston 31 inserted into the end of the .tubular liner II, the latter `having been heated just -`prior-to such insertion.

By :careful selection of dimensions, such as the diameters of the parts and the thickness ofthe insulating sleeve 38, and by proper choice of assembly temperature of parts, the thermalshrink t :may be :made to .stronglycompress the insulating sleeve 38 between the stationarypiston 31 .and the lower end of the tubular liner II. Pressure is still further increased by the external compression on the liner II produced by the sectorshaped blocks I and the outer annular member I 8, which are next assembled in place in that order. The upper edge of the lower piston 31 and the lower internal edge of the tubular liner II may be slightly rounded off to prevent cutting through the insulating sleeve 38 under the conditions of extreme radial compression to which the sleeve is subjected.

The active charge is next inserted in the cavity provided by the liner II and insulating sleeve 38. If the charge is electrically non-conductive, or it may be desirable to do so for other reasons, it may be enclosed in a thin-walled metal capsule 50. Said capsule 55 may be closed at both ends and formed with such thin walls and of suitable metal so as to be easily collapsible. The capsule :dts snugly inside of the insulating sleeve 33 to rest against the end of the piston 31, but extends about one diameter beyond the end of the sleeve 38 toward the piston I2. When the upper movable piston I2 is inserted into the tubular liner II and pressure is applied, the piston will cause the upper end of the capsule 50 to collapse, or mushroom, and make electrical contact with the tubular liner II along the end cylindrical surface thereof, as indicated at 5I.

Electrical contact with the capsule 50 is made at each end by the pistons I2 and 31. (Elastic fluid seals 333 and 3l of Figure 1 are omitted, or, if included in Figure 4, the lower one 3l at least must be made of electrical conducting material.) If the charge itself is electrically conductive, the

metallic capsule 50 may be omitted, in which case, the charge itself makes electrical contact with the ends of the pistons I2 and 31 and with the exposed inner surface of the tubular liner I I at 5 I.

The bomb and piston assembly is insulated from the floor and from the ram 28 by means of the plates or sheets 42 and 36 of insulating material. Electrical current may thus be supplied through the wire 65 and contact post IM to the plate 4I, for passage through the block 39 and piston 31 to enter the capsule 5@ and thence ow through the piston I2, block 29 and plate 35 to the terminal post i3 and wire (l5. Useful heating can thus be produced by the flow of the electrical current lengthwise in the thin wall of the metal capsule 5G. If the charge itself is electrically conductive, or if the capsule is omitted, then the electrical current would flow entirely or in part endwise through the charge itself.

In the latter case, the electrical current required for effective heating might be large. In order to avoid danger of overheating the moving piston I2, it is desirable to provide the outer annular retaining member I8 with an electrical connection through the terminal 48 and wire 49, the electrical circuit being completed through the blocks I5, liner I I and contact at 5I with the capsule Sil in its mushroomed state. Both the wires i5 and 49 may be used in parallel as one side of the electrical circuit, or either one may be used as a potential lead. The important point is that telescoped at its end adjacent the upper piston I2 as said piston advances during compression. Likewise, the capsule 5I), if used, may also crumple and collapse during application of pressure. It is feasible, however, to preserve the integrity of the insulation provided by the sleeve 33 despite such pressure.

As an alternative construction, the tubular liner I I may be insulated from the sector-shaped blocks l5 by insulating the inner face surface at 2G (Fig. 1), or inter-surface 32-33 (Fig. 3) by enamel or the like, in which case the liner may be heated by heavy electrical current flow lengthwise of the liner after provision of suitable end terminals. When using the liner itself as the electrical heating element, I have found that concentration of heat liberation at the center of the bomb can be achieved by reducing the wall thickness of the tubular liner at its mid region. This reduction may take the form of an internal or external annular groove in the tube wall. In the latter case, the space between the liner and the sector-shaped blocks so formed must be filled with insulation, or the longitudinal contour of the inner ends of the sector-shaped blocks I5 must be made to correspond to the outer contour of the liner as modined.

If shims of graded thickness are used between the lateral faces of the sector-shaped blocks I5 in order to grade circumferential compression at will over the faces of the blocks, these same shirns, if made of electrical insulating material such as mica flake, could also be made to serve as part of an electrical heating system using the individual sectors as current elements. It is possible to insulate all or desired parts of the surfaces of each sector so that electrical contact is, or is not made, between the sectors, or between the sectors and the tubular liner, or between the sectors and the outer annular member I8. Many combinations are thus feasible for heating the liner by electrical current flow in series or multiple, long or short, circumferential and/or longitudinal paths by suitable contact with part areas of the sectors, to which sectors electrical current is introduced by a suitable electrical terminal fixed to the sectors. Location of applied heat, in and to the liner, is also of considerable importance and the bomb construction here disclosed makes for great nexibility and convenience in achieving the desired heating conditions.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted hereon other- Wise than necessitated by the scope of the appended claims.

` I claim as my invention:

1. In a high pressure apparatus, an outer annular member having a tapered inner surface, an inner tubular liner having an outer circumferentially fluted surface, and a plurality of sector-shaped blocks defining an inner surface conforming with the outer surface of said tubular liner and defining an outer surface generally conforming with the tapered inner surface of said outer annular member, the dimensions of said liner, blocks and annular member being such that upon assembly said blocks are placed under initial radialv compression.

2. High pressure apparatus comprising a relatively thin-walled tubular member defining a Working volume to be subjected to high pressure, an outer ring-like member concentric with and 1l Y surrounding said tubular member, and a plurality of sector-shaped blocks in mutual laterally supporting relationship interposed between said members upon assembly, said blocks collectively having a greater total effective volume than that volume lying between said tubular member and said ring-like member, and said blocks being compressed within said outer member upon assembly to subject said tubular member to an initial inwardly acting radial compression.

3. High pressure apparatus comprising a relatively thin-walled tubular member defining a working volume to be subjected to high pressure, an outer ring-like member and a plurality of sector-shaped blocks in mutual laterally supporting relationship compressively confined betweeny said members to subject said tubular member to initial radial compression upon assembly f said apparatus, said blocks having longitudinal and radial dimensions at the surfaces of Ycontact with said outer member that are both large in comparison with the corresponding dimensions of said working volume, and said blocks in combination normally occupying a volume greater than that occupied by the blocks upon assembly of said appartus, whereby compression stresses set up in said blocks upon assembly are transmitted directly to said working volume.

4. High pressure apparatus comprising a relatively thin-walled tubular member defining a working volume to be subjected to high pressure and formed of material that is plastically deformable under the pressures to which it may be subjected and an outer ring-like member and a plurality of sector-shaped blocks formed of a material relatively harder than said plastically deformable material and arranged in mutual laterally supporting relationship compressively confined between said members to subject said tubular member to` initial radial compressi-on upon assembly of said apparatus.

5. High pressure apparatus comprising a relativelyY thin-walled tubular member having -an outer circumferentially fluted surface and an inner cylindrical surface defining a working volume to be subjected to high pressure, an outer ring-like member and a plurality of sectorshaped blocks in mutual laterally supporting relationship compressively confined between said members and having surfaces conforming to and in contact with said fluted surface and the inner surface of said ring-like member to subject said tubular member to initial radial compression upon assembly of said apparatus.

6. High pressure apparatus comprising an outer annular member having an inner tapered surface, an open-ended inner tubular liner providingca cylindrical inner working surface, a plurality of ysector-shaped blocks providing when assembled an outer tapered surface for `pressure contact with said inner tapered surface and an inner surface in conforming contact with said tubular liner and inwardly tapered end recesses coaxial with said inner working surface, said blocks serving to transmit radial compression forces created upon assembly of the apparatus to` said tubular liner, and relatively movable rams having pistons for insertion into the open ends of said liner and having tapered end faces for insertion into said tapered end recesses, said pistons having end portions lapped within said cylindrical inner working surface.

7. High pressure apparatus comprising an outer Yannular member having an inner tapeljl.

12 n surface, an open-ended inner tubular liner providing a cylindrical inner working surface, aplurality of sector-shaped blocks providing when assembled an outer tapered surface for pressure contact with said inner tapered surface and an inner surface in conforming contact with said tubular liner and inwardly tapered end recesses `coaxial with said inner working surface and in surface contact with said liner, and relatively movable rams having pistons for insertion into the open ends of said liner and having tapered end faces for insertion into said tapered end recesses, said pistons having end portions lapped within said cylindrical inner working surface and having end seals of plastic sealing material.

8. In a high pressure apparatus having a pair of opposed force-generating elements, a charge confining and retaining structure comprising sector-shaped blocks defining when assembled a central cavity for receiving said elements and having a tapered outer surface, and an annular member for enclosing said assembled blocks and having a similarly tapered inner surface for cooperation with said assembled blocks to hold the same under radially inwardly directed initial compression upon assembly of said member about said blocks, said compression being transmitted directly through said assembled blocks to the area lying between said elements.

9. High pressure apparatus comprising an outer annular member, an open-ended inner tubular member, relatively movable piston elementsv extending into and closing the open ends of said tubular member to define a high pressure working chamber, and sector-shaped blocks confined between said outer annular member and said inner tubular member, said blocks presenting lateral surfaces of initially curved contour to es-ftablish a predetermined circumferential Stress throughout said sector-shaped blocks when said. outer annular member is in assembled'position confining said sector-shaped blocks.

10. High pressure apparatus comprising an outer annular member, an open-ended inner tubular member, relatively movable piston ele-V ments extending into and closing the open ends of vsaid tubular member to define a high pressure working chamber, sector-shaped blocks confined between said outer annular member and said inner tubular member, and shims between the lateral faces of said blocks to establish a predetermined circumferential stress throughout said sector-shaped blocks when said outer annular member is in assembled position confining said sector-shaped blocks.

, 11. High pressure apparatus comprising an outer annular member, an open-ended inner tubular member, relatively movable piston elements extending into and closing the open ends of said tubular member to define a high pressure working chamber, and sector-shaped blocks confined between said outer annular member and said inner tubular member,said blocks presenting lateral surfaces of initially convex contour to establish. a predetermined circumferential stress throughout said sector-shaped blocks when said outer annular member is in assembled position confining said sector-shaped blocks.

12. High pressure apparatus comprising anV outer annular member having an inner generally conical surface, an open-ended inner tubularA member, relatively movable piston elements Vex REFERENCES CITED The following references are of record in the le of this patent:

Number 14 UNITED STATES PATENTS Name Date Rubin Dec. 1, 1885 Buttles Dec. '7, 1926 Graham July 12, 1938 Ernst et al. Feb. 18, 1941 Wacker Feb. l0, 1942 Tooker Sept. 28, 1943 Wacker July 15, 1947 Renier Aug. 31, 1948 Hubbert et al. Sept. 20, 1949 Rubber Age, November 1942, pages OTHER REFERENCES 133 and

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