Abstract:
A hazardous material transport container employing a conventional 55 gal. ring ribbed drum in which a protective shell is slidingly fitted, wherein the shell contains an inner containment vessel, wherein protective spacings are provided between the shell and the vessel and between the shell and the drum, wherein a plurality of elongated strengthening ribs are affixed generally longitudinally to the outer surface of the shell and lie closely adjacent to but slidable within the inner surface of the drum, wherein an upper portion of the shell is welded to a top inner portion of the drum wall, and wherein thermal insulating and impact resistant materials substantially fill the protective spaces.

Description:
This application claims priority under 35 U.S.C. 119(e)(1) based on Applicants Provisional U.S. Patent Application Ser. No. 60/569,753 filed May 10, 2004 and titled “REUSABLE CONTAINER UNIT HAVING SPACED PROTECTIVE HOUSINGS”. 

   BACKGROUND OF THE INVENTION 
   1. Field 
   The present invention is for containers having markedly simplified construction and special utility for the bulk shipment of fluid or solid materials which may be of a toxic or otherwise hazardous nature including radioactive materials. The invention especially concerns novel construction and features which allow repeated reuse of the container even though it is subjected to rough treatment which normally would puncture or otherwise seriously damage such containers as are presently in use for bulk materials transport. 
   Of great concern to the hazardous material transporter, user, Federal Regulators and to the environment is the relative ease with which such conventional containers can be damaged in accidents, often resulting in leaks and spills of toxic or otherwise dangerous chemicals. Such incidents also occur where containers are moved about and stacked or loaded and unloaded on vehicles by fork-lift trucks or the like. During such operations, puncture or other severe damage to the container often occurs. As a result of these experiences, Federal Regulations now substantially restrict the reuse of chemical containers and costly disposal thereof is the necessary consequence. 
   2. Prior Art 
   For an even more onerous use of such containers there has been a need for a new generation of shipping container or packages for the nuclear industry for many years in that the presently utilized fleet of shipping containers is based on 40 year old technology and many of them no longer meet the current regulations such as those regulations recited for packages in 10 CFR 71.71 et seq. Due to recent changes in the regulations many older packages are obsolete due to their inability to successfully pass new more stringent requirements. Several of the staple packages are being removed as options for transport and the industry is in need of a cost effective, safe and reliable alternative. Such containers or packages which find utility for many applications but which may be unsuited for transporting, e.g., uranium dioxide, uranyl nitrate hex hydrate, U233, PU/PuO 2 /MOX and various neutron sources, are shown in U.S. Pat. Nos. 5,595,319; 2,148,278; 2,575,283; 2,596,244; 3,197,066; 3,294,271; 4,184,609; 4,712,711; 4,986,436; and 4,989,447. 
   The present container construction markedly improves the strength and structural integrity of hazardous material containers and makes them reusable. In this regard, the present container can utilize a conventional ring ribbed 55 gal. drum or the like and slide down into it a substantially complete containment vessel and protective shell which has longitudinal strengthening ribs on the exterior longitudinal surface of the shell, which structure facilitates the final assembly and welding together of the container components including the 55 gal. drum. 
   SUMMARY OF THE INVENTION 
   In one preferred embodiment of the present container construction a conventional 55 gal. ring ribbed steel drum having a longitudinal axis is slidingly fitted with an inner protective shell containing a material containment vessel, wherein the shell is spaced from the vessel over all but a top open end portion of the vessel to provide a protective space, a wall section of the shell being affixed to said end portion, wherein a bolted closure cap is provided for sealing said end portion, wherein a drum cover is provided for sealing an open top of said drum, wherein said wall section is spaced downwardly in said drum from said cover to provide another protective space, wherein a plurality of elongated strengthening ribs are affixed generally longitudinally to an outer surface of the shell and lie closely adjacent to but slidable longitudinally within said drum and thereby providing another protective space between the drum wall and said shell, wherein an upper portion of said shell is welded to a top portion of said drum wall, and wherein thermal insulating and impact resistant materials substantially fill said protective spaces. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be understood further from the drawings and description, wherein the dimensions are not to scale or proportion and certain dimensions are enlarged for clarity, and wherein: 
       FIG. 1  is a partially longitudinal cross-section of a preferred embodiment of the invention; 
       FIG. 1A  is a cross-sectional view taken along line  1 A- 1 A in  FIG. 1B ; 
       FIG. 1B  is a cross-sectional view taken along line  1 B- 1 B in  FIG. 1  with vessel  12  removed and showing principal wall structures and vertical reinforcing members; 
       FIG. 2  is a cross-section taken along line  2 - 2  in  FIG. 1  with portions broken away for clarity; 
       FIG. 3  is a cross-sectional view taken along line  3 - 3  in  FIG. 1  with cap structure  70  removed; 
       FIG. 4  is a cross-sectional view taken along line  4 - 4  in  FIG. 1 ; 
       FIG. 5  is an enlarged top ring portion of the protective shell showing further details of construction; 
       FIG. 6  is a view as in  FIG. 5  showing a variation in the top ring construction; and 
       FIG. 7  is a longitudinal cross-sectional view of the polyurethane plug  74 . 
   

   DETAILED DESCRIPTION 
   With reference to the drawings and the claims herein, the present container  7  for hazardous materials  8  is of all steel construction except for protective foam, seals and the like and having a longitudinal axis  9 . A substantially closed and continuous first wall means  10  provides an inner containment vessel  12  for said material and has an open top portion  13 . A substantially closed and continuous second wall means  14  provides a protective shell  15  substantially surrounding vessel  12  and having its inner surface portions such as  16  radially spaced from all but the open top portion  13  of outer surface portions  18  of the vessel to provide a first protective spacing  20  there between. An aperture  22  is formed thru this second wall means  14  at a top portion  24  thereof generally longitudinally of shell  15  for allowing insertion into and welding of open top portion  13  of said vessel to top portion  24 . A cover  46  (blind flange) is adapted to be removably affixed to top portion  24  as with bolts  25  to cover aperture  22 . Sealing means such as elastomeric sealing O-rings  23  and  41  are provided to hermetically seal vessel  12 . 
   A third wall means  26  provides a sealable drum  27 , preferably a conventional ribbed 55 gallon drum having side portions  28 , a bottom  30 , an open top  32 , and a sealable drum lid  34  for closing said open top, wherein outer surface portions  36  of said shell  15  are spaced from inner surface portions  38  of said drum over a major portion thereof to provide a second protective spacing  39  therebetween. Shell  15  has a plurality of strengthening ribs  40  affixed to and spaced around segments of outer surface portions  36  of the shell and extending generally longitudinally thereof substantially from the top  42  to the bottom  44  or reinforcing plate of the shell. 
   The construction of second wall means  14  provides a cylindrical side wall portion  48  which extends longitudinally upwardly beyond top portion  24  and is provided at its top  42  with a ring member  29  which is affixed to an upper inner surface portion  50  of side portion  28  of drum  27 , preferably by welding, whereby a third protective spacing  62  is provided. Ring member  29 , as shown in  FIG. 6 , may comprise a heavy steel annular reinforcing rim  52  welded as at  54  to top portion  42  of side wall portion  48  inner surface portion  50  of the drum as at  56 . Wall means  14  is shown as preferably having a liner section  57  which, during fabrication is welded to  48  and to a bottom reinforcing structure  79  comprising a circular rim member  77  which is part of fabricated lower reinforcing ring comprised of  77  and other circular rim members  94  and  96  and bottom  44  whereby the exact length of the shell is more easily attained. One could, however, construct  48  and  57  as a unitary cylindrical unit of uniform diameter and welded to item  77 . It is noted that the welds are denoted  56  generally. 
   The drum lid  34  preferably has a heavy steel reinforcing flange  64  welded thereto and a top annular gasket  33  of, e.g., heat resistant silicone rubber or neoprene material is positioned between the lid and ring member  29 . A plurality, e.g., 4-10 blind nuts (insert holders)  68  (or 52) are welded to the top portion  42  of wall  14  underneath ring member  29  and aligned holes for bolts  31  are formed through annular reinforcing flange  64 , lid  34 , gasket  33  ring member  29  and into blind nuts  68  to provide threaded bolt or thread insert  88  receiving sockets  69  in the nuts. Where ring member  29  comprises a heavy solid ring  52  as shown in  FIG. 7 , the separate nuts  68  are not needed and the blind bolt or insert hole threads are formed directly into ring  52 . It is noted that nuts  68  as well as the threaded holes in ring  52  can be used to receive thread inserts  88  in situations where, e.g., especially hardened threads and bolts are required. Lock washers  21 , of course, are preferred for all bolts shown in the drawings. A heat resistant sealing material  47  provides an annular gasket for lid  34 . 
   In a preferred embodiment a cap structure generally designated  70  is used for extra protection and preferably is provided with an elastomeric, e.g., neoprene pad  71 . This structure affords extra force protection to blind flange  46  as well as hermetic sealing by, e.g., annular silicone rubber gasket  72 . Bolts  73  threaded into blind apertures  75  affix  70  to top portion  24 . Further, protective spacing  62  is filled by a thermal and impact protective removable polyurethane plug  74  ( FIG. 7 ) which is configured and dimensioned to snugly engage substantially all inner structures such as  48 ,  76 ,  78 ,  80  and  82  which define spacing  62 . 
   Spacing  20  is preferably filled with in-situ foamed closed cell polyurethane  35 , and spacings  39  between the ribs  40  are preferably filled with a ceramic blanket  37 , the compositions of which are more fully described below. 
   The protective shell is preferably constructed from the components comprising upper wall portion  48 , intermediate wall portion or liner  76 , bottom reinforcing structure  79  and the heavy top portion  24 . Components  48 ,  76 ,  77 ,  94  and  96  preferably are rolled steel sections with their ends joint welded to provide annular structures having fairly close tolerance dimensions of, e.g., 0.025 to 0.125 in. While other construction techniques can be employed, it will hereinafter become evident that by starting with these separate component items, the assembly, welding and polyurethane foaming operations are facilitated. 
   The vertical reinforcing members  40  are preferably tied together in a circular array as shown in  FIGS. 1A and 1B  by means of a reinforcing ring structure generally designated  95  and comprising an outer rim  96  and an inner rim  98  welded to the peripheral surfaces of members  40 . In between rims  96  and  98  are semi-circular web members  100  welded to  96  and  98  and to the abutting surfaces of members  40 . Two such structures  95  are shown, preferably in the areas of the drum ribs  102 , however any number of the structure can be provided. 
   With reference to the claims herein, a preferred embodiment of the present invention is defined as a reusable container ( 7 ) for hazardous material ( 8 ), said container having high impact resistance and leak containment characteristics and being readily handleable by conventional fork lift or the like equipment, said container having a longitudinal axis ( 9 ) and comprising a substantially closed and continuous first wall means ( 10 ) providing an inner containment vessel ( 12 ) for said material and having an open top portion ( 13 ), a substantially closed and continuous second wall means ( 14 ) providing a protective shell ( 15 ) substantially surrounding said vessel and having inner surface portions ( 16 ) radially spaced from at least a major portion of outer surface portions ( 18 ) of said vessel to provide a first protective spacing ( 20 ) there between, aperture means ( 22 ) formed thru said second wall means ( 14 ) at a top portion ( 24 ) thereof generally longitudinally of said shell ( 15 ) for allowing insertion into and welding of said open top portion ( 13 ) of said vessel to said top portion ( 24 ) of said shell ( 15 ), a vessel cover ( 46 ) adapted to be removably affixed to said top portion ( 24 ) as with bolts ( 25 ) to cover said aperture means ( 22 ), third wall means ( 26 ) providing a sealable drum ( 27 ) having side portions ( 28 ), a bottom ( 30 ), an open top ( 32 ), and sealable drum lid means ( 34 ) for closing said open top, wherein said shell ( 15 ) has a plurality of strengthening rib means ( 40 ) affixed to and spaced around segments of said outer surface portions ( 36 ) of said shell ( 15 ) and extending generally longitudinally thereof substantially from the top ( 42 ) to the bottom ( 44 ) of said shell, whereby said outer surface portions ( 36 ) of said shell ( 15 ) are spaced from inner surface portions ( 38 ) of said drum over a major portion thereof to provide a second protective spacing ( 39 ) there between, wherein the construction of said second wall means ( 14 ) provides a cylindrical side wall portion ( 48 ) which extends longitudinally upwardly beyond said top portion ( 24 ) and is provided at its top ( 42 ) with a ring member ( 29 ) which is affixed to an upper inner surface portion ( 50 ) of said side portion ( 28 ) of said drum ( 27 ), and wherein protective material is provided in said spacings. 
   The closed cell polyurethane foam used herein has a density range of 5.0 to 7.0 pounds per cubic foot (PCF), and analyzed for the following elemental percentages, each with a tolerance of ±10%: 
   Hydrogen 6.7% 
   Carbon 61.7% 
   Oxygen 26.1% 
   Nitrogen 5.2% 
   Other 0.3% 
   Density measurements of the analytical test samples were performed in accordance with ASTM D-1622. Density measurement of the polyurethane foam as installed was done by simple calculation of the foam weight divided by the container cavity volume. 
   Compressive strength was tested in accordance with ASTM D-1621, Compressive Properties of Rigid Cellular Plastics. Densities in pounds/ft 3  (PCF) of 5.0 and 7.0 gave compressive strengths within a range (PSI) of 85-300. 
   Thermal conductivity measurements were performed in accordance with ASTM C518. Based upon test results the thermal conductivity of the foam K
 
Factor=4.05 Btu-in/(h-sq ft-CF).
 
   Flame retarding testing was performed in accordance with ASTM E84. The flame spread classification was 830 and the smoke developed classification was 300. 
   The foam was tested for Water Absorption in accordance with ASTM C209 Section 14 and the Moisture Content in accordance with ASTM C209 Section 18. The CI1 Urethane foam is a Closed Cell foam. The moisture content of the foam was 2.10%. Water absorption was 0.46% after 2 hours and 0.78% after 24 hours on a volume water/volume product basis. 
   Based on testing performed on samples with mid-range densities of 6.0 pcf, leach able chlorides were &lt;25 ppm and total leach able chlorides were also &lt;25 ppm. Chloride content in any event should be less than 100 ppm. 
   Urethane foam resins and urethane foam and other raw materials and processing chemicals should be stored at room temperature. The urethane foam was formed of two components selected for a rigid polyurethane system that produces a hard foam with a nominal, free rinse core density of 5 to 7 pcf. The system should be a water blown foam formula with a polymeric MDI as the “A” component. The flame retardant should be a mono-pentaerythritol based material. 
   The rigid polyurethane foam is tailored for insulation and is produced in slab or bun form. The raw material typically is PMDI and the blowing agent typically is FC-11, (bp 23.8° C.). Tertiary amines and organotin compounds, e.g., dibutyltin dilaurate, are usually employed as catalysts. The polyols are preblended with surfactant, catalysts and fire retardants. The other component is the isocyanate and the catalysts can be added to either component. 
   Foam in Place Procedure (for Protective Spacing  20 ): 
   
       
       
         
           Calculate the amount of foam required for volume and add 10%. 
           Weigh container to be foamed—Record reading. 
           Weigh raw materials for a 7% flame retardant formulation. 
           Adjust temperature of container to be foamed. 
           Pre-mix flame retardant with a component in a container that will hold all of the components. 
           Add other components and mix. 
           Pour into container cavity. 
           Watch foam rise for any abnormalities. 
           When the rise is complete, allow foam to cure before cutting. 
           Trim excess foam from container. 
           Weigh foamed container. 
           Calculate density of the foam in the container based on container void volume and net weight of the foam installed.
 
Mold Fabrication Foam Procedure (For Plug  74 )
 
           This procedure is to be used for foaming molds, blocks or buns of material to be cut to a particular finished component part to be used in final container. 
           Calculate the amount of foam required for the mold. 
           Adjust the mold temperature. 
           Weigh out the raw materials. 
           Pre-mix flame retardant and a component (usually with the isocyanate) of the urethane system in a container that will hold all components. 
           Add other component (polyol) and mix. 
           Pour evenly into mold. 
           Watch for abnormalities. 
           Once the rise is complete, record total rise height. 
           Once the foam has cured, cut to specified shape. 
           As required take sample and calculate pcf. 
         
       
     
  
   The protective material used for filling protective spacing  39  is a chemical resistant thermal barrier blanket 1.5 in. thick and weighing 8 lbs/ft 3 , and consisting of high Al 2 O 3  and SiO 2  content ceramic fiber spun from molten mineral raw material and having average fiber lengths of 8 inches with substantially uniform diameter. Such blankets are marketed under the name CER-WOOL®, by Vesuvius USA Corporation of Buffalo, N.Y. 
   Further specifications for the present CI-1 container are as follows: 
   
     
       
             
             
             
           
             
           
             
             
           
             
           
             
             
             
           
         
             
                 
             
             
               ITEM 
               WEIGHT KGS 
               WEIGHT LBS 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               1. Relevant Weights of A Loaded CI-1 Shipping Container 
             
           
        
         
             
               CI-1 (Container per se) 
               290 
             
             
               Maximum load per Vessel 
               100 
             
             
               Maximum Gross Weight 
               390 
             
             
               Of Loaded Container 
             
           
        
         
             
               1. MATERIALS OF CONSTRUCTION 
             
           
        
         
             
               55-Gallon Drum 
               16 Ga. C/S 
               UNIA2/X400/S 
             
             
                 
               (Carbon Steel) 
             
             
               Closure Ring 
               12 Ga. C/S 
               UNIA2/X400/S 
             
             
               Drum Bolt 
               C/S 
               SAE I429 Grade 5 
             
             
               Drum Gasket 
               EPDM Closed 
             
             
                 
               Cell Rubber 
             
             
               O-Rings 
               Silicone 
               ASM 3304 F 
             
             
               Flat Gaskets 
               Silicone 
               AMS 3195, MILR 
             
             
                 
                 
               46089 or Equal 
             
             
               Inner Pad 
               Neoprene Rubber 
               ASTM D-2000 
             
             
                 
                 
               SAE J200, MILR- 
             
             
                 
                 
               33065, or Equal 
             
             
               Sheet 
               C/S 
               ASTM A1011 
             
             
               Plate 
               C/S 
               ASTM A36 
             
             
               Angles 
               C/S 
               ASTM A36 
             
             
               Square Tubing 
               C/S 
               ASTM A500 
             
             
               Thread Inserts 
               C/S 
               Fastenal EZLOK Part 
             
             
                 
                 
               No. 60160 or Equal 
             
             
               Closure Bolts 
               Clad C/S 
               ASTM A449 Type 1 
             
             
                 
                 
               Grade 5 
             
             
               Lock Washers 
               Clad C/S 
             
             
               Insulation 
               Ceramic Fiber 
             
             
                 
               Blanket/Board 
             
             
               Vent Plug 
               Acetate 
               ASTM 300 Series 
             
             
                 
             
           
        
       
     
   
   The following chart gives specific preferred compositions and dimensions of structural items as numbered and as shown in the drawings and employed in the construction of the present container. 
   Preferred Assembly Procedure 
   Inner Vessel Assembly: 
   
       
       
         
           1. Cut Tube of vessel  12  to proper length. 
           2. Weld tube bottom end cap  17  to vessel tube. 
           3. Machine the slip-on flange  24 . 
           4. Fit and weld slip-on flange to top of vessel tube. 
           5. Machine vessel cover  46  (blind flange). 
           6. Fit and weld together the rolled caps angle ring  80  and the cap plate  78 .
 
Inner Container Assembly:
 
           1. Cut, roll and weld side wall  48  to appropriate diameter. 
           2. Fit and weld  48  to top ring  29 . 
           3. Fit and weld flange (top portions)  24  to  48 . 
           4. Fit and weld insert holders (blind nuts)  68  to top ring assembly  29  and to  48 . 
           5. Roll and weld bottom angle  77 . 
           6. Fit and weld square tubing  40  (to obtain the proper height of protective shell  15 ) to top ring assembly and bottom rolled angle ring  77 . 
           7. Position the partial assembly and fit and weld liner section  14  to  48  and to bottom angle ring  77 . 
           8. Paint inside areas of inner vessel if required. 
           9. Cut and place the Cer-Wool paper against the inside bottom  19  of item  24  prior to foaming. 
           10. Foam the first protective spacing  20 . 
           11. Cut excess foam off. 
           12. Cut and place Cer-Wool paper onto the top of the cut surface of the poured foam in spacing  20 . 
           13. Close the foam space  20  by fitting and welding bottom reinforcement plate  80  to bottom angle ring  77 . 
           14. Install thread inserts  45  in the slip-on flange  24 . 
           15. Perform leak test on containment vessel  12  as required.
 
Final Assembly
 
           1. Install vent plug pushes  90  (heat fusible plastic for internal pressure relief). 
           2. Wrap outside shell  15  between ribs  40  with Cer-Wool blanket. 
           3. Slide the shell into the outer 55-gallon drum  27 . 
           4. Weld the shell top ring member  29  to the drum at the top of the shell assembly. 
           5. Cut hole, in side of drum for the vent plug coupling  84 . 
           6. Fit and weld coupling  84  to the drum  27 . 
           7. Install the thread inserts  88  into top insert holders (blind nuts)  68  as required. 
           8. Fit and weld the reinforcing flange  64  to the drum lid  34 . 
           9. Clean as needed and paint if required. 
           10. Install all gaskets and pad  71 . 
           11. Install bolts and close cover  46  and cap structure  70 . 
           12. Insert polyurethane plug  74  in spacing  62 . 
           13. Close outer drum lid and torque lid bolts, affix lid closure ring  43  against lid seal  47  and torque its clamping nut for transport. 
           14. Weigh and stencil as required. 
           15. Attach Nameplate. 
         
       
     
  
   A Hypothetical Accident Test Series was executed in accordance with CFR 71, Subpart F and IAEA Safety Series TS-R-1 as required for government approval of such containers. The test package (loaded container) was manufactured in accordance with approved drawings substantially as described herein and was designed for shipment of solid-form high-enriched uranium compounds, metals and uranyl nitrate crystals. It consists of a 5″ OD×26.5″ tall canister (vessel  12 ), surrounded by insulation and an outer 55-gallon drum, with overall dimensions of approximately 24″ OD×35″ tall. There are a total of 21 bolts utilized for the three separate closures. Ceramic Fibers and polyurethane foam make up the insulation materials of the package. The vessel is sealed by use of a set of leak testable o-rings, with the inner vessel acting as the containment boundary. 
   All testing was carried out by Southwest Research Institutes (SwRI&#39;s) appropriate department personnel and witnessed by their Quality Assurance Department under the direction of Century Industries and the SwRI Project Management Team in accordance with the test plan.
         1. The test package was inspected for any pre-test damage and found to be acceptable.   2. The package was weighed and loaded using 90.8 pounds of new steel shot as a test median.   3. The tare weight was 299.2 pounds, with the total gross weight of the package at 390 pounds.   4. O-rings were installed and the cover ( 46 ) positioned and torqued as required to 33 ft-lb using an alternating pattern.   5. A helium leak test was performed using equipment that was calibrated to a sensitivity of 2.2×10 −8  std-cc/secs. The test method conformed to the required leak test standards, with an acceptable pre-test leak rate between 32.−4.2×10 −8  std-cc/secs over a 5 minute test time.   6. The secondary cover ( 70 ) and seals ( 72 ) were positioned and torqued to the same required torque of 33 ft-lb using a calibrated wrench.   7. Top plug insulation ( 74 ) was put into place and the outer drum lid positioned and torqued to the appropriate tension of 33 ft-lbs.   8. The outer drum coves ring clamp ( 43 ) was installed and torqued to 75 ft-lb, to complete the closure of the package.   9. The package was placed into a cooling chamber for 12 hours and the temperature reduced to an ambient temperature of −40° F. on the outer surface of the test package prior to the drop test.   10. The package was then removed from the cooling chamber and a thermocouple protector installed.   11. Drop test were conducted and the results recorded as follows:   a. The first test, a 4 foot drop through the center of gravity @ 58-60 degrees, onto the bolted closure ring ( 43 ) of the drum, which aligned with one of the top bolts on the outer package top, to create a worst case condition, was completed. The damage to the package consisted of an indention approximately 4″-6″ long×¾″ deep. Acceptable.   b. The second test, 30 foot drop through the same damaged area, in the same orientation was conducted. Damage consisted of a growth in the previously damaged area to approximately 12″ long×2″ deep, a minor ripple in the outer side wall, caused from the transfer of energy thru the package to the bottom and a minor dent in the bottom. Impact area top bolt cap sheared off, no openings. There were no tears opening to the inside or other unacceptable conditions found on the package. Acceptable.   c. Drop number three, the crush test, consisted of a carbon steel plate, weighing 1100 pounds, falling from a height of 30 feet from the top surface of the package, onto the package placed in a horizontal position. This was determined to be the worst case position using computer models and preliminary drop testing information previously conducted. Damage to the package was a flattening of the impact sides over areas  12 ″ wide extending the entire length of the package. One tack weld on the reinforcing ring of the drum cover had a minor tear, which exposed an area approximately ½″ long×⅛″ high of the top foam plug. There was additional damage which occurred to the bottom edge of the package in the form a slit in the side wall of the outer drum which was accidentally placed over the test pads steel reinforcing plate edge which was exposed causing a shearing action to occur, this damage was in the form of a tight slit approximately 4″ long. The possibility of welding the area was discussed, but after that discussion it was left as it was. Acceptable.   d. Drop number four, the Puncture test, was conducted using a 6″ diameter×12″ long solid steel bar welded to the test pad, with the package in the horizontal position and the impact area designated between the two vertical internal stiffeners and the middle drum rolling hoops. This drop provided damage to an area of the mid-section approximately 1½″ deep×6″ in diameter, and there were no tears to the surface of the package. Additional damage occurred when the package fell onto the crush test plate lifting point, which was left too close to the drop area, a small indentation occurred with no tearing. Acceptable.   12. Post drop condition photographs were taken and the test package was placed in the thermal soaking chamber and the temperature increased to approximately 120° F. overnight and upon removal wrapped with insulating blankets and electric heating strips for transport to the remote fire testing location.   13. The test package was placed onto the fire pool stand in the prescribed manner and location, the connections and pre-test evaluations completed. Wind shields were put into place to aid in wind control for the actual fire test.   14. The fuel was placed on top of the water bed in sufficient quantity to provide a fire to exceed 30 minutes fully engulfing the package with provisions made to add fuel as required.   15. The pool fire was ignited and the package engulfed. During the initial fire time period of 30 minutes, it was determined that the package lost some flame coverage and the decision was made by Century Industries and SwRI to add approximately 15 minutes to the duration of the fire. Direct contact flame temperatures ranged between 800 and 2150° F. over the 45 minute fire. North and South Slugs provided temperatures averaging about 95° F. at 20 minutes, 135° F. at 30 minutes, 178° F. at 40 minutes and 198° F. at 45 minutes. Two thermocouples located at the exact position of the previously noted accidental tear caused by the shearing action of the test pad plate during the crush test drop, were exposed to higher temperatures than the remaining thermocouples due to the chimney effect caused by the tear and the thermocouples exit point in the top edge of the package. It is reasoned and believed that without the tear in the bottom of the container these thermocouples would have performed in like manner as did the other 6 thermocouples and provided an internal average of around 120° F., over the entire test time. Even considering the accentual damage and the additional time added to the fire test, the average inner vessel temperature was approximately 135° F. Acceptable.   16. The package was shielded from the weather and allowed to cool overnight, and then transported to the immersion test facility.   17. The package was prepared for the immersion test and placed into the immersion chamber with a hydraulic pressure of 23±1 psig applied to the package for 15 minutes. No damage from this test was noted.   18. The package was transported to the leak test area and examined. The top foam plug was in place and in good physical condition upon opening of the container. Minor discoloration was noted within ½″ of the edges of the plug. Portions of the drum gasket ( 33 ) under the outer bolts ( 31 ) was melted, but approximately ⅔ of the gasket was in place and pliable.   19. No damage was noted to the inner secondary cover ( 70 ) or gasket ( 72 ); bolts were still showing the original torque of 33 ft-lbs. and there was no water-in leakage from the immersion testing. Acceptable.   20. The helium leak-test equipment was calibrated and connected to inner vessel cover ( 46 ) and a vacuum pulled. The helium test was completed and showed a leak rate of 2.2−2.4×10 −8  std.-cc/sec. over 5 minute test time. Acceptable.   21. The bolt ( 25 ) torque was checked and two bolts found to be at approximately 28 ft-lbs. and the other 6 at the original 33 ft-lbs.   22. The package was opened and the o-ring gaskets inspected and found to be in pristine condition. The steel shot was removed in order to examine the internal vessel which was found to be in excellent condition.       

   The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications will be effected with the spirit and scope of the invention.