Note: Descriptions are shown in the official language in which they were submitted.
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1;~6843~
HEAVY-DUTY SHIPPING CONTAINER
FOR FLO~ABLE BULK MATERIALS
BACKGROUND OF THE INVENTION
This invention relates to shipping containers for
flowable substances and, more particularly, to heavy-duty
shipping containers for the bulk transport of flowable
bulk materials, including liquids, dry powders or granular
substances, semi-solid materials such as grease, pastes or :
adhesives and, as well, highly viscous fluids, in volumes
10 of at least fifty-five gallons and in quantities of weight
greater than four hundred-fifty pounds.
~:Shipping containers used fo~ the transport of
~;flowable bulk materials must accommodate extraordinary
weight, due to the high density of the contained materials
and, at the same time, must be designed to withstand
damage that can result from the nonuniform and sometimes
cyclic stresses caused by the material shifting during the
handling and transport of the container. Even a minor
puncture or cFack can cause the total loss of the flowable
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material. Heavy-duty shipping containers containing bulk
flowable materials exceed the limits of manual handling
capability and are typically mounted on pallets and
handled by mechanical means such as fork lifts and hand-
lift trucks.
Various types of containers and container
materials have been designed for the transport of flowable
bulk materials. Single wall (double face) corrugated
fibreboard boxes, for example, have been used as inexpen-
sive, disposable containers for light-duty applications.
Sucb fibreboard containers, where necessary, are waxed or
provided with a plastic liner bag. As the volume and
weight of the contained material increases, however, the
pressure of the material within the container causes
bulging of the sides of the container. This makes the
container difficult to stack with other similar contain-
ers. Furthermore, the bulging of the sides of the
container significantly reduces the inherently limited
column strength of single wall containers making this type
of container unsuitable for stacking or heavy-duty applica-
tion.
The term fibreboard is a general term applied to
paperboard utilized in container manufacture. Paperboard
refers to a wide variety of materials most commonly ~ade
from wood pulp or paper stock. Containerboard refers to
the paperboard components -- liner and corrugating
material -- from which corrugated fibreboard is manufact-
ured. Thus, the term fibreboard, as used in the packaging
industry and in tbe present specification and claims, is
intended to refer to a structure of paperboard material
composed of various combined layers of containerboard in
sheet and fluted form to add rigidity to the finished
product. Fibreboard is generally more rigid than other
types of paperboard, allowing it to be fabricated into
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larger sized boxes that hold their shape and have
substantial weight bearing capability.
Double or triple wall corrugated fibreboard, when
made into shipping containers, provides many distinct
5 advantages for the packaging and transport of heavy
loads. Double wall corrugated fibreboard comprises two
corrugated sheets interposed between three flat facing or
spaced liner sheets. In triple wall corrugated fibre-
board, three corrugated sheets are interposed between four
lO spaced facing or liner sheets. Triple wall corrugated
fibreboard, in particular~ compares favorably with wood in
rigidity and strength and, as well, in cost, and provides
cushioning quality not found in wooden containers. In
addition, triple wall corrugated fibreboard, relative to
15 other fibreboard materials, advantageously provides great
column strength. The column strength of triple wall
corrugated fibreboard containers permits stacking, one on
top of the another, of containers containing heavy loads
without excessive buckling or complete collapse of the
20 vertical walls. Triple wall corrugated fi~reboard also
has great resistance against tearing.
Fibreboard shipping containers employing an outer
multi-sided tubular member and a simularly configured
inner reinforcement to strengthen the overall container
25 have been disclosed. See~ for example, U.S. Patents
3,159,326, 3,261,533 3,873,917, 3,937,392, 4,013,16~ and
4,41R,861.
In order to form multi-sided fibreboard tubes, it
is necessary to form major score lines in the fibreboard
to allow bending of the fibreboard along the edges of each
panel of the container which is formed. However~ scoring
; adversely affects the container since the lateral stabil-
ity of the container significantly decreases as the number
of major score lines is increased. The major scoring of
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the container typically permits the container, when empty,
to be shipped in a ~nocked down, flat condition.
Circular cylindrical-shaped containers have long
been regarded as the most efficient shape to use in
containing liquids or dry flowable products. Paperboard
designs utilizing circular cylindrical type containers,
however, have been restricted to small capacity cylind-
rical shapes typlified by the 55 gallon capacity spiral
wound fibre drum. Producing larger containers of this
type has proven impractical, on a commercial basis, due to
a number of reasons including excessive ma~erial and
fabrication costs and the unavailability of fabricating
equipment. Moreover, the fibre drums are rigid and cannot
be folded into a flattened state when empty. Since
existing technology requires that these fibre drums ~e
pre-erected at a central location and then shipped to and
stored empty in an erected or pre-formed condition at user
locations, the utilization of cylindrical fibre drums also
presents handling, shipping, and storing difficulties.
Most importantly, the structural per~ormance and handling
requirements of a fibre drum, as capacity climbs to the
llO gallon to 380 gallon range, have exceeded the indus-
try's ability to produce a readily available commercial
product. Utilization of higher-strength reinforced
plastic or metal drums has not provided a satisfactory
alternative as such materials are typically more expen-
sive, do not increase utilization of cubic storage space,
when empty, and present a variety of disposal problems.
Thus, despite the efficiencies of circular
cylindrical containment, corrugated ~ibreboard has not
been generally used as a circular cylindrical container
material. corrugated fibreboard, particularly in the
heavier grades of multi-wall fibreboard capable of
containing and supporting the weights and hydrostatic
pressures produced by 110 to 380 gallons of contained
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liquid, or an equal volume and weight of flowable solids,
does not lend itself to being fabricated into circular
cylindrical shapes without substantial loss of key
performance features of corrugated fibreboard, that is,
top to bottom compression strength and lateral stability.
SUMMARY OF THE INVENTI~N
The invention is directed to a heavy-duty
shipping container for bulk materials comprising an inner
tubular sleeve of a multi-wall corrugated fibreboard of
substantially circular cross section, adapted to contain a
flowable bulk material, and an outer sleeve of polygonal
cross section assembled about the inner sleeve for its
full length, the outer member also being constructed of a
multi-wall corrugated fibreboard. The inner circumferen-
tial facing of the inner sleeve is formed with a pluralityof false scores extending lengthwise, i.e. substantially
parallel to the length of the inner sleeve or parallel to
the flutes or corrugations thereof.
The outer sleeve is preferably constructed of
triple wall corrugated fibreboard and is preferably
; octagonal in cross section.
The inner sleeve is a corrugated fiberboard
sleeve in the form of a right circular cylinder formed of
a multi-wall corrugated fibreboard such as double wall or,
; 25 preferably, a triple wall corrugated fibreboard which has
been subjected to a bending process to form the false
scores randomly at intervals of one to six inches.
Preferably, the outer sleeve of the container is
provided with bottom end flaps of single-wall corrugated
fibreboard and is provided with a removable upper end cap
formed from folded corrugated fibreboard.
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When formed, shipping containers made in accord-
ance with the invention are designed to contain flowable
materials in volumes of at least 55 gallons and weights
exceeding four hundred-fifty pounds.
Shipping containers of the invention, in compar-
ison to steel or fibre drums presently in use, per unit of
volume are less costly on a material and fabrication
basis. The shipping containers of the invention provide
increased utilization of cubic storage space when the
containers are being shipped or stored empty in that the
- inventive shipping containers can be folded flat when not
is use. Moreover, since tbe materials employed have
recycle salvage value and, as well, are biodegradable,
post-use disposal does not present problems associated
with plastic and metallic containers.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, forming a part of
this specification, and in which reference numerals shown
in the drawings designate like or corresponding parts
throughout the same,
Figure 1 is a schematic perspective view of a
shipping container, partly broken away, formed in accord-
ance with the inqention;
Figure 2 is a top view of a shipping container,
with the top cap removed, formed in accordance with an
embodiment of the invention;
Figure 3 is an enlarged view of the encircled
detail of Fig. 2;
Figure 4 is a section of a portion of a side and
the bottom of the shipping container of Fig. l;
Figure 5 is a top plan view illustrating a blank,
prior to false scoring, from which an inner sleeve of the
shipping container may be formed;
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Figure 6 is a top plan view of a blank from which
an outer sleeve of the shipping containers may be formed;
Figure 7 is a sectional view taken along line 7-7
of Fig. 6;
5- Figure 8 a perspective view showing on end flaps
of and outer sleeve of the shipping containers; and
. Figure 9 is an exploded schematic view, in
perspective, illustrating a shipping assembly embodying
the invention.
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DETAILED DESCRIPTION
The shipping container 10, as disclosed herein,
is constructed with a right circular inner cylindrical
sleeve 12 of a multi-wall corrugated fibreboard substant-
ially coaxially received within an outer sleeve 14 of amulti-wall corrugated fibreboard which has a polygonal
cross section as best shown in Figures 1, 2 and 3.
The inner sleeve 12 is a multi-wall corrugated
fibreboard which may consist of a single wall or double
wall corrugated fibreboard for certain applications. In
accordance with the preferred embodiments of the inven-
tion, the inner sleeve 12 is preferably composed of triple
wall corrugated fibre~oard as is illustrated by Figure 4.
Corrugated fibreboard, particularly heavy grades such as
double and triple wall corrugated fibreboard, when used
for inner sleeve construction, dramatically increases the
stacking strength of the overall container as compared to
a solid fibre and single wall inner sleeves.
The inner sleeve 12, in the preferred embodiment,
is formed from a flat sheet 11 of triple wall corrugated
fibre~oard. The flat sheet 11, as shown in Figure 5, is
first formed with two major score lines 13, 17, provided
preferably at diametrically opposite locations on the
assembled inner sleeve 12, to allow the inner sleeve to be
shipped, when empty, in a knocked down condition, with a
uniform folded slope. The flat sheet 11 is circularly
shaped in a ~ending apparatus, such as a sheet metal
roller or-a modified four bar slitter, by subjecting the
corrugated sheet to a prebreaking process. The prebreak-
ing process comprises passing the corrugated sheet througha curved path having a radius of curvature which causes
the random formation of multiple scores 75, so-called
false scores, running in the direction of the
corrugations, on the smaller radius of the curved sheet.
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The randomly spaced false scores 75, which in the case of
a triple wall corrugated fibreboard occur variously,
approximately from one to six inches apart, help facili-
tate the formation of a nearly perf~ct cylindrical shape
of the inner sleeve 12, when the inner sleeve is placed
within the outer polygonal sleeve, and filled with a
liquid or flowable solid substance. Besides providing
these random scores, the pre~reaking process also
stretches the outer facing of the corrugated fibreboard
sheet, and compresses the inner facing to the extent that
when assembled into a sleeve, and secured by a glue joint,
the sleeve, although it can be folded flat, maintains a
circular cylindrical shape when erected. The end portions
of the sheet, which comprises the circular inner sleeve,
are overlapped and adhesively combined in a lap ~oint.
The outer circumferential facing of the inner sleeve is
not creased or scored but remains smooth.
The randomly-spaced false scores 75 of the
corrugated fibreboard sheet, when assembled into a sleeve
configuration, extend generally parallel to the longi-
tudinal axis of inner sleeve 12. As used herein, it
should be understood that the terminology ~false scores-
does not comprise score lines of the type which are formed
with a s~oring tool but are the type of scores known in
the fibreboard industry as ~false scores" whicb result
from the application of prebreaking stress to sheetstock
materials. As best shown in the enlarged detail view
provided in Figure 3, the false scores only crease the
innermost (on the small diameter side of the sleeve)
facing of the inner sleeve 12 of triple wall fibreboard.
In comparison, the mechanical scores 13, 17 formed to
allow folding of the inner sleeve blank crease the
innermost facing and, as well, the intermediate facings
and flutes of the triple wall fibreboard comprising the
inner sleeve 12. It is critical that the described false
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scores be used to obtain the circl~lar configuration of the
inner sleeve as, for example, use of a multiplicity of
numerous mechanical score lines would debilitate the
strength of the inner sleeve.
outer sleeve 14, in accordance with a preferred
embodiment of the invention, comprises a tubular member
having an octagonal cross section The outer sleeve 1~ is
formed from a substantially rectangular sheet 16 of
corrugated fibreboard, or equivalent, shown in Figure 6
The rectangular sheet 16 is die cut and scored for
folding, by techniques well understood in the art, and
includes a plurality of substantially rectangular wall
panels 18, 20, 22, 24, 26, 28, 30 and 32, foldably con-
nected to each other by lateral score lines 34, 36, 38,
40, 42, 44, 46 and a sealing flange 48 foldably connected
to wall panel 32 via a lateral score line 50. End flaps
52, 54, 56, 58, 60, 62, 64, 66 are formed at one of the
opposite edges of the respective wall panels and are
foldable along score lines 51, 53, 55~ 57, 59, 61, 63, 65
20 which are formed on the end flap approximately one-eigth
inch from the bottom edge 68 of the wall panels. The wall
panels are preferably formed from triple wall corrugated
fibreboard which, as shown in Figure 7, include three
corrugated sheets 70, 72, 7~. The ridges of the corru-
25 gated sheets are adhesively secured to liner sheets 76,
78, 80 and ~2. The end flaps are preferably formed of
single wall corrugated fibreboard, as shown in Fig~ 8.
which is integral to the triple wall side wall panels.
The end panels may be formed on a triple wall combiner
30 machine as part of the combiner process in a manner
well-known to those skilled in the corrugated fibreboard
container industry.
The rectangular sheet 16 is bent along the
lateral fold lines into the form of an octagon, when
35 viewed in cross section. The sealing flange 48 overlaps
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the exposed face of liner 76 and is adhesively secured
thereto, in a known manner, to form outer sleeve 14. The
end flaps are then sequentially folded inwardly of the
outer sleeve 14 so that adjacent flaps overlie each
other. The use of end flaps adds to the structural integ-
rity of the container. The end flaps can be omitted and a
lower end cap, similar to the upper end cap, employed with
less favorable results. Alternatively, both a bottom end
cap and bottom end flaps can be utilized.
The inner sleeve 12 is then inserted into the
outer sleeve 14. The outer sleeve 14 is sized such that
the wall of the inner sleeve 12 touches at approximately
the mid-point of each of the walls of the outer sleeve 14
as typically shown at lS. Gaps 19 are formed between the
inner sleeve 12 and the corners of the outer sleeve 14,
the corners being defined by the lateral score lines
between the wall panels of the outer sleeve 14.
Although the outer sleeve 14 is shown as octagon-
al in cross section, it will be appreciated that any poly-
gonal cross section may be utilized.
The container 10 is preferably closed at its topby a removable end cap ~0, which has a cross section
similar to that of the outer sleeve and, thus, in the
illustrated embodiment has an octagonal configuration.
25 End cap 90 has a downwardly extending peripherial side `
flanges ~2 which extend outside and are engageable with
the ends of the outer sleeve below the upper edge of the
outer sleeve 14. The end cap 90 is not a load bearing
member and, therefore, may be formed from single wall
corrugated fibre~oard.
Figure 9 illustrates a shipping assembly in
accordance with the invention. A separate pallet 96 of
conventional construction is employed beneath the shipping
container to facilitate movement of the containers by a
fork lift or hand lift truck.
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A bottom pad 98 is preferably inserted into the
outer sleeve 14 and rests upon the infolded end ~laps 52,
54, 56, 58, 60, 62, 64. The bottom pad 98, in the illust-
rated embodiment, has an octagonal-shaped cross section
and is designed to be closely received within the outer
sleeve 14. The peripheral edges of the bottom pad 98 bear
against the side walls of the outer sleeve 14. The bottom
pad 98 is preferably composed of triple wall corrugated
fibreboard.
A plastic liner bag 100 is preferably provided
- within the inner sleeve 12 to lleak-proof the container.
The liner bag 100 precludes the flow of the contained
materials between the interstices that may exist in
between the end flaps and at the bottom pad. A suitable
liner bag 100 can be made from a flexible plastic film
material, such as polyethylene extruded film or the like.
In certain applications, a compressible top pad
102 with a circular cross section is provided as a filler
to fill any head space or void area th~t may exist or
occur, for example, due to incomplete filling, settling,
or contraction of the contained material, between the
liner bag 100 and the end cap 90. The top pad 102 is
particularly suited for applications in which a liquid is
contained as it prevents, or at least helps to reduce, the
harmful sloshing or surging of the liquid which tends to
occur during transit motion. However, the compressibility
of the top pad 102 still allows expansion of the liquid,
thereby releasing some of the hydrostatic or hydraulic
pressures which would otherwise be exerted against the
sidewalls and bottom of the container. The top pad 102 is
preferably composed of triple ~all corrugated fibreboard
or polyether foam. The periphery of the top pad bears
against the inner surface of the inner sleeve 12.
Steel strapping 84 is employed to hold the
shipping containers to the pallet 96~ In order to avoid
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damage to the end cap 90, inverted U-shaped steel strap-
ping braces 86 are mounted across the end cap 90 intermed-
iate of both the upper surface and side flanges 92 of the
end cap and the strapping 84. Each strapping brace 86
consists of a flattened central elongated plate and
- depending legs designed to overlie the top surface and
flanges 92, respectively, of the end cap. The braces 8~
are provided with a greater width than the strapping 8~ in
order to more evenly distribute the strap forces over the
shipping container. The surface of the strapping brace 86
is preferably beaded in order to inhibit slippage between
the strapping and the brace. ~hen the strapping braces 86
are tightened down by the strapping 8g, the inner sleeve
12 is positively seated against the bottom pad 98 to
further stablize the contained load. The end flaps are
held in place by the weight of the contained materials
pressing down on the bottom pad and, in conjuction with
the pressure of the strapping, provide a s~rengthening or
resistance t~ lateral deflection at the bottom of the
outer sleeve 14, which is tbe area that is most vulnerable
to buckling or deflection.
A bottom spou~ fitment 88, as is known in the bag`
industry, may be provided. Tha fitment 88 extends through
cutouts formed in the outer sleeve and the inner sleeve.
The fitment 88 is connected to the liner bag to allow
gravity evacuation of the material contained within the
liner bag 100. The fitment extends through aper~ures
formed through the walls of the inner and outer sleeves.
Actual containers, built in accordance with the
inventiont have been subjected to drop tests, vibration
tests and high humidity compression tests with markedly
successful test results. The following examples are
! illustrative and explanatory of portion of the invention~
EXAMP~E I
A shipping container ~as constructed
according to the invention. The outer sleeve
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was formed of a triple wall 1500 AAA grade
corrugated fibreboard. The outer sleeve had
an octagonal cross section and was approxi-
mately 40 inches across and 44 inches high.
The inner sleeve was also formed from triple
wall 1500 (Beach puncture test rating) AAA
grade corrugated fibreboard material bent
into a circular cylindrical shape with random
scores. Single wall bottom end flaps were
employed. An octagonal-shaped bottom pad
formed from 0900 AAA grade corrugated
fibreboard and a top end cap of 275~ single
wall, fluted fibreboard was utilized to close
the ends of the outer sleeYe ~ plastic
liner bag, filled with 220 gallons of water,
was inserted into the container. A top pad
composed of a triple wall 0900 AAA grade
corrugated fibreboard having an octa-
gonal shape was placed on top of the liner
bag to substantially fill the void between
` the liner bag and the top end cap. Three
3/4-inch x .020 inch size steel strappings
were used to attach the con~ainer to a 2-way
entry wooden pallet 44 x 44 inches. TWo
straps were placed in the same direction and
one strap was placed crosswise over the other
two. Each strap was mounted on a five inch
wide brace of 16 gauge beaded sheet metal
with three-inch long legs.
The container was tested using a distri-
bution cycle pa~terned after ASTM standard
D-4169, distribution cycle no. 11 rail,
` trailer on flat car to simulate handling,
vertical linear motion, loose-load-rotary
~` 35 motion vibration and rail switching. The
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liquid was retained within the liner bag
without leakage throughout the entire test
procedure.
(A)
Handling Drc>p Test
In the drop test, the container was
raised six inches off of a concrete floor by
means of a fork lift and dropped on edge.
The test was repeated on the opposite edge.
lQ No leakage occured.
(B)
Vertical Linear Motion Vibration Tests
The container was subjected to vertical
linear motion vibration by placing i~ on the
table of a vertical linear motion vibration
tester having a table displacement of 1.0
inch. The low and medium vibration emported
in vertical linear vibration testing
simulates truck transit conditions and
determines whether destructive resonance of
the container will occur. The container was
horizontally restrained. The container was
placed on the table and subjected to 260 cpm
for 40 minutes. The container was then
placed on an a higher vibration machine,
again restrained in the horizontal direction,
and subjected to 40 minutes of vertical
linear vibration at tbe following frequencies
and displacements:
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Test FrequencyDisPlacement
(m~Fes) (hertz)(lnches)
13 0.12
21.8 0.07
33.3 0.05
1~ 36.3 0.02
No leakage occured throughout the vertical
linear motion vi~ra~ion testing.
(C)
Loose Load-Rotary Motion Vibration Test
The container was also placed on a
rotary motion vibration machine with a table
displacement of 1.0 inch. The rotary
vi~ration test simulates the side-to-side
lS motion which commonly occurs in rail trans-
port or piggy back shipments. The container
was vibrated for twenty minutes at a
frequency of 235 rpm. It was then rotated
ninety degrees and vibrated for another
twenty minutes at 235 rpm. No leakage
occured.
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(D)
Rail Switching-Incline Impact Test
The container was placed on the dolly of
an incline-impact machine for impact against !,
~;~ a bulkhead to simulate train car bumping. A
~` second container (also filled) was placed
behind the first container. The container
was subjected to one impact of 4 mph and two
impacts of 6 mph. No leakage occured.
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EXAMPLE II
A shipping container was constructed
according to the invention ~as set forth in
Example I) for testing after being subjected
to adverse humidity conditions. A plastic
liner bag was filled with 220 gallons of
water and inserted into the container.
The container was conditioned for 72
hours at 90F and a relative humidity of
90~. After 72 hours the conditioned
container was compression tested to si~ulate
container stacking. A load was applied by a
top platen travelling downwardly at a speed
of O.S inch per minute until the container
failed. Failure did not occur until a load
of 8,600 pounds was reached.
EXAMPLE III
A container constructed as in Example I
was conditioned for 72 hours at 73F and a
relative humidity of 50%. A plastic liner
bag was filled with 220 gallons of water and
inserted into the container. ~ load was
applied as set forth in Example II. Failure
of the container did not occur until a load
of 18,000 pounds was reached.
It is a particular feature of the container
according to the invention that the inner sleeve 12 may be
filled with a bulk flow~ble material without bulging.
This is due to the circular cross section of the inner
sleeve 12, which transmits the pressure from the flowable
load, purely into hoop stress in the walls of the inner
sleeve 12, inherently resisting any bulging of those walls.
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The outer sleeve 14, clue to its construction from
a double wall or triple wall corrugate~ fibreboara, is
aaptea to resist endwise crushing loaas, permitting a
number of such containers to be stackea one upon the other.
The enhanced capability of the heavy-duty
shipping container to accommodate and withstand static ana
cyclic loads is attributable to a structure which utilizes
a circular multi-wall fibreboard inner sleeve and an outer
multi-wall fibreboard container against which the inner
sleeve bears. Constructions utilizing solia fibre or
single wall (double face) corrugated fibreboara inner and
outer sleeves are not suitea to use as heavy-duty shipping
containers ana are outside of the scope of the invention.
The term "heavy auty" is used herein to aefine
containers designe~ to accornr,lodate bulk flowable materials
in volumes of at least 55 gallons and weights of 450
pounds and greater. ; ;~
The shipping container design described herein,
when utilized in conjunction with a plastic liner bag, is
suitable for liquiâs and dry, flowable products in volumes
of 55 gallons up to 380 gallons, liquid measure. Liquids
and suspensions which weigh as much as 12.5 lbs. per
gallon and flowable dry solids which weigh as much as 115
lbs. per cubic foot can be effectively container in
fibreboard containers of this design in those volumes.
The upper edge of inner sleeve 12 is initially
positioned above the upper edge of outer sleeve 14, by an
amount which is less than the thickness of bottom pad 98.
; This is done so that when bne conta1ner of the present ~ ~
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invention is stackeo upon another, the lower container
.iill -.ave its inner sleeve 12 pushed aownwarGly, deforming
the outer ~eriphery or bottom paG ~. In this way, both
the inner and the outer sleeves contribute tO the column
strength of the lower container when the sleeves are in
the post-loaded position.
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