CA1233424A - Two-part salvage drum - Google Patents

Abstract

ABSTRACT
A two-piece, molded leak and impact resistant polyethylene storage or salvage drum, comprising two substantially identical basins for receiving an open, damaged or leaking drum containing, for example, toxic or hazardous waste, for handling, transporting and storing such drum The basins are obtained by sectioning a one-piece, closed ended rotationally molded drum which contains only relatively small vent holes at its central periphery to allow for the passage of air during the molding and cooling process. The basins are adapted to contain spills and overflow from open, damaged or leaking drums and can be sealed temporarily or permanently.

Description

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TWO-PART SALVAGE DRUM
BACKGROUND OF INVENTION
The present application relates to a polyethylene storage or salvage drum, comprising two substantially identical halves, referred to as basins, suitable for handling, transporting, storage and, ultimately, for enclosing either temporarily or permanently, damaged or leaking drums, for example, standard, metal drums commonly used to store or dispose of chemicals or toxic and hazardous waste Today's complex hazardoùs waste management includes cleaning up abandoned or "orphaned" sites, bringing existing disposal facilities up to acceptable standards, or at least making them safer, and applying new techniques to isolate hazardous waste so that it can be neutralized, made safer for transportation and amenable for recovery or storage It is frequently necessary to transport open containers of hazardous waste short distances, as by forklift or truck Open or leaking drums may also be transported to off-site management facilities where they are tested and treated Automated treatment and neutralization facilities include conveyor systems for moving and handling open drums 3L~33~2~

which can cause the contents of the drums to splash or spill over, contaminating the equipment with hazardous and corrosive materials, thereby complicating procedures Standard metal drums are often :Eound to have developed minor leaks while in storage, or may be punctured during clean-up operations or in routine handling during warehousing Suitable reuseable, impervious containers, or basins for temporarily receiving an open, or a slowly leaking drum have not been available At present, salvage drums suitable for accepting leaking or open standard 55 gallon drums containing toxic or hazardous waste, are generally cylindrical containers of sufficient height and a diameter great enough to accept the drum These salvage, or overpack, drums serve as overpack containers for temporary or permanent storage or disposal Such overpack containers are not suitable for handling or transporting open drums on conveyor systems because they can not contain splashes or absorb larger spills, due to their relative narrow space between the contained drum and the body of the salvage drum In addition, once a standard damaged drum is inserted into the overpack drum, it is also difficult, or a least impractical, to lift the drum out again without turning the overpack container at least to the side, which in case of an open or leaking drum, is not desirable Furthermore, the existing salvage drums are not capable of receiving severely deformed or irregular drums In view of the above, it is a principal object of this invention to provide a salvage basin into which an open or leaking drum can be put and which will contain splashes and spillage from the drum, while it is being moved, as by forklift or conveyor ~3~

It is also another principal object of the present invention to provide a two part salvage barrel comprising two identical basins, which allows safe transportation of open or leaking drums by enclosing the contained drum either temporarily or permanently It is also an object of this invention to provide a rigid, sturdy salvage basin into which a leaking drum i5 quickly and easily placed, and easily removed without spilling the contained liquid It is a further object of this invention to provide a storage or salvage drum that can be transported and stored when empty in a space-conserving manner It is another object of this invention to provide a storage or salvage drum which meets the U.S. Department of Transportation Specification 173~3 for transporting leaking metal or plastic drums It is also an object of this invention to provide a method for economically manufacturing one-piece, molded chemical resistant salvage basins SUMMARY OF THE INVENTION
The above and other beneficial objects and advantages are attained in accordance with the present invention by the method of manufacturing a one-piece, rotationally molded polyethylene drum comprising two identical basins, each in the shape of a frustum having its lancer end open towards the center of the drum and its base at the closed end of the drum AEter the one-piece drum is removed from the mold, it is separated into two approximately equal halves to form the basins The one-piece molded drum can be cut in two using a bandsaw, router or other convenient means The larger, open end of the basin terminates i.n an integral flange member One basin serves as the receiver of the open or 334i~

leaking drum and the second identical basin serves as the cover and is placed upside down onto the first basin Each basin has a flange at its open end The two flanges can be secured together, either temporarily by means of a gasket and boltsl a mechanical clamp or similar means, or permanently, as by spin welding or other bonding method To assemble the drum, the basin that serves as the cover is placed upside down onto the basin that serves as the receiver The two open ends, o that is, the two flange members meet and can be secured together at their annular peripheries The flange members allow a choice of closures for the drum: by inserting a gasket between the two flange members, the drum can be sealed by bolting the flange members together, or by other mechanical means, such as clamps;
in the alternative, the two basins can be bonded together as by spin weldingl The bottoms of the polyethylene basins can be molded flat, but in the preferred embodiment, the bottom is provided with a raised annular section in the interior of the basin, adapted to mate with the rim of a standard metal drum and thereby provide stability for the metal drum during movement, as on a conveyor system or when being transported by forklift The raised annular section also provides means for centering the metal drum when it is transported or stored in a vertical position This configuration also provides additional strength and rigidity to the base of the salvage drum A reduction in storage space is achieved by nesting one basin inside the other In one embodiment about five basins use the same cubic space required for one assembled drum ~3~4~4 E~RIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG l is an elevational view of a one-piece rotationally molded polyethylene drum of the present invention FIG 2 is a bottom view of a basin, along section line 2-2 of FIG l FIGS. 3, 4, 5 and 6 are enlarged partial detail views illustrating alternative embodiments for separating the basins FIG 7 is an elevational view of an assembled salvage barrel, or drum, comprising two substantially identical salvage basins.
FIG 8 is an enlarged detail view illustrating the closure by means of a gasket and nuts and bolts FIG 9 is an elevational view of several salvage basins nested one inside the other for transportation or storage DETAILED DESCRIPTION OF THE PREY~RRED EMBODIMENT
The present invention is illustrated in the accompanying drawings wherein the same components bear identical reference numerals throughout the different vies Accordingly, in ~IG~ l there is shown the one-piece molded polyethylene drum 5 of generally circular cross-section having symmetrical upper and lower sections 10 and 10' about horizontal plane A A passing through the center of the drum The one-piece drum 5 is produced in a die of coeresponding configuration by conventional rotational molding techniques well known in the art Rotational molding procedures and apparatus are well established and, forming no part of the invention claimed, are not described., Vent holes 6 are provided in the 3~

periphery of the central section 1l. to allow for the passage of air during the molding operation The drum can be fabricated from either high or low density linear polyethylenet or from cross-linked polyethylene which is available from a number of commercial sources The choice of materials is dependent upon the subsequent use of the invention, as will be described in more detail below The one-piece rotationally molded drum 5 comprises the relatively narrow, straight-sided central section 11~ joined to which are symmetrical, intermediate generally straight-sided shoulder sections 12 and 12', which in turn are joined to the inwardly tapered end sections 10 and 10'~ As shown in FIG. 1, the diameter of the shoulder sections, 12 and 12', is somewhat less than the diameter of the central section 11, and is slightly greater than the maximum diameter of the tapered end sections lC and 10'~ The integral top 15' and bottom 15 are closed, and in a preferred embodiment, illustrated in FIGS 1 and 2, the inside surfaces of the closed ends 15 and 15' are provided with a raised annular section 22 adapted to engage the rim around the bottom of a standard metal or plastic drum When the rotational molding operation is completed, the mold is opened, and the drum 5 which shrinks slightly upon cooling, is removed After the drum 5 has been removed from the molding apparatus, it is separated into two approximately equal half sections to provide a pair of salvage basins 20 and 20'~ The separation of the upper and lower halves is accomplished by any convenient means, such as a router or power saw means The drum halves can be separated at one or more positions about the periphery of the central section, depending upon the particular use and configuration desired for the salvage basins 33~2~

For example, as illustrated in FIG.. 3A, by separating the upper basin 20' with a vertical cut where flange 14' joins the sidewall of central seclion 11, the lower basin 20 is provided with an upwardly extending ridge 25 on the horizontal flange 14~ As illustrated in FIG 3B, when the upper, or cover basin 20', is placed on the bottom basin 20, the flanges 14 and 14' mate and are held in position by the ridge 25d In addition to providing improved stability to the assembly, while it is being used as a temporary enclosure, this configuration reduces the possibility of spills or leaks when the assembly is being moved The two basins can also bé separated by removing entirely the sidewall of central section 11 This will result in basins 20 and 20' each having outwardly extending horizontal flanges 14 and 14l~
As illustrated in FIGSo 4A and 5A, the removal of central section 11 can advantageously be accomplished by either a single vertical cut, as with a band saw, or a pair of horizontal cuts that are approximately flush with the facing flange surfaces 14 and 14'~ By eliminating the ridge on both halves, smooth flange surfaces 16 and 16' are obtained In a further embodiment, illustrated in FIGS
6A and 6B, the pair of salvage basins 20 and 20' are both provided with an upturned ridge 25 and 25', respectively, by making a single cut along the line of the plane of symmetry A-A, described in FIG l These basins are not well adapted to mate with each other to provide the salvage, or overpack, barrel described below, which is a further preferred embodiment of the invention As illustrated in FIG 7, when basin 20' is used as a cover by being placed upside down onto basin 20, the flanges 14 and 14' meet and they can be secured /

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~8--to one another in several different ways us illustrated in FIG 8, a chemical resistant gasket 21, for example, an expanded closed cell polyethylene foam, may be inserted between the opposing flange surfaces 16 and 16' and both flanges 14 and 14' may be bolted together For this type of closure ? each flange is provided with about six or more smooth-sided holes 18 and 18' through which a corresponding number of bolts 17 may be inserted Each bolt 17 is secured by a corresponding nut 19~
Alternatively, the mated salvage basins can be secured by mechanical clamping means, such as by a conventional drum ring clamp of the type used with metal drums When a permanent closure is preferred, the basin 20' which serves as a cover can be spin, or friction, welded to the bottom basin 20~ Jo accomplish this method of sealing, the flange 14' of cover basin 20', while spinning, is forced onto the flange 14 of basin 20 under sufficient pressure to create substantial frictional heat which melts the interface of 16 and 16' and fuses the flange 14' of the cover basin to the flange 14 of the bottom basin when the spinning is stopped, the interface is permitted to cool and the flanges 14 and 14' are fused or welded together Procedures and equipment for spin welding of closures for polyethylene drums to encapsulate hazardous waste have been developed under the auspices of the U.S. Environmental Protection Agency This closure method offers the maximum leak resistance and is advantageous for permanent encapsulation of the contents When spin welded closures are to be employed, it is preferred to use salvage basins made of linear low density polyethylene. For other closures, the drum can be made of either high or low density linear polyethylene, or crosslinked polyethylene 3~2~

FIG 9 illustrates a nested assembly of salvage basins The protruding peripheral, general:ly cylindrical shoulders 12, insure that the basins do not nest too tightly by limiting the extent to which one basin may be inserted inside the other, which insures that the basins are easily separated from each other after stacking.
Typical dimensions for a preferred embodiment suitable for transporting or containing a standard 55 gallon drum result in a basin having a volume of about 46 gallons (174 liters (All metric conversions are approximate and for purposes of illustration only This basin has an outer flange diameter of about 30" (76 cm); the inside diameter of the flange is about 28" (71 cm) the total height of a basin is about 20" ~51 cm);
the height of the protruding peripheral shoulder is about 5" (13 am In a preferred embodiment, the incline of the frustum from its larger end to its smaller end is about 7 The diameter of the bottom of the basin is about 24" (Çl cm); the annular section at the bottom of the basin ha an outside diameter of about 21" (53 cm) and an inside diameter of 12" (31 cm); and the height of this raised section is 3/4" ~2 am After a standard 55 gallon (208 liter drum is inserted, there is sufficient space in the interior of the basin to add filler or absorbent material to minimize shifting of the drum during transportation, and to absorb any liquid waste which may leak or spill out during transportation

Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. As an article of manufacture, a one-piece rotationa-lly molded, closed ended polyethylene drum of circular cross-section and symmetrical upper and lower halves, comprising a relatively narrow, straight-sided central section, intermediate generally straight-sided shoulder sections, and inwardly tapered end sections, where the diameter of the shoulder sections is less than the diameter of the central section and greater than the maximum diameter of the end section, said central section being joined to the upper and lower shoulder sections by projecting flange sections normal to the central section.

2. The article of claim 1 where the diameter of the central section is from about 1 to 3 inches greater than the diameter of the shoulder section.

3. the article of claim 1 in which the central section is provided with vent holes.

4. The article of claim 1 in which the inside diameter of the closed ends is greater than the outside diameter of the standard metal shipping drum.

5. The article of claim 1 where the inside surface of the closed end comprises a raised annular section adapted to engage the ring of a standard metal drum.

6. A pair of rotationally molded polyethylene salvage basins of generally circular cross-section adapted to receive and contain between them a standard metal drum, comprising a first salvage basin having a tapered lower section, an intermediate shoulder section and a horizontal outwardly extending flange, and a second salvage being inverted relative to the first basin and having a tapered upper section, an intermediate shoulder section and an outwardly extending horizontal flange adapted to mate with the flange of the first basin, said basins being obtained by separating the drum of claim 1 into two approximately equal portions along the line defined by a plane parallel to the ends of the drum and passing through the central section.

7. The salvage basins of claim 6 which further comprise sealing means intermediate the mated flange surfaces.

8. The salvage basins of claim 7 which further comprise means for securing the mated flange surfaces.

9. The salvage basins of claim 6 in which the horizontal flange of the first basin terminates in an upwardly extending ridge.

10. A pair of salvage basins obtained by separating the drum of claim 1 into two approximately equal portions along the line defined by the intersection of a plane parallel to the ends of the drum and passing through the central section.

11. A pair of salvage basins as in claim 10, where each basin has a planar horizontal, outwardly extending flange obtained by separating the drum by cutting the central section along two horizontal planes parallel to the ends of the drum, proximate the corners of the central section.

12. A pair of salvage drums as in claim 10, where each basin has a planar horizontal, outwardly extending flange, obtained by separating the drum by cutting the projecting flange sections inside of and proximate to the central section.

13. A pair of salvage drums as in claim 10, where the horizontal, outwardly extending flanges of the two basins have a ridge extending away from the main part of the drum such that, when the second basin is placed on the first basin, the ridges mate, the drums being formed by cutting the central section along a horizontal plane lying between the top and bottom of that section, parallel to the ends of the drum.

14. A pair of salvage drums as in claim 10, where the horizontal flange of the first basin terminates in an upwardly extending ridge such that when the second basin is placed on the first basin, the upwardly extending ridge secures the second basin in place, the drums being formed by cutting one projecting flange section inside of and proximate to the central section.