GB2267466A

GB2267466A - Dunnage bag

Info

Publication number: GB2267466A
Application number: GB9311737A
Authority: GB
Inventors: Michael George Stone; Greta Stoker; Andrew John Fulcher; Frank Nattrass; Mark Andrew Nattrass
Original assignee: Booth & Son Ltd L; TRADCO
Current assignee: Booth & Son Ltd L; TRADCO
Priority date: 1992-06-06
Filing date: 1993-06-07
Publication date: 1993-12-08
Also published as: GB9311737D0

Abstract

A dunnage bag comprises an inner inflatable bag of a fluid impermeable material eg polyethylene, inside an outer covering bag 1, wherein the outer bag is made of a circular woven fabric eg polypropylene so that there are no longitudinal side seams in the outer bag. This, among other advantages, improves the strength of the dunnage bag, particularly during inflation of the inner bag. The invention also provides an outer covering bag for use as part of the dunnage bag. <IMAGE>

Description

DUNNAGE BAG Field of the Invention This invention relates to a dunnage bag, of the type used to stabilise loads during storage and transit; and also to an outer covering bag for use as part of such a dunnage bag.

Background to the Invention "Dunnage bags" are already well known, for use in stabilising loads during their storage and transit. The simplest form of dunnage bag comprises an inflatable bag made from a fluidimpermeable material. This is placed, in its deflated state, in the gap between items of cargo in a storage container (for instance, in the hold of a cargo ship). The bag is then inflated, usually with air but sometimes with another fluid, until it substantially fills the gap in which it was placed.

The inflated bag then serves to stabilise the items of cargo between which it is positioned, and to protect them from damaging one another. It is thus especially useful for protecting goods whilst they are in transit.

Some dunnage bags comprise an inner inflatable bag of the type described above, together with an outer covering bag which protects and strengthens the inner bag. The outer covering bag is typically made from a relatively strong material such as paper or fabric. An example of a dunnage bag comprising such an outer covering bag is described, for instance, in GB1,052,586. The bag described in that document comprises an outer bag made of strength-providing layers of, for instance, burlap, sisal, rayon and paper.

In previously described dunnage bags, the outer covering bag has always had a longitudinal side seam, as well as two end seams, to hold the covering fabric together in the bag shape.

This is the case, for instance, in the outer bag described in GB-1,052,586 (see Figures 2, 3 and 5). This longitudinal seam naturally represents an area of relative weakness in the outer bag, particularly since it is in the circumferential direction (ie, in a direction such as produces stress upon the longitudinal side seam) that dunnage bags are typically subjected to the greatest stress, both during and after inflation of the inner bag. The existence of the vulnerable seam area means that the dunnage bag can burst relatively easily, particularly if over-inflated. The consequences of such an explosion in a storage container are clearly quite serious.

Outer covering bags on conventional dunnage bags are typically made, at present, from either multi-ply paper, or from woven synthetic fabrics such as nylon, coated with plastics coatings. These can often be relatively expensive to produce.

It is therefore an aim of the present invention to provide a dunnage bag, and an outer covering bag for a dunnage bag, which overcome or at least mitigate the above described problems.

Statement of the Invention According to a first aspect of the present invention there is provided a dunnage bag comprising an inner inflatable bag of a fluid impermeable material, inside an outer covering bag, wherein the outer bag is made of a circular woven fabric so that there are no longitudinal side seams in the outer bag.

There are a number of advantages inherent in a dunnage bag in accordance with the invention. Firstly, the use of a circular woven fabric (ie, a fabric having a continuous weft thread, woven around in a similar manner to that in which socking is woven), and the consequent lack of longitudinal side seams in the outer bag, makes the bag on the whole much stronger than outer bags on conventional dunnage bags. There are no seam areas vulnerable to circumferential stresses exerted on the outer bag during and after inflation of the inner bag. Whilst the outer bag will still need seams at its two opposite ends, it will experience much less stress in these regions anyway.

Another advantage arising from the lack of longitudinal side seams is that information may be printed on the side edges of the outer bag, in which position it will be most prominent.

Normally printing is not possible in these regions because of the presence of one or more side seams.

The use of a woven fabric for the outer bag means that the bag can be manufactured relatively inexpensively. Fabric will also grip relatively well the surfaces against which it is placed (for instance, the sides of items of cargo between which the dunnage bag is positioned), increasing the chances of the bag remaining correctly positioned during transit of the cargo. Fabric also absorbs friction relatively easily, compared to, say, paper. This is an extremely important advantage, since friction between items of cargo and dunnage bags can lead to increases in temperature which may be very undesirable in closed containers where cargo is being stored or transported.

The fabric from which the outer bag is made may be any natural or manmade fabric, one preferred fabric being polypropylene.

A typical weight for the fabric might be, for instance, 2,000 denier. Ideally, the outer bag is of a strength sufficient to withstand pressures of up to around 2 atmospheres, although the exact strength of the bag will depend very much on the circumstances in which it is to be used. These circumstances will also, naturally, affect the type and weave of fabric to be used for the outer bag.

The end seams of the outer bag are preferably stitched together. This means that manufacture of the outer bag is a relatively simple and inexpensive affair, requiring only that a continuous length of circular woven fabric of the correct circumference be chopped into individual lengths, and two free ends of one length be sewn together to form a complete outer bag.

Because the outer bag is relatively inexpensive to produce, it may be disposable. Alternatively, it may be strong enough for re-use with the same or with a different inner bag.

The inner inflatable bag of the dunnage bag of the present invention must be made from a fluid impermeable material, of which polyethylene is a suitable example. The quality and thickness of this material will again depend on the uses to which the dunnage bag is to be put, the inflation pressures which it must withstand, the number of times it is to be reused, etc. The inner bag will comprise a fluid inlet, through which it may be inflated. The outer bag thus also needs a fluid inlet, preferably corresponding in position to the fluid inlet of the inner bag, through which access may be gained so as to inflate the inner bag. The fluid inlets are preferably positioned at or near the corners of the outer and inner bags.

Preferably the inner bag is secured to the outer bag, either permanently or releasably.

Information may be printed on, or otherwise affixed to, the outer covering bag, in particular in its side regions, where such information is generally more visible in use.

According to a second aspect of the present invention there is provided an outer covering bag for use as part of a dunnage bag as described above as being in accordance with the invention, the outer bag being made of a circular woven fabric such that it does not have any longitudinal side seams.

The present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings, of which: Figure 1 shows in perspective view a dunnage bag in accordance with the invention; and Figure 2 shows a schematic end view of a storage container in which two dunnage bags such as those shown in Figure 1 are in use.

Detailed Description of the Drawings The dunnage bag shown in Figure 1 comprises an outer covering bag 1, inside which is an inner inflatable bag (not shown) of a fluid-impermeable material. The outer bag 1 has a front face, 2, a rear face (not shown) and two opposing side faces, 5, one of which is shown in Figure 1. The bag is made from a circular woven polypropylene fabric (with a continuous weft thread) and hence has no longitudinal side seams. It does, however, have two seams 3, 4 at its two opposite ends. These seams are stitched together.

Outer bag 1 has a fluid inlet 6 in its front face, 2, which corresponds in position to an air inlet valve in the inflatable bag inside the outer bag. Through these inlets, a fluid such as air may be used to inflate the inner bag in use. The outer bag 1 provides protection and reinforcement for the inner bag.

The dunnage bag shown in Figure 1 is illustrated in a semiinflated state. Its dimensions depend upon the uses to which it is to be put, but, typically, its front face 2 might measure lm x 2m.

Information may be printed on the side(s) or side region(s) of the dunnage bag, as shown in the region 7 in Figure 1.

Because there are no longitudinal side seams in the bag, this information may be printed in a region such as 7 where it will be most visible when the bag is in use. The information may relate, for instance, to the dunnage bag itself and to the uses to which it may be put.

The outer bag 1 of the dunnage bag shown in Figure 1 is intended to be disposable after use, since it is relatively simple and inexpensive to manufacture. It is, however, stronger and more durable (particularly because of its lack of longitudinal side seams) than conventional layered paper outer bags, and as such could well be reusable a number of times.

In Figure 2, the dunnage bag of Figure 1 is shown in use in a cargo storage/transport container 8. Two dunnage bags 9 of the type shown in Figure 1 are shown in their inflated condition between items of cargo 10. The printed regions 7 of the dunnage bags are visible.

To use the dunnage bags, they are positioned in their deflated state between the items of cargo 10, and then inflated with air, via inlets 6, until they fill as nearly as possible the gaps between the items 10. Thus, as shown in Figure 2, they prevent or at least inhibit movement of the items 10 relative to one another and relative to the side walls of the container 8, thus protecting the items during their storage and transit.

When the cargo items 10 are to be removed from container 8, the dunnage bags 9 are allowed to deflate and removed from between the items.

Claims

1. A dunnage bag comprising an inner inflatable bag of a fluid impermeable material, inside an outer covering bag, wherein the outer bag is made of a circular woven fabric so that there are no longitudinal side seams in the outer bag.

2. A dunnage bag according to Claim 1, wherein the outer bag is made of circular woven polypropylene.

3. A dunnage bag according to Claim 1 or Claim 2, wherein the weight of the fabric from which the outer bag is made is about 2,000 denier.

4. A dunnage bag according to any one of the preceding claims, wherein the outer bag is of a strength sufficient to withstand pressures of up to around 2 atmospheres.

5. A dunnage bag according to any one of the preceding claims, wherein the end seams of the outer bag are stitched together.

6. A dunnage bag according to any one of the preceding claims, wherein the inner inflatable bag is made from polyethylene.

7. A dunnage bag according to any one of the preceding claims, wherein the inner bag comprises a fluid inlet, through which it may be inflated, and the outer bag comprises a second fluid inlet, corresponding in position, in use, to the fluid inlet of the inner bag, through which second fluid inlet access may be gained from the outside of the dunnage bag to inflate the inner bag.

8. A dunnage bag according to Claim 7, wherein the fluid inlets are positioned at or near the corners of the outer and inner bags.

9. A dunnage bag according to any one of the preceding claims, wherein the inner bag is secured to the outer bag.

10. A dunnage bag according to any one of the preceding claims, wherein information is printed on, or otherwise affixed to, the outer covering bag.

11. A dunnage bag according to Claim 10, wherein the information is printed on or affixed to the side regions of the outer covering bag.

12. A dunnage bag substantially as herein described with reference to the accompanying illustrative drawings.

13. An outer covering bag for use as part of a dunnage bag according to any one of the preceding claims, the outer bag being made of a circular woven fabric such that it does not have any longitudinal side seams.

14. An outer covering bag according to Claim 13, which is adapted to be disposable after use.

15. An outer covering bag according to Claim 13, which is capable of being re-used, after its first use with an inner bag, with the same or a different inner bag.

16. An outer covering bag for use as part of a dunnage bag according to any one of Claims 1-12, the outer covering bag being substantially as herein described with reference to the accompanying illustrative drawings.