Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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INTRODUCTION
This application relates to floating containment barriers
and, more particularly, to containment booms which are
collapsible and self-inflating.
BACXGROUND OF THE INVENTION
In recent years, there has developed an expertise in
designing floating containment barriers, due in large measure
to environmental concerns when oil or other foreign substances
unnecessarily contaminate the natural state of water. Whereas
booms were previously made from substantially solid material
such as cork, foam, and the like, and were used to delineate
areas of water and for containment purposes other than
contamination, booms may now be used to contain oil and other
contamination and must have the capability to be deployed on
short notice in the event of an oil spill or other mishap to
prevent the spread of undesirable contamination. Hence, an
objective in the state of floating containment barriers is to
have a containment boom located in a readily accessible storage
location, occupying a minimum amount of storage space and being
capable of quick deployment when needed.
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The objective of minimum storage space being occupied is
met by having the boom adapted to be air inflatable. Such a
boom also incorporates a desirable weight reduction relative to
substantially solid booms.
Present air containable floating containment booms may be
either of two types. The first type is the inflatable boom.
In this boom, air is supplied under pressure to the buoyancy
chamber causing the boom to be inflated throughout its length.
This type of boom has the advantage of being deployed from a
single Iocation which may be desirable in situations where
quick deployment and minimum manpower is required. The boom is
fed into the water from one deployment point, air under
pressure is provided to the buoyancy chamber and the boom
inflates throughout its length under the influence of the air.
The second type of air containable floating containment
boom is the self-inflating type. This boom is deployed using
two locations because the buoyancy chamber needs to be
stretched in order to cause a suction in the boom which creates
an ingress of air through appropriately designed one-way check
valves. In this type of boom, hoops or other methods of
support are necessary to provide support for the buoyancy
chamber walls wXich cannot be allowed to totally collapse in
which case there would be no suction created.
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Inflatable containment booms, however, have inherent
problems. It is desirable, in such booms, to have a single valve
for inflating the boom both because of material cost and for
efficiency of inflation procedure. Providing a single valve,
however, obviously dictates a buoyancy chamber with no air
impervious bulkheads located therein. With no such bulkheads, a
single leak anywhere in the walls of the buoyancy chamber may
result in the boom eventually sinking because of the egress of
air and the ingress of water. To deal with this problem to some
extent, air may be continuously supplied to the boom but this
unsatisfactory solution is clearly of limited value.
Self-inflating containment booms, on the other hand, overcome
these leakage and inflation problems by utilising a series of
compartments in the buoyancy chamber separated by water impervious
bulkheads. Each compartment is appropriately designed to
incorporate a one-way check valve which allows for the ingress of
air upon the expansion of the buoyancy chamber when the boom is
deployed. Nevertheless, two locations are necessary in order to
provide the appropriate expansion.
The manufacture of present self-inflating floating
containment booms which utilize water impervious bulkheads and
restraining means within the buoyancy chamber to prevent the
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collapse of the buoyancy chamber walls has, in the past, been
inefficient. In relation to the manufacture of the water
impervious bulkheads, a first approach was by providing a
diamond-shaped piece of flexible bulkhead material (the
"diamond"). The diamond was positioned such that the
short-axis between the opposed apexes of the diamond-shape was
substantially aligned with a longitudinal axis of the buoyancy
chamber. The two adjacent sides on one side of the diamond
were then bonded to the buoyancy chamber which was subsequently
folded over and the unbonded sides of the diamond were folded
over the bonded strips. The open sides of the buoyancy chamber
were then bonded together while, at the same time, the unbonded
sides of the diamond were bonded with the edge strip of the
buoyancy chamber at the interface.
This technique, however, was subsequently found to be
disadvantageous. Two separate heat seal or bonding operations
were needed when the bulkhead material was originally bonded to
the buoyancy chamber material. Further, when the diamond was
folded back on itself, there were six layers of fabric
appearing at the forwardmost portion of the bulkhead opening
along the interface. When this material was bonded, an uneven
bonding was created because the thickness of material at the
interface would suddenly change and a situation was created
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where leaks could and did appear. Finally, the inherent
diamond-shape of the bulkhead created point loading conditions
where the fabric was subject to excessive loads under certain
environmental conditions resulting in tears occurring in the
bulkhead.
SUMMARY OF THE INVENTION
According to the present invention, there is disclosed a
method of producing a tubular containment boom comprising
folding each of a plurality of substantially identically shaped
rectangular pieces of bulkhead material, each along one of its
bisecting axes; bonding an edge portion transverse to the
bisecting axis; opening the opposed unbonded edge portion while
allowing the bonded edge portion to fold inwardly; positioning
said bonded and opened bulkhead material on material used for
the buoyancy chamber of said containment boom with said
unbonded edge portion being transverse to the longitudinal axis
of said buoyancy chamber; bonding said unbonded edge of said
bulkhead material to said buoyancy chamber material;
positioning and bonding hoop envelopes on said buoyancy chamber
material; encasing a plurality of plastic hoops, each within a
flexible sleeve; inserting each of said hoop and sleeve within
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each of said hoop envelopes; closing the circumference of said
hoop by inserting the respectively opposed ends in a ferrule
adapted to receive said ends; crimping said ferrule on each
respective end of said hoop; encasing said ferrule within said
flexible sleeve; folding said buoyancy chamber and bulkhead
material along said bisecting axis whereby said bonded edge
portion opens outwardly and assumes a position transverse to
said bisecting axis and the unbonded edge opposed to said
bisecting axis assumes a position between the interface of the
walls of said buoyancy chamber where said walls meet beneath
thP longitudinal axis of said containment boom; and bonding
said interface of the walls of said buoyancy chamber and said
unbonded edge.
BRIEF DESCRIPTION OF THE SEVERA~ VIEWS OF THE DRAWINGS
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An embodiment of the invention will now be described, by
way of example only, with reference to the accompanying
drawings in which:
Figure 1 is a view of the containment barrier or boom of
the present invention in assembled and deployed condition
with the buoyancy chamber hoops and water tight bulkheads
shown in cutaway;
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Figures 2A-2C depict three steps involved in producing the
watertight bulkhead before it is positioned on the walls of
the buoyancy chamber material;
Figures 3A and 3B depict two steps involved in bonding the
watertight bulkhead within the buoyancy chamber;
Figure 3C is a sectional view taken along the plane III C -
III C of Figure 5A.
Figures 4A and 4B show the hoop pocket and enclosed hoop
and envelope in the buoyancy chamber, both in the initial
unassembled condition of the boom and in the partially
assembled condition of the boom; :
Figures 5A and 5B are detail views of various hardware
attached to the boom; and
Figures 6A-6C depict an end~connector of the boom in bottom
view with various connections to the boom parts.
DESCRIPTION OF SPECIFIC EMBODIMENT
A floating containment barrier or boom is shown generally
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at 10 in Figure l. It comprises a buoyancy chamber 11, a
flexible skirt 12 extending downwardly-from the buoyancy
chamber 11, a control passageway 23 and a chain envelope 16 all
manufactured from a single piece of polyester reinforced
polyvinyl chloride (nP.V.C."). Boom-end connectors 13,14 are
positioned on respectively opposite ends of the boom 10. They
are designed to allow for connection between individual
sections of boom and, since the end connectors form no part of
the present invention, they will not be further described.
A chain tension member 15 extends between end connectors
13,14. The chain tension member 15 acts to maintain the end
connectors 13,14 in aligned position and to provide ballast for
the boom 10. The chain tension member 15 is mounted within the
chain envelope 16 formed in the lowermost portion of the
flexible skirt 12 and is connected to the end connectors 13,14
by bolted connections 27,28. The left hand end connector 13
with its bolted connection 27 is shown in more detail in Figure
6C which is representative of both end connectors 13, 14.
Check valve assemblies 17 are located in the uppermost
portion of the buoyancy chamber 11. They are manually inserted
in check valve retainers 40 when the boom 10 is deployed and
act to allow the ingress of air while preventing the ingress of
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water and egress of air, thereby keeping the boom inflated and
without water in the buoyancy chamber. When the boom 10 is
removed from the water, the check valve assemblies 17 are
manually removed to allow the air within the buoyancy chamber
11 to escape and to allow compaction of the boom 10. The check
valves 17 will not be described in specific terms since their
construction forms no part of the present invention.
A restraining means or hoop 18 (Figure 4) is inserted in a
sleeve 19 made from neoprene foam and acts to keep the walls of
the buoyancy chamber 11 from collapsing. The hoop 18 and
sleeve 19 are retained on a circumference of the inner wall of
the buoyancy chamber 11 by an unsupported P.V.C. envelope 20
bonded by heat sealing to the wall of the buoyancy chamber 11.
The hoop 18 terminates in an aluminum ferrule 21 which, upon
insertion of the opposite end of the hoop, is crimped over that
end and forms a permanent connection for the two hoop ends.
The hoop 18 enclosed within sleeve 19 is encased by envelope 20
which is bonded to the buoyancy chanber 11.
Water and air impervious bulkheads 22 (Fig. ll)are mounted
to the inner walls of the buoyancy chamber 11 at regular
intervals along the boom length and are adapted to form a
barrier to water and air between adjacent compartments of the
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boom 10. Each bulkhead 22 is manufactured from a rectangularly
shaped piece of unsupported P.V.C. and is connected to the
walls of the buoyancy chamber utilizing the manufacturing
techniques disclosed hereafter.
The control passageway 23 is positioned directly below the
buoyancy chamber 11. Unlike the buoyancy chamber 11, the
control passageway 23 is not divided into sections or
compartments. Rather, there is one section only~ A valve 24
is mounted on the end of the control passageway 23 furthest
removed from the initially deployed end, which it has been
assumed, is the right hand end of the boom 10 as seen in Figure
1 and provides ingress for air under pressure to inflate the
control passageway 23 when the boom 10 is deployed. The
construction of valve 24 forms no part of the present invention
and since its construction is known, it will not be
specifically further described.
In addition to these specified portions of the containment
barrier, there are also miscellaneous pieces of hardware
utilized for various purposes.
An anchoring shackle 31, best seen in Figure SA, is
attached through chain 15 and a cutout 47 is provided in the
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chain envelope 16 at the point where the shackle 31 is
attached. The anchoring shackle 31 is used to anchor the boom-
10 or it may be used as a means to attach additional ballast.
A tagline bracket 32, best seen in Figure 5B, is mounted on
the interface 25 of the heat bonded area between the buoyancy
chamber 11 and the control passageway 23. The tagline bracket
32 consists of two anchor brackets 33,34 which are
interconnected by rivets 35,36 and which sandwich the fabric
material at the interface 25. Anchor lines 37,38 are attached
to the anchor brackets 33,34. The tagline bracket 32 is
typically used when a pair of booms 10 are being towed through
contamination to funnel it towards a contamination remover such
as a skimmer or the like and the booms are maintained in the
form of a "V" shaped funnel while operating. In such event,
lines are attached to respectively opposed tagline brackets 32
on each boom to maintain the "V" shape.
The end connectors 13,14, one of which is representatively
shown in Figure 6, hold the sealed end portion 44 of each end
of the boom by the use of first and second aIuminum tubes
42,43, respectively, as will be hereinafter explained.
AIuminum tube 43 is held in place within end connector 13 by
bolted connection 27 on the bottom and end connector handle 45
on the top (Figure 1).
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OPERATION
The method of making the boom 10~commences by selecting an
appropriately dimensioned boom membrane material of the
aforementioned polyester supported P.V.C. and thereupon marking
the positions for the installation of the hoop envelopes 20
(Figure 4), the bulkheads 22, the check valve retainers 40 and
the control passageway valve 24. The bulkheads 22 are partially
assembled prior to their installation in the boom 10. With
reference to Figures 2 and 3, a rectangular piece of unsupported
P.V.C. bulkhead material 46 is folded as indicated along the
short axis B-E bisecting the material. Corners C,D then fall on
corners A,F as seen in Figure 2B. The edge portion E-DF is then
bonded along the area 39 by heat sealing. Corner C (Figure 2C)
is then opened outwardly as indicated and corner DF and bonded
edge area 39 are allowed to move inwardly. The bulkhead material
46 is subsequently positioned on the inner walls of the buoyancy
chamber 11 (Figure 3A) with the axis B-E falling along the line
X-X running longitudinally along the top of the buoyancy chamber
11. The edge portion C-B-A of the bulkhead is then bonded to the
material of the buoyancy chamber 11 by heat sealing.
Proceeding simultaneously with the installation of the
~bulkhead material 46, the unsupported P.V.C. hoop envelopes 20
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are also installed in the buoyancy chamber 11. With reference
to Figure 4A the hoop sleeve 19 of neoprene foam material is
appropriately positioned on the buoyancy chamber material 48
under the hoop envelope 20 and the edges of the envelope 20 are
bonded by heat sealing to the boom membrane material after
inserting the hoop 18 with a ferrule 21 crimped on one end.
In addition to the heat sealing operations described above
for bonding the bulkheads 22 and the hoop envelopes 20 to the
buoyancy chamber 11, check valve retainers 40 and any retainer
necessary for the control passageway valve 24 are also
installed by heat sealing in their appropriate positions.
As seen in Figure 48, the hoop 18 has a ferrule 21
previously assembled on one end by crimping. Following the
installation of the check valve and control passageway valve
retainers, the opposite end of the hoop 18 is inserted into the
open end of ferrule 21 and the ferrule 21 is crimped on this
end. The buoyancy chamber material then encircles the hoop 18.
After the assembly of the hoops 18 and again with reference
to Figures 3A, 3B and 3C, the corner DF is pulled~o~twardly and
downwardly such that the edge portion CA-DF lies along and is
sandwiched between the interface 25 where the buoyancy chamber
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material meets after the buoyancy chamber material encircles
the hoops 18 as particularly well shown in Figure 3C. There
is, therefore, a four layer depth of material running along the
interface 25 where the edge portion CA-DF of the bulkhead 22 is
sandwiched. The interface 25 together with edge portion CA-DF
of the bulkhead 22 is then bonded together by heat sealing.
Thus, a watertight seal along both the buoyancy chamber
interface 25 and bulkhead edge portion CA-DF is achieved which
causes a water and air impervious seal between the compartments
of the buoyancy chamber 11 located on opposite sides of the
bulkhead 22 when the boom is in its final assembled condition.
Following the assembly of the buoyancy chamber 11, the
bulkheads 22 and the hoops 19, the control passageway 23 is
formed. The control passageway 23 will have previously been
appropriately dimensioned and any necessary retainer for the
control passageway valve 24 has been installed. Bonding is
made along the control passageway seal 26 (Figure 3C) by heat
sealing.
The chain envelope 16 is subsequently formed by folding the
lower end of the flexible skirt 12 upwardly the required
distance and bonding the chain envelope seal 41 again by heat
sealing. Cutouts 47 are made in the chain envelope 16 to
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provide space for the anchoring shackle 31. It may be
necessary to form a double thickness of fabric material in the
chain envelope area and, if so, the skirt 12 is appropriately
dimensioned so that it may be folded into the double thickness
configuration.
The completion of the chain envelope seal 41 ter~inates the
longitudinal boom bonding operations.
With reference to Figure 6A, the left hand end connector 13
is shown in plan view adjacent the left hand end portion of the
buoyancy chamber material 48. An aluminum tube 42 extends
substantially the width of the end of the boom 10 and the boom
material 48 is bonded about the tube 42 at 44 by heat sealing.
The walls of the buoyancy chamber 11, the ends of the control
passageway 23 and the ends of the chain envelope 16 are all
bonded along the transverse edges of the boom 10 extending from
aluminum tube 42 to form transverse edge seal 44. The
transverse edge seal 44 is then partially wrapped about a
second aluminum tube 43 and the tube 43 with the sealed
material wrapped thereabout is slidably mounted from the bottom
upwardly in end connector 13 and its position is seen in Figure
6B. An identical procedure both for sealing and for mounting
to the end connector 14 is used at the opposite transverse end
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of the boom 1~. The aluminum tubes 43 inserted in end
connectors 13,14 are prevented from sliding out of the end
connectors by end connector handles 45 (Figure 1) inserted in
the top of the end connectors 13,14 and by bolted connections
27,28 in the bottom of the end connectors 13,14, which are
installed after the installation of the aluminum tubes 43. The
bolted connections 27,28 are inserted through the end
connectors 13,14 while attaching the chain 15, one end
connector 13 being representatively shown in Figure 6C.
~ he tagline bracket 32 (Figure 5B) and the anchoring
shackle 31 (Figure 5A) are installed as is self-evident from
the illustrations. The boom is now in its manufactured
condition.
There are two deployment possibilities. In the first
instance, the boom 10 may be deployed by attaching one end of
the boom 10 to a sea or bottom anchor (not shown) and moving
the deployment vessel away from the anchor or, alternatively,
two vessels may be used, one for feeding the boom into the
water and the other for creating tension on the boom and
expanding that portion of the buoyancy chamber 11 between the
bulkheads 22. In any event, control passageway 23 is not
utilized with this technique of boom deployment. As the boom
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10 is fed into the water from its position of deployment, the
check valves 17 are manually inserted in their retainers 40.
As the tension on the boom 10 expands the buoyancy chamber 11
b-etween the bulkheads 22, a suction within the buoyancy chamber
is created and the check valve assemblies 17 allow ingress of
air into the various compartments of the buoyancy chamber 11
between the bulkheads 22 thus inflating the boom 10. Since
egress of air from the check valves 17 is not permitted by the
check valves 17, the boom 10 remains in its inflated condition.
In the second instance, the boom 10 may be deployed without
the use of an anchor or a second vessel. -In this case, the
check valves 17 are again manually inserted into their
receptacles 40 as the boom 10 is deployed into the water. When
the boom 10 is entirely deployed, an air pressure line is
connected to control passageway valve 24 and the control
passageway 23 is inflated. As the control passageway 23 is
inflated, it causes the buoyancy chamber 11 to expand between
the bulkheads 22 and the resulting suction causes the ingress
of air through the check valves 17 into the buoyancy chamber 11
thus causing inflation of the boom 10. Following inflation,
the air pressure line may be removed from the control
passageway 40 and, since the check valves prevent the egress of
air from the buoyancy chamber 11, the boom remains in its
inflated position.
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Certain changes may be made to the boom design. If, for
example, the boom 10 is to be a length such that the control
passageway 23 will not inflate the entire length of the boom,
the control passageway may be divided into chambers with a
control passageway valve 24 inserted in one end of each
chamber. In this event, only a portion of the length of the
boom is deployed until the end of each control passageway
chamber is encountered whereupon the particular control
passageway is inflated through each valve 24 and causes only
that portion of the boom corresponding to the length of the
particular control passage to expand and permit self-inflation.
While the materials specified throughout the disclosure have
been found to be satisfactory in use, many other materials are
also available. For example, although the boom membrane
material is specified as being supported vinyl, it is clear
that other supported materials would include nylon,
Kevlar T-M or polyester, each coated with vinyl, P.V.C.,
urethane, neoprene, Shelterite T-M- XR5 or Hypalon T-M-
Similarly, while the bulkhead and hoop envelopes are specified
as being unsupported P.V.C., they may also be made from a
supported material. Accordingly, they may be made from the
coatings and fabrics specified above, as well as the materials
specified in the disclosure and any other appropriate material
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which is flexible and air impervious. Further, while the
material specified for the ferrule 21 is aluminum and the
material specified for the sleeve 19 is neoprene foam, it should
be clear that many other appropriate materials are available for
the former and any appropriate closed cell foam would be suitable
for the latter.
While the boom 10 is specified as being stored without the check
valves 17 in their retainers 40, it is, however, usually
preferable to store the boom 10 with the check values 17
installed in order to allow for easier and faster boom deployment.
Under certain conditions, it may be desirable to insert
strips between the bulkheads in the interface 25 prior to bonding
the strips being made of material appropriate to the material
used in the manufacture of the boom. This will alleviate the
problems of discontinuous heat sealing when a "four layer"
thickness of material in the interface is encountered as the
bulkhead is sealed with the interface.
Other changes and modifications to the invention may be
readily apparent in addition to those specified to those skilled
in the art without departing from the scope of the invention
which should, therefore, be limited only by the accompanying
claims.
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