Note: Descriptions are shown in the official language in which they were submitted.
CA 022368~7 1998-0~-06
WO97/17565 PCT/CA96/00738
Descri~tion
Method and APParatus for Lininq a Conduit
Technical Field
The present invention relates to methods and apparatus
for lining a conduit. More particularly, the invention is
directed to methods and apparatus for lining such conduits
particularly for repairing damaged, weakened, or leaking
conduits that are located in areas that are difficult to gain
access, for example, sewer pipes or other conduits that are
located underground.
Backqround Art
Conduit systems for carrying water or waste water, for
example, and other liquid and fluid conveyance systems, as
well as conduit systems that house communication lines, for
example, are typically located underground and, in general,
are not easily accessible after installation. Such systems
are disclosed in the aforementioned U.S. Patent Nos. 5,119,862
and 5,351,720.
Over a period of time, such conduit systems can become
damaged, weakened, or can otherwise begin to leak at the
~oints between adjacent conduit sections, for example. The
problems associated with such systems, and a number of
previous repair methods and apparatuses are disclosed, for
example, in the aforementioned U.S. Patent Nos. 5,119,862 and
5,351,720.
It is known to line and/or repair damaged conduits from
within and without the need for excavation. Such methods and
apparatus utilize liner sections that are placed within a
cracked or damaged conduit which is expanded from a coiled
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-2-
configuration to a final configuration in which the liner is
secured against the inner surface of the damaged conduit.
Various means, such as a bladder that is expandable via a
source of compressed air, can be employed for exerting
internal pressure from within the coiled liner so that the
liner is expanded radially outwardly into a final position.
One must ensure, in the exertion of the radial expansion
force, that a force, particularly an excessive force, is not
placed against the damaged conduit, thereby further damaging
the already damaged conduit.
Disclosure of Invention
It is an object of the present invention to improve upon
known internal conduit lining methods and apparatus and,
particularly, repair methods and apparatus. Although the
present invention is contemplated as having its greatest
utility in repairs, it is also contemplated that the lining
apparatus of the invention can be employed prior to any need
for repair.
The present invention provides methods and apparatus that
do not require significant internal pressures to be applied
to the damaged conduit section and, therefore, that do not
risk the possibility of additional damage to the damaged
and/or weakened conduit section. Further, compressed air
apparatus are not necessary for implementation of the
invention. Still further, conduit joints repaired with the
methods and apparatus of the present invention are stabilized,
are completely sealed, and the repair is long-lasting.
To this end, the present invention is directed to a liner
apparatus for repairing conduits in which a sheet of plastic,
spirally coiled in transverse cross section, which, due to its
open cross section, can be coiled onto a reel. Such reels of
plastic are known.
CA 022368~7 1998-0~-06
The longitudinal edges of the open cross section have a
matching, or complementary, configuration. Such configuration
can take the shape, for example, of matching sawtooth sections
for forming a mechanical lock of the spiral sheet into a
cylindrical conduit liner.
The spirally curled sheet of plastic, or liner, is pulled
into the conduit under repair, a sewer, e.g., from the far
access chamber so that the liner is positioned in the sewer
end-to-end in the curled configuration.
Once the curled liner is properly placed in position in
the sewer, a torpedo-shaped member, or torpedo, is pulled by_
a cable through the liner. The diameter (ID) of the torpedo
is preferably slightly greater than the desired inside
diameter of the liner so that, as the torpedo is pulled-
through the spiralled liner, the liner is unfurled
sufficiently to bring the matching locking edges of the liner
into alignment and secure the liner into a desired cylindrical
shape adjacent to the inside surface of the conduit under
repair.
~ More specifically, as the maximum diameter of the torpedo
passes a given location along the length of the curled liner,
the respective longitudinal edges of the liner are slightly
over-expanded. As the torpedo passes, due to the internal or
locked-in stresses of the material from which the liner is
made, the previously curled liner tends to move in the
direction to assume its original curled configuration. During
such movement, the sawtooth or other matching mechanical
locking form of the edges engage and retain the liner in the
desired cylindrical configuration. Since the sawteeth, or
other mechanical locking forms, are on the longitudinal edge
surface of the plastic liner, the resulting cross-section is
perfectly circular, rather than overlapped.
AMENDED SHEET
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W097/l756~ PCT/CA~ C~8
In a further embodiment of the invention, the locking of
the sleeve in the uncoiled position can include, in addition
to the aforementioned mechanical locking of the edges, the use
of a thermosettable, thermoplastic or thermofusible coating
on the liner at least near the locking edges so that, after
expansion of the liner into the unfurled installation
position, the coating is heated, thereby melting same,
including the melting of the coating on the locking edges of
the sleeve. Upon removal of the heating source, the edges of
the sleeve are thereby welded together. One method of heating
and melting the layer of thermoplastic coating, for example,
is by means of resistance elements, i.e., electrical wire,
embedded in the coating layer. once the liner is in place
after the aforementioned movement of the torpedo, current is
applied to the resistance elements, thereby melting the
plastic at the edges and fusing the edges together.
As an alternative, a quantity of solvent can be provided
for fusing the locking edges of the plastic liner to fuse the
edges chemically.
It is contemplated that the plastic liner can be made of
high-density polyethylene or a softer version of PVC. Other
plastics can also be used. The torpedo is contemplated as
being made from any suitable material, including metals and/or
plastics and/or combinations thereof, for performing the
function described herein and its internal and external
structure and shape, as well, can take any appropriate form
provided that the torpedo has a sufficient structural
integrity for performing such function.
Brief Description of Drawinqs
The above and additional objects, characteristics, and
advantages of the present invention will become even more
apparent in the following detailed description of preferred
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embodiments, with reference to the accompanying drawings which
are presented as non-limiting examples, in which:
.
FIG. l illustrates the liner of the invention, in
transverse cross section, in a curled, pre-installation
configuration;
FIG. 2 schematically illustrates the liner being fed from
a storage reel, while in the curled pre-installation
configuration, into a sewer system for lining at least a
portion thereof;
FIG. 3 illustrates the liner, in transverse cross
section, in an uncurled, installation configuration;
FIG. 4 is a detail illustration of a portion of the liner
shown in FIG. 3;
FIG. 5 schematically illustrates a torpedo-shaped member
positioned within an end of a length of the curled liner, the
liner being positioned within a conduit section to be lined
or repaired, whereafter the torpedo-shaped member is moved
through the liner to uncurl same to cause the locking edges
to become engaged so that the liner will assume its uncurled
locked configuration; and
FIG. 6 illustrates the torpedo-shaped member.
FIG. 7 is similar to FIG.4 and illustrates an
alternative ~orm ~or the locking edges of the liner.
Best Modes ~or ~a~rvina Out the Invention
With respect to the drawings, only enough o~ the
construction o~ the invention has been depicted, to
simplify the illustration, as needed ~or those o~ ordinary
skill in the art to readily understand the underlying
principles o~ the invention and, there~ore, to permit them
to make and use the invention.
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FIG. 1 illustrates a cross-sectional view of the sheet
of plastic 1, in a relaxed ¢urled configuration, the sheet
being used as a liner for an underground conduit, for example.
The liner has a pair of longitudinally extending edge portions
2, 3, which are interlocked in a final configuration, as
described below.
In FIG. 2, the curled liner 1 is shown being fed from a
coiled storage reel 4 into a sewer system 5 and, more
specifically, within a lengthy pipe or conduit 6 thereof which
is in need of repair. An installation cable 11 can be used
to exert a pulling force to longitudinally extend the curled
liner 1 as the liner is unreeled.
As shown in FIGS. 3 and 4, the longitudinal edges 2, 3
of the curled liner 1 have a matching, or complementary,
configuration. Such configuration can take the shape, for
example, of matching sawtooth surfaces 2a, 3a, as seen in the
detail drawing of FIG. 4. These surfaces 2a, 3a, function as
a mechanical lock when the liner is caused to uncurl from the
configuration shown in FIG. 1 to the configuration shown in
FIG. 3, i.e, into a cylindrical conduit liner.
To accomplish a repair, the liner 1, in the form of a
spirally curled sheet of plastic, is pulled by a cable 7 into
the conduit or "host pipe" to be lined, such as a sewer, e.g.,
from the far access chamber 8 so that the liner is positioned
in the sewer end-to-end in the curled configuration.
FIG. 5 illustrates the curled liner 1 lying end-to-end
in the sewer pipe 6 under repair or, in any case, to be lined
by means of the liner. Once the curled liner 1 is properly
placed in position in the sewer pipe, a torpedo-shaped member,
or torpedo 9, is pulled by the cable 7 through the liner 1.
A control cable lO is attached to an opposite end of the
torpedo. Of course, prior to insertion of the torpedo 9, the
liner 1 is in its curled configuration as shown in FIG. 1.
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If necessary, additional section(s) of curled liner can be
positioned end-to-end and affixed together by known means,
including mechanically connecting or plastic or chemically
fusing the ends together.
The diameter (ID) of the liner l, generally correspondi~g
to the maximum diameter of the torpedo 9, as illustrated in
FIG. 6, is preferably slightly greater than the desired inside
diameter of the liner l so that, as the torpedo is pulled
through the curled liner, the liner is unfurled sufficiently
to bring the matching locking edges 2, 3 of the liner l into
alignment and to secure the liner into a desired cylindrical
shape adjacent to the inside surface of the conduit or host
pipe.
More specifically, as the maximum diameter of the torpedo
passes a given location along the length of the curled liner,
the respective longitudinal edges of the liner are positioned
generally in a mutually confronting relationship so that, as
the torpedo passes, due to the internal or locked-in stresses
of the material from which the liner is made, the previously
curled liner tends to move in the direction to assume its
original curled configuration. During such movement, the
sawtooth or other matching mechanical locking form 2a, 3a of
the edges engage and retain the liner l in the desired
cylindrical configuration. Since the sawteeth, or other
mechanical locking forms, are on the longitudinal edge surface
of the plastic liner, the resulting cross-section is
essentially perfectly circular, rather than overlapped.
In a further embodiment of the invention, the locking of
the sleeve in the uncoiled position can include, in addition
to the aforementioned mechanical locking of the edges, the use
- of a thermosettable, thermoplastic or thermofusible coating
on the liner at least near the locking edges so that, after
expansion of the liner into the unfurled installation
position, the coating is heated, thereby melting same,
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-8-
including the melting of the coating on the locking edges of
the sleeve. Upon removal of the heating source, the edges of
the sleeve are thereby welded together. One method of heating
and melting the layer of thermoplastic coating, for example,
is by means of resistance elements, i.e., electrical wire,
embedded in the coating layer. Once the liner is in place
after the aforementioned movement of the torpedo, current is
applied to the resistance elements, thereby melting the
plastic at the edges and fusing the edges together.
As an alternative, a quantity of solvent can be provided
for fusing the locking edges of the plastic liner to fuse the
edges chemically.
It is contemplated that the plastic liner can be made of
high density polyethylene or a softer version of PVC. Other
plastics can also be used. The torpedo is contemplated as
being made from any suitable material, including metals,
plastics, alloys, or other materials that are suitable for
performing the function described herein and the internal and
external structure and shape of the torpedo, as well, can take
any appropriate form provided that the torpedo has a
sufficient structural integrity for performing its function.
The term "torpedo" as utilized herein is not intended to
limit the invention to a particular shape of the member 9.
In fact, the term is intended to include any other shape that
includes a tapered leading end for easily expanding the curled
liner.
Finally, although the invention has been described with
reference of particular means, materials and embodiments, it
is to be understood that the invention is not limited to the
particulars disclosed and extends to all equivalents within
the scope of the claims.
=
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_g _
FIG. 7 illustrates a variation of the locking edges
illustrated in FIG. 4. Therein, the sawtooth surface 2a
~ includes an extending portion 12 which becomes positioned,
prior to the liner assuming the installation position,
against the host pipe 6. During expansion by means o~ the
torpedo member 9, a mating portion 13 of the sawtooth
surface 3a becomes engaged with the portion 12 o~ sur~ace
2a to prevent over-expansion o~ the liner 1 against the
host pipe and to ensure the accurate fitting and locking of
the edges 2 and 3 o~ the liner 1.
Tn~l~.strial A~licabilitV
The invention disclosed herein is applicable to
methods and apparatus for lining a conduit, particularly
with respect to methods and apparatus ~or repairing
damaged, weakened, or leaking conduits that are located in
areas that are difficult to gain access, ~or example, sewer
pipes or other conduits that are located underground, as
described and shown herein.
