Note: Descriptions are shown in the official language in which they were submitted.
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METHODS FOR REHABILITATING CONDUITS USING STRUCTURAL LINERS
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of structural pipe
lining for conduit
rehabilitation and more specifically, to methods for rehabilitating conduits
using structural liners.
BACKGROUND OF THE INVENTION
[0002] A significant portion of water mains throughout North America are made
from unlined
cast-iron pipe as this was the preferred material for water distribution
systems up until the mid-
1970s. Over time the carrying capacity of these water mains may be severely
reduced or
compromised as the pipes begin to deteriorate. One major cause of
deterioration in these pipes
or conduits is corrosion. As the cast-iron corrodes, the interior wall of the
pipe becomes pitted as
material is lost, thereby forming tubercules. This corroded material, in
combination with mineral
deposits, is known as encrustation and tuberculation.
[0003] Different solutions exist for addressing these problems. One solution,
known as "open-
cut replacement", requires a work area to be excavated to expose the pipe in
need of repair and
replacing the iron piping system altogether. While this solution may be
appropriate where the
structurally integrity of the pipe has been too badly compromised to be
rehabilitated, it tends to
be very costly and labour-intensive and as a result, may not be ideally suited
to cases where the
structural integrity of the existing pipe remains adequate.
[0004] Other solutions involve rehabilitating the pipe or conduit by lining
its interior surface
with cement mortar (often referred to as a "spray-on liner") or by deploying a
structural liner
within the pipe. These conduit rehabilitation solutions may be implemented
cost-effectively
using trenchless technology techniques which minimize the excavation work
required.
[0005] Canadian Patent No. 2,361,960 of Mercier describes a method of
rehabilitating a
conduit having protruding service connections using a cured-in-place
structural liner. The liner
is made up of two (2) concentric tubular jackets ¨ an outer jacket and an
inner jacket - made of a
flexible material that is capable of being impregnated by an adhesive resin.
Bonded to an inner
surface of the inner jacket is an impermeable film made of a material
impermeable to liquid. The
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conduit rehabilitation method described in this patent requires as a
preliminary step that the
tubular jackets of the liner be impregnated with a curable adhesive resin. The
liner is then
inserted into one end of the conduit and pulled into place. Once the liner is
in position, a shaping
step is performed to urge the liner to conform to the inner wall of the
conduit. During the
shaping or forming of the liner, the liner is pushed up against the protruding
end of the service
connection. The adhesive resin impregnated within the liner is urged to flow
around the
threading of the protruding end so as to at least partially fill the spaces
defined between the
threading of the protruding end. Next heated water is flowed through the now
lined conduit to
cause the curable adhesive resin to cure. Once cured, the liner will be form a
rigid structure that
is bonded to the outer surface of the conduit. Thereafter, access to the
service connection can be
restored by drilling a hole into the liner at the location of corporation
stop.
100061 In the field, the method for water conduit rehabilitation described in
Canadian Patent
No. 2,361,960 has been found to be successful and relatively easy and cost
effective to deploy.
However, while in most cases, the seal achieved by the cured adhesive resin
about the protruding
end of the service connection has proven to be adequate, there have been some
field
applications where this seal has failed. In such applications, the failure of
the seal has resulted in
water infiltrating or seeping around the corporation stop and between the
liner and the outer
surface of the conduit, thereby compromising the water tightness of the liner
in that region and
making remedial action necessary. As it may be appreciated, such remedial
action is to be
avoided as much as possible as it tends to create a service disruption and
tends to increase the
costs of conduit rehabilitation.
[00071 In light of the foregoing, it would be advantageous to have a method
for rehabilitating
conduits using cured-in-place structural liners with improved sealing around
the service
connections so as to obviate the drawbacks associated with the above-described
prior art conduit
rehabilitation methods. Preferably, such improved sealing could be provided in
a relatively
simple, cost-effective manner and without unduly extending the time required
to carry out the
conduit rehabilitation method.
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SUMMARY OF THE INVENTION
[0008] In accordance with one embodiment of the present invention, there is
provided a
method for rehabilitating a tubular conduit having an inner conduit space and
at least one service
connection tied into the tubular conduit. A portion of the at least one
service connection
protrudes into the inner conduit space. A liner is provided for covering the
inner surface of the
tubular conduit. The liner is made of a flexible material capable of being
impregnated with a first
curable adhesive resin and has a film made of a material impermeable to liquid
bonded onto the
inner surface of the liner. Also provided, is a flexible sealing member made
of a second curable
adhesive resin. The method includes the steps of providing access to the inner
conduit space of
the tubular conduit and snugly fitting the sealing member onto the protruding
portion of the at
least one service connection in surrounding relation therewith. The liner is
impregnated with the
first curable adhesive resin and then inserted into the tubular conduit.
Thereafter, the liner is
shaped to conform to the inner surface of the tubular conduit with a portion
of the liner bearing
against the protruding portion of the at least one service connection. The
method further includes
the step of curing the first curable adhesive resin in the liner and the
second curable adhesive
resin in the sealing member so as to: (a) initially cause the second curable
adhesive resin to
deform and to at least partially occupy gaps between the protruding portion of
the at least one
service connection and the liner and, (b) subsequently cause the first curable
adhesive resin and
the second curable resin to harden. The liner and the sealing member together
form a unitary
structure and a seal about the protruding portion of the at least one service
connection once the
first curable resin and the second curable resin have hardened. Thereafter the
service connection
is opened from within the inner conduit space.
[0009] In another feature, the method further includes, prior to the snugly
fitting step,
transporting the sealing member to a location directly below the protruding
portion of the at least
one service connection. In an additional feature, the sealing member has a
body provided with a
central aperture. The snugly fitting step further includes: aligning the
central aperture of the
sealing member with the protruding portion of the at least one service
connection; causing the
protruding portion of the at least one service connection to be received
within the central
aperture of the sealing member; urging the top surface of the sealing member
to bear against the
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inner surface of the tubular conduit and causing the body of the sealing
member to flex to
conform to the curvature of the inner surface of the tubular conduit.
[0010] In yet another feature, the method further includes the step of a
providing a robot. The
robot includes a transport skid for traveling within the inner conduit space,
a lift assembly
supported on the skid and a holder mounted on the lift assembly for retaining
the sealing
member. The snugly fitting step is carried out by a remote controlled robot.
The method further
includes the steps of: placing the sealing member into the holder; moving the
transport skid in
the tubular conduit to a location directly below the protruding portion of the
at least one service
connection; actuating the lift assembly to raise the sealing member up to the
protruding portion
of the at least one service connection.
[0011] In still another feature, the shaping step and the curing step are
carried out concurrently.
In a further feature, the curing step includes exposing the first curable
adhesive resin in the liner
and the second curable adhesive resin in the sealing member to heat. The
exposing step includes
circulating hot pressurized water within the space defined by the inner
surface of the liner.
[0012] In yet another feature, the second curable adhesive resin is the same
as the first curable
adhesive resin. In a further feature, the first curable adhesive resin is made
from a 3:1 ratio of
resin to hardener and the second curable adhesive resin is made from between a
1:1 ratio of resin
to hardener to a 3:1 ratio of resin to hardener. The second curable adhesive
resin has a curing
temperature that is less than or equal to the curing temperature of the first
curable adhesive resin.
The curing temperatures of the first and second curable adhesive resins lie
between
approximately 64 C and approximately 74 C.
[0013] In an additional feature, the sealing member has an annular body
provided with a
central aperture. The annular body has an outer diameter and an inner diameter
corresponding to
the diameter of the central aperture. The ratio of annular body outer diameter
to annular body
inner diameter ranges between approximately 1.5 and approximately 2Ø In
another feature, the
annular body has a top surface, a bottom surface and a thickness T measured
between the top and
bottom surfaces. The thickness T measures between approximately 2.0 mm and
approximately
5.0 mm.
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[0014] In accordance with another embodiment of the present invention, there
is provided a kit
for rehabilitating a tubular conduit having an inner conduit space and at
least one service
connection tied into the tubular conduit. A portion of the service connection
protrudes into the
inner conduit space. The kit includes a liner capable of being shaped to
conform to the inner
surface of the tubular conduit. The liner is made of a flexible material
capable of being
impregnated with a first curable adhesive resin and has a film made of a
material impermeable to
liquid bonded onto the inner surface of the liner. Also provided is, a
flexible sealing member
made of a second curable adhesive resin. The sealing member is configured to
snugly fit onto the
protruding portion of the at least one service connection in surrounding
relation therewith. When
the liner is shaped to conform to the inner surface of the tubular conduit,
the sealing member is
snugly fitted onto the protruding section of the at least one service
connection and the first and
second curable adhesive resins are cured, the liner and the sealing member
together form a
unitary structure and a seal about the protruding section of the at least one
service connection.
[0015] In an additional feature, the liner is a multi-ply liner. In another
feature, the liner is an
inversion-type liner. In still a further feature, the liner has an outer
jacket for placement against
the inner surface of the tubular conduit and an inner jacket. The inner
surface of the inner jacket
corresponds to the inner surface of the liner.
[0016] In still another feature, the first curable adhesive resin is made from
a 3:1 ratio of resin
to hardener and the second curable adhesive resin is made from between a 1:1
ratio of resin to
hardener to a 3:1 ratio of resin to hardener. In yet another feature, the
second curable adhesive
resin is the same as the first curable adhesive resin. The second curable
adhesive resin has a
curing temperature that is less than or equal to the curing temperature of the
first curable
adhesive resin. The curing temperatures of the first and second curable
adhesive resins lie
between approximately 64 C and approximately 74 C.
[0017] In yet another feature, the sealing member has an annular body provided
with a central
aperture. The annular body has an outer diameter and an inner diameter
corresponding to the
diameter of the central aperture. The ratio of annular body outer diameter to
annular body inner
diameter ranges between approximately 1.5 and approximately 2Ø
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[0018] In a further feature, the annular body has a top surface, a bottom
surface and a thickness
T measured between the top and bottom surfaces. The thickness T measures
between
approximately 2.0 mm and approximately 5.0 mm.
[0019] In still a further feature, a robot is provided for snugly fitting the
sealing member onto
the protruding portion of the at least one service connection. The robot
includes a transport skid
for traveling within the inner conduit space, a lift assembly supported on the
skid and a holder
mounted on the lift assembly for retaining the sealing member. The lift
assembly is operable to
raise the holder toward the protruding portion of the at least one service
connection.
[0020] In accordance with yet another embodiment of the present invention,
there is provided a
rehabilitated conduit. The rehabilitated conduit includes a tubular conduit
having an inner
conduit space and at least one service connection tied into the tubular
conduit. A portion of the at
least one service connection protruding into the inner conduit space. Also
provided is, a liner
made of a flexible material impregnated with a first curable adhesive resin.
The liner has a film
made of a material impermeable to liquid bonded onto the inner surface of the
liner. The liner is
cured in place and shaped to conform to, and bonded to, the inner surface of
the tubular conduit.
The rehabilitated conduit further includes a sealing member made of a second
curable adhesive
resin. The sealing member is mounted onto the protruding portion of the at
least one service
connection in surrounding relation therewith and is cured in place. The liner
and the sealing
member together forming a unitary structure and a seal about the protruding
portion of the at
least one service connection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The embodiments of the present invention shall be more clearly
understood with
reference to the following detailed description of the embodiments of the
invention taken in
conjunction with the accompanying drawings, in which:
[0022] FIG. 1 is a perspective view of a main conduit provided with a service
connection, the
inner wall of the main conduit shown covered with a liner for rehabilitating
the main conduit in
accordance with an embodiment of the present invention;
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100231 FIG. 2 is a cross-sectional view of the main conduit shown in FIG. 1
taken along line
'1_1";
[0024] FIG. 3 is an elevation view of a liner prior to being deployed for use
in rehabilitating a
conduit, in accordance with an embodiment of the present invention;
[0025] FIG. 4 is a top plan view of an annular sealing member in accordance
with an
embodiment of the present invention;
[0026] FIG. 5 is an enlarged partial cross-sectional view of the main conduit
illustrated in FIG.
1, with the main conduit and service connection being shown prior to the
installation of the liner,
and an annular sealing member being fitted onto the inflow end of the service
connection;
[0027] FIGS. 6a and 6b depict other cross-sectional views of the main conduit
illustrated in
FIG. 1 taken on an axis perpendicular to line "1-1", showing a robot within
the main conduit
fitting the annular sealing member onto the inflow end of the service
connection;
[0028] FIG. 7 is an enlarged cross-sectional view of the holder provided on
the robot
illustrated in FIGS. 6a and 6b, shown exploded from the annular sealing
member;
[0029] FIG. 8 is an enlarged partial cross-sectional view similar to that
illustrated in FIG. 5
showing the sealing member fitted onto the service connection and the liner
deployed within the
main conduit prior to curing; and
[0030] FIG. 9 is an enlarged partial cross-sectional view similar to that
illustrated in FIG. 5
showing the liner and the sealing member in the main conduit after curing; and
[0031] FIG. 10 is an enlarged partial cross-sectional view similar to that
illustrated in FIG. 5
showing the inflow end of the service connection unobstructed and open to
allow flow of water
therethrough.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0032] The description which follows, and the embodiments described therein
are provided by
way of illustration of an example, or examples of particular embodiments of
principles and
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aspects of the present invention. These examples are provided for the purposes
of explanation
and not of limitation, of those principles of the invention. In the
description that follows, like
parts are marked throughout the specification and the drawings with the same
respective
reference numerals.
[0033] Referring to FIGS. 1 and 2, there is shown a main conduit or pipe
generally designated
with reference numeral 20. In the present embodiment, the main conduit 20 is a
municipal
conduit which runs below ground and forms part of a network of water works
conduits
delivering potable water to residents of a neighbourhood via service
connections disposed in
fluid communication with the main conduit 20. One such service connection 22
having a
corporation stop 24 is shown in FIG. 1. The service connection 22 and
corporation stop 24
shown in the drawings are merely representative. A main conduit like main
conduit 20 would
have a large number of such service connections and corporation stops.
[0034] However, it should be appreciated that in alternative embodiments, the
main conduit
could be a stand-alone pipe and could be located above ground. In other
embodiments, the main
conduit could be used to convey other pressurized fluids (i.e. liquids or
gasses). Moreover, the
main conduit could be an oil pipe, an HVAC duct, a gas main, sewer line, an
industrial effluent
line or the like.
[0035] The main conduit 20 has a generally tubular configuration defined by a
conduit wall 26
provided with an outer surface 28 and an inner surface 30 (best shown in Fig.
5). The inner
surface 30 would ordinarily bound the conduit space through which the water
flows within the
main conduit 20. However, in this embodiment, the main conduit 20 was damaged
(e.g. it had
cracks or other structural or physical anomalies or deficiencies) and was in
need or repair. As
will be explained in greater detail below, the main conduit 20 was
rehabilitated using a cured-in-
place, composite material liner 32 which conformingly lines, and may be bonded
to, the inner
surface 30 of the conduit wall 26. Accordingly, it is the inner surface 34 of
the liner 32 which
now defines the conduit space S 1 through which the water flows.
[0036] As shown in FIGS. 2 and 5, the corporation stop 24 is disposed
generally perpendicular
to the conduit 20 and has a tapered inflow end 46 which extends (or taps) into
the conduit 20
through a threaded aperture (not shown) defined in the conduit wall 26. A pipe
wall 36 defines
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the generally tubular configuration of the corporation stop 24. The pipe wall
36 has an inner
surface 38 which defines a pipe space S2 of substantially constant internal
diameter IDI, and an
outer surface 40. Male threading 42 provided on the outer surface 40 of the
pipe wall 36 is
engageable with corresponding female threading 48 surrounding the aperture in
the conduit wall
26 to allow the portion 44 of the corporation stop 22 to be securely attached
to the main conduit
20.
[0037] When the corporation stop 24 is secured in place, the inflow end 46 of
the portion 44
protrudes beyond the inner surface 30 of the conduit wall 26 and into the
conduit space S1, a
distance D. In the present embodiment, the distance D is 0.5 inch. In other
embodiments, the
distance D may vary and could be greater or lesser than 0.5 inch. In most
cases, the distance D
will be less than I inch. As best shown in FIG. 3, the pipe wall 36 is
chamfered at the tip of the
inflow end 46.
[0038] In this embodiment, the liner 32 used to rehabilitate main conduit 20
is of the type
described in Canadian Patent No., 2,361,960 of Mercier. While the structure
and construction of
such liners is generally known to those skilled in the art, for the sake of
completeness, a brief
description of the liner 32 follows. As best shown in FIG. 3, the liner 32
includes two concentric
tubular jackets ¨ an outer jacket 50 and an inner jacket 52 received within,
and surrounded by,
the outer jacket 50. Voids or spaces 54 exist between the inner surface 56 of
the outer jacket 50
and the outer surface 58 of the inner jacket 52. As explained below, prior to
deployment of the
liner 32 within the main conduit 20, the voids 54 are at least partially
filled with a curable
adhesive resin with which to impregnate the outer and inner jackets SO and 52.
[0039] The outer and inner jackets 50 and 52 are made of a flexible material,
preferably a
woven textile. In the present embodiment, the woven textile is a plain-weave
polyester. In
alternative embodiments, the woven textile may be a synthetic polymeric fiber,
such as a
polyester fiber, a glass fiber or a carbonaceous fiber. The jacket material is
selected to allow the
outer and inner jackets 50 and 52 to be sufficiently impregnated with the
curable adhesive resin,
while permitting air to escape therefrom. Moreover, the jacket material should
be robust enough
to withstand the tensile stresses resulting from being pulled into place
during deployment in the
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main conduit 20, and the relatively high, internal fluid pressures which exist
in the main conduit
once rehabilitated.
[0040] Bonded to the inner surface 60 of the inner jacket 52 is a thin layer
or film 62 of
material which is impermeable to liquid. In this embodiment, the material is
impermeable to
water and potable water compatible. While in this embodiment, the film 62 is
made of a
polyurethane elastomer, in other embodiments, the material may be
polyethylene, polyamide,
synthetic rubbers and any other elastomers of polymeric resins. Once the liner
32 is in place in
the main conduit 20 and the rehabilitated main conduit 20 is back in service,
the film 62 serves to
maintain a watertight barrier preventing water from seeping through the outer
and inner jackets
50 and 52.
[0041] The curable adhesive resin with which the outer and inner jackets 50
and 52 are
impregnated, may be obtained by mixing a resin and a hardener. The resin may
be an epoxy,
polyurea, vinyl ester or any other suitable resin. In the present embodiment,
the resin and
hardener are both manufactured and sold by Adhpro Adhesives Inc. of Magog,
Quebec, Canada,
under the product identifiers 65071 AQUEDUC A-071 and 95071 AQUEDUC B-071,
respectively. These products are safe and are compatible for use with potable
water.
[0042] Preferably, the ratio (by volume) of resin to hardener in the curable
adhesive resin is
3:1 and the adhesive resin cures at a temperature ranging between
approximately 64 C and
approximately 74 C. In this embodiment, the curing temperature of the adhesive
resin is 64 C.
The curing temperature could be different if other curable adhesive resins are
used. The curable
adhesive resin serves a dual purpose. Once cured, it permits the liner 32 to
adhere to the inner
surface 30 of the main conduit 20 and it forms part of the liner structure.
[0043] While in the preferred embodiment, the adhesive resin is cured with hot
water, it will be
appreciated that this need not be the case in every application. In other
embodiments, where a
different adhesive resin is employed, the adhesive resin could be cured with
steam, with the
exposure to an ultraviolet (UV) light, or with the introduction of a curing
catalyst.
[0044] Referring now to FIG. 4, there is shown a resilient gasket or sealing
member 70 in
accordance with an embodiment of the invention. As will be explained in
greater detail below,
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the sealing member 70 is designed to fit onto the end 46 of the corporation
stop 24 and to
provide enhanced sealing between the liner 32 and the corporation stop 24 once
cured. The
sealing member 70 has a generally molded body 72 defined by a relatively thin
sidewall 74. The
sealing member shown in FIG. 4 is initially formed as a disc into which an
aperture is punched
out. In other embodiments, the sealing member could be molded as an annular
body obviating
the need for a hole punching step. Preferably, the thickness T of the sidewall
74 lies between
approximately 2.0 mm and approximately 5.0 mm. In the present embodiment, the
thickness T
of sidewall 74 measures 3.7 mm.
[0045] When selecting the appropriate thickness T for the sidewall 74, the
distance D should
be taken into account. Preferably, the greater the distance D, the greater the
thickness T should
be. In this regard, it has been found that: (a) a thickness T of 2.0 mm tends
to be suitable where
the distance D measures less than approximately 12.7 mm; (b) a thickness T of
between 2.5 mm
and 3.0 mm tends to be suitable where the distance D measures between
approximately 12.7 mm
and approximately 15.875 mm; (c) a thickness T of between 3.0 mm and 4.0 mm
tends to be
suitable where the distance D measures between approximately 15.875 mm and
approximately
19.05 mm; and (d) a thickness T of between 4.0 mm and 5.0 mm tends to be
suitable where the
distance D measures between approximately 19.05 mm and approximately 25.4 mm.
It should
be appreciated that in certain applications, a different thickness T could be
selected for a given
distance D.
[0046] The sidewall 74 has a first surface 76 and an opposed second surface 78
(as best shown
in FIGS 4 and 5), and is bounded circumferentially by an outer edge 80 and
inner edge 82. The
aperture 84 defined by the inner edge 82 is sized only slightly larger than
the inflow end 46 to
allow a snug fit between the sealing member 70 and the pipe wall 36 - more
specifically,
between the sidewall 74 and the threading 42 on the outer surface 40. The
annular body 72 has
an inner diameter ID2 which corresponds to the diameter of the aperture 84,
and an outer
diameter 0D1.
Preferably, the 0D1 :1D2 ratio ranges between approximately 1.5 and
approximately 2Ø In this embodiment, the outer diameter 0D1 measures 55 mm;
the inner
diameter ID2 measures 30 mm; and the 0DI:ID2 ratio is 1.83.
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[0047] Preferably, the outer diameter 0D1 measures between 45 mm and 65 mm. In
this
regard, it has been found that: (a) a sealing member having a 45 mm outer
diameter 0D1 tends to
be suitable for use with a corporation stop having an inner diameter IDI which
measures
approximately 12.7 mm, (b) a sealing member having a 55 mm outer diameter 0D1
tends to be
suitable for use with a corporation stop having an inner diameter IDI which
measures
approximately 15.875 mm; (c) a sealing member having a 60 mm outer diameter
0D1 tends to be
suitable for use with a corporation stop having an inner diameter ID' which
measures
approximately 19.05 mm; and (d) a sealing member having a 65 mm outer diameter
0D1 tends to
be suitable for use with a corporation stop having an inner diameter ID' which
measures
approximately 25.4 mm. In certain applications, an outer diameter 0D1
different than that set
out above could be selected for a given inner diameter 'Di. However, it is
preferred that the
0D1:ID1ratio be between approximately 2.5 and approximately 4Ø
[0048] While it is preferred that the sealing member have a generally circular
footprint, it will
be appreciated that in other embodiments the footprint of the sealing member
could be shaped
differently. For instance, the sealing member could be configured to have an
oval, square or
rectangular footprint.
[0049] The sealing member 70 must be sufficiently resilient so that during
installation onto the
inflow end 46 of the corporation stop 24 as the sealing member 70 is being
placed up against the
main conduit 20 it can flex to conform to the curvature of the inner surface
30 of the main
conduit 20, as shown in FIGS. 5 and 8. As explained in greater detail below,
during the curing
process the sealing member 70 will merge or integrate with the liner 32 to
form a unitary
structure therewith. To further this end, it is preferable that the sealing
member 70 be made of
the same or substantially the same combination of resin and hardener as the
curable adhesive
resin (i.e. a resin to hardener ratio of 3:1). However, the resin to hardener
ratio for the sealing
member 70 need not be 3:1 in every application. In some applications, it may
be advantageous
to use a resin to hardener ratio of less than 3:1. For instance, the resin to
hardener ratio could lie
between 3:1 and 1:1. It has been found that using a resin to hardener ratio of
1:1 tends to enhance
the malleability of the sealing member 70. This in turn tends to facilitate
shaping the sealing
member 70 to conform to the curvature of the outer surface 30, when the
sealing member 70 is
fitted onto the corporation stop 24. As an additional advantage, it has been
found that sealing
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members made using a resin to hardener ratio of 1:1 can be stored for longer
periods of time
without deteriorating than those made with a resin to hardener ratio of 3:1.
[0050] It should be appreciated that the exact ratio of resin to hardener used
to fabricate the
sealing member 70 will vary depending on the specific resin and hardener
combination selected.
[0051] To ensure that the sealing member 70 properly merges with the liner 32
during the
curing process, the temperature required to cure the constituent resin and
hardener mixture of the
sealing member 70 should be no greater than the curing temperature of the
curable adhesive resin
which impregnates the liner 32. While in this embodiment, the curing
temperature of the sealing
member 70 is equal to the curing temperature of the curable adhesive resin, in
alternative
embodiments, the curing temperature of the sealing member 70 could be less
than the curing
temperature of the curable adhesive resin.
[0052] Referring now to FIGS. 6a, 6b and 7, there is shown a robot 100 which
is used to fit the
sealing member 70 onto the inflow end 46 of the corporation stop 24. The robot
100 includes a
transport skid 102 sized to fit within the space Si of the main conduit 20,
and a scissor lift
assembly 104 supported on the skid 102. The skid 102 has a front end 106, an
opposed rear end
(not shown) and a sidewall 108 which extends between the front and rear ends
to define the
generally tubular body of the skid 102. At the front end 106, a large section
of the upper portion
of the sidewall 108 has been cut away to accommodate the placement of the
scissor lift assembly
104. Tethered to each of the front and rear ends of the skid 102 is a chain or
cable 110 which is
in turn connected to a front/rear motorized winch (not shown). To move the
skid 102 to a desired
position within the main conduit 20, the front or rear winch may be activated
to pull the skid 102
frontward or rearward in a sled-like fashion along the conduit wall 26 of the
main conduit 20.
[0053] The scissor lift assembly 104 has a pair of spaced apart, first and
second base blocks
112 and 114, and a movable platform 116. First and second lateral pairs of
scissor arms 120 and
122 (only one such pair being visible in FIGS. 6a and 6b) connect the base
blocks 112 and 114
to the platform 116. Also provided is a re-circulating (or endless) threaded
screw 124 actuated
by a motor (not shown). The second base block 114 has a threaded aperture (not
shown) which
is adapted to receive and engage the re-circulating screw 124. When the motor
is energized, the
re-circulating screw 124 is urged to rotate in a clockwise or counter-
clockwise direction. The
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rotation of the screw 124 causes the second base block 114 to move or ride
along the screw 124
toward or away from the first base block 112, thereby shortening or
lengthening the distance
between the tips 126 and 128 of the scissor arms 120 and 122. It will be
understood that the
platform 116 will be raised above (or moved away from the base blocks 112 and
114) by
shortening the distance between the tips 126 and 128. In contrast, the
platform 116 will be
lowered toward the base blocks 112 and 114 by lengthening the distance between
the tips 126
and 128. The tip 128 of scissor arm 122 is captively engaged within the
horizontal slot 129
defined on the lateral face 131 of the platform 116 adjacent the front end 133
thereof During the
raising and lowering of the platform 116, the tip 128 travels forwardly or
rearwardly within the
slot 129.
[0054] In alternative embodiments, the scissor lift assembly could be
configured differently.
For instance, it could be provided with only a single pair of scissor arms and
the assembly for
lowering and raising the platform could be configured without a re-circulating
screw and motor.
The scissor lift assembly could be actuated pneumatically. In still other
embodiments, the
scissor lift assembly could be replaced with other known vertical displacement
mechanisms.
[0055] Attached to the platform 112 via a fastener 130 is a holder or
retaining member 132
which is adapted to retain the annular sealing member 70 and allow its
accurate placement on the
corporation stop 24. With reference to FIG. 7, the holder 132 has a generally
cylindrical body
134 extending between upper and lower ends 136 and 138. A short distance
upward from the
lower end 138, a step 140 is formed where the diameter of the body 134
increases. The body
134 is hollowed out at the upper end 136 to form two, relatively thin-walled,
spaced apart,
concentric rings ¨ an inner ring 142 and an outer ring 144. The upper edge 146
of the inner ring
142 sits relatively lower than the upper edge 148 of the outer ring 144. The
inner ring 142 and
the outer ring 144 co-operate with each other to define a seat or a station
150 for snugly retaining
the annular sealing member 70. More specifically, when mounted within the
holder 132, the
second surface 78 of the sealing member 70 is supported on the upper edge 146
of the inner ring
142 with the outer edge 80 of the sidewall 74 bearing against the inner
surface 152 of the outer
ring 144.
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[0056] In this embodiment, the station 150 with its concentric rings 142 and
144 is well-
adapted to accommodate the annular sealing member 70. However, as mentioned
above, in other
embodiments, the sealing member could be configured differently. More
specifically, it could be
formed to have a non-circular footprint. In such cases where the footprint of
the sealing member
is non-circular, it will be appreciated that the holder could configured to
provide a suitable
station for accommodating such a sealing member.
[0057] Preferably, the holder 132 is made of a translucent or transparent
material so as to
facilitate placement of the sealing member 70 onto the corporation stop 24 by
the operator of the
robot. In this embodiment, the holder 132 is made from NSF polyurethane
polished to a
transparent finish. In other embodiments, other suitable materials may be
used.
[0058] An exemplary method of rehabilitating the main conduit 20 using the
liner 32 and the
sealing member 70 is now described in greater detail. Prior to deploying the
liner 32 and the
sealing member 70 into the main conduit 20 to be rehabilitated, a number of
preliminary steps
are carried out, namely: (a) arranging access to the main conduit 20 to be
rehabilitated; (b)
cleaning the inner surface 30 of the main conduit 20; (c) fitting the sealing
member 70 onto the
service connection 24; and (d) pre-treating the liner 32 prior to insertion
into the main conduit
20. Steps (a), (b) and (d) are generally known to those skilled in the art of
structural pipe lining
and are substantially as described in Canadian Patent No. 2,361,960.
Nonetheless, for the sake
of completeness, these steps are described briefly below.
[0059] More specifically, two spaced apart, first and second access pits (not
shown) for
accessing opposing ends of the main conduit segment to be rehabilitated, are
selected and
prepared. The first access pit serves as the entry point through which the
liner 32 may be inserted
into the main conduit 20, while the second access pit is intended as an exit.
Disposed at the
second access pit is machinery (for instance, a winch ¨ not shown) operable to
pull the liner 32
through the main conduit 20 during the installation procedure.
[0060] The main conduit 20 is cleaned or scoured to remove any deposits,
scales or
encrustations which may have accumulated on the inner surface 30. This
cleaning step tends to
facilitate deployment of the liner 32 and enhance adhesion or bonding contact
between the liner
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32 and the main conduit 20, thereby reducing the risk of liner failure.
Locating and mapping of
the service connection 22 may also take place at this time.
[0061] Once the preliminary preparatory work on the main conduit 20 has been
completed and
prior to the insertion of the liner 32 in the main conduit 20, the sealing
member 70 may be fitted
onto the service connection 22. This step is performed using the robot 100
(shown in FIGS. 6a
and 6b) equipped with a video camera (not shown). The sealing member 70 is
first manually
placed into the station 150 of the holder 132 and then the robot 100 is
introduced at one end of
the main conduit 20. Using a remote control and television unit (both not
shown) and the front
and rear winches (not shown), an operator directs the robot 100 to the precise
location of the
service connection 22 within the main conduit 20. Thereafter, the operator
actuates the scissor
lift assembly 104 to raise the platform 112 up to the corporation stop 24. As
the second base
block 114 travels along the re-circulating screw 124 toward the first base
block 112, the gap
between the tips 126 and 128 of the scissor arms 120 and 122 is narrowed
resulting in the
platform 112 being lifted or raised (as shown in FIGS. 6a and 6b). With the
aperture 84 of the
sealing member 70 aligned with the corporation stop 24, the sealing member 70
may then be
fitted onto the inflow end 46 with the inner edge 82 of the body 62 snugly
engaging the threading
42 on the portion 44 of the corporation stop 24. As best shown in FIG. 5, the
robot 100 urges the
first surface 76 of the body 72 to abut the inner surface 30 of the main
conduit 20. As it does so,
the sealing member 70 flexes to conform to the curvature of the inner surface
30.
[0062] Prior to inserting the liner 32 in the main conduit 20, the liner 32 is
saturated with a
curable adhesive resin. This liner treatment step may be performed at the job
site or at an
appropriate off-site location. The curable adhesive resin is injected into the
voids 54 between the
outer and inner jackets 50 and 52 using injection techniques commonly known in
the art. To
encourage uniform distribution of the curable adhesive resin within the liner
32, the liner 32 is
passed through a set of compression rollers. The pressure applied by the
compression rollers
urges the curable adhesive resin to flow from the voids 54, through the inner
surface 56 and
ultimately, to the outer surface 92 of the outer jacket 50, thereby ensuring
that the outer surface
92 is substantially covered with curable adhesive resin and that air is
substantially removed from
the jackets 50 and 52. It will be appreciated that, in other embodiments,
different techniques
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could be used saturate the liner with curable adhesive resin and ensure its
even distribution
therein.
[0063] While it is generally preferred that the liner treatment step follow
installation of the
sealing member 70 onto the service connection 22 so as to avoid premature
curing of curable
adhesive resin before the liner 32 is in position with the conduit 20, it need
not be the case in
every application. In certain embodiments, the liner treatment step could be
performed prior to
installing the sealing member 70.
[0064] Once the liner 32 has been treated with the curable adhesive resin, it
can be introduced
into the main conduit 20 through the first access pit using the "winch-in-
place" technique. The
liner 32 is pulled through the length of the main conduit 20 (by the machinery
stationed at the
second access pit) until a selected location has been reached. Once in
position, the liner 32 is
ready to be conformingly applied against the inner surface 30 of the main
conduit 20. This is
achieved by using liner shaping or forming techniques generally known to those
skilled in the
art, such as a "pressure-expandable" technique. More specifically, a generally
cylindrical
shaping member (not shown) is introduced into one end of the liner 32 and is
pushed through the
main conduit 20 toward the opposite end thereof by (preferably cold)
pressurized water. As the
shaping member passes through the liner 32, it urges the outer jacket 50 of
the liner 32 to be
pressed up against the inner surface 30 of the main conduit 20 and enhances
distribution of the
curing adhesive resin through the outer jacket 50. The curing adhesive resin
may be urged to
flow into, and fill, any cracks formed in the inner surface 30. The pressure
of the water maintains
the outer jacket 50 against the inner surface 30 after passage of the shaping
member.
[0065] When the shaping member travels over the location where the inflow end
46 of the
corporation stop 24 protrudes into the space Si, the outer jacket 50 is pushed
up against the
inflow end 46 thereby blocking the inflow aperture of the corporation stop 24
and creating a
bulge or protrusion 160 in the liner 32, as shown in FIG. 8. Curable adhesive
resin on the outer
surface 92 of the outer jacket 50 is urged to spread onto the inflow end 46
and the body 72 of the
sealing member 70. In the vicinity of the inflow end 46, voids 102 are formed
between the outer
surface 92 of the outer jacket 50 and the inner surface 30 of the main conduit
20 (see FIG. 8).
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[0066] Once the liner 32 has been formed, the curing process may be initiated
by circulating
hot pressurized water through the conduit space S2 for a suitable period of
time. The temperature
of the pressurized water will depend on the curing temperature of the curable
adhesive resin and
the resin/hardener mixture in the sealing member 70. In this embodiment, the
temperature of the
pressurized water is maintained at 64 C. As the hot pressurized water passes
through the liner
32, the heat from the water causes the viscosity of the curable adhesive resin
impregnated in the
liner 32 and the resin/hardener mixture in the sealing member 70 to drop. This
reduction of
viscosity softens the curable adhesive resin and the resin/hardener mixture
and allows them to
fuse (merge or integrate) with each other. As a result of the pressure exerted
on it by the liner
32, the body 72 of the sealing member 70 is urged to deform and fill or occupy
the voids 102, in
particular, the spaces surrounding the threading 42 on the inflow end 46 (as
best shown in FIG.
9). After the hot pressurized water is re-circulated for a sufficient period
of time, the curable
adhesive resin and the resin/hardener mixture will have hardened with the
liner 32 and the
sealing member 70 now forming a robust unitary (or integrated) structure which
is firmly bonded
to the main conduit 22 and the corporation stop 24.
[0067] While it is generally preferred that the liner forming step be
performed prior to the
curing step, it will be appreciated that, in other embodiments, the liner
forming and curing steps
could be performed concurrently by flowing hot pressurized water to form the
liner.
[0068] With the liner 32 and the sealing member 70 now properly cured and the
hot
pressurized water drained from the main conduit 20, the service connection 22
can now be
opened to restore the free flow of potable water therethrough. The robot 100
is introduced into
the rehabilitated main conduit 20 and is directed to the location within the
conduit 20 where the
bulge or protrusion 160 is. The location of protrusion 160 may be known from
the mapping
activities previously performed. Using the video camera (not shown) mounted on
the robot 100,
the operator positions the robot 100 directly beneath the protrusion 160 and
lifts a drilling tool
(not shown) up to the protrusion 160 at the precise location of the service
connection 22. The
operator then activates the drilling tool to create an opening through the
liner 32 that provides
access to the pipe space S2 of the corporation stop 24. Such drilling action
on the wall of the
liner 32 tends not to affect the water tightness of the rehabilitated conduit
20. The curable
adhesive resin (and resin/hardener mixture from the sealing member 70) that
surrounds the
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threading 42 on the inflow end 46 provides enhanced sealing in the region and
tends to form a
tight bond with the liner thereby enhancing the structural integrity of the
rehabilitated conduit 20
in that area and promoting water tightness. FIG. 10 shows the inflow end 46 of
the service
connection 22 unobstructed and open to allow flow of water therethrough. After
opening of the
service connection 22, a final inspection takes place to ensure the liner has
been properly
deployed. Upon satisfactory inspection, the now rehabilitated main conduit 20
is flush cleaned,
disinfected (e.g. by chlorination) and the service is restored.
[0069] An exemplary method of rehabilitating a conduit using a cure-in-place
liner and a
sealing member for fitting in surrounding relation with the protruding end of
a corporation stop
has been described above. However, it will be appreciated that, in accordance
with the principles
of the present invention, the sealing member is not limited to being used
solely in conjunction
with dual-jacket liners of the type described above. The sealing member can
also be successfully
deployed or used with other types of cured-in-place pipe liners. For example,
the sealing
member could be used with inversion-type liners such as those described in
Canadian Patent No.
2,630,074 of Anders et al and United States Patent No. 6,117,507 of Smith.
[0070] In the case of an inversion liner, the sealing member would be snugly
fitted onto the
inflow end of the corporation stop in much the same manner as described above.
The sealing
member would be fabricated from a resin (preferably, a thermoset resin), which
when cured,
would fuse (merge or integrate) with the inversion liner to form a unitary (or
integrated) structure
therewith.
[0071] To deploy the inversion liner, the steps described above in respect of
liner 32 would be
generally followed with minor modifications. More specifically, the inversion
liner would be
impregnated or saturated with a curable resin (preferably, a thermoset resin),
such as the resin
sold by Novoc Performance Resins, LLC of Sheboygan, Wisconsin and marketed
under the
NOVOCTM brand, prior to being inserted into the main conduit. Following the
impregnation, the
inversion liner would be inserted into the main conduit. This would achieved
using known
inversion techniques, such as those described in United States patent No.
6,117,507 of Smith.
One such known technique involves
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introducing an elbow feed member into one end of the main conduit, turning the
leading end of
the inversion liner back onto itself and fixing it to the lower end of the
elbow feed member. A
fluid, such as water or air, is then pumped into the elbow feed member. As the
pressurized fluid
flows through the elbow feed member it exerts a force on the folded back
portion of the
inversion liner, thereby causing the liner to invert into and along the
interior of the main conduit.
The action of the pressurized fluid against the walls of the inversion liner
would shape the liner
to conform to the inner surface of the main conduit. With the inversion liner
formed or shaped,
the curing process could be initiated by circulating hot pressurized water
through the conduit
space for a suitable period of time. As described above, as the hot
pressurized water passes
through the inversion liner, the heat from the water causes the viscosity of
the curable adhesive
resin impregnated in the inversion liner and the resin/hardener mixture in the
sealing member to
drop. This reduction of viscosity softens the curable adhesive resin and the
resin/hardener
mixture and allows them to fuse (merge or integrate) with each other. As a
result of the pressure
exerted on it by the inversion liner, the sealing member is urged to deform
and fill or occupy the
voids that surround the threading on the inflow end of the corporation stop.
After the hot
pressurized water is re-circulated for a sufficient period of time, the
curable adhesive resin and
the resin/hardener mixture will have hardened with the inversion liner and the
sealing member
now forming a robust unitary structure which is firmly bonded to the main
conduit and the
corporation stop. Thereafter, a final inspection will be performed and the
service connection 22
may be opened to restore the free flow of potable water therethrough as
described above.
[0072] While the foregoing description discloses using a sealing member in
accordance with
the principles of the present invention with different types of cured-in-place
liners, it should be
appreciated that the sealing member could also be used to similar advantage
with thermoformed
PVC liners (also referred to as "fold and form" liners). An exemplary method
of rehabilitating a
conduit using a "fold and form" liner and a sealing member is now described.
As a preliminary
matter, a folded thermoformed polyvinyl chloride (PVC) liner for covering the
inner surface of
the tubular conduit to be rehabilitated and a flexible sealing member, are
provided. The liner is
fabricated from a PVC compound which is selected for its flexibility and its
thermo-plastic
memory. The sealing member is made from a material which, when cured, is
capable of fusing
(merging or integrating) with the PVC liner to form a unitary (or integrated)
structure therewith.
The material may be a curable adhesive resin or other suitable composition.
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[0073] Access is provided to the inner conduit space of the tubular conduit.
Next, the sealing
member is snugly fitted onto the protruding portion of the at least one
service connection in
surrounding relation therewith, as described in greater detail above. The
folded liner is pre-
heated to a predetermined temperature to allow it to become pliable (or
malleable) enough such
that it may be pulled in place within the conduit with minimal resistance.
Once sufficiently pre-
heated, the folded liner is inserted into the conduit and pulled therethrough
using a cable and
winch.
[0074] The next step of the method involves shaping or forming the liner to
cause the liner to
unfold and conform to the inner surface of the conduit. This can be achieved
by delivering steam
or hot pressurized air through the liner. As the liner is being shaped over
the inflow end of the
corporation stop which protrudes into the conduit space, the wall of the liner
is pushed up against
the inflow end thereby blocking the inflow aperture of the corporation stop
and creating a bulge
or protrusion in the liner. Exposed to the raised temperature of the steam or
hot pressurized air,
the material of the sealing member cures. As it does so, the sealing member
is: (a) initially
caused to deform and to at least partially occupy the gaps between the
protruding portion of the
at least one service connection and the liner; and (b) subsequently urged to
harden. Once
hardened, the sealing member forms a unitary structure with the liner and
creates a seal about the
protruding portion of the at least one service connection. After the liner has
been formed, it is
cooled for a predetermined period of time using compressed air or a mixture of
compressed air
and water. Thereafter, a final inspection will be performed and the service
connection can be
opened to restore the free flow of potable water therethrough as described
above.
[0075] As will be appreciated by a person skilled in the art, the use of a
sealing member made
of a curable adhesive resin or other material which is capable, on the one
hand, of deforming to
fill in the voids around the corporation stop and on the other hand, merging
or integrating with
the liner to form a unitary structure when cured, provides an elegant solution
to the sealing
problems encountered with the prior art conduit rehabilitation methods
discussed above.
Advantageously, this solution is relatively simple, quick and inexpensive to
deploy and can
easily be incorporated into existing conduit rehabilitation methods.
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