Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR HEAT CURING OF PIPE LINERS
BACKGROUND OF THE INVENTION
This invention relates, generally, to pipe liners that are used to repair
buried pipes without
excavation. More particularly, it relates to an apparatus and method that
reduces the amount of
time required to complete such repairs.
Methods of rehabilitating damaged pipes by inverting an tubular liner
impregnated with curable
resin are known. The known methods of installing a liner to repair a buried
pipe, while it
remains underground, involve inserting a liner into the pipe and forcing the
liner into
engagement with the inner walls of the pipe by inflating a bladder. The liner
is impregnated with
curable resins prior to insertion and the bladder must remain inflated until
the resin cures. The
time required for resin to cure, however, ranges from three to eight hours,
depending upon
ambient temperatures. Thus there is a need for an apparatus and method that
provides a shorter
curing time regardless of ambient temperatures.
SUMMARY OF THE INVENTION
The long-standing but heretofore unfulfilled need for an apparatus and method
that shortens
resin curing times is now met by a new, useful, and non-obvious invention.
The apparatus includes a curing cap having an inflation port, a curing port
and a drainage port. A
remote source of pressurized fluid (preferably air) is placed in fluid
communication with the
inflation port. The apparatus also includes a manifold having an outlet, a
first inlet in valved
fluid communication with a heated fluid source, a second inlet in valved fluid
communication
with a pressurized fluid source and a third inlet in valved fluid
communication with the drainage
port.
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A flexible curing tube is slidably received by the curing port while
maintaining a substantially
fluid-tight seal. The flexible tube has a first end in fluid communication
with (via the manifold)
a source of heated fluid (such as water or steam) and the second end has a
substantially spherical
guide thereon. The second end of the flexible tube also includes a plurality
of perforations to
allow fluids to pass there through. During curing operations, the heated fluid
flows through the
flexible tube and exits, through said perforations, into the interior of an
inverted liner tube.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and objects of the invention,
reference should be made
to the following detailed disclosure, taken in connection with the
accompanying drawings, in
which:
Fig. 1 is a perspective view of an illustrative curing cap;
Fig. 2 is a side plan view of an illustrative curing cap;
Fig. 3A is a side plan view of an inversion head, with an un-inverted tubular
liner positioned
thereon;
Fig. 3B is a side plan view of an illustrative curing cap installed in an
inversion head, which is in
turn installed in the open end of an liner tube;
Fig. 4A is a side plan view of an illustrative curing cap installed in an
inversion head with the
flexible tube extending there through;
Fig. 4B is a side plan view of an illustrative curing cap installed in an
inversion head with the
flexible tube extending there through and into the lumen of the tubular liner;
Fig. 5 is a diagrammatic view of an illustrative manifold.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
While the present invention is shown for use with sewer pipeline repair, the
present invention
can be utilized for repairing other types of pipes, ducts, tunnels and shafts,
such as gas, water,
oil, steam and compressed air conduits. Figs. 1 and 2 depict an illustrative
embodiment of the
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novel curing cap which is denoted as a whole by the reference numeral 10.
Curing cap 10
includes substantially circular body 12 having an outer side 12a and inner
side 12b. Outer side
12a further includes inflation port 14, curing port 16 and discharge port 18.
All ports are
preferably arranged to provide unidirectional fluid communication between
outer side 12a and
inner side 12b of circular body 12. Inner side 12b of circular body 12 is
received by intake 22 of
inversion head 20 (Fig. 3A). Discharge end 24 releasably engages the interior
of open end 26a of
liner tube 26.
Two types of liner tubes are commonly used. The first type of liner comprises
a felt or fiberglass
lining, having a closed end and an open end impregnated with a curable resin.
The second type
includes a lining composition of two (2) main layers; a first layer comprising
an inflatable
bladder having a closed end and an open end, and a second layer of felt or
fiberglass lining that
is impregnated with a curable resin.
Liner tube 26 preferably comprises a felt layer (26b) and a plastic layer
(26c) as is known in the
art. The felt layer is adapted to absorb a liquid resin, and the plastic layer
is adapted to provide
an impervious smooth continuous surface. Prior to inverting the liner tube,
the plastic layer is
located on the outside of the liner tube and the felt layer is located on the
inside. During the
inversion process (described below), the liner tube 26 is inverted so that the
felt layer is on the
outside of the liner tube and the smooth plastic layer is on the inside of the
liner tube. Use of an
impermeable coating on the liner tube allows the liner tube to be inflated and
inverted without
the use of a separate bladder. In embodiments using an inflatable bladder, the
bladder overlies
the felt lining and is contact with plastic layer 26c.
Prior to inversion, intake 22 of inversion head 20 is connected (via a tubular
conduit) to a liner
dispensing unit (which normally include a source of pressurized air). The
dispensing unit holds
the length of resin soaked liner prior to delivery. During inversion, the air
under pressure flows
through the system from the dispensing unit toward inversion head 20.
As shown in FIG. 3A, open end 26a of liner tube 26 is fitted over discharge
end 24 of inversion
head 20 and is secured in place to create an airtight connection there around
ensuring the air
under pressure causes the closed leading end of liner tube 26 (not shown) to
follow a path of
travel through curing cap 20 into the interior or lumen of the pipe, thereby
inverting said liner as
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said closed end is propelled to the distal end of the pipe by said heated
fluid under pressure (see
FIG. 3B).
Accordingly, liner tube 26 is fully inverted along its entire extent when the
closed end of liner
tube 26 reaches the distal end of the pipe. The rubber layer or uncoated
lining layer now forms
the interior surface of liner tube 26 and the resin-impregnated outer layer
now forms the exterior
layer and is pressed against the inner sidewalls of the pipe by the pressure
of said gaseous or
liquid fluid.
Air from the inversion compressor further causes liner 26 (or bladder/liner
combination) to
expand radially so that the resin coated surface of liner 26 comes into
contact with the interior of
the pipe to be repaired. Air pressure is continued, either directly against
the interior of the liner
(or inflatable bladder) to force the resin-coated surface of liner 26 into
contact with the interior
of the pipe.
Once liner tube 26 is fully inverted, inversion head 20 is uncoupled from the
dispensing unit and
compressed air source. Turning now to Fig. 4A, curing cap 10 is then coupled
with intake 22 of
curing cap 20 (FIG. 3B). Inflation port 14 is connected to an air compressor,
not shown, via
airline 14a. Air from the compressor maintains the pressure within liner 26 to
keep the resin-
coated surface (26b) of liner 26 in contact with the interior of the pipe.
Curing port 16 is connected, via flexible curing tube 16a, to manifold 30 (see
Fig. 5), which is in
turn in fluid communication with a heated fluid source and an air compressor,
not depicted. In
an alternative embodiment, however, it is possible to use a single air
compressor connected to
the manifold to provide connections to both inflation port 14 and curing port
16. Curing port 16
is preferably of a slip-ring configuration, but can be adapted for any
configuration that allows
curing curing tube 16a to slide through curing port 16 while maintaining a
substantially fluid-
tight seal.
Drainage port 18 is also connected to manifold 30 and provides fluid
communication, via
drainage line 18a, from the interior of the pipe outward to manifold 30.
Manifold 30, Fig. 5, includes heat inlet 32, air inlet 34 and outlet 36. Heat
inlet 32 is in fluid
communication with a heating source which provides heated fluid (i.e. hot
water or steam) to the
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system. The flow of heated fluid into the system is controlled by heat valve
32a, and the
temperature and/or pressure of the heated fluid is monitored by gauge 32b. Air
inlet 34 is in
fluid communication with a drainage air compressor which provides air, under
pressure, to the
system. The flow of air under pressure into the system is controlled by air
valve 34a, and the
temperature and/or pressure of the air is monitored by gauge 34b. As
previously stated, the
drainage air compressor can be replaced by the inversion air compressor using
linkages as know
in the art. Both heat fluid inlet 32 and air inlet 34 are in open fluid
communication with outlet
valve 36. For example, when heat valve 32a is open then heated fluid is
permitted to pass
through manifold 30 thereby exiting outlet 36 and entering the system via
curing tube 16a.
Manifold 30 also includes drainage inlet 38, connected to drainage line 18,
which further
comprises drainage valve 38a and temperature/pressure gauge 38b. Fluids
leaving the system via
drainage line 18a can be monitored via gauge 38b and disposed of when safe
through drainage
outlet 38c.
Another aspect of the inventive method occurs after liner tube 26 has been
inverted and is being
held against the sides of the pipe under pressure. This aspect includes the
steps of inserting
curing curing tube 16a into the lumen of liner tube 26, opening heat valve 32
so that heated fluid
flows through manifold 30, via outlet 36, into curing curing tube 16a and into
the lumen of liner
tube 26.
Curing tube 16a is an elongate flexible tube including substantially spherical
guide 17 at its
distal end. Curing tube 16a also includes a series of perforations (19)
proximal to spherical guide
17. Once liner tube 26 is fully extended, curing tube 16a is fed through
curing port 16 thereby
advancing guide 17 through the lumen of liner tube 26. The substantially
spherical shape of
guide 17 allows the distal end of the tube to easily navigate comers and
bends. Once properly
positioned, the heated fluid passes through curing tube 16a and out
perforations 19 into the
lumen of liner tube 26 near its distal end. This ensures liner tube 26 is
heated from the distal
(closed) end toward the proximal (open) end.
As the heated fluid fills the lumen of the liner tube from the distal end, the
air under pressure
used to invert the liner tube is permitted to escape through drainage port 18
and back to manifold
via drainage line 18a. Gauge 38a is monitored as the fluids (air under
pressure, steam or hot
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water) pass there through. When the gauge shows the temperature of the
drainage fluids are
substantially equal to the temperature of the heated fluid entering the
system, this indicates that
the heated fluid has reached the proximal end of liner tube 26. It can now be
assumed liner tube
16 is now substantially filled said heated fluid. Heat valve 32a and drainage
valve 38a can then
be closed, fully or partially, so that liner tube 26 is not over-pressurized.
The resin cures within a
significantly abbreviated time because the heat of the heated fluid is
conducted by the inflatable
bladder (or plastic liner layer (26c) into the resin-impregnated layer (26b)
where it acts as a
catalyst.
When the resin has sufficiently cured, drainage valve 36a is opened to allow
the lumen of the
liner tube to be emptied. To facilitate drainage, air valve 34a is opened
forcing air under
pressure through perforations 19 in the distal end of curing tube 16a. This
air under pressure
forces any remaining heated fluid through drainage port 18, through line 18a
and into drainage
inlet 38a. Inversion head 20 and curing cap 10 can be removed once all heated
fluids are
removed from the lumen of liner tube 26.
The invention is illustrated by the preceding embodiments. These embodiments
are provided to
aid in the understanding of the invention and are not to be construed as a
limitation with regard
to the arrangement of the parts shown in the figures or the order of steps
provided.
It will thus be seen that the objects set forth above, and those made apparent
from the foregoing
disclosure, are efficiently attained and since certain changes may be made in
the above
construction without departing from the scope of the invention, it is intended
that all matters
contained in the foregoing disclosure or shown in the accompanying drawings
shall be
interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover
all of the generic and
specific features of the invention herein described, and all statements of the
scope of the
invention that, as a matter of language, might be said to fall therebetween.
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