U.S. patent application number 15/138079 was filed with the patent office on 2016-08-18 for underground pipe refurbishment via separation of expanded longitudinal cut.
The applicant listed for this patent is Titan CMP Solutions LLC. Invention is credited to Roger W. Thompson.
Application Number | 20160238182 15/138079 |
Document ID | / |
Family ID | 54352661 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160238182 |
Kind Code |
A1 |
Thompson; Roger W. |
August 18, 2016 |
UNDERGROUND PIPE REFURBISHMENT VIA SEPARATION OF EXPANDED
LONGITUDINAL CUT
Abstract
A method for refurbishing an existing host pipe, in which an
in-situ longitudinal cut is made in the interior wall of a
subterranean host pipe. An expansion tool is moved along a path
inside the host pipe, stopping at one or more stations on the way.
At each station, responsive to isolated outward radial force from
the expansion tool, the interior diameter of the host pipe is
increased via separation of the longitudinal cut. A new rigid liner
pipe is inserted inside the expanded host pipe to operationally
replace the host pipe. In some embodiments, grout is deployed in
the annular space between liner pipe and host pipe. Expansion of
the host pipe via separation of the longitudinal cut optimizes the
refurbishment job and enables the original host pipe, as expanded,
to contribute structurally to the refurbished pipe system.
Inventors: |
Thompson; Roger W.; (Boise,
ID) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Titan CMP Solutions LLC |
Boise |
ID |
US |
|
|
Family ID: |
54352661 |
Appl. No.: |
15/138079 |
Filed: |
April 25, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14849037 |
Sep 9, 2015 |
9322503 |
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15138079 |
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14732565 |
Jun 5, 2015 |
9175798 |
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14849037 |
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62008119 |
Jun 5, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16L 55/18 20130101;
F16L 55/1657 20130101; F16L 55/163 20130101; F16L 55/165 20130101;
F16L 2101/12 20130101; F16L 2101/30 20130101; E03F 2003/065
20130101; F16L 55/1658 20130101; F16L 55/44 20130101 |
International
Class: |
F16L 55/165 20060101
F16L055/165 |
Claims
1. A method comprising: making an in-situ longitudinal cut through
an interior wall of a subterranean host pipe; upon completion of
the longitudinal cut, introducing an expansion tool into the host
pipe and moving the expansion tool along a path inside the host
pipe, the path having at least one station at which the expansion
tool stops, the expansion tool having expansion and retraction
modes, the expansion tool adapted to generate isolated outward
radial force when in expansion mode; expanding the host pipe using
the expansion tool at each station to increase an interior diameter
of the host pipe a predetermined amount via separation of the
longitudinal cut through the interior wall; and inserting a rigid
liner pipe inside the host pipe.
2. The method of claim 1, in which an annular space is formed
between the liner pipe and the host pipe, the method further
comprising: at least partially filling the annular space with
grout.
3. The method of claim 1, further comprising, prior to making the
longitudinal cut, cleaning the host pipe and removing interior
debris therefrom.
4. The method of claim 3, further comprising: capturing an image of
an internal condition of the host pipe immediately after said
cleaning step.
5. The method of claim 1, further comprising: capturing an image of
an initial internal condition of the host pipe on at least one
occasion selected from the group consisting of (1) before said
expanding step and (2) after said expanding step.
6. The method of claim 2, further comprising: stabilizing the liner
pipe with stabilization measures before at least partially filling
the annular space with grout.
7. The method of claim 1, in which the expansion tool is a
generally elongate cylindrical expansion tool having an end
assembly rotatably connected to an expansion assembly, the
expansion assembly including a stationary radial force surface
generally opposed to a floating radial force surface, the expansion
assembly adapted to generate isolated outward radial force when
actuated by displacing the floating radial force surface away from
the stationary radial force surface, and in which the expanding
step of the method further comprises, at each station: stopping the
expansion tool; actuating the expansion assembly until the
stationary radial force surface and the floating radial force
surface exert isolated outward radial force on opposing portions of
the interior wall of the host pipe; increasing the unobstructed
interior diameter of the host pipe via non-destructive plastic
separation of the longitudinal cut through the interior wall;
de-actuating the expansion assembly until at least one of the
stationary radial force surface and the floating radial force
surface disengages from the interior wall; and rotating the
expansion assembly a predetermined rotational displacement.
8. The method of claim 7, in which the end assembly further
includes at least two extendable radial stabilizers, and in which
the method further comprises, prior to actuating the expansion
assembly, extending the radial stabilizers to engage the interior
wall of the host pipe and hold the end assembly rotationally
immobile.
9. The method of claim 1, further comprising: withdrawing the
expansion tool from the host pipe before inserting the rigid liner
pipe.
Description
PRIORITY CLAIM AND RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority to
co-pending, commonly-invented, commonly-assigned U.S.
nonprovisional patent application "NONDESTRUCTIVE REFURBISHMENT OF
UNDERGROUND PIPES", Ser. No. 14/849,037, filed Sep. 9, 2015, which
in turn is a continuation of and claims priority to
commonly-invented, commonly-assigned U.S. nonprovisional patent
application "TRENCHLESS REFURBISHMENT OF UNDERGROUND PIPES", Ser.
No. 14/732,565, filed Jun. 5, 2015 (now U.S. Pat. No. 9,175,798),
which in turn claims priority to now-expired, commonly-invented,
commonly-assigned U.S. provisional patent application "TRENCHLESS
METHOD FOR REFURBISHING EXPANDABLE PIPES", Ser. No. 62/008,119,
filed Jun. 5, 2014. This application claims priority to, and the
benefit of, Ser. No. 14/849,037, Ser. No. 14/732,565 and Serial No.
62/008,119, and incorporates the entire disclosures of Ser. Nos.
14/849,037, 14/732,565 and 62/008,119 by reference.
FIELD OF THE DISCLOSURE
[0002] This disclosure is directed generally to methods for
refurbishing buried expandable pipes without open cut replacement
(i.e., without digging the pipe out of the ground). This disclosure
is further directed to items of equipment that facilitate the
disclosed refurbishment methods.
BACKGROUND
[0003] The term "expandable", as applied to an existing buried pipe
or culvert, is used as a defined term of art throughout this
disclosure. By "expandable", this disclosure refers to culverts and
pipes having an existing wavy or folded annular or circumferential
profile, such that, responsive to a controlled radial force, the
"waves" or "folds" will collapse or "smooth out", allowing a
limited expansion of the effective inside diameter of the pipe
without intentionally rupturing the pipe. It is expected that many
culverts or pipes falling within this definition will be metal, and
will be corrugated or "accordion" in profile. However, the term is
not limited to corrugated or accordion profiles on metal pipes or
culverts.
[0004] Expandable culverts of interest in this disclosure primarily
include buried pipes that carry, for example, water under roads and
structures, usually to allow a stream to flow under a road or to
carry runoff from the uphill side of a road to the downhill side.
Utility piping and other infrastructure may also be carried within
such culverts. Such culverts can be made from various materials,
but are often made from corrugated metal because it provides
flexibility and strength while remaining relatively light and
inexpensive. Consequently, expandable metal pipe culverts have been
widely used in road construction projects over the last 50
years.
[0005] The service life of an expandable metal culvert varies,
depending on factors such as climate, maintenance, water flow, and
the condition of the surrounding soil. However, this type of
culvert came into widespread use in the 1950s, and many are now
reaching the end of their useful life and need to be repaired or
replaced (or refurbished) before they fail. Expandable metal
culverts can fail in different ways. For example, rust and
corrosion can cause the pipe to leak, or even to disintegrate and
collapse. Leaks can lead to erosion around the pipe and the
resulting lack of structural support can cause the pipe to break.
Pipe failure can wash out roads and bridges and cause environmental
damage to the waterways they drain into.
[0006] Culverts can be repaired, or refurbished, by building a new
culvert or digging the existing pipe up and replacing it ("open
cut" methods). But these methods can be costly and time-consuming.
Further, open cut methods may impractical because of traffic volume
(the road will likely have to be closed during open cut
operations), terrain, or climate. However, culverts can sometimes
be refurbished without digging them up. This process is referred to
in the industry as trenchless replacement technology. In this
method, a new pipe is attached to a tool that is pushed or pulled
through the existing damaged pipe. The tool head intentionally
breaks or splits the old pipe as it drags the new liner pipe in
behind it (this technique is also called "pipe bursting"). These
methods allow culverts to be replaced with minimal disruption to
traffic flow on any roadway above the culvert and with less impact
on the waterway the culvert drains into. However, it should be
noted that such "pipe bursting" techniques are "destructive" to the
host pipe (i.e., the old pipe being replaced), rendering the host
pipe effectively useless to provide support or peripheral
protection, for example, to a new liner pipe.
[0007] One example of the destructive "pipe bursting" technology in
use today is disclosed in Unitracc publication "Hydraulic and
Static Pipe Bursting", Feb. 16, 2011, available as of the date of
this disclosure at:
http://www.unitracc.com/know-how/fachbuecher/rehabilitation-and-maintenan-
ce-of-drains-and-sewers/rehabilitation/replacement-en/replacement-by-the-t-
renchless-method-en/unmanned-techniques-en/pipe-bursting-en/hydraulic-and--
static-pipe-bursting-en. According to this reference, a
hydraulically expandable tool head shatters a surrounding existing
brittle host pipe (typically clay or unreinforced concrete) as it
is drawn down the length of the existing pipe. A replacement pipe
follows close behind the tool head.
[0008] A further example of current trenchless technology is
disclosed in U.S. Pat. No. 4,602,495 to Yarnell. Yarnell is a
"non-destructive" alternative to destructive "pipe bursting"
techniques such as disclosed in Unitracc, described above. Yarnell
teaches an expandable tool head being drawn down an existing
brittle host pipe in which "irregularities" have made it difficult,
for example, to draw a new liner pipe through the pipe. Such
"irregularities" include neighboring sections of existing pipe
becoming misaligned and no longer coaxial, or soil pressure causing
sections of the brittle pipe to fracture and partially collapse,
constricting the original inner diameter of the pipe. A conical
nose and expandable "leaf members" on the tool head temporarily
remediate the "irregularities", primarily by pushing the broken
host pipe back against soil pressure, so that the effective
original internal diameter of the host pipe can be temporarily
restored. At that point, an inner liner pipe can be drawn
through.
[0009] Current destructive trenchless methods for replacing or
refurbishing culverts are inadequate for some kinds of host pipes.
Existing cutting and bursting techniques have had limited success
on host pipes made from expandable materials such as corrugated
metal. The principle upon which current technology "bursts" pipe
requires a conical front end of the tool head (or "cutting head")
to be dragged through the existing pipe, forcing the pipe over the
body of the cutting head until it fractures or "bursts". The
outside diameter of the body of the cutting head is thus chosen to
be larger than the inside diameter of the pipe, causing the pipe to
rupture as the cutting head is dragged through. There is thus a
force placed on the existing pipe by the cutting head that has both
longitudinal and radial components. Problems arise when this
technique is used on flexible and expandable pipes such as
corrugated pipes. Rather than bursting or splitting corrugated
pipes, conventional techniques often compress the pipe
longitudinally, which can cause the pipe to fold up in front of the
tool like an accordion. Not only does this accordion effect make
the overall pipe replacement process slower and more expensive, it
can potentially cause the tool to get stuck in the old pipe or
block the path for the new pipe. An existing expandable pipe may
become so badly "accordioned" that a section may require spot
digging and removal in order to complete the overall replacement
job.
[0010] Further, non-destructive pipe replacement techniques in the
prior art (such as the Yarnell disclosure, described above) have
been directed to temporarily restoring an ailing host pipe to as
close its original condition as possible, so that an inner liner
pipe can be installed. Because the host pipe is temporarily
restored to its original condition (or close to original), the
thickness of the liner pipe, once installed, inevitably reduces the
operational diameter of the repaired pipe. In applications where
pipe flow or capacity is important, such operational diameter
reduction can become disadvantageous.
SUMMARY OF DISCLOSED TECHNOLOGY AND TECHNICAL ADVANTAGES
[0011] The tools and processes described in this disclosure address
the problems set forth in the "Background" section above, and other
problems in the prior art. The described methods reject the prior
art notion of relying on a pulling force to split the host pipe in
destructive mode. In a first embodiment, a first refurbishment
method utilizes a cylindrical hydraulic tool that expands and
contracts in non-destructive mode. The tool is inserted into the
host pipe via tensioned cables and hydraulically powered segments
or stabilizers on the outside surface of the tool expand outward in
a radial direction. In some variations of the first embodiment, the
expansion tool may be functionally not dissimilar from the tool
disclosed in Yarnell. In other variations, the expansion tool may
be in accordance with a new design as disclosed herein with
reference to FIGS. 17A through 17D and associated text.
[0012] The first refurbishment method is deployed on expandable
host pipes such as corrugated host pipes. The expansion of the tool
imparts radial force only against the inside surface of the host
pipe, perpendicular to its longitudinal axis. The goal of the
expansion step is to "smooth out" the "waves" in the periphery of
the host pipe via radial force, without intentionally rupturing the
host pipe. It is understood that in places, the wall of the host
pipe may break unintentionally, especially where the host pipe is
corroded or cracked. However, because the applied radial force is
perpendicular to the pipe wall, it does not fold or bunch the host
pipe. Further, with careful application of the first refurbishment
method, such ruptured zones of host pipe should be limited. The
structural integrity of the expandable host pipe is thus
substantially preserved wherever possible, allowing the host pipe
to provide support or an external layer of protection, for example,
to the inner liner pipe when it is installed.
[0013] In a second embodiment, a second refurbishment method
includes a designated cutting step to cut the host pipe
longitudinally, in situ, along its entire length, prior to
expansion. In this second embodiment, the expansion of the host
pipe enlarges the host pipe's diameter by separation of the host
pipe material either side of the cut line, rather than "smoothing
out" the "waves" in the periphery of the host pipe (per the first
refurbishment method). Advantageously the host pipe cut line is at
the low point ("invert" or nadir) of the pipe, although this
disclosure is not limited in this regard. Examples of situations
when the second refurbishment method (longitudinal cut line) might
be selected over the first refurbishment method (smoothing out
waves) include: (1) when the host pipe is particularly corroded and
brittle, and less susceptible to consistent plastic radial
deformation of the periphery waves; (2) when the wall of the host
pipe is particularly thick, or has been constructed with a number
of overlapping metal joints, again making it difficult to obtain
consistent plastic radial deformation of the periphery waves. It
will be nonetheless appreciated that in accordance with the second
refurbishment method (longitudinal cut line), as with the first
refurbishment method (smoothing out waves), the structural
integrity of the host pipe is thus substantially preserved wherever
possible, allowing the host pipe to provide support for, or an
external layer of protection to, the inner liner pipe when it is
installed. In this way, expansion of the host pipe via
non-destructive plastic deformation optimizes the refurbishment job
and enables the original host pipe, as expanded, to contribute
structurally to the refurbished pipe system.
[0014] Regardless of whether the first refurbishment method
(smoothing out waves) or the second refurbishment method
(longitudinal cut line) is selected, the host pipe is expanded
section by section, each section being approximately the same
length of the tool. Presently preferred embodiments of the tool may
be 4-6 feet in length, although this disclosure is not limited in
this regard. Once a section of host pipe is expanded, the
expandable members on the tool are fully retracted. The tool is
then advanced further into the host pipe and the next section is
expanded. Once the host pipe is completely expanded, the new liner
pipe can be installed via conventional methods, such as sliplining.
The new liner pipe has a rigid tubular profile prior to
installation and is deployed to operationally replace the host
pipe.
[0015] Once the new liner pipe is installed, it is then stabilized
in preparation for grouting the annular space between the host pipe
and the liner pipe. The inner liner pipe may be stabilized, for
example, by filling it with a fluid (such as water), or
alternatively pressurizing it internally. Once the inner liner pipe
is stabilized, grout or a similar material is injected under
pressure into the annular space between the host pipe and the new
liner pipe. The purpose of stabilizing the inner liner pipe is to
give the inner liner pipe strength against deformation or collapse
while the grout is being injected around it in liquid form. Once
the grout has cured, inner liner pipe stabilization measures can be
removed (e.g. via emptying the fluid or de-pressurizing the pipe).
It should be noted that in the embodiments illustrated and
described below, the annular space is filled with grout as much as
possible, and advantageously completely filled. However, in other
embodiments (not illustrated or described below) the annular space
is at least partially filled with grout.
[0016] Some variations of the grouting phase (according to either
the first or second refurbishment methods) deploy inflatable
bulkheads at each end of the annular space between the host pipe
and the liner pipe. An example of such an inflatable bulkhead is
disclosed below with reference to FIGS. 20-21 and associated text.
Once inflated, the bulkheads temporarily seal the annular space at
either end, (1) allowing the annular space to be filled efficiently
and cleanly with grout, and (2) holding the grout in place at the
ends while it cures. Structure in at least one bulkhead includes a
grout hose fitting that passes through the inflated chamber of the
bulkhead, allowing grout to be injected into the annular space
while the bulkhead is inflated.
[0017] In some situations in the first refurbishment method
(smoothing out waves), an additional step of cutting a section of
the host pipe may be required prior to expanding and plastically
deforming the waves in the periphery of the pipe. As already noted,
in some situations the host pipe may have become corroded,
especially near the bottom (or "invert") if the pipe has been
exposed to standing water for long periods. Such corroded portions
of the host pipe are inelastic and likely to crack or shatter when
expanded. A controlled cut of the host pipe prior to expansion
facilitates proper execution of the expansion step in such corroded
portions.
[0018] In other situations, characteristics of the host pipe itself
may require that an additional step of cutting the host pipe may be
advantageous prior to expanding the host pipe. For example, a
common process for manufacturing corrugated host pipes involves
helically rolling a continuous length of metal and forming it into
a pipe with a spiral seam. Such spiral seams may be welded,
riveted, or otherwise formed into an inelastic helical pathway
along the finished host pipe. Applying expansion forces to these
inelastic seams may cause the pipe to crack or burst at the seam.
Alternatively the seams may be so strong that they resist and
defeat the expansion step in the host pipe areas surrounding the
seam. In such cases, similar to the situations described above with
respect to corroded host pipe, a controlled cut of the host pipe
prior to expansion facilitates proper execution of the expansion
step.
[0019] Adding a cutting step prior to expansion of the host pipe
may also be advantageous at the joints between lengths of host pipe
as found in situ. When originally laid, lengths of host pipe may be
joined by any conventional method, such as riveting, welding, or
bolting together. Lengths of host pipe may have been "folded over"
at the ends during installation, to facilitate engagement between
neighboring lengths during the joining process. Alternatively,
special "joint pieces" may have been used, in which a short piece
of oversized host pipe is deployed over both ends of the host pipe
pieces to be joined. The joint piece is then tightened down around
both ends of the host pipe via band-type threaded fasteners. As a
result, joints between lengths of host pipe in situ may present
double or more the wall thickness, as well as further inelasticity
due to the specific type of joining process originally used. As
before, applying expansion forces to these inelastic joints may
cause the host pipe to crack or burst at the joint. Alternatively
the joints may be so strong that they resist and defeat the
expansion step in the host pipe areas surrounding the joint. In
such cases, similar to the situations described above with respect
to corroded host pipe or a helical seam, a controlled cut of the
host pipe prior to expansion facilitates proper execution of the
expansion step.
[0020] According to a first embodiment, therefore, this disclosure
describes a method for refurbishing an existing expandable pipe,
the method comprising the steps of, in sequence: (a) providing an
existing expandable host pipe, the host pipe having an expandable
interior wall with a known unobstructed internal diameter; (b)
providing an expansion tool having expansion and retraction modes,
the expansion tool adapted to generate isolated outward radial
force when in expansion mode; (c) moving the expansion tool along a
path inside the host pipe, the path having stations at which the
expansion tool stops; (d) expanding the host pipe during step (c),
step (d) further including, at each station: (d1) stopping the
expansion tool; (d2) placing the expansion tool in expansion mode;
(d3) engaging the interior wall of the host pipe with the expansion
tool while in expansion mode; (d4) responsive to isolated outward
radial force from the expansion tool, increasing the unobstructed
interior diameter of the host pipe a predetermined amount via
non-destructive plastic deformation of the interior wall; (d5)
switching the expansion tool to retraction mode; and (d6) moving
the expansion tool to the next station; (e) withdrawing the
expansion tool from the host pipe; (f) inserting a rigid liner pipe
inside the host pipe, the liner pipe having a rigid tubular profile
prior to insertion and deployed to operationally replace the host
pipe, an annular space created between the liner pipe and host pipe
when the liner pipe is inserted inside the host pipe; and (g) at
least partially filling the annular space with grout.
[0021] According to a second embodiment, this disclosure describes
a method for refurbishing an existing pipe, the method comprising
the steps of, in sequence: (a) providing an existing host pipe, the
host pipe having a length, the host pipe further having an interior
wall with a known unobstructed internal diameter; (b) making a
longitudinal cut through the interior wall along the length of the
host pipe; (c) providing an expansion tool having expansion and
retraction modes, the expansion tool adapted to generate isolated
outward radial force when in expansion mode; (d) moving the
expansion tool along a path inside the host pipe, the path having
stations at which the expansion tool stops; (e) expanding the host
pipe during step (d), step (e) further including, at each station:
(e1) stopping the expansion tool; (e2) placing the expansion tool
in expansion mode; (e3) engaging the interior wall of the host pipe
with the expansion tool while in expansion mode; (e4) responsive to
isolated outward radial force from the expansion tool, increasing
the unobstructed interior diameter of the host pipe a predetermined
amount via non-destructive plastic separation of the longitudinal
cut through the interior wall; (e5) switching the expansion tool to
retraction mode; and (e6) moving the expansion tool to the next
station; (f) withdrawing the expansion tool from the host pipe; (g)
inserting a rigid liner pipe inside the host pipe, the liner pipe
having a rigid tubular profile prior to insertion and deployed to
operationally replace the host pipe, an annular space created
between the liner pipe and host pipe when the liner pipe is
inserted inside the host pipe; and (h) at least partially filling
the annular space with grout.
[0022] According to a third embodiment, this disclosure describes a
method for refurbishing an existing pipe, the method comprising the
steps of, in sequence: (a) providing an existing host pipe, the
host pipe having a length, the host pipe further having an interior
wall with a known unobstructed internal diameter; (b) making a
longitudinal cut through the interior wall along the length of the
host pipe; (c) providing a generally elongate cylindrical expansion
tool, the expansion tool having an end assembly rotatably connected
to an expansion assembly, the end assembly including at least two
extendable radial stabilizers, the expansion assembly including a
stationary radial force surface generally opposed to a floating
radial force surface, the expansion assembly adapted to generate
isolated outward radial force when actuated by displacing the
floating radial force surface away from the stationary radial force
surface; (d) moving the expansion tool along a path inside the host
pipe, the path having stations at which the expansion tool stops;
(e) expanding the host pipe during step (d), step (e) further
including, at each station: (e1) stopping the expansion tool; (e2)
extending the radial stabilizers to engage the interior wall of the
host pipe and hold the end assembly rotationally immobile; (e3)
actuating the expansion assembly until the stationary radial force
surface and the floating radial force surface exert isolated
outward radial force on opposing portions of the interior wall of
the host pipe; (e4) responsive to step (e3), and locally at the
stationary radial force surface and the floating radial force
surface, increasing the unobstructed interior diameter of the host
pipe a first predetermined amount via non-destructive plastic
separation of the longitudinal cut through the interior wall; (e5)
de-actuating the expansion assembly until at least one of the
stationary radial force surface and the floating radial force
surface disengages from the interior wall; (e6) rotating the
expansion assembly a predetermined rotational displacement with
respect to the end assembly; (e7) repeating steps (e3) through (e6)
until the unobstructed interior diameter of the host pipe is
increased overall at least a second predetermined amount via
non-destructive plastic separation of the longitudinal cut through
the interior wall; (e8) retracting the radial stabilizers until at
least one of the radial stabilizers disengages from the interior
wall of the host pipe; and (e9) moving the expansion tool to the
next station; (f) withdrawing the expansion tool from the host
pipe; (g) inserting a rigid liner pipe inside the host pipe, the
liner pipe having a rigid tubular profile prior to insertion and
deployed to operationally replace the host pipe, an annular space
created between the liner pipe and host pipe when the liner pipe is
inserted inside the host pipe; and (h) at least partially filling
the annular space with grout.
[0023] The processes and tools described in this disclosure provide
several advantages compared with conventional methods. First, as
noted already, because the expansion forces are controlled and
perpendicular to the host pipe wall, issues with the pipe folding
up like an accordion are obviated. The disclosed processes are
further non-destructive and preserves wherever possible the
integrity of the host pipe, so that the host pipe may continue to
contribute to operational longevity once the pipe refurbishment job
is finished.
[0024] The disclosed processes further expand the outside diameter
of the host pipe (by removing the existing "waves" or "folds", or
by separating the host pipe either side of a controlled cut),
leaving the host pipe larger in diameter than before. Introducing
the inner liner pipe may thus, in certain applications, preserve
the operational diameter of the pipe once the refurbishment job is
finished. This retention of operational diameter may be highly
advantageous in applications where pipe flow or capacity is
important.
[0025] Another advantage of the disclosed processes is that the
host pipe is completely expanded before the inner liner pipe is
introduced (by sliplining or other conventional methods). In the
prior art, and particularly in pipe bursting techniques that are
destructive to the host pipe, the inner liner pipe is generally
inserted to follow right behind the bursting tool as the tool moves
along the host pipe. Causing the inner liner pipe to follow right
behind the bursting tool avoids premature collapse of the
surrounding soil into the tunnel void created by the burst host
pipe. However, coordination of deployment of the inner liner pipe
right behind the pipe bursting can make the logistics of the job
difficult. Further, should there be an unintended collapse of the
surrounding soil before the inner liner pipe can provide support,
the inner liner pipe can become stuck, putting success of the job
in jeopardy.
[0026] By contrast, the new processes described in this disclosure
fully expand the host pipe, and substantially retain the host
pipe's structural integrity, before the inner liner pipe is
introduced. Since the host pipe is completely ready to receive the
inner liner pipe, and is still supporting the surrounding soil, the
inner liner pipe can be deployed quickly and efficiently using
conventional methods such as sliplining. The disclosed processes
are thus predictive of a much higher job success rate. Moreover,
unlike refurbishment methods of the prior art (such as pipe
bursting), the new processes of this disclosure create an annular
space in which grout can be deployed, further enhancing the
strength, performance and longevity of the finished refurbishment
job.
[0027] Another advantage of the disclosed processes (and
particularly those embodiments including cutting steps), is that
they may achieve better results when applied to host pipes
manufactured with a spiral seam. As noted, this type of pipe is
constructed from a coil of metal that is formed into a pipe with a
helical seam. The edges of the seam may be folded together along
the entire length of the pipe to create a rigid body that is
typically stronger than pipes with a longitudinal seam, making
conventional pipe bursting difficult. Because the expansion forces
in the processes described in this disclosure are applied
perpendicular to the host pipe wall, the spiral seam may unravel
and elongate without the "accordion" effect mentioned above.
Alternatively, in embodiments including cutting steps, longitudinal
cuts on the spiral seam allow proper execution of the expansion
step. Thus, the integrity of the host pipe and its contribution to
supporting the new pipe are preserved, even in operations where the
host pipe is manufactured with a spiral seam.
[0028] It will be understood that host pipe expansion via
unraveling of a spiral seam (per the previous paragraph), or
following controlled cutting of the host pipe (per earlier
disclosure), may be in addition to "smoothing out" the waves or
folds in a corrugated or other expandable host pipe. The radial
force provided by the expansion tool will enable both operations,
thus expanding the host pipe by (1) increasing the circumference of
the host pipe by unraveling the spiral seam, and/or (2) increasing
the circumference of the host pipe by separating the host pipe
material either side of the cut in the host pipe, and/or (3)
"smoothing out" the waves or folds in the host pipe.
[0029] The grout (or other material) injected into the annular
space between the host pipe and new liner pipe provides additional
advantages over conventional trenchless methods, which typically
omit this step. First, it secures the new liner pipe in position so
it does not move or settle. Next, the grout fills voids in the soil
under the host pipe, reducing the likelihood of pipe deflections
from differential settlement. The grout also fills voids in the
soil above the host pipe, which reduces point loads and impacts
caused if those voids collapse (which is a major source of
operational deflection and collapse of culverts).
[0030] The foregoing has outlined rather broadly some of the
features and technical advantages of the disclosed trenchless pipe
refurbishment technology, in order that the detailed description
that follows may be better understood. Additional features and
advantages of the disclosed' technology may be described. It should
be appreciated by those skilled in the art that the conception and
the specific embodiments disclosed may be readily utilized as a
basis for modifying or designing other structures for carrying out
the same inventive purposes of the disclosed technology, and that
these equivalent constructions do not depart from the spirit and
scope of the technology as described and as set forth in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] For a more complete understanding of the embodiments
described in this disclosure, and their advantages, reference is
made to the following detailed description taken in conjunction
with the accompanying drawings, in which:
[0032] FIGS. 1 through 12 are a "freeze frame" series of
illustrations of operations in accordance with a first embodiment
of the disclosed technology (the "first refurbishment method" as
described in the "Summary" section above);
[0033] FIG. 1A is a section as shown on FIG. 1;
[0034] FIG. 13 is a flow chart illustrating a first embodiment of a
method of refurbishing an underground pipe in accordance with the
disclosed technology (the "first refurbishment method" as described
in the "Summary" section above);
[0035] FIG. 14 is a flow chart illustrating a variation of the
method of FIG. 13, adding a cutting step;
[0036] FIGS. 15, 16, 18A through 18G, 19 and 22 illustrate a
"freeze frame" series of operations in accordance with a second
embodiment of the disclosed technology (the "second refurbishment
method" as described in the "Summary" section above);
[0037] FIGS. 17A through 17D illustrate features and aspects of one
embodiment of expansion tool 700 that may be used generally for
tubular expansion, including in association with either the "first
refurbishment method" or the "second refurbishment method" also
disclosed herein;
[0038] FIGS. 20 and 21 illustrate features and aspects of
inflatable bulkhead 820 that may be used generally for sealing
annular spaces to be grouted, including in association with either
the "first refurbishment method" or the "second refurbishment
method" also disclosed herein; and
[0039] FIG. 23 is a flow chart illustrating a second embodiment of
a method of refurbishing an underground pipe in accordance with the
disclosed technology (the "second refurbishment method" as
described in the "Summary" section above).
DETAILED DESCRIPTION
[0040] For the purposes of the immediately following disclosure,
FIGS. 1, 1A, and 2 through 12 should be viewed together. Any part,
item, or feature that is identified by part number on one of FIGS.
1, 1A, and 2 through 12 has the same part number when illustrated
on another of FIGS. 1, 1A, and 2 through 12.
[0041] FIGS. 1 through 12 illustrate a "freeze frame" series of
operations in accordance with a first embodiment of the disclosed
technology (the "first refurbishment method" as described in the
"Summary" section above). It will be recalled that the "first
refurbishment method" expands the host pipe primarily by plastic,
non-destructive deformation of the "waves" (typically corrugations)
in the periphery of the host pipe.
[0042] FIGS. 1 through 10 depict expansion tool 100. It will be
appreciated that expansion tool 100 is illustrated functionally and
highly schematically on FIGS. 1 through 10. As shown (for example)
on FIGS. 3 and 4, expansion tool 100 comprises expansion members
110. In the example illustrated, expansion tool 100 is an elongate,
substantially cylindrical tool comprising four (4) longitudinal
expansion members 110. Other embodiments of expansion tool 100 (not
illustrated on FIGS. 1 through 10) may comprise a different number
of expansion members 110, and this disclosure is not limited in
this regard. Expansion tool 100 further comprises conventional
structure (again not illustrated on FIGS. 1 through 10) for
remotely extending and retracting expansion members 110 in a radial
direction, perpendicular to the longitudinal axis of expansion tool
100. In preferred embodiments, conventional hydraulic actuating
technology may be deployed to remotely extend or retract expansion
members 110, but again this disclosure is not limited in this
regard.
[0043] Referring momentarily to FIGS. 17A through 17D and
associated text disclosure, an alternative embodiment of an
expansion tool is illustrated that would also be suitable for
expansion tool 100 as depicted on FIGS. 1 through 10. Although the
expansion tool illustrated in FIGS. 17A through 17D is described in
detail below with reference to a second embodiment of the disclosed
technology (the "second refurbishment method" as described in the
"Summary" section above), it will be understood that the expansion
tool of FIGS. 17A through 17D is not limited to that second
embodiment, and may be used in other embodiments, including the
first embodiment as illustrated on FIGS. 1 through 10.
[0044] Returning now to FIGS. 1 through 12, existing host pipe H on
is metal and has a wavy or corrugated profile, and falls within the
definition of "expandable" pipe coined at the beginning of this
disclosure. For purposes of easy reference, such definition is
repeated here. By "expandable", this disclosure refers to culverts
and pipes having an existing wavy or folded annular or
circumferential profile, such that, responsive to a controlled
radial force, the "waves" or "folds" will collapse or "smooth out",
allowing a limited expansion of the effective inside diameter of
the pipe without intentionally rupturing the pipe.
[0045] FIG. 1A is a section as shown on FIG. 1, and illustrates
corrugations C on host pipe H. While currently preferred
embodiments refer to host pipe H having corrugations C as shown on
FIG. 1A, it will nonetheless be appreciated that this disclosure is
not limited in this regard. It will be understood that the scope of
this disclosure includes any "expandable" host pipe H, per the
above definition.
[0046] In FIGS. 1 and 2, expansion tool 100 is approaching and
entering host pipe H to begin expansion of corrugations C. It will
be noted that, with further reference to FIG. 3, expansion members
110 are in a retracted state during longitudinal movement of
expansion tool 100 through host pipe H. It will be further noted
that at least one end (and on FIGS. 1 through 12, both ends) of
expansion tool 100 is/are tapered. Such tapers are an optional but
advantageous feature to assist with easy movement up and down host
pipe H without catching or snaring on corrugations C. However,
importantly, such tapers impart no longitudinal forces on
corrugations C or host pipe H during longitudinal movement of
expansion tool 100 within host pipe H. Expansion tool 100 imparts
isolated outward radial force on host pipe H. This is in
distinction to prior art tools and processes where dragging such
tapers through constricted pipe openings caused bursting of the
host pipes (usually brittle host pipes) via a combination of
longitudinal force and radial force. As noted in the "Summary"
section above, such longitudinal forces are disadvantageous in
expandable pipe applications. As will be explained further, the
tapered ends of expansion tool 100 as illustrated, for example, in
FIG. 1, advantageously make no material contact with corrugations C
while expansion tool 100 moves longitudinally through host pipe H
with expansion members 110 in a retracted state. The tapered ends
only make contact with corrugations C via radial force, while
expansion tool 100 is stationary and with expansion members 110 in
an extended state.
[0047] In FIG. 4, expansion tool 100 has reached a first station
within host pipe H and is now stationary. Expansion members 110 are
actuated to expand host pipe H, causing a limited and predetermined
plastic deformation of corrugations C via radial force only.
Advantageously, the predetermined deformation is sufficient to
"flatten out" corrugations C without intentionally rupturing host
pipe H. As noted above in the "Summary" section, some parts of host
pipe H, especially along the lower surface, may be so corroded that
the radial force applied by expansion members 110 may
unintentionally rupture host pipe H. However, because the applied
radial force is perpendicular to the longitudinal axis of host pipe
H, it does not fold or bunch host pipe H. Further, with careful
application of the method, such unintentionally ruptured zones of
host pipe H should be limited.
[0048] In FIG. 5, expansion members 110 are in the process of being
retracted, and expansion tool 100 is being made ready to be moved
on to its next station. In FIG. 6, expansion tool 100 has reached
its next station and is stationary again. As noted earlier, the
number of expansion members 110 provided on a particular expansion
tool 100 may vary per user design choice. However, expansion
members 110 advantageously do not operate independently. Rather,
they extend and retract in unison, exerting uniform radial force
around the circumference of host pipe H, which helps keep expansion
tool 100 centered and balanced as it operates on host pipe H.
[0049] It will be seen in FIGS. 5 and 6 that the leading tapered
end of expansion tool has imparted a radial force on corrugations C
during the actuation of expansion members 110 while expansion tool
100 was stationary. However, it will be further seen and
appreciated that as expansion tool 100 is moved on to its next
station, with expansion members 110 in a retracted state, the
tapered end makes no contact with corrugations C.
[0050] FIGS. 7 through 9 show the above-described process repeated
through second and third stations, until, as shown on FIG. 10,
expansion tool 100 has passed completely through host pipe H,
leaving it temporarily in an expanded state. In FIG. 7, expansion
members 110 are actuated, causing a causing a limited and
predetermined deformation of corrugations C via radial force only.
In FIG. 8, expansion members 110 have been retracted, whereupon
expansion tool 100 has been moved longitudinally to a third station
in host pipe H. Once stationary, expansion members 110 are extended
and retracted again in FIG. 9 to cause a limited and predetermined
plastic deformation of corrugations C via radial force only.
[0051] As shown on FIG. 11, an inner liner pipe 200 may now be
deployed inside the expanded host pipe H. In currently preferred
embodiments, and as illustrated on FIGS. 11 and 12, inner liner
pipe has a smooth profile on both inner and outer surfaces,
although this disclosure is not limited in this regard. Other
embodiments may deploy a corrugated liner pipe 800 to give liner
pipe additional intrinsic strength. Inner liner pipe 200 may
typically be made of a light weight, hard wearing material, such as
16 to 20 gauge steel, or PVC, or a fiber-resin composite. It will
be nonetheless appreciated that this disclosure is not limited to
any specific material for inner liner pipe 200.
[0052] It will be further appreciated from FIGS. 11 and 12, that
with host pipe H now in an expanded state, the outside diameter and
wall thickness of inner liner pipe 200 may be selected to provide
an inner diameter of inner liner pipe 200 that is comparable to the
effective operating diameter of host pipe H before expansion. By
"comparable", the inner diameter of inner liner pipe 200 may be
selected to be at least as large as the effective operating
diameter of host pipe H before expansion, if not larger. As noted
in the "Summary" section of this disclosure above, this aspect of
disclosure may be particularly advantageous in applications where
the capacity of flow capability of host pipe H is desired to be
maintained or even improved after refurbishment.
[0053] Also, as noted in the "Summary" section of this disclosure
above, the introduction of inner liner pipe 200 only after host
pipe H has been completely expanded greatly enhances the
probability of the success of the job. This is in contrast to prior
art processes where the inner liner pipe has to follow right after
a host pipe bursting tool in order to avoid collapse of the
surrounding soil into the host pipe void. Further, the introduction
of inner liner pipe 200 only after host pipe H has been completely
expanded allows the annular space between inner liner pipe 200 and
host pipe H to be grouted.
[0054] FIG. 12 shows grout 300 deployed in the annular space
between host pipe H and inner liner pipe 200. In the illustrated
embodiment, grout 300 advantageously fills the annular space. In
other embodiments, the annular space is at least partially filled
with grout 300. When fully cured, grout 300 serves several
purposes. In combination with host pipe H and inner liner pipe 200,
grout 300 forms a "layered" refurbished pipe that is robust in and
of itself, and which is also supported properly by the surrounding
soil. Grout 300 also assists in minimizing leaks, both into inner
liner pipe 200 from the surrounding soil, and vice versa. Grout 300
may also fill voids in the soil surrounding host pipe H.
[0055] FIG. 13 is a flow chart illustrating a first embodiment of a
method of refurbishing an underground pipe in accordance with the
disclosed technology (the "first refurbishment method" as described
in the "Summary" section above). The embodiments described above
with reference to FIGS. 1 through 12 may be used in the method of
FIG. 13. On FIG. 13, blocks 401 through 409 recite, in summary
form, the steps of the method 400, which are described in greater
detail in the written disclosure immediately below.
[0056] Block 401 on FIG. 13 refers to the step of memorializing the
initial condition of the host pipe prior to beginning any
refurbishment operations. While this may be accomplished by
conventional image-capture methods such as video or still
photography, this disclosure is not limited in this regard.
[0057] The next step is to clean the host pipe (block 402), if
necessary. The host pipe often contains dirt and other organic
matter in its native state before refurbishment begins. This
cleaning step may be completed by any method suitable to the nature
and condition of the particular host pipe and its surrounding
geography. In some embodiments, the cleaning step may require the
contents of the host pipe to be captured and removed from the site.
When the cleaning is complete, the next step is to memorialize the
condition of the cleaned host pipe (block 403), again via
conventional methods.
[0058] Block 404 on FIG. 13 refers to the step of running a pipe
expansion tool through the host pipe to expand the host pipe,
consistent with the disclosure above accompanying FIGS. 1 through
12. In preferred embodiments, tensioned cables are connected to
both ends of the pipe expansion tool, which enables the operator to
move the expansion tool longitudinally in either direction inside
the host pipe. The operator also controls conventional hydraulic
extension and retraction of the expansion members on the expansion
tool when the expansion tool is stationary at a preselected station
inside the host pipe. Again, see disclosure above with reference to
FIGS. 1 through 12.
[0059] In some applications (not illustrated), the host pipe may be
made from shorter segments of expandable pipe that are joined by a
band or sleeve that overlaps the joint where the segments abut.
Occasionally, these joints may prove impractical to expand because
of the additional strength the band provides at the joint. In these
cases, the host pipe or the exterior band (or both) may need scored
or cut prior to running the expansion tool through the host pipe.
The scoring or cutting process can be completed via conventional
techniques appropriate to the material and condition of the host
pipe. This cutting step is described in greater detail below with
reference to FIG. 14, and particularly with reference to block 504
on FIG. 14.
[0060] Continuing with FIG. 13, and consistent with the disclosure
above accompanying FIGS. 1 through 12, the step of running the
expansion tool (block 404 on FIG. 13) is accomplished by (a) moving
the expansion tool longitudinally to a first station in the host
pipe, (b) holding the expansion tool stationary while expanding the
expansion members, (c) retracting the expansion members until the
expansion tool is in a fully retracted state, (d) moving the
expansion tool longitudinally to the next station, and (e)
repeating substeps (b) through (d) until the host pipe is fully
expanded. In this way, the entire length of the host pipe is
expanded and prepared to receive the new inner liner pipe.
[0061] It may be advantageous in some cases to evaluate the
condition of the expanded host pipe before inserting the new inner
liner pipe, again via conventional image-capture techniques.
Additionally, or alternatively, it may be desirable pass a mandrel,
"drift", or similar inspection instrument through the fully
expanded host pipe way to verify that it has been expanded to the
desired diameter and roundness. Portions of the host pipe found to
require further work may be selectively expanded again by moving
the expansion tool into longitudinal position and actuating the
expansion members.
[0062] Once the expansion operations referred to in block 404 are
complete, the new inner liner pipe is inserted ("sliplined") into
the expanded host pipe (block 405 on FIG. 13). This may be done via
conventional methods suitable to the conditions of the particular
project (e.g., the geography and soil type of the surrounding
terrain, the type and size of the replacement pipe, and the
coefficient of friction between the new pipe and the host pipe).
Suitable "slipline" methods may include, for example, using a crane
to place the inner liner pipe in position, in segments or in a
single piece, and then pulling the inner liner pipe through the
host pipe with cables and a winch. This disclosure is not limited
to any user-selected method of inserting, or "sliplining" the inner
liner pipe into place.
[0063] In many applications of expandable (and typically
corrugated) host pipes, the expansion operation will typically
increase the diameter of the host pipe by one to four inches. Thus,
the new inner liner pipe can be selected to provide a comparable
(i.e. the same or larger) inside diameter as the operational
diameter of the original host pipe. The new inner liner pipe may be
made from any material that meets the industry standards. In
preferred embodiments, the new pipe is made from 16 to 20 gauge
steel because it provides strength and fire-resistance while
maintaining enough flexibility to negotiate any dimensional
anomalies that remain in the host pipe after the expansion. Other
inner liner pipes may be made, for example, from PVC or fiber-resin
composites.
[0064] Next, the new inner liner pipe is stabilized in preparation
for grouting the annular space between the host pipe and the new
liner pipe (block 406 on FIG. 13). As mentioned above in the
"Summary" section, such stabilization may be accomplished by, for
example, filling the inner liner pipe with a fluid (such as water)
or pressurizing the inner liner pipe. Pressurization may be done
using any conventional techniques, such as temporarily sealing the
ends of all or a segment of the inner liner pipe with collar
gaskets before introducing fluid under pressure. The stabilization
step protects the new inner liner pipe during the subsequent
grouting process (block 407) where the weight of the uncured grout
could cause an unpressurized inner liner pipe to buckle or deform.
In presently preferred embodiments, the pressurizing fluid is air
or water, but this disclosure is not limited in this regard.
[0065] In other embodiments (not illustrated), particularly where
pressurization of the inner liner pipe may be impractical or
unsuitable, inner liner pipe may be filled with a liquid instead,
such as water. Similar to pressurization, filling the inner liner
pipe with liquid protects the new inner liner pipe during the
subsequent grouting process (block 407) where the weight of the
uncured grout could cause an otherwise empty inner liner pipe to
buckle or deform.
[0066] Block 407 on FIG. 13, as noted above, refers to the step of
filling the annular space between the host pipe and the new inner
liner pipe (while stabilized) with grout. Preferably, the grout
fills the annular space, but in some embodiments the annular space
is at least partially filled with grout. This is done via any
conventional technique, such as pressure-injecting a conventional
cement grout, or by injection of a hydrophilic resin and water.
Such hydrophilic resins have a strong affinity for water, and
expand on contact with water. When cured, the resin becomes an
effective grout.
[0067] A common failure in conventional sliplining operations is
caused by voids left surrounding the exterior of the inner liner
pipe. Voids below the liner pipe reduce structural support for the
pipe which may cause the pipe to buckle under its own weight.
Additionally, voids above the pipe may collapse and create a point
load on the pipe, which can deform or break the pipe. Pressurized
grout fills not only the space between the host pipe and the new
inner liner pipe, but can also help fill voids in the soil around
the exterior of the host pipe and thereby reduce the frequency of
those failures.
[0068] Returning to FIG. 13, block 408 refers to the step of
removing the stabilization measures from the inner liner pipe.
Typically this will involve draining the inner liner pipe of fluid
(fill liquid or pressure fluid) after the grout has cured. Block
409 refers to the step of memorializing the condition of the new
refurbished pipe after the inner liner pipe has been deployed and
the annular space has been filled with grout. Again, conventional
methods appropriate to the nature of the projects may be used to
perform this step. In some cases, it may be necessary to have an
inspection performed by the proper regulatory authority.
[0069] FIG. 14 is a flow chart illustrating a variation of the
method of FIG. 13, adding a cutting step. As such, FIG. 14 depicts
a variation of the "first refurbishment method" as originally
described in the "Summary" section above. The embodiments described
above with reference to FIGS. 1 through 12 may be used in the
method of FIG. 14. On FIG. 14, blocks 501 through 510 recite, in
summary form, the steps of the method 500, which, with the
exception of block 504, are described in greater detail in the
written disclosure immediately above with further reference to the
corresponding steps in method 400, depicted on FIG. 13.
[0070] Comparison of FIGS. 13 and 14 will show that the primary
difference is the addition of block 504 in method 500 on FIG. 14,
in which selected portions of the host pipe may be cut prior to the
step of running the expansion tool. Apart from the disclosure
associated with block 504 (which follows immediately below), all of
the disclosure above associated with method 400 on FIG. 13 applies
in all respects to the corresponding steps in method 500 on FIG.
14. As noted, the following disclosure focuses on block 504 on FIG.
14.
[0071] Block 504 on FIG. 14 refers, as noted, to the step of
cutting selected portions of the host pipe prior to the step of
running the expansion tool (block 505). As discussed above in the
"Summary" section of this disclosure, situations may arise during
refurbishment operations in which it may be advantageous to make
such cuts in the host pipe prior to expansion. Such situations
include, for example, (1) when the host pipe is corroded at its
invert, or (2) when the host pipe includes a helical seam, such as
a spiral lock seam, or (3) at host pipe joints, where lengths of
host pipe were spliced together end-to-end when the host pipe was
originally laid in situ. In such situations, the host pipe may be
relatively inelastic in the areas around the anomaly, as compared
with areas away from the anomaly. Applying expansion pressure on
such inelastic zones may cause undesirable effects, such as the
host pipe bursting or cracking around the anomaly. Alternatively,
in such situations, the host pipe may be disproportionately
stronger than in the areas around the anomaly, and thus
disproportionately resistant to expansion. The anomaly thus tends
to constrain the expansion tool from delivering its planned amount
of deflection of the host pipe in order to accommodate the inner
liner pipe when deployed later. Overall, any one of a number of
adverse effects may result. For example, (1) cracked or burst host
pipe may not be able to function properly as a support around the
inner liner pipe, and/or (2) an unexpanded section of host pipe may
obstruct the inner liner pipe from being sliplined in, and/or (3)
an unexpanded section of host pipe may cause the inner liner pipe
to get stuck during sliplining operations, and/or (4) an unexpanded
section of host pipe may obstruct proper distribution of grout
between host pipe and inner liner pipe.
[0072] In situations where the locations of corroded or
disproportionately strong host pipe are known and can be
anticipated, it may be advantageous to preemptively cut the host
pipe through the anomaly prior to expansion. This may be done using
any conventional cutting apparatus, such as a remotely controlled
cutting buggy running along a track disposed in the bottom (invert)
of the host pipe. The cutting buggy may provide rotary cutting
wheels, for example, to make the cuts through the wall of the host
pipe. In other applications, the cutting buggy may provide other
cutting apparatus, such as oxycetaline cutting or electric arc
gouging/cutting. This disclosure is not limited to any particular
cutting apparatus used to perform the cutting step in block 504 on
FIG. 14.
[0073] It will be appreciated that according to the "first
refurbishment method" (smoothing out waves) originally described in
the "Summary" section above, the host pipe will expand differently
during pipe expansion, per block 505 on FIG. 14, in areas where the
host pipe has been cut, per block 504 on FIG. 14. Per earlier
disclosure associated with FIGS. 1 through 12, host pipe expansion
exerts radial forces on the host pipe. In areas where the host pipe
has not been cut, the radial forces flatten the corrugations on the
host pipe, and cause circumferential deflection of the host pipe,
leaving a host pipe of larger effective internal diameter after
expansion. In contrast, in areas where the host pipe has been cut,
the radial forces will also cause the host pipe to "open up" where
it has been cut, via bending at the circumferential point opposite
the cut. Such "opening up", assuming the associated bending
deflection of the host pipe is plastic, will have the same overall
effect of leaving a host pipe of larger effective internal diameter
after expansion.
[0074] To avoid doubt, while currently preferred embodiments
throughout this disclosure so far, have referred to corrugated
culverts and pipes as the host pipe, it will be appreciated that
the inventive aspects of this disclosure are not limited in this
regard. It will be understood that the methods and tools of this
disclosure in accordance with the "first refurbishment method"
(smoothing out waves) are operable on any expandable host pipe
falling within definition of "expandable" as set forth earlier,
namely culverts and pipes having an existing wavy or folded annular
or circumferential profile, such that, responsive to a controlled
radial force, the "waves" or "folds" will collapse or "smooth out",
allowing a limited expansion of the effective inside diameter of
the pipe without intentionally rupturing the pipe.
[0075] FIGS. 15, 16, 18A through 18G, 19 and 22 illustrate a
"freeze frame" series of operations in accordance with a second
embodiment of the disclosed technology (the "second refurbishment
method" as described in the "Summary" section above). It will be
recalled that the "second refurbishment method" expands the host
pipe primarily by separating a longitudinal cut made along the
length of the host pipe, (rather than by "smoothing out" the
"waves" in the periphery of the host pipe per the "first
refurbishment method"). FIGS. 17A through 17D illustrate features
and aspects of one embodiment of expansion tool 700 that may be
used generally for tubular expansion, including in association with
either the "first refurbishment method" or the "second
refurbishment method" also disclosed herein. FIGS. 20 and 21
illustrate features and aspects of inflatable bulkhead 820 that may
be used generally for sealing annular spaces to be grouted,
including in association with either the "first refurbishment
method" or the "second refurbishment method" also disclosed
herein.
[0076] For the purposes of the immediately following disclosure,
FIGS. 15 through 22 should be viewed together. Any part, item, or
feature that is identified by part number on one of FIGS. 15
through 22 has the same part number when illustrated on another of
FIGS. 15 through 22.
[0077] FIG. 15 illustrates a first stage of the second
refurbishment method, in which existing host pipe 600 is to be
refurbished. Similar to host pipe H on FIGS. 1 through 12, host
pipe 600 on FIG. 15 is illustrated with corrugations 601. This is
because buried host pipes requiring refurbishment, of which host
pipe 600 on FIG. 15 is typical, are frequently corrugated pipes.
However, it will be understood that corrugations 601 in host pipe
600 are ancillary to the second refurbishment method. As described
in the "Summary" section above, the second refurbishment method is
directed to plastic deformation of the host pipe via separation of
a longitudinal cut, in contrast to the first refurbishment method,
which is directed to plastic deformation of the host pipe via
"smoothing out" of the waves in the corrugations.
[0078] Quite frequently, existing host pipe 600 will have a
gradient or slope from one end to the other, to encourage surface
runoff drainage through the host pipe from the surrounding terrain.
This gradient is illustrated on FIG. 15 by host pipe 600 having
upper end 602U and lower end 602L. It will be appreciated that in
some situations, not illustrated, host pipe 600 may be level, in
which case 602U and 602L would not apply. In such situations, the
second refurbishment method described in this disclosure is the
same, except that any of the associated disclosure discussing the
effect of a host pipe gradient or slope does not apply.
[0079] On FIG. 15, host pipe 600 is being cleaned, and having
internal debris D removed, before commencement of refurbishment
operations. Optionally, the internal condition of host pipe 600 may
also be memorialized immediately before and/or after cleaning. Such
memorialization may be accomplished by convention image-capture
technology such as video or still photography, and this disclosure
is not limited in this regard.
[0080] The cleaning stage illustrated on FIG. 15 may be
accomplished by any suitable conventional protocol. FIG. 15
illustrates one example of a suitable cleaning protocol. This
disclosure is not limited to the cleaning protocol illustrated and
described with reference to FIG. 15.
[0081] With further reference to FIG. 15, cleaning fluid spray head
603 is inserted into host pipe 600 from lower end 602L. Supply
hose/handle 604 enables spray head 603 to be moved up and down the
length of host pipe 600. In the embodiment illustrated on FIG. 15,
spray head is directional, and shoots cleaning fluid back down the
gradient to lower end 602L. Debris D from the cleaning process
washes with the gradient down to lower end 602L, where it drains
out of host pipe 600. A suitable container, such as net bag 605,
catches the solids in debris D as they drain, enabling later
offsite disposal of the solids. It will be appreciated that in the
embodiment of FIG. 15, advantage may be taken of the gradient from
upper end 602U to lower end 602L in order to assist cleaning and
draining. This disclosure is not limited in this regard, however.
Examples of cleaning fluids that may be dispensed by spray head 603
include steam or high pressure water. Alternatively, a solvent may
be added.
[0082] FIG. 16 illustrates the cutting stage of the second
refurbishment method. A longitudinal cut 615 is made in host pipe
600 along the entire length of host pipe 600. Advantageously,
longitudinal cut 615 is made in the bottom or "invert" (nadir) of
host pipe 600, although this disclosure is not limited in this
regard. The cutting stage illustrated on FIG. 16 may be
accomplished by any suitable conventional protocol. FIG. 16
illustrates one example of a suitable cutting protocol. This
disclosure is not limited to the cutting protocol illustrated and
described with reference to FIG. 16.
[0083] In FIG. 16, and electrically-powered buggy 610 moves up the
gradient in host pipe 600, from lower end 602L to upper end 602U,
on track 612. Electric supply cables and/or pull cables 613 deliver
power to buggy 610. Buggy 610 may be self-propelled on track 612,
or may require to be pulled along track 612. Rotating circular saw
611 is attached to buggy 610, and is also powered electrically.
Circular saw 611 is pre-set for parameters such as rotation speed,
depth of cut, etc., in order to make a suitable longitudinal cut
615 in host pipe 600.
[0084] In the embodiment illustrated on FIG. 16, buggy 610 moves up
the gradient from lower end 602L to upper end 602U, as shown by the
arrow on buggy 610. Running the buggy uphill enables good control
over the speed at which buggy 610 moves, so as to encourage a clean
longitudinal cut 615. This disclosure is not limited, however, to
direction of travel of buggy 610.
[0085] In other embodiments (not illustrated) buggy 610 may be
self-propelled on large wheels (without a track), or via continuous
self-propelled tracks (such as seen on bulldozers or military
tanks). This disclosure is not limited to any particular type of
propulsion of buggy 610, with or without track 612. In selecting a
propulsion method for buggy 610, however, attention should be paid
to the fact that buggy 610 may have a "bumpy ride" if it runs
directly on corrugations 601 in host pipe 600. Such a "bumpy ride"
may affect the quality of longitudinal cut 615.
[0086] FIGS. 18A through 18F are a series of "freeze frame"
illustrations depicting the host pipe expansion stage of the second
refurbishment method. The expansion stage of the second
refurbishment method may be accomplished by any suitable
conventional expansion protocol. FIGS. 18A through 18F illustrate
one example of a suitable expansion protocol using a specially
developed expansion tool, illustrated on FIGS. 17A through 17D,
customized to provide suitable isolated outward radial force in the
expansion stage. As noted in the disclosure above associated with
FIGS. 1 and 2, isolated outward radial force is highly advantageous
in the expansion stage in order to minimize buckling or accordion
deformation of the host pipe. This disclosure is not limited,
however, to the expansion protocol illustrated and described with
reference to FIGS. 18A through 18F, deploying the expansion tool
illustrated and described with reference to FIGS. 17A through
17D.
[0087] Earlier disclosure is worth repeating here to underscore the
advantage of isolated outward radial force provided during
expansion of host pipe 600 on FIGS. 18A through 18F. Such isolated
outward radial force is in distinction to prior art tools and
processes where dragging oversized conical or tapered tools through
constricted host pipe openings caused bursting of the host pipes
via a combination of longitudinal force and radial force. As noted
in the "Summary" section above, bursting of the host pipe destroys
the host pipe's ability to be part of the refurbishment, and
requires the inner liner pipe to be brought in immediately behind
the bursting tool in order to prevent collapse of the surrounding
soil previously supported by the host pipe. Further the
longitudinal forces created in pipe bursting can cause the host
pipe to buckle, or to collapse into an accordion shape, creating
severe operation difficulties for the refurbishment operation.
[0088] Looking first at FIGS. 17A through 17C, expansion tool 700
is a generally elongate, cylindrical assembly that displaces in
three directions, indicated on FIG. 17A by arrows 701A, on FIG. 17B
by arrow 701B and on FIG. 17C by arrows 701C. FIG. 17A depicts
expansion tool 700 including a generally conical end assembly 720,
in which two extendable stabilizers 725 reside. Actuation of
stabilizers 725 causes them to extend in the direction of arrows
701A from a flush position (see FIG. 17C) to an extended position
(see FIGS. 17A and 17B). The purpose of actuating stabilizers 725
is so that, when expansion tool 700 is within host pipe 600 (not
shown on FIGS. 17A through 17C), stabilizers 725 may engage the
interior wall of host pipe 600 and hold end assembly 720
rotationally immobile. When de-actuated, stabilizers 725 move in
the opposite direction to arrows 701A on FIG. 17A, and return
towards a flush position as illustrated on FIG. 17C.
[0089] FIG. 17B depicts expansion tool 700 further including end
assembly 720 rotationally connected to expansion assembly 710. As
will be described below with reference to FIG. 17D, internal
mechanisms in expansion tool 700 enable expansion assembly to make
a controlled relative rotation with respect to end assembly 720, as
indicated on FIG. 17B by arrow 701B. The controlled rotation is
bi-directional, as selected by the operator (that is, in the
direction of arrow 701B and in the opposite direction of arrow
701B).
[0090] FIG. 17C depicts expansion assembly 710 on expansion tool
700 further able to expand and retract. Upon actuation, floating
radial force surface 711B separates from stationary radial force
surface 711A in the direction of arrows 701C. FIG. 17C further
depicts that such separation, upon actuation, is enabled by
corresponding separation of a series of neighboring internal
arcuate segments 713. When de-actuated, floating radial force
surface 711B retracts towards stationary radial force surface 711A
in the opposite direction of arrows 701C.
[0091] FIG. 17D depicts internal mechanisms in expansion tool 700
suitable to enable the features and displacements of expansion tool
700 that are illustrated and described immediately above with
reference to FIGS. 17A through 17C. In the embodiment of FIG. 17D,
all of the internal mechanisms are hydraulic, although this
disclosure is not limited in this regard. Looking at FIG. 17D, and
with momentary reference to FIG. 17A, extension and retraction of
hydraulic pistons 721 in end assembly 720 enables corresponding
extension and retraction of stabilizers 725 in the direction of
arrows 701A (and in the reverse of arrows 701A). Note that the mass
of end assembly 720 on FIG. 17D has hidden a second hydraulic
piston 721 from view.
[0092] With continuing reference to FIG. 17D, and with momentary
reference to FIG. 17B, actuation of hydraulic motor 731 causes
rotation of pinion gear 732. It will be appreciated from FIG. 17D
that hydraulic motor 731 and pinion gear 732 are connected to
expansion assembly 710 on FIG. 17B. Pinion gear 732 on FIG. 17D
engages with ring gear 733. FIG. 17D depicts ring gear 733
connected to end assembly 720. Thus, actuation of hydraulic motor
731 causes controlled relative rotation of end assembly 720 and
expansion assembly 710, shown on FIG. 17B by arrow 701B (and in the
reverse of arrow 701B).
[0093] With continuing reference to FIG. 17D, and with momentary
reference to FIG. 17C, extension and retraction of hydraulic
pistons 712 enables corresponding separation and retraction of
arcuate segments 713, which in turn causes corresponding separation
(expansion) and retraction of stationary radial force surface 711A
and floating radial force surface 711B, as shown on FIG. 17C by
arrows 701C (and in the reverse of arrows 701C). It will be noted
in the embodiment of expansion tool 700 in FIGS. 17A through 17D,
one radial force surface (711A) is stationary, while the other
radial force surface (711B) is floating, i.e. extends and retracts.
This disclosure is not limited in this regard, and suitable
expansion tools in other embodiments may include opposing radial
force surfaces that float in concert with each other.
[0094] As noted above, FIGS. 18A through 18G are a series of
"freeze frame" illustrations depicting the host pipe expansion
stage of the second refurbishment method. The example of expansion
tool 700 (as illustrated and described above with reference to
FIGS. 17A through 17D) is used throughout FIGS. 18A through 18F to
illustrate the second refurbishment method. FIGS. 18A through 18F
are end elevation views as shown generally on FIG. 17D, showing
expansion tool 700 in operation within host pipe 600. FIG. 18G
depicts host pipe 600 after expansion operations on host pipe 600
are complete, with expansion tool 700 removed and inner liner pipe
800 inserted.
[0095] It will be understood that the expansion operations to be
described immediately below with reference to FIGS. 18A through 18F
are done over the length of host pipe 600 on a station-by-station
basis. That is, the length of host pipe 600 is divided into a
series of stations each approximately the longitudinal length of
expansion assembly 710 as shown on FIG. 17B. In the expansion
stage, expansion tool 700 moves along a path inside host pipe 600
stopping at each station to perform expansion operations, before
moving on to the next station.
[0096] In FIG. 18A, at the first station, stabilizers 725 are
extended from end assembly 720 to engage the interior wall of host
pipe 600 and hold end assembly 720 rotationally immobile.
Longitudinal cut 615 on FIG. 18A is substantially as created by
circular saw 611 on FIG. 16.
[0097] In FIG. 18B, floating radial force surface 711B separates
from stationary radial force surface 711A, per arrow 701C, until
floating radial force surface 711B engages a local section of the
interior wall of host pipe 600. In FIG. 18C, continued actuation of
expansion assembly 710 (refer FIG. 17B) causes stationary radial
force surface 711A to move towards and engage a local section of
the interior wall of host pipe 600 opposite floating radial force
surface 711A, as indicated by arrow 740. Sometime between FIGS. 18B
and 18C (advantageously when stationary and floating radial force
sections 711A and 711B are both touching host pipe 600, but before
deformation pressure is engaged), stabilizers 725 may be retracted,
as shown on FIG. 18C. Alternatively (not illustrated), stabilizers
725 may remain extended and engaged on host pipe 600 during FIG.
18C. With continuing reference to FIG. 18C, continued separation of
stationary and floating radial force surfaces 711A and 711B causes
local plastic, non-destructive deformation of host pipe 600 at the
local sections of the interior wall on which stationary and
floating radial force surfaces 711A and 711B are engaged. More
specifically, locally at stationary and floating radial force
surfaces 711A and 711B, continued separation of stationary and
floating radial force surfaces 711A and 711B increases the
unobstructed interior diameter of host pipe 600 by a predetermined
amount via non-destructive plastic separation of longitudinal cut
615.
[0098] It will be understood that between FIGS. 18C and 18D,
although not illustrated, stationary and floating radial force
surfaces 711A and 711B are retracted, and if necessary (i.e. if
previously retracted), stabilizers 725 are extended again to engage
the interior wall of host pipe 600 and hold end assembly 720
rotationally immobile. Expansion assembly 710 (refer FIG. 17B) is
then rotated a predetermined rotational displacement with respect
to end assembly 720. Referring now to FIG. 18D, the operations
described above with reference to FIG. 18C are repeated on a new
local section of the interior wall of host pipe 600. Per FIG. 18D,
continued separation of stationary and floating radial force
surfaces 711A and 711B increases the unobstructed interior diameter
of host pipe 600 at this new local interior wall section by a
predetermined amount via non-destructive plastic separation of
longitudinal cut 615.
[0099] Moving on to FIG. 18E, it will be understood that between
FIGS. 18D and 18E, again although not illustrated, expansion
assembly 710 (refer FIG. 17B) is again rotated a predetermined
rotational amount with respect to end assembly 720, per the steps
described in the immediately preceding paragraph with reference to
operations between FIGS. 18C and 18D. Referring now to FIG. 18E,
the operations described above with reference to FIGS. 18C and 18D
are repeated on a new local section of the interior wall of host
pipe 600. Per FIG. 18E, continued separation of stationary and
floating radial force surfaces 711A and 711B increases the
unobstructed interior diameter of host pipe 600 at this new local
interior wall section by a predetermined amount via non-destructive
plastic separation of longitudinal cut 615.
[0100] Moving on to FIG. 18F, it will be understood that between
FIGS. 18E and 18F, again although not illustrated, expansion
assembly 710 (refer FIG. 17B) is again rotated a predetermined
rotational amount with respect to end assembly 720, per the steps
described in the immediately preceding paragraph with reference to
operations between FIGS. 18D and 18E. Referring now to FIG. 18F,
the operations described above with reference to FIGS. 18C, 18D and
18E are repeated on a new local section of the interior wall of
host pipe 600. Per FIG. 18F, continued separation of stationary and
floating radial force surfaces 711A and 711B increases the
unobstructed interior diameter of host pipe 600 at this new local
interior wall section by a predetermined amount via non-destructive
plastic separation of longitudinal cut 615.
[0101] The operations described above with reference to FIGS. 18A
through 18F are repeated until the unobstructed interior diameter
of host pipe 600 is increased overall, at the first station, a
desired amount via non-destructive plastic separation of
longitudinal cut 615. Expansion tool is moved on to the second and
subsequent stations, and expansion operations as described above
with reference to FIGS. 18A through 18F are repeated at each
station until the unobstructed interior diameter of host pipe 600
is increased overall, at the second and subsequent stations, a
desired amount via non-destructive plastic separation of
longitudinal cut 615. Eventually, the unobstructed interior
diameter of host pipe 600 is increased overall, over its entire
length, a desired amount via non-destructive plastic separation of
longitudinal cut 615.
[0102] At this point, the expansion stage of the second
refurbishment method is complete. Expansion tool 700 is withdrawn,
and a new inner liner pipe 800 is inserted inside the expanded host
pipe 600. FIG. 18G shows, in cross-section, host pipe 600 expanded
per expansion operations described above with reference to FIGS.
18A through 18F, with liner pipe 800 inserted inside. Liner pipe
800 may be inserted inside host pipe 600 by any suitable method,
and preferably by sliplining as described above with reference to
FIGS. 11 and 13. In currently preferred embodiments, liner pipe 800
has a smooth profile on both inner and outer surfaces, although
this disclosure is not limited in this regard. Other embodiments
may deploy a corrugated liner pipe 800 to give liner pipe
additional intrinsic strength. Different deployments may call for a
balance between liner pipe strength for a given diameter or weight,
versus the coefficient of friction generated when inserting the
liner pipe into the host pipe. Liner pipe 800 may typically be made
of a light weight, hard wearing material, such as 16 to 20 gauge
steel, or PVC, or a fiber-resin composite. It will be nonetheless
appreciated that this disclosure is not limited to any specific
material for liner pipe 800.
[0103] It will be further appreciated from FIG. 18G that, with host
pipe 600 now in an expanded state, the outside diameter and wall
thickness of liner pipe 800 may be selected to provide an inner
diameter of liner pipe 800 that is comparable to the effective
operating diameter of host pipe 600 before expansion. By
"comparable", the inner diameter of liner pipe 800 may be selected
to be at least as large as the effective operating diameter of host
pipe 600 before expansion, if not larger. As noted in the "Summary"
section of this disclosure above, this aspect of disclosure may be
particularly advantageous in applications where the capacity of
flow capability of host pipe 600 is desired to be maintained or
even improved after refurbishment.
[0104] Purely by way of example, and not limiting this disclosure
in any way, many existing host pipes needing refurbishment are in a
range of unexpanded diameters of between 18'' and 24''. Current
embodiments of expansion tools consistent with this disclosure are
16''-22'' in unexpanded diameter and are configured to generate up
to 5'' of local expansion. This allows inner liner pipes of
0.5''-1'' wall thickness to be easily inserted into expanded host
pipes and retain/replicate the original unobstructed diameter of
the host pipe.
[0105] Further, as noted in the "Summary" section of this
disclosure above, the introduction of liner pipe 800 only after
host pipe 600 has been completely expanded greatly enhances the
probability of the success of the job. This is in contrast to prior
art processes where the inner liner pipe has to follow right after
a host pipe bursting tool in order to avoid collapse of the
surrounding soil into the host pipe void. Further, the introduction
of liner pipe 800 only after host pipe 600 has been completely
expanded allows the annular space between liner pipe 800 and host
pipe 600 to be grouted.
[0106] The grouting stage of the second refurbishment method is
illustrated on FIGS. 19 and 22. The grouting stage illustrated on
FIGS. 19 and 22 may be accomplished by any suitable conventional
protocol. FIGS. 19 and 22 illustrate one example of a suitable
grouting protocol using specially developed inflatable bulkheads
820, illustrated on FIGS. 20 and 21, customized to dispense liquid
grout in the annular space between liner pipe 800 and host pipe
600, and retain the grout while it cures. This disclosure is not
limited, however, to the grout protocol illustrated and described
with reference to FIGS. 19 and 22, deploying the inflatable
bulkheads illustrated and described with reference to FIGS. 20 and
21.
[0107] FIG. 20 depicts inflatable bulkhead 820 comprising
inflatable ring 821 supplied (inflated) via inflation valve 822.
Inflatable ring 821 may be made from conventional inflatable
materials, such as rubber or rubber composites, and inflation valve
822 is conventional. Inflatable bulkhead 820 also includes at least
one (on FIG. 20, three) grout fittings 823. Grout fittings 823 pass
through inflatable ring 821 and are conventionally sealed at their
points of insertion through the wall of inflatable ring 821. Grout
fittings 823 are adapted to allow liquid grout to pass through.
They may be made of any conventional material such as brass,
stainless steel, etc. Each grout fitting 823 has a connector on one
end suitable for connection with a conventional liquid grout
hose.
[0108] FIG. 19 depicts grout G being injected into the annular
space between liner pipe 800 and host pipe 600. Preferably the
annular space is completely filled with grout G. However, in some
embodiments the annular space is at least partially filled with
grout G. Inflatable bulkheads 820 are installed over either end of
liner pipe 800, and under host pipe 600, and thereby seal the
annular space at either end. Since inflatable bulkheads 820 are
advantageously made of rubber (or a rubber-like material) and are
inflatable, the same bulkhead may be used for several combinations
of outside diameters of liner pipe 800 and corresponding expanded
internal diameters of host pipe 600. For the same reason,
inflatable bulkheads 820 provide good seals of the annular space at
either end of liner pipe 800 and host pipe 600 regardless of
surface or shape irregularities at the points of contact with
inflatable bulkheads 820. Consistent with the disclosure
immediately above with reference to FIG. 20, liquid grout G is
injected into the annular space on FIG. 19 through one inflatable
bulkhead 820 via grout fittings 823. Inflatable bulkheads 820
retain grout G in the annular space while it cures. Once grout G is
cured, inflatable bulkheads 820 may be deflated and removed. At
this point, refurbishment of host pipe 600 according to the second
refurbishment method is substantially complete, and the refurbished
assembly has a cross-section as shown on FIG. 22.
[0109] It will be appreciated from FIG. 19 that liquid grout G may
be injected into the annular space between liner pipe 800 and host
pipe 600 from either or both ends. If only injected from one end,
the inflatable bulkhead 820 at the non-injection end may be a plain
bulkhead without grout fittings 823, or else the grout fittings 823
at the non-injection end may be temporarily plugged.
[0110] FIG. 21 is a cross-section as shown on FIG. 19, and shows
the operational interface between inflatable bulkhead 820 and liner
pipe 800/host pipe 600 in more detail. Inflatable ring 821 is
installed between liner pipe 800 and host pipe 600 and inflated via
inflation valve 822. Grout fitting(s) 823 dispense grout G into the
annular space between liner pipe 800 and host pipe 600.
[0111] Although not specifically illustrated on FIGS. 19 through
21, it may be advantageous to stabilize liner pipe 800 during
grouting operations. It will be recalled from disclosure above of
the first refurbishment method that stabilization of the liner pipe
(via, e.g., filling with water or pressurizing with air) during
grouting operations was advantageous while the grout cured, in
order to prevent possible deformation or even collapse of the liner
pipe under the weight or pressure of the liquid grout. See
"Summary" section above and discussion of block 406 on FIG. 13. The
foregoing discussion of liner pipe stabilization during grouting
operations applies equally to the second refurbishment method, and
where applicable, the prior disclosure above is incorporated here
by reference. As noted, while optional, liner pipe stabilization
may be advantageous in some deployments.
[0112] FIG. 23 is a flow chart describing aspects of the second
refurbishment method, summarizing much of the foregoing disclosure
with reference to FIGS. 15 through 22. Many of the blocks on FIG.
23 are similar to or the same as corresponding labels on FIGS. 13
and 14. The corresponding discussion above of FIGS. 13 and 14,
where applicable, applies to FIG. 23 and is incorporated here by
reference. Where FIG. 23 differs from FIG. 13 or 14, the discussion
above with reference to FIGS. 15 to 22 applies.
[0113] Although the inventive material in this disclosure has been
described in detail along with some of its technical advantages, it
will be understood that various changes, substitutions and
alternations may be made to the detailed embodiments without
departing from the broader spirit and scope of such inventive
material.
* * * * *
References