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Claims  |
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What is claimed is:
1. A method of providing a sealed bond between a manhole having an annular
top face and a manhole frame configured to mount on the annular top face,
the method comprising the steps of
establishing an annular channel on the annular top face of the manhole,
filling the annular channel with a liquid sealing material, then
putting the manhole frame over the annular top face of the manhole in
contact with the liquid sealing material in the channel, and
curing the liquid sealing material to bond the manhole to the manhole frame
and establish a fluid-tight seal therebetween to block inflow of fluid
into the manhole through a space between the manhole and the manhole
frame.
2. The method of claim 1, wherein the manhole frame includes an annular
bottom face and further comprising the step of preparing the annular
bottom face of the manhole frame prior to the putting step to promote
bonding of the manhole frame to the liquid sealing material upon curing of
the liquid sealing material.
3. The method of claim 2, wherein the preparing step includes the step of
applying a primer to the bottom annular face.
4. The method of claim 2, wherein the preparing step includes the step of
scaling the bottom annular face.
5. The method of claim 1, wherein the liquid sealing material is one of a
polyurethane encapsulate, epoxy, and fiberglass that is formulated to cure
after a predetermined period of time to establish a water-tight pliable
seal bonding the manhole to the manhole frame.
6. The method of claim 1, wherein the curing step includes the step of
delaying the putting step for a predetermined period of time to allow the
liquid sealing and bonding material to provide means for supporting the
weight of the manhole frame in spaced relation to the manhole.
7. A method of providing a sealed bond between a manhole having an annular
top face and a manhole frame configured to mount on the annular top face,
the method comprising the steps of
establishing an annular channel on the annular top face of the manhole,
filling the annular channel with a liquid sealing material,
putting the manhole frame over the annular top face of the manhole in
contact with the liquid sealing material in the channel, and
curing the liquid sealing material to bond the manhole to the manhole frame
and establish a fluid-tight seal therebetween to block inflow of fluid
into the manhole through a space between the manhole and the manhole
frame, wherein the establishing step further comprises the steps of
placing an inside channel ring on the annular top face of the manhole
adjacent to an interior side wall of the manhole,
placing an outside channel ring on the annular top face of the manhole
adjacent to the exterior side wall of the manhole, the inner diameter of
the outside channel ring being greater than the inner diameter of the
inside channel ring to establish the annular channel therebetween.
8. The method of claim 2, wherein the establishing step further includes
the step of using an adhesive material to hold the inside and outside
channel rings in place on the annular top face during the filling,
putting, and curing steps.
9. The method of claim 7, wherein the establishing step further includes
the step of preparing the annular top face of the manhole prior to the
placing steps to promote bonding of the manhole to the liquid sealing
material upon curing of the liquid sealing material.
10. The method of claim 9, wherein the preparing step includes the step of
applying a primer to the annular top face.
11. The method of claim 9, wherein the preparing step includes the step of
scaling the annular top face.
12. The method of claim 7, wherein the inside channel is made of structural
foam.
13. The method of claim 7, wherein the outside channel ring is made of
structural foam.
14. A method of bonding a manhole frame to a manhole to block inflow of
fluid into the manhole through a space between the manhole frame and the
manhole, the method comprising the steps of
placing a separate mold on the manhole to establish a walled reservoir on
the manhole,
filling the walled reservoir with a liquid sealing material,
contacting the manhole frame to liquid sealing material in the walled
reservoir, and
supporting the manhole frame on the mold as the liquid sealing material
cures to establish a fluid-tight sealed bond between the manhole frame and
the manhole.
15. The method of claim 14, wherein the placing step includes the steps of
providing a mold and using an adhesive material to hold the mold in place
on the manhole during the filling and contacting steps.
16. The method of claim 15, wherein the using step is completed prior to
the filling step.
17. The method of claim 15, wherein the mold includes two separate mold
members.
18. The method of claim 17, wherein each mold member is ring-shaped.
19. The method of claim 14, wherein each mold sealing material is one of a
polyurethane encapsulate, epoxy, and fiberglass that is formulated to cure
after a predetermined time to establish a water-tight pliable seal bonding
the manhole frame to the manhole.
20. A method of bonding a manhole frame to a manhole to block inflow of
fluid into the manhole through a space between the manhole frame and the
manhole, the method comprising the steps of
placing a mold on the manhole to establish a walled reservoir on the
manhole,
filling the walled reservoir with a liquid sealing material,
contacting the manhole frame to liquid sealing material in the walled
reservoir, and
supporting the manhole frame on the mold as the liquid sealing material
cures to establish a fluid-tight sealed bond between the manhole frame and
the manhole, wherein the manhole includes an annular top face and the
placing step includes the steps of providing an inside channel ring having
a first inner diameter and an outside channel ring having a second inner
diameter greater than the first inner diameter, positioning the inside
channel ring on the annular top face of the manhole, and positioning the
outside channel ring on the annular top face of the manhole around the
inside channel ring and in spaced-apart relation to the inside channel
ring to define the reservoir therebetween.
21. The method of claim 20, wherein the manhole includes a cylindrical
interior wall contiguous to the annular top face, the inside channel ring
includes a radially inner annular wall, and the inside channel ring is
positioned on the annular top face in coaxial relation to the manhole to
lie adjacent to the cylindrical interior wall.
22. The method of claim 20, wherein the manhole includes a cylindrical
exterior wall contiguous to the annular top face, the outside channel ring
includes a radially outer annular wall, and the outside channel ring is
positioned on the annular top face in coaxial relation to the manhole to
lie adjacent to the cylindrical exterior wall.
23. The method of claim 20, wherein the channel rings are made of dense
material to provide means for supporting the manhole frame in contact with
liquid sealing material in the reservoir and in spaced-apart relation to
the underlying annular top face of the manhole.
24. The method of claim 23, wherein the dense material is structural foam.
25. A method of providing a sealed bond between a first manhole section
having an annular top face and a second manhole section configured to
mount on the annular top face, the method comprising the steps of
establishing an annular channel on the annular top face of the first
manhole section;
filling the annular channel with a liquid sealing material, then
putting the second manhole section over the annular top face of the first
manhole section in contact with the liquid sealing material in the
channel, and
curing the liquid sealing material to bond the first manhole section to the
second manhole section and establish a fluid-tight seal therebetween to
block inflow of fluid into the manhole through a space between the first
and second manhole sections.
26. The method of claim 25, wherein the second manhole section includes an
annular bottom face and further comprising the step of preparing the
annular bottom face of the second manhole section prior to the putting
step to promote bonding of the second manhole section to the liquid
sealing material upon curing of the liquid sealing material.
27. The method of claim 26, wherein the preparing step includes the step of
applying a primer to the bottom annular face.
28. The method of claim 26, wherein the preparing step includes the step of
scaling the bottom annular face.
29. The method of claim 25, wherein the liquid sealing material is one of a
polyurethane encapsulate, epoxy, and fiberglass that is formulated to cure
after a predetermined period of time to establish a water-tight pliable
seal bonding the first and second manhole sections.
30. A method of providing a sealed bond between a first manhole section
having an annular top face and a second manhole section configured to
mount on the annular top face, the method comprising the steps of
establishing an annular channel on the annular top face of the first
manhole section,
filling the annular channel with a liquid sealing material,
putting the second manhole section over the annular top face of the first
manhole section in contact with the liquid sealing material in the
channel, and
curing the liquid sealing material to bond the first manhole section to the
second manhole section and establish a fluid-tight seal therebetween to
block inflow of fluid into the manhole through a space between the first
and second manhole sections, wherein the establishing step further
comprises the steps of
placing an inside channel ring on the annular top face of the first manhole
section adjacent to an interior side wall of the first manhole section,
placing an outside channel ring on the annular top face of the first
manhole section adjacent to the exterior side wall of the first manhole
section, the inner diameter of the outside channel ring being greater than
the inner diameter of the inside channel ring to establish the annular
channel therebetween.
31. The method of claim 30, wherein the establishing step further includes
the step of using an adhesive material to hold the inside and outside
channel rings in place on the annular top face during the filling,
putting, and curing steps.
32. The method of claim 30, wherein the establishing step further includes
the step of preparing the annular top face of the first manhole section
prior to the placing steps to promote bonding of the first manhole section
to the liquid sealing material upon curing of the liquid sealing material.
33. The method of claim 32, wherein the preparing step includes the step of
applying a primer to the annular top face.
34. The method of claim 32, wherein the preparing step includes the step of
scaling the annular top face.
35. The method of claim 30, wherein the inside channel ring is made of
structural foam.
36. The method of claim 30, wherein the outside channel ring is made of
structural foam.
37. A method of bonding a first manhole section to a second manhole section
to block inflow of fluid into the manhole sections through a space between
the first and second manhole sections, the method comprising the steps of
placing a separate mold on the first manhole section to establish a walled
reservoir on the first manhole section,
filling the walled reservoir with a liquid sealing material,
contacting the second manhole section to liquid sealing material in the
walled reservoir, and
supporting the second manhole section on the mold as the liquid sealing
material cures to establish a fluid-tight sealed bond between the first
and second manhole sections.
38. The method of claim 37, wherein the placing step includes the steps of
providing a mold and using an adhesive material to hold the mold in place
on the first manhole section during the filling and contacting steps.
39. The method of claim 38, wherein the suing step is completed prior to
the filling step.
40. The method of claim 38, wherein the mold includes two separate mold
members.
41. The method of claim 40, wherein each mold member is ring-shaped.
42. The method of claim 37, wherein the liquid sealing material is one of a
polyurethane encapsulate, epoxy, and fiberglass that is formulated to cure
after a predetermined time to establish a water-tight pliable seal bonding
the manhole frame to the manhole.
43. A method of bonding a first manhole section to a second manhole section
to block inflow of fluid into the manhole sections through a space between
the first and second manhole sections, the method comprising the steps of
placing a mold on the first manhole section to establish a walled reservoir
on the first manhole section,
filling the walled reservoir with a liquid sealing material,
contacting the second manhole section to liquid sealing material in the
walled reservoir, and
supporting the second manhole section on the mold as the liquid sealing
material cures to establish a fluid-tight sealed bond between the first
and second manhole sections, wherein the first manhole section includes an
annular top face and the placing step includes the steps of providing an
inside channel ring having a second inner diameter and an outside channel
ring having a second inner diameter greater than the first inner diameter,
positioning the inside channel ring on the annular top face of the first
manhole section, and positioning the outside channel ring on the annular
top face of the first manhole section around the inside channel ring and
in spaced-apart relation to the inside channel ring to define the
reservoir therebetween.
44. The method of claim 43, wherein the first manhole section includes a
cylindrical interior wall contiguous to the annular top face, the inside
channel ring includes a radially inner annular wall, and the inside
channel ring is positioned on the annular top face in coaxial relation to
the first manhole section to lie adjacent to the cylindrical interior
wall.
45. The method of claim 43, wherein the first manhole section includes a
cylindrical exterior wall contiguous to the annular top face, the outside
channel ring includes a radially outer annular wall, and the outside
channel ring is positioned on the annular top face in coaxial relation to
the first manhole section to lie adjacent to the cylindrical exterior
wall.
46. The method of claim 43, wherein the channel rings are made of dense
material to provide means for supporting the second manhole section in
contact with liquid sealing material in the reservoir and in spaced-apart
relation to the underlying annular top face of the first manhole section.
47. The method of claim 46, wherein the dense material is structural foam.
48. A manhole seal molding kit having component parts capable of being
assembled in the field at a manhole for providing a mold for containing a
sealing and bonding material between a manhole having an annular top face
and a manhole frame or section configured to mount on the annular top
face, the kit comprising the combination of
an inside channel ring having a first inner diameter and being configured
to be mounted on the annular top face of the manhole adjacent to an
interior side wall of the manhole,
an outside channel ring having a second inner diameter and being configured
to be mounted on the annular top face of the manhole adjacent to an
exterior side wall of the manhole, the second inner diameter being greater
than the first inner diameter so that the inside and outside channel rings
are configured to be positioned in coaxial alignment and spaced-apart
relation on the annular top face to form an annular channel thereon having
a radially outer boundary established by the outside channel ring, a
radially inner boundary established by the inside channel ring, and an
annular bottom wall established by the annular top face of the manhole,
whereby the inside and outside channel rings may be mounted on the manhole
to provide a mold forming an annular channel configured to contain a
curable sealing and bonding material in contact with the manhole and a
manhole frame resting on the inside and outside channel rings as the
sealing and bonding material cures.
49. The manhole seal molding kit of claim 48, wherein the inside channel
ring is made of structural foam.
50. The manhole seal molding kit of claim 48, wherein the outside channel
ring is made of structural foam.
51. The manhole seal molding kit of claim 48, wherein each of the inside
and outside channel rings provides means for blocking radial flow of
liquid sealing material deposited into the annular channel to retain the
liquid sealing material in the annular channel while it cures.
52. The manhole seal molding kit of claim 48, wherein the channel rings are
made of dense material to provide means for supporting the manhole frame
in contact with sealing and bonding material contained in the annular
channel and in spaced-apart relation to the underlying annular top face of
the manhole.
53. The manhole seal molding kit of claim 52, wherein the dense material is
structural foam. |
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Claims |
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Description |
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BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to manhole sealing systems and, in particular, to an
apparatus and method for molding a sealing material to establish a
fluid-tight seal and bond either between a manhole and a manhole frame
supported on the manhole (or between two sections of a manhole). More
particularly, this invention relates to an apparatus and method for
providing a mold that can be filled with sealing material to establish a
barrier seal on top of a manhole to block unwanted inflow of groundwater
into the manhole through a space between the manhole and manhole frame (or
between two sections of a manhole).
A manhole is a large diameter vertical pipe often made of brick or a series
of precast concrete sections that extends downward from a point just below
street level to a buried sewer pipe included in a municipal sewerage
system. Typically, a heavy cast iron manhole frame is placed on the
circular top edge of the manhole to hold a manhole cover above the top end
of the manhole at street level. While the manhole cover is visible to
someone standing on the street, the manhole frame supporting the cover
usually is hidden mostly from view by the surrounding street or sidewalk
as long as the manhole cover is in place to block access into the manhole.
In some cases, the street or sidewalk pavement around the manhole frame
acts to hold the manhole frame in place on the manhole. It is also known
to use bolts or other hardware to anchor the manhole frame to the
underlying manhole. The familiar manhole cover rests on a circular ledge
provided near the top end of the manhole frame to lie at street level.
Removal of the manhole cover from the frame exposes a vertical access
aperture that extends downwardly through the hollow manhole frame to
enable service workers to pass through the manhole frame to reach the
downwardly extending manway passage provided inside the manhole.
Unwanted leakage or "inflow" of fluids such as rainwater or groundwater
into a manhole connected to a sewage disposal sewer system is a serious
problem. The typical sewage treatment plant provided to process sewage
conducted through a sewage disposal system is designed to handle sewage
only and is not designed to have enough capacity to handle large volumes
of surface water that leak into the sewage disposal sewers through leaky
manholes. Typically, each municipality will include two separate sewerage
systems. One system of sewers is provided to carry off sewage and other
refuse liquids and waste products to a sewage treatment plant. The other
system is often referred to as the "storm sewer" system and is connected
to street drains and the like to carry off surface water.
A small or large gap between the top face of the manhole and the bottom
face of the manhole frame (or at the joint between two abutting manhole
sections) can provide just enough space for significant amounts of
rainwater, groundwater, or other liquids to leak from the surrounding
ground into the manhole and the sewage disposal sewer pipes connected to
the manhole. Manhole leakage problems can cause too much surface water or
other fluids to be introduced into the sewage disposal sewer system at one
time and therefore overload the capacity of various sewage treatment
stations included in the sewerage system. The capacity of a sewerage
system having a sizable number of leaky manhole frames can be overloaded
quite easily during prolonged and heavy rainstorms.
A gap between a manhole frame and an underlying manhole large enough to
permit surface water to leak into a manhole can develop in several
different ways. Manhole frames tend to vibrate due to loads applied by
traffic moving on the street and over the manhole cover and, over time,
such vibration can cause even heavy manhole frame to move off the
underlying manhole to form a gap therebetween. Such movement can occur
even though the manhole frame is initially anchored in some way to the
manhole. Also, any seal established between the manhole and manhole frame
can deteriorate or fail over time and cause a leakage gap to develop.
A leakage gap can also develop at the joint between two abutting manhole
cylinders. Manholes are typically formed by connecting precast concrete
cylinders together in series to establish a long manhole unit. Water
inflow problems can also arise if any leakage occurs at the joint between
a pair of adjoining cylinders. Poor anchoring and sealing connection
problems are not limited only to manhole frame/manhole connections. It is
also common for leaks to develop because one manhole cylinder has moved
relative to an adjoining manhole cylinder or because a seal provided
between the two cylinders has failed.
An apparatus and method for molding a sealing material to establish a
fluid-tight sealing bond closing any gap between an inground manhole and a
manhole frame without removing the manhole frame from its mounted position
on the manhole would simplify rehabilitation of leaky manholes. An
apparatus and method that could also be used to fill and close any gap at
the joint between abutting manhole cylinder portions would also provide
many benefits to manhole installation and rehabilitation work crews. Also,
an apparatus and method that could be applied to solve fluid inflow
problems affecting a great number of manholes in a sewerage network
quickly, at low cost, and without making it necessary for service workers
to carry a lot of extra tools would be welcomed by many managers of city
and metropolitan sewerage systems.
According to the present invention, an innovative method is provided for
providing a sealed bond between a manhole having an annular top face and a
manhole frame configured to mount on the annular top face of the manhole.
The method can also be used to provide a sealed bond between two adjacent
manhole sections. The method includes the steps of establishing an annular
channel on the annular top face of the manhole and filling the annular
channel with a liquid sealing material. The method further includes the
steps of putting the manhole frame (or other manhole section) over the
annular top face of the manhole and in contact with the liquid sealing
material in the channel and then curing the liquid sealing material. Once
cured, the liquid sealing material bonds the manhole to the manhole frame
(or other manhole section) and establishes a fluid-tight seal therebetween
to block inflow of fluid into the manhole through a space between the
manhole and the manhole frame (or other manhole section).
In preferred embodiments, the annular channel is established on top of the
manhole by placing an inside channel ring on the annular top face of the
manhole adjacent to an interior side wall of the manhole and placing an
outside channel ring on the annular top face of the manhole adjacent to
the exterior side wall of the manhole. The inner diameter of the outside
channel ring is greater than the inner diameter of the inside channel ring
so that the two channel rings can be arranged on top of the manhole to
establish the annular channel therebetween. It is preferable to use an
adhesive material to hold the inside and outside channel rings in place on
the annular top face of the manhole during the filling, putting, and
curing steps.
It is desirable to prepare the surface of the annular top face of the
manhole prior to placing the inside and outside channel rings thereon to
promote bonding of the manhole to the liquid sealing material contained in
the annular channel upon curing of the liquid sealing material. Likewise,
it is desirable to prepare the surface of the annular bottom face of the
manhole frame (or other manhole section) prior to placing the manhole
frame on top of the channel rings to promote bonding of the manhole frame
to the liquid sealing material contained in the annular channel upon
curing of the liquid sealing material. The liquid sealing material is
preferably either polyurethane encapsulate (such as ENCAPSEAL), epoxy, or
fiberglass that is formulated to cure after a predetermined period of time
to establish a water-tight pliable seal blocking inflow of water into the
manhole through the space between the manhole and the manhole frame (or
other manhole section) and bonding the manhole to the manhole frame (or
other manhole section).
Advantageously, the method in accordance with the present invention can be
used to bond a manhole frame (or other manhole section) to a manhole in
such a way as to block inflow or leakage of fluid into the manhole. A
novel manhole seal molding kit is provided to enable workers to practice
the inventive method in the field easily and at low cost. The kit has
component parts such as the inside and outside channel rings which are
capable of being assembled in the field at a manhole to provide a mold for
containing a liquid sealing and bonding material in a walled reservoir in
contact with a manhole frame (or other manhole section) and an underlying
manhole.
Once the two channel rings are properly positioned and retained on the
manhole, liquid sealing material can be deposited in the annular channel
formed by the coaxially aligned channel rings. The heavy manhole frame (or
other manhole section) can then be lowered onto the top portion of the
channel rings to lie in contact with the pool of liquid sealing material
retained in the annular channel. Once the sealing material hardens or
cures in the annular channel mold, a fluid-tight seal is established to
block or plug any gap between the manhole frame (or other manhole section)
and the manhole, and the manhole frame (or other manhole section) is
bonded to the manhole to anchor the manhole frame (or other manhole
section).
Additional objects, features, and advantages of the invention will become
apparent to those skilled in the art upon consideration of the following
detailed description of preferred embodiments exemplifying the best mode
of carrying out the invention as presently perceived.
BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description particularly refers to the accompanying figures in
which:
FIG. 1 is an elevation of a manhole showing an inside channel ring and an
outside channel ring in place on the top face of the manhole in accordance
with the present invention;
FIG. 2 is a view of the manhole of FIG. 1 during filling of an annular
channel formed between the inside and outside channel rings with a liquid
sealing material and of a manhole frame configured to mount on the manhole
and support a manhole cover at street level;
FIG. 3 is an elevation of the manhole of FIGS. 1 and 2 showing the manhole
frame in its mounted position after the liquid sealing material has cured
to form a pliable seal and bond the manhole frame to the manhole;
FIG. 4 is an enlarged view showing use of an air vent tube to discharge air
from a ring-shaped mold cavity defined by the manhole, inside and outside
channel rings, and manhole frame;
FIG. 5 is a view of a manhole wherein a grade ring is used to elevate the
manhole frame relative to the manhole and a pair of inside channel rings
and a pair of outside channel rings are used to establish one annular mold
cavity channel above the grade ring and another annular mold cavity
channel below the grade ring; and
FIG. 6 is a sectional view of two adjacent manhole cylinder sections and a
pair of inside and outside channel rings positioned therebetween to mold a
pliable seal bonding and sealing the upper manhole cylinder section to the
lower manhole section.
DETAILED DESCRIPTION OF THE DRAWINGS
The top portion of a manhole 10 is illustrated in FIG. 1. Typically, a
manhole is a cylindrical structure made of brick or a series of precast
concrete sections that is provided to permit a worker to gain access to a
subterranean sewerage system (not shown) connected to the bottom of the
manhole. Manhole 10 includes a ring-shaped top face 12 and a cylindrical
interior side wall 14 defining an internal manway passage 16.
Initially, the ring-shaped top face 12 is prepared to promote bonding of a
sealing material to be placed in contact with the top face 12. For
example, the face 12 can be cleaned and treated by sandblasting, wire
brushing, scaling, or knocking. It is also possible to use a pneumatic
tool to vibrate and hit the top face 12 of the manhole 10 to ready the top
face 12 to receive a primer such as methel ethel ketone. Once primed, the
top face 12 is prepared to receive a mold apparatus 18 and to be contacted
by a liquid sealing material 38.
A mold apparatus 18 is positioned on top face 12 to form a mold cavity 32
on top of the manhole 10. Mold apparatus 18 can be provided using a field
kit including an inside channel ring 20 and an outside channel ring 22.
Preferably, an adhesive material 24 is used to hold the inside and outside
channel rings 20, 22 in place on the top face 12 of the manhole 10 as
shown in FIG. 1. For example, contact cement, available from Bitumastic,
is a suitable adhesive for this purpose.
Inside channel ring 20 has an inner diameter 26 and is configured to fit on
the top face 12 of manhole 10 to lie in close proximity to the top edge 28
of the cylindrical interior side wall 14 as shown in FIG. 1. Outside
channel ring 22 has an inner diameter 30 that is greater than the inner
diameter 26 of the inside channel ring 20. When arranged on the top face
12 as shown in FIG. 1, the inside and outside channel rings 20, 22 are
positioned in coaxial alignment and spaced-apart relation to form a
circular channel or mold cavity 32 therebetween. A radially inner boundary
of the circular channel 32 is established by a radially outwardly facing
side 34 of the inside channel ring 20. A radially outer boundary of the
circular channel is established by a radially inwardly facing side 36 of
the outside channel ring 22.
The inside and outside channel rings 20, 22 thus cooperate with the top
face 12 of the manhole to form a circular channel 32 that serves as a mold
for containing a liquid sealing and bonding material 38 as shown in FIG.
2. A sealant dispensing tube 40 is used to dispense liquid sealing bonding
material 38 into the circular channel 32. Suitable sealing and bonding
materials include ENCAPSEAL polyurethane, available from PG,10 Miller
Pipeline Corporation; fiberglass, available from DuPont Chemicals; and a
variety of well-known epoxies and polyurethanes. These materials are
formulated to cure after a predetermined period of time.
A manhole frame 42 is shown in FIG. 2 and sized to mount on top of the
channel rings 20, 22 placed on the top face 12 of manhole 10. Manhole
frames 42 are well-known structures that are usually made of cast iron and
configured to support a round manhole cover. Manhole frame 42 includes a
circular, ring-shaped base 44, an upright cylindrical member 46, and a
plurality of circumferentially spaced-apart vertical support webs 48
stiffening the upright orientation of cylindrical member 46. The
cylindrical member 46 includes an annular interior side wall 50 and a
radially inwardly extending annular ledge 52 forming a seat for supporting
a round manhole cover 54 thereon as shown best in FIG. 3. The annular
ledge 52 is formed to include a central opening 56 providing an access
aperture to permit a worker to gain entry into the manway passage 16 of
the manhole 10 once the manhole cover 54 is removed.
After the liquid sealing and bonding material 38 is poured into the mold
cavity provided by circular channel 32 and before that material 38 sets
up, a manhole frame such as frame 42 is set down onto the top surfaces of
the inside and outside channel rings 20, 22 so that substantially the
entire underside 56 of the ring-shaped base 44 that lies in the space
between rings 20, 22 contacts the liquid sealing and bonding material 38.
Preferably, the channel rings 20, 22 are made of a sturdy rubber or
structural foam such as closed-cell polyurethane foam so that the rings
20, 22 can support the weight of the manhole frame 42 and hold the manhole
frame 42 in vertically spaced-apart relation to the top face 12 of manhole
10 while the sealing and bonding material 38 cures. The channel rings 20,
22 are impermeable to the extent necessary to cause the liquid sealing and
bonding material 38 to be retained in the annular channel 32 until the
material 38 cures.
In one embodiment, the liquid sealing and bonding material 38 is allowed to
"set up" enough so that it alone can support the weight of the manhole
frame 42 (or a manhole section as shown in FIG. 8) without relying on
support provided by the channel rings 20, 22. Using this technique, the
sealing and bonding material is allowed to catalyze enough to support a
manhole frame 42 but not enough to disallow a bond between the manhole
frame 42 and the manhole 10. The ambient temperature on the day the liquid
sealing and bonding material 38 is poured into annular channel 32 is one
important factor affecting how fast the material 38 catalyzes.
Essentially, the sealing and bonding material 38 is formulated to cure
after a predetermined time to establish a water-tight pliable annular seal
58 shown bonding the manhole frame 42 to the manhole 10. Preferably, the
underside 56 of the ring-shaped base 44 is prepared using one or more of
the above-described preparation techniques to enhance bonding of the
liquid sealing and bonding material 38 to the manhole frame 42 as it cures
to form the pliable annu | | |
