Note: Descriptions are shown in the official language in which they were submitted.
s~
This invention relates to the installation of sanitary sewers,
and is particularly concerned with the problem of tightly sealing a man-
hole against inflow or outflow of liquid, at the points where a sewer
pipe passes through its walls. The invention also relates to elastomeric
gaskets for resiliently supporting and sealing the space between a pipe
and the surrounding surface of an opening through which the pipe passes.
The invention also relates to a method and a means for installing a gasket
in the peripheral wall of an opening in a manhole for sealing a pipe
passing through such opening. This invention also relates to an apparatus
for supporting a rubber sealing ring or gasket in position while a concrete
structure is cast thereabout, the apparatus serving the deEine an opening
in the concrete structure and to support the rubber-sea]ing ring in posi~
tion while the concrete is formed thereabout in securing relation. This
invention also relates to an apparatus and method for use in the formation
of manholes. In particular, the invention is also concerned with the pro-
duction of precast manhole bases.
The construction of concrete manholes is hea~ dirt~ work and
the m~n who engage in this t~pe ~f w~rk are usually classified as unskilled
labour, the use of the pre-cast base having a pipe section precast therein
and pre-sealed thereto have also been proposed heretofore. Such pre-sealed
structures lack the flexibility needed to accommodate changes that are
frequently dictated by conditions encountered in the field and which are
not known at the time the installation is in the design or planning s-tage.
Hence it is advantageous if a method that is devised for sealing the annu-
lar opening between sewer pipes and concrete manholes is simple, inexpensive
and easy to follow and use.
When forming openings in poured concrete structures it is
necessary to permit ample time for the concrete to set to a relatively rigid
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5~
condition, before the apparatus used to Eorm the opening in the concrete
wall can be removed. Clearly, the longer the setting time, the more forms
that must be used in order to enable the concrete objects to be produced
on a mass production basis. Conversely, the shorter the curing time, the
lower the capital investment that must be made in terms of forms, opening
forming inserts, and the like. If the opening forming inserts are removed
too soon, before the concrete is sufficiently set, the rubber gasket being
set in the concrete opening may be jarred or moved prematurely, and con-
sequently the water-tightness of the seal may be broken, Furtherrnore,
in a heavy business like the concrete pouring business~ and concrete being
a good fastening agent, it is frequently necessary to use a sledge hammer
or some other heavy object to break loose an insert forming an opening in
a concrete wall, These heavy removal techniques contribute to the proba-
bility that the seal formed in place in the poured concrete will be jarred
in a manner which breaks the water-tightness of the seal~
While it is important to keep the interior of a manhole reasonably
dry, this has proved to be a difficult objective to accomplish where pipes
pass through a manhole wall~ Concrete cannot economically be installed with
precisely smooth surfaces. Gaskets and other seals are not always effec-
tive in situations of the type. Too often water seeps past them, where
irregularities, holes or humps are present in the concrete~
The sealing methods and seal constructions heretofore used are
generally time consuming in application, and thus require that ample curing
time be given to the concrete before forms can be removed. Long curing
times for poured concrete, particularly in mass production situations, in-
creases the cost of manufacture of the poured concrete forms. Furthermore~
complicated pouring techniques tend to increase the cost of -the poured
concrete structures.
One proposed sealing technique has been the installation of 0-
rings between suitably shaped collars which surround the pipe and mate
with the inner surface of the opening through which the pipe passes. This
has not been entirely successful, however, for minor imperfections in the
concrete will permit the seepage of moisture past the 0~ring gasket.
Furthermore, such a gasket must be tight along at least two lines of con-
tact,-and this doubles the problem of avoiding irregularities and rough-
ness at any point which comes in contact with the 0~ring. Since the 0~
ring is solid, it is not easily forced into different shapes in order to
conform to local irregularities in the surface or to imperfections in con~
centricity. Since the 0-ring can roll upon itself, it needs extraneous
fittings to make it stay in place.
Because of the conditions under which sewer pipe is installed,
it frequently happens that a section of pipe will lie at an angle to the
overall axis of the pipe, due to subsidence in a muddy trench, lack of care
in back filling, or any of numerous other causes~ When such a condition
arises and affects a section of pipe which is to pass through the wall of a
manhole, it is quite important that the opening through which the pipe
passes should be so constructed as to allow for variations in alignment.
As noted hereinbefore, it has been proposed to use molded gaskets
of elastomeric material and shaped like an ordinary washer. Such washers
are embedded in concrete about their outer margin, and lie normal to the
axis of the pipe. They are subject to the disadvantage that the elastomer
used has lirnited stretch in radia].ly outward direction. That is, even
though it can be made with an undersized hole~ so that the pipe will
stretch the material on being inserted, the amount of stretch is not suf-
icient, in the plane of the gasket, to provide enough freedom for dis-
tortion to preserve a tight seal.
The shear stress imposed on sewer pipe passing through a manhole
opening may be ~ery severe. Sometimes it is suEficiently substantial to
break the pipe right off. If the load, including not only the weight of
the pipe and its contents, but also that imposed by fill, traffic stress,
and vibration, is great, the pipe will be driven down into the inner edge
of the rubber in the lower part of the gasket, directly under the pipe,
and the amount of compression may be sufficient to cause the top of the
pipe to pull away from the inner upper edge of the gasket, thus leaving
a small but opening between gasket and pipe. If the elasticity of the
elastomeric material is sufficient to ensure that its upper rim will follow
the pipe even under the stress conditions stated, it is probably so
"tight" that insertion of the pipe is practically impossible. This fac-
tor is important, for the choice of elastomeric material is limited. The
~STM specifications for rubber gasketed sewer pipe are quite strict. The
elastomer usually conforms to ASTM 13, SBR 1200, or to ASTM 361, Poly-
styrene, TS 2400.
If the embedded portions of the gasket are planar and extend in
a normal direction away from the pipel they may be pulled right out of the
concrete in which they are embedded, under stress of axial movement of the
pipe.
~ne problem which faced the prior art was to provide an improved
technique for positively and permanently anchoring the gasket in the ce-
mentitious material which defines the inner surface of the opening. The
problem did not appear to be solvable by the use of individually molded
unitary gasket washers ["washers" as used herein, refers to centrally~
apertured articles of disk~like shape], since they lack sufficient resis-
tance to compression in their lower, inner portion, which carries the major
load, and were too subject to peripheral separation from the pipe in their
upper portions. Furthermore, such washers would have to be stocked in many
sizes.
~ s noted above, typical prior art structures include a sealing
ring formed of rubber or rubber-like material which is inserted into the
annular cavity formed in the usual pipe joint, whether this joint be
formed between pipe sections or between the entry end of a second of pipe
and the hole in a concrete manhole. Such prior art structures have not
proven to ben entirely satisfactory from the standpoints of ease of in-
stallations, durabili-ty and economy. On one such structure, a sealing ring
inserted into the joint cavity is provided with two flanges which may be
forced apart by means of an auxiliary sealing wedge. The friction of en-
gagement between the sealing ring and the opposing walls of the annular
cavity provide the holding power against dislodgement, but it has been
found that pressure fluid internally of the pipes can blow out the seal or
produce leakage. In another prior art structure, annular metal clamps are
used to secure the sealing ring into the cavity; however, this has proven
to be costly and time consuming in the manufacture and installations thereof.
Du~ch Patent 290,612 of Raatjes dated June 10, 1963 provided a
ring-shaped sealing member of the detachable, flexible coupling being lo-
cated at the radially outwards or inwards directed ring respectively of the
recess, forming the inner or outer surface of the coupling part that com-
prises the sealing me~ber and forming, at both sides of the recess, a strip
whose diameter in the axial direction gradually decreased, beginning at the
edge of the recess. The cross-sectional pattern of the anchoriny member
of the molded washer shown therein seemed to be likely to remain embedded in
its surrounding concrete, no matter how severe the stress upon it might
become. But there seemed to be no way to convert a lineal extrusion having
this cross-sectional shape into a disk-like washer, and no practical way to
provide the endless cavity unless it could be formed by extrusion. Thus,
this Netherlands Patent merely illustrated a gasket in the shape of a
washer, having a corrugated face and having a rim embedded in concrete.
Pressure of the pipe entering the washer distorted the latter, and effected
a seal between pipe and opening. Unfortunately, if the material of which
the gasket is composed was too stiff, it would not permit easy insertion
of the pipe, or, if not stiff enough, it would permit tiny spaces to open
up, under the stress of traffic shocks, through which water could flow.
Several other proposals have made in the past in Canadian Patent
No. 964,043, issued March 11, 1975, to Harry ~. Skinner, disclosed an
apparatus adapted to support a rubber-sealing ring or gasket in posi-tion
while a concrete structure is cast thereabout, the apparatus serving to
define an opening in the concrete structure and to support the rubber-seal-
ing ring in position while the concrete was formed thereabout in securing
relation. The rubbex seal was an elaborate and expensive genexally V~shaped
rubber sealing ring, which fitted between the circular opening in the man-
hole and the pipe penetrating into the interior of the manhole. The sealing
qualities of the rubber seal were said to be enhanced by applying outward
pressure on the arms of the V-shaped seal by driving a wedge-shaped material
into the space existing between the arms of the V~shaped seal. This system
was relatively successful but the V-shaped seal was prone to ripping or
tearing when the pipe is introduced into the interior of -the manhole.
Canadian Patent No. 971,997, granted July 29, 1975, to John
Ditcher, provided a method for installing a sealing member which yieldingly
spans the annular space between the exterior surface of a sewer pipe when
it passed through theopening in the wall of a manhole, and the inner surface
of the opening through which the pipe passed Ditcher disclosed an A-
shaped sealing ring, of a particular specified cross-sections. This A-
shaped seal performed reasonably well but was prone to breaking because of
its hollow-core construction. Further, the two legs of the A-shaped seal
were rather widely angled, and this construction, when the A shaped seal
was distorted by inserting the pipe through the opening in the manhole, tended
to place considerable lateral and upward pressure on the two legs of the
seal, with the result that one or both of the two legs broke free from the
concrete in which the legs are embedded.
The invention provided in Canadian Patent 971,997, issued July
29, 1975 to John Ditcher provided a method for installing a sealing element
for use between the outer surface of a pipe and an opening in a wall through
which the pipe passes. The method included casting a wall of settable
material about a particularly described shaping member. The shaping member
was provided with means defining a peripheral channel to engage a peripheral
gasket ring of resilient material and to house a subs-tantial portion only of
the ring. A remaining portion of the ring was leEt extending into the set-
table material as it is being emplaced. The material was allowed to set and
thereafter the shaping member was removed. This was said to provide a
sealing member within the manhole opening.
The invention in Canadian Patent 996,150 issued Aug. 13, 1976 to
John Ditcher provided a gasket for sealing the space between a pipe and the
surrounding surface of an opening through which the pipe passed. The gasket
was composed of elastomeric material, having, throughout its extend~ a uni-
form cross-section. The gasket is made from an extruded rubber strip, hav-
ing a cross section in the shape of a capital A. When properly positioned
in the manhole opening, the apex of the A was exposed~ and extended radially
inwardly to make first contact with the surface of the pipe. The legs of
the A extended outwardly, and were embedded in cementitious material which
lined the opening in the manhole wall. There was some difficulty in in-
stallation because the elastomeric gasket was made from an extrusion in the
cross-sectional form of a capital A, and hence it required some distortion
of the gasket, to fit this gasket onto the mold rings.
Canadian Patent No. 1,018,331, issued October 4, 1977, to Ronald
E. Yoakum, disclosed a means of automatically affecting a seal at the junc-
tures between a manhole and its inlet and/or outlet sewer pipe connections
by the use of a seal. It also taught a method of installing the seal.
A complex shaped elastomeric annular sealing means was positioned circum
ferentially within the opening in the manhole, was intricately connected to
the wall portion of the manhole and was adapted for automatically engaging
the sewer pipe which was inserted through the manhole opening. The seal
provided a connection which was purportedly water proof. The Yoakum seal
was rather complex in construction and hence both expensive and difficult
to install. The construction of the seal involved a number of grooves and
projections, and hence because of the nature of poured concrete which does
not flow readily into small corners and openings, it was difficult to ob-
tain a water-tight seal, par-ticularl~ when the dry casting technique of
pouring concrete was used.
The invention in Canadian Patent 1,073,938 issued Aug. 18, 1980
to John Ditcher provided a molded elastomeric gasket for resiliently sup-
por-ting a sewer pipe in a manhole opening and sealing the space between
the wall of the opening and the surface of the pipe. The gasket had an
outer cylindrical flange member connected to a main bulbous body portion
by a composite inwardly directed annular web and an outwardly directed
annular web. The main body portion was intetrally connected to region of
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the inner surface o- the cylindrical flange member and inteyral a "T"
cross-section head which was to be embedded in the materi.al lining the manhole
opening.
The invention in Canadian Patent 1,077,692 issued May 2Q, 1980
to John Ditcher was based on the discovery that a seal having all of the
desired properties could be made by utilizing an extrusion having a pipe-
contacting part which, instead of being of A-shape was pear-shape in sec-
tion and was unitarily provided with a T-shaped anchoring part, the stem
of the T being united with the bottom of the pear-shaped part and affording,
when longitudinally considered, a web of substantial height and th.ickness.
Such an extrusion can be used effectively only if handled in the complex
manner specifically set forth.
The invention in Canadian Patent 1,079,993 issued June 2~, 1980
to Dominique Palazzo provided a sealing system, and a method of installation
therefor, whereby the annular opening existing between an opening through
the wall of a concrete manhole, and the inlet~outlet connection of the
sewer pipe or conduit could be effectively and inexpensively sealed in a
water-tight manner, to eliminate infiltration andfor ex-filtration of
liquids into and out of the manhole. The seal is provided was said to be
of sufficient flexibility in construction and design that it would be
capable of continuing to maintain a water-tight seal between the manhole
and the conduit, even when the manhole-conduit combination is subjected
to significant degrees of distortion due to shifting earth, and relative
mis-alignment occurs between the manhole opening and the conduit. The
anchoriny legs were subject to stress and strain, and, even though they
were firmly embedded i.n the concrete, were subject to breakage at theix
flexive points, thus being prone to leakage.
The invention in Canadian Pa-tent 1,112,468 issued Nov. 17, 1981
to ~. Poulette provided a method for installing a~gasket in the peripheral
wall of an opening in a masonry wall a particularly complicated series of
steps using special complicated apparatus. The installing step required a
high degree of expertise and adjustments for deficient sizes was difficult
Typical seals were also disclosed in U.S. Patent Nos. 2,924,~27
2,935,349; 3~348,850 and 3,382,438. Such annular seals were secured in
place either by frictional contact with the walls defining the clearance or
in the alternative by auxiliary clamping devices assembled to the pipe or
to the concrete structure. Such sealing arrangements suffered from the
disadvantage of being diEficult and time consuming to install as well as
being subject to leakage or blowout~
Another example of such gasket is shown in U.S, Patent No~ 3,
832,438, issued August 27, 1974. That gasket consists generally of a peak
portion which engages the pipe and a leg portion which is embedded in con-
crete around the peripheral wall of the opening. In the above patent, the
peak portion of the gasket is positioned in a recess formed between the
mating edges of two oppositely tapered metal molds. The molds are mounted
between the walls of a form and concrete is poured between the walls to
embed the leg portion of the gasket in the peripheral wall of the opening
when the concrete is set.
Another prior art gasket is embedded in the wall of the riser
and projects inwardly of the opening through the riser to engage the outer
surface of the intersecting feed pipe. The gasket is made of a resilient
material which permits the gasket to yield and form a tight seal when the
intersecting pipe is thrust into position.
The invention in U.S. Patent 3,727,876~ issued April 17, 1973
to L.R. Keyser provided a three-piece assembly for the installation of the
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seal. The assembly includes inner and outer mold members, and a ring-shaped
sustaining plate. Thus, this patent provided ap~aratus for forming a void
through a molded wall during fabrication thereof and supporting a gasket
for embedment in the wall about the void.
The invention in U.S. Patent 3,758,060, issued Sept~ 11, 1973
to H.W. Skinner et al provided an apparatus for forming a pipe ]oint sealing
device which serves the dual purpose of supporting a rubber-sealing ring
in position while concrete was cast thereabout and also for defining the
opening into which the sealing ring is installed. This mold device included
plug structure of particular specification. ~lere, too, the major problem
was of easy adjustability. This patent suffered the de-iciency that ad-
justments for different locations of the manhole openings were difficult.
The invention in ~.S. Patent 3,759,285, issued Sept. 18, 1973
to R.E. Yoakum provided an in situ seal in a hole in the wall of a manhole
which was said to permit independent movement of ei-ther the pipes or the
base to maintain the seal and yet to accommodate changing job conditions.
However, because of the embedment means within the coverete, the seal
could be worked lose and hence cause leakage.
The invention in U.S. Patent 3,787,061,issued ~an. 22, 1974 to
R.E. Yoakum provided an in situ seal in a hole in the wall of a manhole in
which the pipe engaging portion was a pair of spaced apart ribs, releasably
biased inwardly but adapted to be flattened into sealing engagement with the
pipe. Such flattening did not always, however, provide a continuous water-
tight seal or movement or misalignment of the pipe or manhole~
In the invention in ~.S. Patent 3,874,068, issued April 1, 1975
to F.W. Skinner et al a pipe joint sealing device is provided which includes
an annular resilient body of rubber-like material. This body is generally
a V-shaped cross-section which includes radially inner and outer annular body
-- 11 --
portions or flanges which is secured to the hole in the wall of the man-
hole by casting or molding concrete around the outer periphery or flange
of the sealing ring such that when the concrete hardens, the ring is
locked into position. A major deficiency is that, in order to effect a
seal between the concrete manhole and the pipe a wedge of rubber material
must be inserted into the space between the inner and outer flanges.
The invention in U.S. Patent 4,333,662 issued June 8, 1982 to
William D. Jones provides a gasket which is particularly suited for seal-
ing the annular space between a pipe and a port in an underground struc-
ture is disclosed. The gasket comprises a hollow annular ring which sur-
rounds the pipe and is connected by a narrow neck to a base at least
partially embedded in the underground structure. The base has means ex-
tending around its outer periphery to mount the seal securely in the
manhole and to provide a block against water seepage across the periphery
of the gasket.
The invention in U.S. Patent 4,387,900 issued June 14, 1983 to
Jack Ditcher et al provides a resilient gasket having an outer annular
flange positioned within a manhole opening and maintained thereagainst un-
der compression by means of a compression band. The gasket is provided
with a central opening defined by an enlarged beaded periphery having an
elasticity adapted to tightly encircle the outer periphery of the pipe.
A folded intermediate section is arranged between and integrally ~oined
to the outer flange and the beaded inner periphery, the intermediate sec-
tion is comprised of first and second diagonally aligned annular portions
integrally joined along a fold to define a V shape which imparts a yielda-
bility enabling the gasket to maintain a watertight seal between the man-
hole opening and the pipe, even in the presence of a significant misalign-
ment therebetween. A strap is positioned about the intermediate section
of the gasket adjacent the inner beaded periphery to enhance the water-
tight seal between the gasket and the pipe. The compression band may be
provided with pairs of substantially V--shaped slots which enable the band
to assume a curvature in a direction transverse to the curved periphery in
order to conform to the curvature of the manhole opening. The clamping
band is formed of a material which is impervious to the surrounding envir-
onment and has a gap and a segment hingedly connected to the main bodythereof for placement in the gap and against the interior surface oE the
gasket to lock the compression band in position and maintain the gasket
flange under compression. An expansion assembly includes an expansion ring
which cooperates with a hydraulic jack and is positioned against the com-
pression band to expand the compression band into position against the
gasket flange and to apply a force uniformly around the compression band
to insure proper positioning and locking of the clamping band.
While each of the above disclosed patented devices may function
satisfactorily for its intended purpose, none has all of the att~ibutes
of a commercially desirable seal. For instance, such a seal should pro~
vide leak resistance up to 10 psi. and should enable the pipe to be de-
flected omnldirectionally up to 20~ with respect to its receiving port.
A satisfactory pipe seal should also prevent the pipe from contacting the
bottom of the pipe-receiving port in response to transverse shear loads on
the pipe as may be imposed by backfill and traffic loads adjacent the man-
~hole. The seal should also be sufficiently compressible as to accommodate
variations in the outside diameters of pipes of different materials which
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have the same nominal inside diameters. I~he seal should also be mounted
securely in place and should be capable of in-field adjustments and repair
to accommodate unusual situations. A desirable seal must also be suffici~
ently foolproof as to be capable of being installed by relatively unskilled
labor, and the seal must be capable of being installed rapidly and in a
minimum amount of time.
In spite of all the aforementioned prior art there is still a
need for an arrangement and method for joining the ends of burried pipe to
a manhole wherein precise location of the manhole is not required, and
whereby a joint can be easily and quickly made. It is also desirable that
a seal be effected automatically when a pipe is inserted into an opening
in the wall of a manhole, and that such seal be maintained upon the
occurrence of universal relative movements of either the manhole or the
pipeline.
It is an object of an aspect of the present invention to provide
a method for installing a sealing member which yieldingly spans the space
betwen a sewer pipe which passes through the wall of a manhole and the inner
surface of the opening through which the pipe passes.
It is an object of another aspect of the invention to provide
shaping elements which will impart the desired configuration to the opening
through which the pipe passes, which can be readily installed at the time
the manhole is being cast, and whose location can be readily controlled at
will, and which can readily removed after the concrete sets.
It is an object of yet another aspect of the invention to con-
figure shaping elements in such a way as to enable them to receive and secure,
ly hold in place an elastomeric gasket whiah surrounds the entire periphery
of the opening and which will hold that gasket element in its intended
position with portions thereof extending outwardly from the shaping element
to be embedded in the concxete as the manhole is poured.
It is an object of still another aspect of the invention to
provide a gasket which can be readily be formed by the extrusion of an elas-
tomeric material, and which, as formed, is readily deformable so that it
may locally yield to accommodate itself to irregularities in surface or in
concentricity as it yieldingly spans the distnace between a sewer pipe and
the surface of the opening through which the pipe passes.
An object of a still further aspect of the present invention is
to provide means automatically effecting a seal at the juncture between a
manhole and its inlet and/or outlet pipe connections when a pipe is inserted
therein and for maintaining the effectiveness of the seal during and after
the occurrence of universal relative movement of either the manhole struc-
ture or the pipe structure.
It is an object of another aspect of the present invention to
provide a new method and apparatus for installing a gasket in the peripheral
wall of an opening in a masonry wall.
It is an object of another aspect of this invention to provide a
combination gasket-supporting and concrete-molding device so arranged that
upon positioning the same in a concrete mold, a concrete structure may be
cast with the hole being formed by the device and a sealing ring or gasket
permanently interlocked into the perimeter of the opening.
It is an object of still another aspect of this invention to pro-
vide an apparatus for forming the opening in a concrete structure and mount-
ing a rubber-sealing ring in relation thereto, the device being constructed
such that once the concrete hardens it may be simply and quickly removed
therefrom.
It an object of yet another aspect of this invention to provide
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a pipe joint sealing device which permits some relative movement between
a section of pipe and another structure to which it is jointed without
causing failure of the seal or damage to the pipe.
An object of another aspect is to provide a manhole joint
arrangement that can be pre-manufactured and which then requires no tools
to install on site.
An object of a further aspect is to provide a manhole joint
arrangement that allows for variations to occur in the relative positions
of the manhole and the pipe connected thereto.
By one broad aspect of this invention, an apparatus is provided
for installing a gasket having a pipe-engaging portion and anchoring por-
tion in the peripheral wall of an opening in a masonary wall, comprising:
(a) an inner mold member of dished shaped having radially outwardly ex-
tending flanges thereon of greater diameter than the opening; (b) an outer
mold member of complementary dished shaped having side flanges thereon
of the same diameter as the opening; (c) means between the outer periphery
of a flange on the outer mold member and a flange on the inner mold mem-
ber adopted to recieve the pipe engaging portion of the gasket and to
allow the anchoring portion of the gasket to project radially outwardly;
and (d) means for temporarily but firmly securing the inner mold to the
outer mold.
By another aspect of this invention, a forming apparatus for
usw in installing in place a sealing ring in the peripheral surface of a
circular opening through a wall formed from a settable material comprising:
(a) an inner mold member of dished shaped having radially outwardly ex-
tending flanges thereon of greater diameter than the opening; (b) an
- 16 -
outer mo].d member of complementary dished shaped having side Elanges there-
on oE the same diameter as the opening; (c) rneans between the outer peri-
phery of a flange on the outer mold member and a flange on the inner mold
member adapted to receive the pipe-engaging portion of the gasket and to
allow the anchoring portion of the gasket to project radially outwardly;
and (d) means for temporarily but firmly securing the inner mold to the
outer mold and to the outer shell designed to form the peripheral surface.
By still another aspect of this invention, a me-thod is provided
for installiny a gasket having a pipe-engaging portion and an anchoring
portion in the peripheral wall of an opening in a poured-in-place masonry
wall, comprising : (i) erecting a form including an inner wall and an outer
wall to define the poured-in-place masonry wall; (ii) providing an assembly
of (a) an inner mold member of dished shaped having radially outwardly ex-
tending flanges thereon of greater diameter than the opening; (b) an outer
mold member of complementary dished shaped having side flanges thereon of
the same diameter as the opening; and (c) a gasket having a pipe engaging
portion and an anchoring portion disposed in means between the outer
periphery of a flange on the outer mold member and a flange on the inner
mold member adapted to receive the pipe-engaging portion of the gasket and
to allow the anchoring portion of the gasket to project radially outwardly;
(iii) suspending the assembly at a desired preconceived location between
the ilmer and outer walls of the form by a depending bar having spaced
apart means thereon to be joined temporarily but firmly to cooperating
means on the assembly; (iv) in filling the space between the walls o:E the
form with settable material, so as to embed the anchoring portion of the
gasket in the settable material; and (v) after setting of the material,
17 _
s~
removing -the form, ~le inner mold member and the outer mold member so as
to leave the pipe~engaging porti~n of the gasket is not embedded in the
set material projecting into the space intended to receive the pipe.
By a still furtiler aspect of this invention, a m~lded elasto-
meric circular gasket is provided for resiliently supporting a sewer pipe
in a manhole opening and sealing the space between the wall of the opening
and the surface of the pipe, the transverse cross-section of the gasket
having: (a) a generally triangular head, having a forward face provided
with an arcuate depressing therein, and a sloping rear face; (b) a gen-
erally rectangular body, integral with the generally triangular head; and
(c) a generally "L" shaped leg depending from the body, and coextensive
with the rear face of the body.
By a further aspect of this invention, a method is provided
for sealing the space between a pipe and an opening in a wall through
which the pipe passes, which method comprises (i) providing a molded
elastomeric circular gasket for resiliently supporting a sewer pipe in a
manhole opening and sealing the space between the wall of the opening and
the surface of the pipe, the transverse cross-section of the gasket hav-
ing^ (a) a generally triangular head, having a forward face provided with
an arcuate depressing therein, and a sloping rear face; (b) a generally
rectangular body, integral with the generally triangular head; and (d) a
generally "L" shaped leg depending from the body, and coextensive with the
rear face of the body; (ii) posi-tioning and supporting the gasket so that
it is located between wall~defining surfaces with its central axis being
general].y perpendicular to the plane of the wall and with its "L"-shaped
leg extending radially outwardly; (iii) filling the wall space surrounding
the gasket with suficient settable material to fill the space and embed
- 18 -
the entire "L"-shaped leg in the settable material; and (iv) allowing -the
settable material to set.
By another aspect of this invention, there is provided for use
in forming a fluid-tight seal between a pipe and a wall opening through
which the pipe passes, a molded elastomeric circular gasket for resilient-
ly supporting a sewer pipe in a manhole opening and sealing the space be-
tween the wall of the opening and the surface of the pipe, the transverse
cross-section of the gasket having: (a) a generally triangular head, hav-
ing a forward face provided with an arcuate depressing therein, and a
sloping rear face; (b) a generally rectangular body, integral with the
generally triangular head; and (c) a generally l'L" shaped leg depending
from the body, and coextensive with the rear face of the body.
By yet another aspect of this invention, there is provided,
for use in forming a fluid-tight seal between a pipe and a wall opening
through which the pipe passes, the combination of a mass of settable
material externally configured to provide the wall opening and a molded
elastomeric circular gasket for resiliently supporting a sewer pipe in a
manhole opening and sealing the space between the wall of the opening and
the surface of the pipe, the transverse cross-section of the gasket having:
~a? a generally triangular head, having a forward face provided with an
arcuate depressing therein, and a sloping rear face; (b) a generally rec~
tangular body, integral with the generally triangular head; and (c) a
generally "L" shaped leg depending from the body, and coextensive with the
rear face of the body extending circumferentially about the opening in the
mass with the entire "L" shaped leg being embedded in settable material
with the head portion of the gasket protruding into the opening.
-- 19 --
~5~
By another aspect of this invention, there is provided, in
combination, a concrete manhole structure having a manhole opening
through which a sewer pipe can pass and a molded elastomeric circular
gasket for resiliently supporting a sewer pipe in a manhole opening and
sealing the space between the wall of the opening and the surface of -the
pipe, the transverse cross-section of the gasket having: (a) a generally
triangular head, having a forward face provided with an arcuate depressing
therein, and a sloping rear face; (b) a generally rectangular body, in-
tegral with the generally triangular head; and (c) a generally "L"
shaped leg depending from the body, and coextensive with the rear face of
the body positioned between the inner and outer walls of the manhole and
extending circumferentially about the wall opening with the entire "L"-
shaped leg being embedded in the concrete surrounding the manhole opening
and with the head portion of the gasket protruding into the manhole open-
ing on the periphery thereof.
By a further aspect of this invention, a shaping element is
provided to define the inner surface of an opening through a wall of
settable material as it is being formedf the shaping element comprising:
inner and outer mating parts, releasably securable together and providing
an inner peripheral wall configured to produce an inner surface to the
opening of the desired size and shape, and an outer peripheral wall
configured to produce an outer surface to the opening, each of the parts
having a transverse flange extending from its periphery, and having means
associated with the Elange to cooperate with the flange upon the other
element, the flanges providing a periphera]. channel; and means associated
with the inner portions of the inner and outer mating parts to secure both
parts together.
- 20 -
~3 ~
By another aspect of this invention, there is provided in a
device for establishing a watertight seal between the inner surface of an
opening in a manhole wall and the outer surface of a sewer pipe passing
through the opening, apparatus for positioning a peripheral gasket of
elastomeric material in a locus within the concre-te of the manhole wall,
the apparatus comprising: an outer shaping element having a peripheral wall
structure of the shape desired for the outer portion of the opening through
the wall and terminating in a flange; an inner shaping element having a
peripheral wall adapted to complement the outer element in providing the
desired shape for the finished opening, the wall terminating in an outwardly
extending flange; the adjacent surfaces of the flanges of the inner and
outer elements providing, between the opposing surfaces, a peripheral re-
cess which configured to receive and support a portion of the gasket
strip first mentionsa; the shaping elements being provided with releasable
clamping means simultaneously to site the shaping elements at a predeter-
mined location within the manhole wall thereby to site the opening, and to
hold them together in use and impose a limited pressure on the gasket~
By yet another aspect of this invention, there is provided, in
a method of installing a sealing element for use between the outer surfaces
of a pipe and an opening in a masonry wall through which the pipe passes,
which method comprising the steps of: casting a wall of settable material
about a sectional shaping membsr sited at a predetermined movable location
with respect to the masonry wall configured to produce an opening at the
desired location and of the desired dimensions to pass the pipe in slight-
ly spaced relation thereto; the shaping member being provided with means
defining a peripheral channel configured to engage a peripheral gasket
ring of resilient material and to house a substantial portion only of the
ring, leaving a remaining portion extending into the settable material as
it is being emplaced; permitting the material to set, and thereafter re-
moving the shaping member.
By still another aspect of this invention a method is provided
for installing a sealing element in the peripheral surface of an opening
through the body of a manhole wall, wh:ich method comprises the steps of
installing at a predetermined movable :Location, between the inner and
outer shells of a form for casting the concrete wall of a manhole, a two-
part mold, comprising: (a) an inner mold member of dished shaped having
radially outwardly extending flanges thereon of greater diameter than the
opening, (b) an outer mold member of complementary di.shed shaped having
side flanges thereon of the same diameter as the opening; the mold being
configured to hold a portion only of an elastomeric gasket strip, leaving
other structure of the gasket strip projecting outwardly from the mold;
positioning the mold between the shells by means of a depending bar held
to the outer shell and temporarily but firmly secured to and pouring
settable material into the space between the inner and outer shells so as
to surround and enclose the mold, and so as to surround and enclose those
portions of the gasket strip which are not received within the mold; per-
mitting the settable material to set, and then removi.ng the inner and
outer forms and separating and removing the two parts of the mold, thus
leaving that portion of the gasket strip which had been embedded in the
mold projecting into the opening in the body of the manhole wall.
By yet another aspect of this invention, a method is provided
for manufacturing a pre-cast portion of an access pit for underground
piping systel~ comprising the steps of: assembling an annular elastomeric
seal body on a mandrel, two part mandrel comprising: (a) an inner mold
member of dished shaped having radially outwardly extending flanges thereon
of greater diameter -than the opening; (b) an outer mold member of comple-
mentary dished shaped having side flanges thereon of the same diameter as
the opening; (c) means between the outer periphery of a flange on the
outer mold member and a flange on the inner mold mernber adapted to re-
ceive the pipe-engaging portion of the gasket and to allow the anchoring
portion of the gasket to project radially outwardly; fixing the assembly
to one of a pair o~ form members and positioned between the members by
means of a depending bar held to the outer shell and temporarily but
firmly secured to; pouring concrete between the form members and around
the assembly; and removing the form mernbe~s and the mandrel after the con-
crete has set.
As described above, the present invention involves, in one as-
pect the concept of providlng a first support for the pipe, which support
is sufficiently resilient to compensate for stress and for shear, is
sufficiently flexible to accomodate extensive misalignment of the pipe,
and yet is capable of affording an absolutely fluid tight seal in the rim
of the opening. The gasket of an aspect of the present invention is
easy to install, comparatively inexpensive to make, and extremely relia~
ble in use. The sealing system of an aspect of the invention utilizes a
continuous profile having a generally triangular shaped head, including
flat face portion provided with an inset arcuate depression, a sloping
rear face, a flat base and flat rear wall extending downwardly to a for-
wardly-facing "L"-shaped leg~ An effective water-tight seal is estab-
lished when the pipe is inserted through the opening in the manhole be-
cause the outer diameter of the pipe, being of greater diameter than the
inner diameter of the sealing
- 23 -
ring, causes the pipe to contact and distort the ruhber sealing ring such
that the rubber sealing ring applies pressure to the external surface of
the pipe, therehy providing a water-tight seal between sealing ring and
the pipe.
The cylindrical ring is preferably positioned on the rim de-
fined between the inner and outer mating dished mold rings so that its
triangular shaped head is within the peripheral groove, and the "L"-
shaped corresponding leg projecting outwardly. The complementary parts of10
the mold rings are clamped in place wi-th the inverted manhole hold and
held therein by the adjustment securement clamping stavel.
A suitable mold ring according to an aspect of this invention
for the installation of the novel gasket of an aspect of this invention
consists of inner and outer shells oE dished shaped which are so configured
that when assembled they define between them a peripheral groove which
accommodates the triangular-shaped head, leaving the "L"-shaped leg free.
In aspects of the present invention, the inner and outer shells are pro-
vided with complementary rectangular insets, provided with mating holes
for adjustahle securement within the manhole mold by the adjustment se-
curement clamping stave. Concrete or other cementitious~materiaI is
then applied to mold the manhole and also to define the peripheral wall of
the opening in the manhole wall. The cementitious material covers the
llL-shaped leg" and embeds it, but the triangular;shaped head is exposed,
and is adapted to yield to receive the pipe inserted therein, upon separa-
tion and removal oE the mold parts.
One of the advantages of aspects of the present in~ention is
- 24 -
the unexpected discovery that extrusions having the cross~section form
described can often be used with pipes of different sizes, without alter-
ing their cross-sectional dimensions. A11 that is necessary is to change
the length of the extrusion and the diameter of the mold rings. This
capacity to coact with pipe of many different sizes is believed to be due,
in part at least, to the fact that the manner of use places considerable
compression on the inner flattened face portion of the gasket, and causes
tension on its outer, sloping periphery. As a consequence, the gasket
of an aspect of the present invention hugs the pipe tightly.
It must be reali~ed that, in the past, the part of the gasket
which lies at the bottom of the opening, when in use, had to sustain most
of the load of the pipe and its contents, and in addition had to resist
environmental stresses, which may be imposed upon the pipe outside of the
manhole by the weight of the fill, or by impacts due to traEfic shock,
or by the dead weight of passing vehicles. If the prisr art gasket were
to be used, it could yield too much under these stresses, and become
ovexly compressed at the bottom of the opening. The pipe could then
pull away from the gasket at the upper part of the opening, thereby
allowing fluid to pass the seal. Since the stresses imposed may some~
times be measured in thousands of pounds, particularly where the pipe i5
large - say 24" or 30" in diameter, it was thought to be necessary to em-
ploy a molded gasket ring which would manifest both sufficient resis~
tance to compression at the bottom of the opening and sufficient capaci-
ty for expansion at the top.
The gasket of an aspect of this invention described herein is
remarkably adapted to meet this problem~ It cooperates with a xim on
- 25
the interior of the hole in the manhole to support such considerable
weight without the need for a large mass of elastomeric material to be
present to carry the weight imposed, Moreover, the flattened gasket pro-
vides an extensive rubbery seal between the pipe and the hole.
The other major need is to ensure that the gasket ring is so
firmly anchored in the concrete as to resist any stress which might tend
to dislodge it. This is ensured by the deep embedding of the "L-shaped"
leg, as well as by the embedding of the base of the body in the surround-
ing concrete~
The concrete material used in casting the manhole will usually
be a fairly stiff mix. Therefore, the forms can be stripped from the
freshly cast pipe fairly soon after casting. This permits a minimum
number of forms to be used in the operation and appreciably reduces the
capital expenditures which would otherwise be necessary if the forms
were retained about the pipe until they had cured.
By the same token it is desirable that the mold members may
also be removed from the freshly cast pipe at the same time the pipe form
is removed so that the mold members may also be reused and the number
necessary kept to a minimum. However, as noted above, it is important
that the gasket be shaped and positioned properly with respect to the hole
in the wall of the manhole.
While the freshly cast concrete is capable of sustaining its
own weight, some support must be provided for the resilient gasket to
insure that it remains around and positioned correctly in the riser wall
until the concrete has cured to a degree sufficient to retain the gasket
in place. At the same time, as noted above, it is desirable that the
- 26 -
relatively expensive, void defining mold members, which also support the
gasket during the cas-ting operation, be removed at the time the form is
stripped from the riser for reuse.
In the accompanying drawings,
Fig. l is a perspective view of the manhole with a sewer pipe
installed therein according to one embodiment of this invention;
Fig. 2 is a cross-section through line II~II of Fig. li
Fig. 3 is a perspective view of the gasket of an embodiment of
this invention;
Fig. 4 is a transverse cross~section of the gasket of Fig. 3
embedded in the concrete of the manhole around the hole;
Flg, 5 is an e~ploded side elevational view of the two part
mold of an emb~diment of this invention for the installation of the gas-
ket in the hole in the manhole;
Fig. 6 is a horizontal cross-sectional view of the two;part
mold of Fig. 5 in installed attitude; and
Fig. 7 is a horizontal cross-sectional view of the hole in the
manhole after removal of the two~part mold,
As seen in Figure 1 the manhole lO is a precast cylindrical
member 11 with a concrete sewer pipe 12 extending through an opening 13
therein.
The opening 13 is provided with a cast~in~situ gasket 14, shown
in greater detai] in Figures 3 and 4. The gasket is a cast)elongated
rubber gasket formed into an endless circular form It consists of a
head portion 15 including a front face 16 and a rear faca 17. Front
face 16 includes an upper deflectable flange 18, an arcuate inset l9 and
a lower, embedable portion 20. The rear face 17 is shorter than the
27 ~
front face 16 and is~joined thereto by a sloping face 21.
The rear face 17 extends downwardly to a leg 22 which is gen-
erally of "L"~shaped i.e. in the form of a downward extension 23 and a
forward-acing foot 24, defining a recessed zone 25 therebetween.
As seen in Figure 6 and 7, the manhole 10 is cast with the hole
13 therein and with the gasket 14 cast-in-situ by means of a manhole form
including inner and outer cylindrical walls 25, 26 and a pair of com~
plementary mold rings 27, 28. m e inner mold ring 27 incl~ldes a main
dished central circular area 30, having an annular rim 31 coextensive
therewith. A reduction rectangu]ar flange 32 in the fotm of a radially
inwardly extending portion 33 and an annular rim portion 34 leads to an
expansion flange 35, terminating in a dished terminal rim 36.
Outer mold xing 28 includes a main central dished area 40 mat-
ing with dished portion 30 and annular rim 31 and a stepped portion 41
mating with portion 33. Stepped portion 41 enlarges to an expansion
flange 42 which continues as an intermediate rim 43 and an outer rim 44
terminating in a facia 45~
Before the assembled inner and outer mold rings 27, 28 are
placed within the manhole form, the gasket 14 is placed thereon, with
face 16 of the gasket abutting face 34 of inner form, and s]oping face 21
abutting expansion flange 42. In this way only face 16 and sloping face
21 are adapted to be exposed, with the removal~ of the gasket 14 being
adapted to be embedded in the concrete.
In its installation in the manhole form, the two-part
mold rings 27, 28 are assembled with their mating rectangular
insets 46, 47 respectively together and with the gasket 14
therearound as described above. The mold ring unit is
- 28 -
- -
then suspended in -the inverted manhole form by means of rec-tangular
fixing bar 48 which has an upper crown 48a and a depending f]ange 48b and
which is provided with spaced apar-t apertures 49 to align with apertures
50a, 50b, in the insets 47, 46, respectively. A set screw 48c holds the
bar 48 to the outer shell ~6 ~See Fig. 6). When ~he mold ring assembly
is at the predetermined position in the manhole mold to provide aperture
13 at the preselected location, bolts 51 are passed through washers 51a,
apertures 49, and 50a and 50b, and through washer 51b, and are held
thereon by nuts 52.
Then the concrete is poured into the manhole form and when set,
the forms and the mold rings are removed to provide a manhole with an
aperture therein having a gasket molded in-situ.
The unique cooperation of the manhole opening 13 and the gasket
14 in maintaining a seal when sewer pipe 12 is inserted as shown in Figure
2. ~ere is is seen that the weight oE the sewer pipe 12 forces the head
15 of the gasket into its fully compressed position. However excess com-
pression is prevented by contact of the sewer pipe 12 at 60 with flattened
annulus 61 of the opening 13 where the base 62 of the sloping face 21 in~
tersects the lo~Jer portion of the manhole opening 13. Sealing contact is
maintained because of the amount of contact between areas 63 of the
sewer pipe 13 and 64 of the gasket 14.
This compression does not result in any transfer of forces
to the leg 22, since the forces are absorbed by the compression of the
upper portion 18 of the front face 16 into the arcuate depression 18.
Moreover, the lower portion 20 of the fron-t face is encased by the con-
crete. Thus, the lower portion of the head of the gasket and the entire
leg 22 are free from forces which might tend to loosen the gasket from
within the concrete.
- 29 -
