Note: Descriptions are shown in the official language in which they were submitted.
2018863
CONCRET-E PIPE ADAPTOR
Technical Field
The present invention pertains to pipe fittings and, more particularly, to a
concrete pipe fitting for coupling plastic pipe to a concrete structure such as a
5 manhole, a pipe, or the like.
Background of the Invention
Sewage and drainage systems typically use underground pipes to convey
sewage, storm water, and other waste material to a treatment facility or waste
disposal site. These pipes are routed through manholes at various locations.
1 Manholes are used to provide access to the system for cleaning and repair.
Manholes are also used when there is a change of grade or direction to maintain
the proper flow of waste material.
In the past, sewage pipes have been formed of concrete. These concrete
pipes were attached into the manhole and sealed in place with cement grout.
15 Because concrete pipes are porous, they frequently do not remain watertight. In
addition, concrete pipes tend to fracture when improperly backfilled. Because ofpublic health concerns, regulations in many localities require that plastic or PVC
pipe be used instead of concrete, and that all pipe connections achieve some
degree of watertightness.
The use of plastic pipe with concrete manholes makes it very difficult to
obtain a proper seal where the two come together because of the incompatibility
of plastic and concrete. In one ,~)r~posed method for overcoming this problem, aconcrete cylinder with an axial bore is formed and a gasket is then rolled inside
the bore. In some instances, t~l ~asket i, he~d in position in the bore by cutting a
25 channel around the inside of tr,c~ bore and then rolling the gasket in place in the
channel.
20 1 8863
This method has several dlsadvantages. First, when
the plastlc plpe ls backfllled wlth soll, the welght pushlng
down on the pipe causes the plpe to crush the gasket at the
bottom of the plpe, leavlng a gap between the top of the plpe
and the gasket. Thls gap also occurs when the plpe ls not
posltioned perpendlcular to the seal. In addltlon, the welght
of the backflll causes movement of the plpe, whlch can crack
the cyllnder. As a result, these cyllnders frequently fall to
achieve or malntaln a watertlght connectlon. Furthermore,
cuttlng a channel lnside the bore of the plpe requlres the use
of carbon- or diamond-tlpped cuttlng tools. Thls type of
machlning ls expenslve, tlme-consumlng, and can weaken the
concrete. The present lnventlon ls dlrected to overcoming
these drawbacks.
Summary of the Invention
The present lnventlon provldes a method of
constructlng an adaptor for connectlng plastlc plpe to a
concrete structure such as a manhole, a plpe, or the llke, the
method comprlslng the steps of: placlng an outer form on a
support member; placlng a lower form on sald support member
generally concentrlcally wlthln sald outer form, sald lower
form havlng a top surface; placing a gasket on sald top
surface of sald lower form so that flanges on sald gasket
pro~ect outward toward said outer form; placlng an upper form
on said gasket such that a space ls formed between sald outer
form and sald upper and lower forms; and pourlng a llquld
concrete mlxture lnto sald space.
62839-1237
20 1 8863
The present lnvention also provldes a method of
constructlng an adaptor for coupllng plastic pipe to a
concrete structure comprlslng the following steps: placing a
lower form having a top surface on a support member; placing
a gasket on said top surface of said lower form; placing a
top form on said gasket; placing an outer form generally
concentrically around sald lower and upper forms on sald
support member to clrcumscrlbe sald upper and lower forms to
form a space around sald upper and lower forms lnto whlch a
portlon of sald gasket pro~ects; and pouring llquld concrete
into said space.
The present invention also provldes an adaptor for
connecting pipe to a concrete structure, sald adaptor
manufactured according to the steps of: constructing an inner
form assembly including a first form, a second form positioned
ad~acent said first form, and a seal located between said
first and second forms wherein a portion of said seal is
disposed between said first and second inner forms and a
portion of seal pro~ects outward from said forms; placing an
outer cylinder generally concentrically around said inner form
assembly, said outer cylinder being separated from said inner
form assembly to define a space therebetween; pouring a
liquid concrete mlxture into said space and allowing sald
mixture to harden so as to form a concrete body with an axial
bore defined by sald first and second inner forms; and
removing said outer cylinder and removing said inner forms so
that said seal is partially embedded ln sald concrete body and
at least partially extends lnto sald axial bore.
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62839-1237
- 20 1 8863
The flexlble seal is cast in the body to proiect
into the axlal bore and may comprlse a one-plece flexlble seal
that circumscrlbes the bore and has at least one flange
pro~ectlng lnto the bore. Preferably, the seal ls a twln seal
that has two flanges proiectlng into the bore.
Preferably, the inslde diarneter of the bore
decreases from a rnaxirnurn diameter at each end of the bore to a
mlnlmum dlameter at the center of the bore.
The space that clrcumscrlbes the lower and upper
forms and into which a portion of the gasket pro~ects may
contaln a relnforclng wlre mesh. The support rnernber ls
preferably vibrated to settle the concrete mixture in the
space.
The concrete mlxture may comprlse two parts of
coarse sand, one part of flne sand, and one and one-half parts
of cement.
As wlll be readily appreclated from the foregolng
descrlptlon, the present lnvention provides an adaptor that is
easily formed from concrete. Because the seal is cast into
place, no additional labor or machining ls requlred to lnsert
the seal or to cut a channel for retaining the seal. The
cone-shaped internal bore allows for variation in the
alignment of the pipe in the adaptor, thus avoiding cracking
or fracturing of the pipe or adaptor if the pipe should shift
position after backfilling. Furthermore, affixing the adaptor
to a manhole with llquld cement and uslng a dlrectlonal twln
seal achleves an alr and water tlght condltlon that exceeds
all government requlrements.
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62839-1237
2018863
Brief DescrlPtion of the Drawings
The foregolng and other features and advantages of
the present lnventlon wlll be more readlly appreclated as the
same becomes better understood by reference to the following
detalled descriptlon when taken ln con~unctlon wlth the
following drawlngs, whereln
FIGURE 1 is a cross-sectlonal slde vlew of an
adaptor formed ln accordance wlth the present lnventlon;
FIGURE 2 ls a top vlew of the adaptor of FIGURE l;
FIGURE 3 ls an isometrlc vlew in partlal cutaway
illustratlng the form for maklng the adaptor of FIGURE l;
FIGURE 4 ls a slde vlew and partlal cross sectlon of
the adaptor of FIGURE 4 coupllng a plastlc plpe to a manhole;
FIGURE 5 ls an isometrlc view in partial cutaway
lllustratlng an alternatlve form for maklng the adaptor of
FIGURE l; and
FIGURE 6 ls a top vlew of a rlng mold used ln the
form of FIGURE 5 for maklng the adaptor of thls lnventlon.
Detalled Descrlptlon of the Preferred Embodlment
Referrlng lnitlally to FIGURES 1 and 2, an adaptor
10 ls shown havlng a generally cyllndrlcal body 12.
Preferably, the body 12 ls formed of concrete. A longltudlnal
axlal bore 14 ls formed ln the body 12 that communlcates wlth
flrst and second open ends 16 and 18. The lnslde and outside
surfaces 20 and 22 of the
- 3b -
62839-1237
2~18863
--4
body 12 have a smooth finish. A mesh screen 21 is formed in place inside the
concrete body 12. As shown more clearly in FIGURE 1, the inside diameter of the
bore 14 decreases from a maximum diameter at each end 16 and 18 to a minimum
diameter at the center of the bore 14. Ideally, the taper is one-fourth inch
diameter for every four inches of length.
Cast in place on the inside surface 22 is a flexible seal 24 that circumscribes
the internal bore 14. The seal 24 shown in the representative embodiment is a
directional twin-seal that is well known in the art and commercially available.
Consequently, it will not be described in detail. Briefly, the seal 24 is formed of
neoprene or other similar pliable mat-~erial. Two flanges 26 and 28 project into the
bore 14. Each flange 26 and 28 has two faces, a first face 30 that lies in a plane
perpendicular to the longitudinal axis X of the bore 12, and a second face 32 that
is inclined diagonally downward towards the first end 16 of the body 12 and the
first face 32, as shown more clearly in FIGURE 1.
As such, a pipe inserted into the second end 18 will meet little resistance
from the inclined second faces 32. However, the first faces 30 will resist
movement of the pipe in the opposite direction, thus holding the pipe in place.
The seal 24 further includes a body portion 34 with two projecting lips 36 that are
encased on the concrete body 12 for holding the seal 14 in place.
The adaptor 10 so described is constructed using a unique mold 38 shown in
FIGURE 3. The mold 38 is comprised of a support base 40, a hollow outer
cylinder 42, a lower form 44, and an upper form 46. The support member 40 has a
central raised portion 48 that projects upward from the top surface 50 of the
support member 40. The lower form 44 is a hollow, truncated cone having an
inside diameter at its base that is sized to fit over the raised portion 48.
The lower form 44 has a top surface 52 on which rests a seal 54 having the
same configuration as the seal 24 described above. Placed on top of the seal 54 is
the upper form 46. The upper form 46 is also a truncated cone that is not
necessarily hollow. When placed on the seal 54, the upper form 46 is inverted sothat the base of the form 46 is facing upward. The upper and lower forms 44 and
46 are constructed to have a one-fourth-inch taper to every four inches of.
height. A cone 56 is placed on or integrally formed with the upper form 46 for
directing liquid cement around the upper form 46. The outer cylinder 42 is placed
on the top surface 50 of the support member 40 to circumscribe the lower and
upper forms 44 and 46, thus forming a space 58 between the lower and upper
forms 44 and 46. A wire mesh screen 60 is placed in the space 58 to circumscribethe lower and upper forms 44 and 46.
2018863
--5--
The steps of the method of constructing the adaptor 10 include the step of
first placing the lower form 44 on the support member 40. To insure the lower
form 44 remains in place when the liquid concrete is poured, the base of the lower
form 44 is fitted over the raised portion 48 on the support member 40. Next, theseal 54 is placed on the top surface 50 of the lower form 44 so that the flanges(not shown) of the seal project outward from the lower form 44. In other words,
the flanges project into the space 58 that will be created. Next, the upper
form 46 is inverted and placed on top of the seal 54. Finally, if the cone 56 isformed separate from the upper form 46, the cone 56 is then placed on the upper
form 46. The outer cylinder 42 is then placed around the lower and upper
forms 44 and 46 to create the space 58. If reinforcement is desired, the wire
mesh screen 60 is then placed into the space 58 at a desired location. Finally,
liquid concrete is then poured into the space 58 and allowed to harden. To insure
the space 58 is free of air bubbles, the support member 40 may be vibrated with a
shaker or other similar device that is well known in the art prior to hardening of
the liquid concrete.
The support member 40, the outer cylinder 42, and the upper and lower
forms 44 and 46 may be constructed of wood, metal, plastic, cardboard, or other
suitable material. The reinforcing mesh 60 is commercially available and may be
cut from a preformed roll and hooked together. It has been found that a mesh of
1" x 2" has been suitable for this application. The mixture of the liquid concrete
that has been found to be most suitable for the present invention consists of two
parts coarse sand, one part fine sand, and one and one-half parts cement. This
creates smooth surfaces on the body 12 for a better fit and unrestricted water
flow.
Although the steps of the method of the present invention have been
described in a certain order, it is to be understood that they may be performed in
other orders without departing from the spirit and scope of the present
invention. For instance, the outer cylinder 42 may be placed on the support
member 40 before or after the lower and upper forms 44 and 46 are in place.
Similarly, the screen mesh 60 may be placed on the support member 40 before or
after the outer cylinder 42 and the lower and upper forms 44 and 46. However, toinsure proper spacing between the outer shell 42, the wire mesh 60, and the upper
and lower forms 44 and 46, it is preferable that at least the lower form 44 be
placed on the support member 40 first. However, this may not be required if
positioning tabs are placed on the support member 40 to locate the position of the
outer cylinder 42 and the wire mesh 60. Consequently, it is to be understood that
2018~63
the method of constructing the present invention may be performed otherwise
than as described specifically herein without departing from the spirit and scope
of the invention.
Turning now to FIGURE 4, the adaptor 10 is shown in use coupling a plastic
pipe 62 to a manhole 64. In most applications, the manhole 64 has preformed
knockouts located at predetermined locations in its wall 66. These knockouts areremoved by workers to create an opening that is sized to receive the adaptor 10.The adaptor 10 is held in place in the manhole 64 by cement grout 68, as shown.
The adaptor 10 is positioned in the manhole 64 so that the directional seal 24 has
the inclined faces inclined toward the manhole 64. As such, the plastic pipe 62 is
easily inserted into the adaptor 10 and past the seal 24. The clearance 70 formed
between the pipe 62 and the adaptor 10 by the cone-shaped bore 14 allows for
variation in the directional orientation of the pipe 62 without destroying the
watertight integrity of the seal 24.
An alternative method of manufacturing the adaptor 10 is described with
respect to FIGURES 5 and 6. Form 38' is used as a mold to shape the adaptor 10
out of liquid concrete in a manner identical to that described in the first method
of manufacture. Form 38' includes the support member 40 with raised portion 48
and outer cylinder 42 disclosed with respect to the first-described form 38.
Form 38' further includes a lower form 44' and an upper form 46' that are similarly
shaped and perform the same general function as the first-described lower and
upper forms 44 and 46, respectively.
A ring mold 74, secured between the lower and upper forms 44' and 46', is
dimensioned to define a seating space 76 in the concrete body in which the
flexible seal 24 is secured. Ring mold 74 is an O-ring formed out of reinforced
rubber or other plastic material that has a sectional profile identical to the
sectional profile of the seal body portion 34 secured in the concrete body 12.
Mounting bores 80 are formed in the mold 74 so that it can be secured to
complementary mounting pins 82, shown in phantom, that extend from the lower
and upper forms 44' and 46'. A handle 84, shown in phantom, is integrally formedto the inner surfaces of the mold 74 to provide a handhold for collapsing and
withdrawing the mold.
If the ring mold 74 is formed out of plastic it may be desirable to provide the
mold with a diagonal slit 86 as depicted in FIGURE 6 to facilitate the removal of
the mold from finished work pieces. If the mold 74 is formed out of rubber or
material with similar flexible properties, the mold can be a continuous ring.
2018863
According to this method of manufacture, the form 38' is initially assembled
as in the first method of manufacture. The ring mold 74 is secured between the
lower and upper forms 44' and 46'. The mesh screen 60, not shown in FIGURE 5 to
simplify illustration of this embodiment of the invention, is placed in the
5 mold 38'. Concrete is then poured into a space 58' defined by the lower and upper
forms 44' and 46', the mold 74, and the outer cylinder 42 to form the body 12.
After the concrete has hardened, the lower and upper forms 44' and 46' and
the ring mold 74 are removed. The ring mold 74 is removed by collapsing the moldso that it is freed from the newly-defined seating space 76 and then withdrawing10 it from the bore 12. The flexible seal 24 is then secured into the seating
space 76. When the seal 24 is secured into the seating space 76, epoxy or other
suitable adhesive may be used to fasten the seal to the adaptor body 12.
The foregoing description has been limited to specific embodiments of the
invention. It will be apparent, however, that variations and modifications may be
15 made to the invention, with the attainment of some or all of the advantages of
this invention. For instance, the adaptor 10 may be formed to have other cross-
sectional shapes other than cylindrical or circular, such as square, hexagonal,
etc. In addition, pressure grouting and/or pressure molding can be used to fill the
forms with cement grout. The wire mesh may be replaced with a fibrous material
20 that is added to the grout for strength. Moreover, the exact steps of
manufacturing may similarly be modified without departing from the scope of the
invention. For example, in some embodiments of the invention, it may be
desirable to provide a metal mold formed of a number of arcuate members
arranged to collapse inwardly so that after the seal seating space is formed, the
25 mold can be removed. Alternatively, the mold may comprise elements that are
integral with the upper and lower forms, such as hingedly attached flaps, that are
locked in place when the form is first assembled. Therefore, it is the object ofthe appended claims to cover all such variations and modifications as come within
the true scope of the invention.
