Note: Descriptions are shown in the official language in which they were submitted.
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~ ~GASKET FOR MAKING JûINTS IN CORRUGATED PLASTIC PIPE
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BACKGROUND OF THE INYENTION
he present invention relates to elastomeric gaskets, and more
specifically to gaskets for sealing a telescopic joint between a
;pair of tubular members, such as corrugated plastic pipe.
It is well known to form a telescopic joint between two corrugated
plastic pipe sections with one end of one pipe section having an
enlarged bell portion_ An elastomeric gasket is ~laced around one
end of one section which is~then inserted into an enlarged bell end
of a second pipe section.
Such gaskets generally are profiled to conform to the pipe
corrugations. They usually include an upper surface which is
compressed as one end of a pipe section i5 inserted into an
enlarged end of a section pipe section. However, as one end of a
pipe section enters the enlarged end of another pipe section, the
gasket tends to roll from the corrugations. When this happens, the
seal may be imperfect so that ground water may infiltrate into the
sewer system or sewage or other fluid passing through the~pipe may
leak into the soi1 surrounding the pipe joint.
;~he improved gasket of our invention has eliminated the problem of
the gasket rolling out of the corrugation by utili~ing an~;anchor
portion connected to a sealing portion. The anchor portion holds
the sealing portion in place as the end of one pipe section~is
inserted into the enlarged end of a second pipe section.
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BRIEF SUMMARY OF ~HE INVENTIDN
This invention relates to an improved elastomeric ~asket ~or making
a joint between a pair of tubular sectlons such as corrugated
plastic pipe. The primary use is low pressure or gravity flow
applications such as sewer lines.The gasket includes an anchor
portion connected to a sealing portion. The anchor portion ;s
adapted to be disposed in a pipe groove and extend out of the pipe
groove to provide a slight interference fit as two pipe ends are
telescoped together. The sealing portion is adapted to be disposed
in another pipe groove and extend out of the pipe groove to provide
a substantial interference fit as t~o pipe end sections are
telescoped together.As two pipe ends are telescoped together, the
anchoring portion of the ~gask~t is engaged before the sealing
portion. A pipe end easily slides over the anchor portion trapping
it in a pipe groove. The pipe end then engages and compresses the
sealing portion. The sealing portion is held in another pipe
groove by the anchor portion.
- ~ It is a principal object of the present invention to provide an
elastomeric gasket which will not rotate or otherwise become
unseated from pipe corrugations as one end of a pipe section is
inserted into the enlarged end of a second pipe section.
An advantage of our invention is elimination of maintenance costs
and repair for leaky joints discovered after a pipe line has been
installed.
The above and other objects, features and advantages of our
invention will become apparent upon consideration ~f the detailed
description and appended drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of one embodiment of an elastomeric
gasket of the invention;
FIG. 2 is a cross section of the gasket of FIG. 1 fitte~ into
corrugations of one end of a pipe section; -
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FIG. 3 shows a partial cross-section of the gasket of Fig.
~orming a seal ;n a telescopic joint;
FIGS. 4 and 5 snow enlarged cross-sections in stages of partial and
complete assembly respectively of a telescopic joint;
FIG. 6 is a cross-section of another embodiment of the gasket;
FIG. 7 shows a partial cross-section of the gasket of FIG. 6forming a seal in a telescopic joint;
FIG. 8 is a cross-section of a further embodiment of the gasket;
FIG. 9 shows a partial cross-section of the gasket of FIG. 8
forming a seal in a telescopic joint; and
FIG. 10 shows a partial cross-section of thè gasket of FrG.
forming a seal in a further embodiment of a telescopic joint.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 3 shows a joint formed between a first pipe end section 11
inserted into an enlarged end member 13 of a second pipe section
12. The pipe sections of FIG. 3 include double plastic walls
having a s000th inside wall 14 fused to a corrugated outside wall
15 having an integral bell or enlarged end 13.
Referring to FIG. 1, reference numeral 10 refers to an elastomeric
gasket for forming the joint of FIG. 3 and includes an anchor
portion 16, a connecting portion 18 and a sealing portion 20.
Although gasket 10 could be used to form a joint between metal,
concrete, or other tubular sect;ons having at least two annular
grooves on one end section, it has particular use with corrugated
plastic pipe.
Anchor portion 16 includes an upper sloping surface 34 and a lower
root portion 22 received within a first corrugation 42. Sealing
portion 20 includes an upper raised surface 26 and a lower root
portion 24 received wi~hin a second corrugation 44. Root portion
24 is preferably somewhat smaller than root portion 22 so as to
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provide a void 28 in corrugation 44 when the gasket is not
compressed. Preferably, the void is provided by having root
portion 24 extend the full depth of the corrugation. However, the
width of root portion 24 is less than that of the w;dth oF the
corrugation. As shown, the width of root portion 24 1s somewhat
less than root portion Z2.
Connecting portion 18 ;ncludes a substantially planar upper surface
and a lower surface 32. Lower surface 32 lays on outside
surface 36 of pipe 11. If the pipe is corrugated, surface 36 is
the crest of a corrugation.
Raised surface 26 extends substantially above upper surface 30 of
connecting portion 18. In a preferred embodiment, raised surface
26 includes a pair of gently sloping sides 46 converging toward
each other to form an apex 48. In the embodiment shown, the slope
is 45.
FIG. 4 and FIG. 5 show a joint being made using gasket 10 during
installation of two tubular members. Gasket 10 preferably is
disposed within the first two corrugations on the outside end of
pipe section 11 as shown in FTG. 2. The end of this pipe section
is then inserted into an enlarged or bell end of second pipe
section 12.- Although not necessary, it is preferred the inside
diameter of enlarged member 13 of pipe section 12 be slightly less
than the outside diameter of connecting portion 18. In any event,
the inside diameter of enlarged member 13 must be less than the
outside diameter of sealing portion 20.
As shown in FIG. 4, lower surface 32 of connecting portion 18 is
serrated and has relief portions 38. When the diameter of enlarged
member 13 is less than the outside diameter of connectlng portion
18, leading edge 50 easily slides over upper surface 34 of anchor
portion 16 and slightly compresses connecting portion 18~providing
a slight interference fit. The slight compression of connecting
portion 18 causes the e1astomeric material to flow or be displaced
toward pipe surface 36. As leading edge 50 moves toward -sealing
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portion 20, relief portions 38 are c1Osed. The anchor portion is
trapped in corrugation 42.
Similarly, leading edge 50 slides over raised surface 26 displacing
the elastomeric material causing it to flow and thereby filling
voids 28 in second corrugation 44. See FIG. 5. Since the outside
diameter of the sealing portion 20 is substantially greater than
the inside diameter of enlarged member 13, there is a substantial
interference fit between raised surface 26 and leading edge 50.
Sealing portion 20 tries to rotate from corrugation 44 and along
pipe surface 36. This rotation is prevented by anchor portion l6.
As noted above, upper surface 34 of anchor portion 16 must provide
minimal resistance as leading edge 50 slides over gasket lO. As
shown in FIG. 2, upper surface 3~ preferably has a gentle slope of
about 30 to minimize interference with leading edge 50. It is
further preferred to have a slightly raised portion 40. In the
event the inside diameter of enlarged portion 13 is slightly
greater than the outside diameter of connecting portion 18, raised
portion 40 may ~rovide a slight interference fit. -In any event,
the primary seal is formed between enlarged portion 13 and sealing
portion 20.
FIG. 6 and FlG. 8 show additional embodiments of gasket I0. FlG. 6
shows gasket I0 having a pair of sealing portions 20 interconnected
by a pair of connecting portions 18. FIG. 8 shows gasket lO
identical to that in FIG. I except sealing portion 20 is positioned
within the third corrugation from the end of pipe section 11. Any
number of anchor or sealing portions could be possible. FlG. 7 and
FIG. 9 show telescopic joints being formed between two pipe end
sections using the gaskets of FIG. 6 and FIG 8, respectively.
FIG. lO shows another embodiment for making a joint. In the event
it is not possible to form a bell or enlarge one end of each pipe
section, conventional sleeve 52 may be used. Sleeve 52 is enlarged
on both ends to receive ends of pipe sections 11 and 12. ~ Sleeve
52 is provided with centering stop 54. It should be no~ed the
relative positions of anchor portions 56 and sealing portions 7~
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are reversed on the two pipe sections. ~he anchor portions are
always innermost relative to the sealing portions inside sleeve 52.
The telescopic joints shown in FIG. 3, FIG. 7, FIG. 9 and FIG. 10
are all formed by having corrugations on the outside of the pipe
sections. The joint could also be formed by having annular grooves
on the inside of enlarged member 13 or sleeve 52 instead of grooves
or corrugations on the outside of the pipe sections. If the
grooves are on the inside wall, gasket 10 would be disposed within
the grooves inside enlarged member 13 or sleeve 52. Then, a
telescopic joint is formed by inserting a pipe end section within
enlarged member 13 or sleeve 52.
Typical dimensions for synthetic rubber gaskets used on double wall
corrugated plastic pipe to make water tight joints according to our
invention were as follows:
; 4 Inch (102 mm) 6 Inch (152 mm~
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Corrugation Spacing .42"( 10.7 mm) .52"( 13.2 mm)
Corrugation Depth .13"( 3.3 mm) .22"( 5.6 mm)
Corrugation Width .21"( 5.3 mm) .2]"( 5.3 mm)
Gasket Diameter Seal Portion 4.20"(106.7 mm) 6.26"(159.0 mm)
Pipe Bell Inside Diameter4.10"(104.1 mm) 6.15"(156.2 mm)
A variety of natural or synthetic rubbers such as isoprene or
ethylene propylene diene momomer (EPDM) could be used as the gasket
material. A material we have found especially satisfactory is
EPDM.
It will be understood that various modifications can be made to our
invention without departing from the spirit and scope of it.
Therefore, the limits of our invention should be determined from
the appended claims.
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