Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKGROUND OF THE_INVENTION
This invention relates to a major axis alignment
indicator for an oval sewerpipe.
Synthetic resin pipes having generally elliptical
cross sections, oval or egg-shaped for example, are being
increasingly used as drainpipes or sewerpipes in place of con-
ventional circular pipes, as waste materials may flow therethrough
at considerably high speeds to prevent clogging accumulations.
Elliptical pipes of this type are much more difficult
to install than conventional circular pipes, however, since
according to hydrographic principles they must be laid with their.
major cross-sectional axes vertically oriented in order to
promote optimum flow conditiGns. Such accurate vertical align-
ment or orientation is difficult to accomplish wLth the naked :.
eye, and it is thus necessary to employ plumb lines, level rods, .:
or the like during installation.
In the prior art an alignment mark has been placed on ~: -
the outer surface of an end.portion of an elliptical pipe to
designate the major cross-sectional axis of the pipe, and such
mark is used as a vertical plumb guide when laying the pipe.
When the pipe is laid in the typical ground trench, however,
the mark on the bottom edge of the pipe sinks into and is ..
obscured by the trench bottom earth and cannot be seen, whereby
accurate vertical axis alignment is very difficult. ~A~ ,.,.'''., ,'
SUMMARY OF THE INVENTION
The drawbacks and disadvantages of the prior art are
e~fectively overcome b~ the present invention, according to
which the female end of an elliptical drain or sewerpipe is
30 provided with an installation alignment mark on the inner edge
surface or on the end face of the pipe to designate at least one
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1 major Crss-sectional a~is point or intersection. The pipe is
installed with such internal alignment mark on the bottom side
of the pipe in a ground trench whereby the mark is not buried in
or hidden by the trench bottom earth, and is cooperable with a
second internal or external alignment mark on the opposite side
of the pipe end to fac~tate the accurate vertical orientation of
the major axis with the aid of a plumb line or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
9~ In the drawings:
Fig. 1 shows a longitudinal cross-sectional view of an
elliptical drainpipe or sewerpipe according to the present
invention,
Fig. 2 shows a cross-sectional end view taken along
line II-II in Fig. 1, and
Fig. 3 shows a longitudinal cross-sectional view
illustrating a method of producing ths pipe end shown in Fig. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to th~ drawings, reference numeral 1
designates a drainpipe or sewerpipe having an egg-shaped cross-
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section and fabricated from a rigid synthetic resin, such aspolyvinyl chloride. The end portion of the pipe 1 has an
increased diameter to form a female opening 2 ~or receiving an
inserted, matingly configured male pipe end, and the inner surface
of the female opening is provided with an annular recess 21 to
accommodate a packing gland or ringO Recesses 3, 4 are provided
on the inner surface of the end portion of the opening 2 at the
opposite ends of the major axis of tha pipe, and serve as align-
ment marks during installation. The pipe is laid with its more
30sharply angled side, correspondiny to recess 4, on the bottom in
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1 order to achieve op timum f low conditions. The upper recess 3
is therefore not strictly required for alignment purposes, but
rather an outer projection 31 which is inherently produced
when forming the recess 3 is used in conjunction with the
lower recess 4 to achieve accurate orientation. That is, the
pipe 1 is placed in a trench, a plum'b line or the like i5 SUS-
pended adjacent the female opening 2, and the pipe is then
rolled until a line joining the projection 31 and recess 4 is
aligned with or parallel to the vertical plumb line. Alter-
10 natively of course, a conventional construction or carpenters
level can be used. ~'
The recesses 3, 4 can be replaced by marks or grooves
molded or scored into the planar end face of the pipe edge, or -
on the inner and outer surfaces'thereof, with e~ual facility.
The essential criterion is that the alignment marksj whatever
their specific form, be visible to the installing workmen and -
not obscured, hidden, or buried when the pipe is in situ.
Referring now to Fig. 3, a core piece or plug 5, 1!. ".,.' ., ,
whose outer shape corresponds to ~he desired inner configuration
20 of the female openLng 2, is provlded with short proje~tions 51
positioned at the two intersections of the major'cross-
sectional axis of the pipe with its end face. A passage 52
therein serves for'~the introduction of a pressurized ~luid.
The end portion of the synthetic reæin pipe is heat softened
and force fitted over the core, whereby it expands to ~orm the
female opening 2 and the recesses 3, 4 defined by the two
projections 51. Split molds 6 are then mounted over the pipe
~end so that their annularly recessed middle portions are aligned
with the annular ring communicating with the passage 52. When
~30 a pressurized fluid is applied to the passage 52 the adjacent pipe
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1 circumference expands to form the packing recess 21. Reference
numerals 7 designate 0-ring seals. After the pipe has been
cooled the split molds 6 and then the core plug 5 are removed,
to thus complete the molding of the female end configuration
shown in Fig. 1.
When an asymmetrical egg-shaped pipe configuration as
shown in the drawings, or with a symmetrical oval or elliptical
shaped pipe, the insertion alignment of the male pipe end is
automatic and inherent since it will only fit when properly
tO vertically oriented.
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