Note: Descriptions are shown in the official language in which they were submitted.
CA 02847520 2014-03-25
METHODS OF MANUFACTURING AN EXPANSION COMPENSATOR
FIELD
[0001] This disclosure relates generally to methods for manufacturing
an
expansion compensator for connecting pipes and fittings that are used to
convey
a fluid.
INTRODUCTION
[0002] Piping systems are used to convey liquids and/or gasses
within, or
between, residential, commercial, and/or industrial buildings. For example,
most
residential buildings have a potable water distribution system for providing
cold
and/or hot water at one or more locations within the building (e.g. sinks,
showers,
dish or clothes washing machines).
[0003] Typically, piping systems are made up of a number of
components
including straight or curved pipe sections, fittings (e.g. elbow fittings),
valves, etc.
to provide an interior flow path for the liquid being conveyed. Typically, a
piping
system (such as a system comprising thermoplastic pipes), is assembled such
that the components are joined in a manner that provides a durable connection
that prevents or inhibits the components from separating or cracking due to
mechanical, thermal, and/or hydraulic stresses applied to the piping system.
Separation of any of the components of the piping system or cracking of any
element of the piping system may permit fluid to leak out of the piping system
and, e.g., thereby damage the surrounding structure, e.g., the walls of a
building
which enclose the piping system.
[0004] Thermoplastic pipes (such as polyvinyl chloride (PVC) and/or
chlorinated polyvinyl chloride (CPVC) pipes) may be subject to thermal
expansion and/or contraction after installation. For example, a length of a
thermoplastic pipe used for conveying fluid at an elevated temperature (e.g.
hot
water) may be subject to axial expansion and/or contraction based on the
relative
temperature of the fluid being conveyed, and the ends of the pipe may exert an
- 1 -
CA 02847520 2014-03-25
axial force (either compressive or tensile) on the fittings, valves, or other
parts of
the piping system to which they are connected. Typically, hot water usage is
intermittent. Therefore, hot water may be conveyed through a pipe for a period
of
time thereby heating the pipe. Subsequently, the flow of water will be
terminated
and the water in the pipe will cool as heat is dissipated to the ambient
surrounding structure. This heating and cooling will cause the pipe to expand
and
contract axially. This cycle may be repeated several times a day or an hour.
Continued thermal cycling of thermoplastic pipes (e.g., PVC and/or CPVC pipes)
can result in a failure of the piping system and result in a leak.
[0005] Further, in a high rise building, plastic pipes that are mounted
vertically to transport water between floors are mechanically constrained in
their
mechanical positions due to their mechanical attachment to transversely
mounted pipes that deliver water horizontally to the various rooms or
locations on
the floors of the building. As such, when plastic pipes such as those made of
PVC and CPVC are heated by the water that they transport, significant forces
are
created within the walls of the pipe due to the thermal expansion. These
forces
may exceed the buckling strength of the pipes, especially for pipe diameters
under 6 inches, which may cause the plastic pipes to bend and/or buckle. This
stress may result in a leak.
[0006] Once an installation is complete (e.g., the interior walls of a
building
are finished or a piping system is buried under a road), accessing the piping
system to repair a leak is typically time consuming and expensive.
SUMMARY
[0007] The following introduction is provided to introduce the
reader to the
more detailed discussion to follow. The introduction is not intended to limit
or
define any claimed or as yet unclaimed invention. One or more inventions may
reside in any combination or sub-combination of the elements or process steps
disclosed in any part of this document including its claims and figures.
- 2 -
CA 02847520 2014-03-25
[0008] An expansion compensator may expand and/or contract in
response to an applied axial force (compressive or tensile) that may arise
from
expansion and/or contraction of one or more lengths of pipe. For example, one
or
more such expansion compensators can be installed between a length of pipe
and a fitting so that the axial forces that may be imposed on the pipe and/or
the
fitting due to thermal expansion and/or contraction of the length of pipe may
be
reduced. These axial forces may be borne by, or primarily borne by, or
substantially borne by the expansion compensator and not by the pipe and/or
the
fitting. In the case in a high rise building (as compared to a house), each
portion
of the piping system that conveys hot water to each floor will be subjected to
thermal expansion and contraction cycling. Without the use of an expansion
compensator, the total expansion which may occur in the piping system carrying
hot water to the top floor will be the aggregate of the expansion occurring
for
each floor of vertical rise, which may prevent the use of plastic piping.
[0009] An expansion compensator suitable for use with a plastic piping
system may comprise an outer metal conduit and an inner plastic liner that are
secured together. Such an expansion compensator may be manufactured by
expanding a pre-formed plastic liner inside an elongate metal conduit that
already has an expansion/contraction section so as to form an inner plastic
liner
that has an expansion/contraction section. The pre-formed plastic liner (which
may be pre-heated) may be expanded by applying pressure internally in the pre-
formed plastic liner. In order to enable the pre-formed plastic liner to
deform and
form the expansion/contraction section, the pre-formed plastic liner may be
pre-
heated and/or may be heated during the deformation process. For example, the
pre-formed plastic liner may be deformed using a fluid, preferably a heated
fluid
under pressure applied on the inside of the pre-formed plastic liner to both
soften
and displace the pre-formed plastic liner. The process may be characterized as
analogous to hydroforming a pre-formed plastic liner against the metal
conduit,
- 3 -
CA 02847520 2014-03-25
using the inner surface of the metal conduit as a mold for the pre-formed
plastic
liner.
[0010] An advantage of this design is that the profile of the
expansion/contraction section of the pre-formed plastic liner may be the same
as
or similar to the profile of the expansion/contraction section of the outer
metal
conduit. Alternatively, or in addition, the expansion/contraction section of
the pre-
formed plastic liner may be aligned with the expansion/contraction section of
the
outer metal conduit. Accordingly, for example, if the expansion/contraction
sections are in the form of a bellows, then each ridge of the bellows section
of
the inner plastic liner may be nested between two spaced apart opposed walls
that define a ridge of the bellows section of the outer metal conduit.
Accordingly,
when the expansion compensator contracts due to an axial force applied
thereto,
the bellows section of the inner plastic liner may deform in the same
direction,
and concurrently with, the bellows section of the outer metal conduit.
[0011] In one embodiment, an expansion compensator suitable for use
with a plastic piping system may comprise an outer metal conduit and an inner
plastic liner wherein the inner plastic liner is secured to the outer metal
conduit
such that the outer metal conduit supports the inner plastic liner and absorbs
stresses imposed on the inner plastic liner due to thermal cycling of the
piping
system. At least one, and preferably each end of the outer metal conduit and
the
inner plastic liner may be provided with a connector that may secure the outer
metal conduit and the inner plastic liner together to provide a unitary body
(i.e.,
so that together the outer metal conduit and the inner plastic liner act as a
single
body). The connector(s) may be provided by being overmolded over the end(s) of
the outer metal conduit and the inner plastic liner.
[0012] In another embodiment, an expansion compensator suitable for
use
with a plastic piping system may comprise an outer metal conduit and an inner
plastic liner wherein the outer metal conduit and the inner plastic liner may
be
secured together and wherein the axial stiffness of the metal conduit is
greater
- 4 -
CA 02847520 2014-03-25
than the axial stiffness of the inner plastic liner so that the outer metal
conduit
absorbs more (optionally a substantial portion or essentially all) of stresses
imposed on the expansion compensator due to thermal cycling of the piping
system. Accordingly, while axial forces imposed by a piping system may be
borne by, or primarily borne by, or substantially borne by the expansion
compensator, these axial forces may, in turn, be preferentially borne by
(e.g.,
borne by, or primarily borne by, or substantially borne by) the outer metal
conduit.
[0013] In one or both of these embodiments, the outer metal conduit
and
the inner plastic liner may be secured together such that fluid flowing in the
piping system is not exposed to the outer metal conduit (e.g., the inner
plastic
liner defines the outer wall of the flow path through the expansion
compensator
from a pipe or fitting connected at one end of the expansion compensator to a
pipe or fitting connected at the other end of the expansion compensator).
[0014] A further advantage is that the fluid in the piping system is
exposed
only to the inner plastic liner. Accordingly, the outer metal conduit will not
be
exposed to the fluid, e.g., water, which may cause the metal to corrode over
time.
At the same time, the inner plastic liner is reinforced or supported by the
outer
metal conduit thereby reducing the stress imposed on the inner plastic liner
and
reducing the likelihood of the inner plastic liner cracking thereby resulting
in a
leak.
[0015] Another advantage is that by utilizing a metal conduit to
reinforce
the inner plastic liner, the expansion/contraction section (e.g., a bellows or
accordion section) of the inner plastic liner may be made of a thinner
material
which increases the flexibility of the inner plastic liner and reduces the
likelihood
of the inner plastic liner cracking over time due to expansion and contraction
caused by thermal cycling. In particular, since the inner plastic liner is
reinforced
or supported by the outer metal conduit, the axial forces imposed on the
expansion compensator are preferentially absorbed by the outer metal conduit
- 5 -
CA 02847520 2014-03-25
and the stress imposed on the inner plastic liner is reduced, which reduces
the
likelihood of the inner plastic liner cracking thereby resulting in a leak.
[0016] The pipe may be made of a plastic material known in the
piping
arts. The plastic material may be a thermoplastic material and may be one or
more of acrylonitrile butadiene styrene (ABS), PVC, CPVC, ethylene vinyl
acetate (EVA), polyethylene (PE), and the like. Preferred materials comprise
PVC and/or CPVC.
[0017] An advantage of using such expansion compensators is that
plastic
piping may be used in installations requiring a long run of piping, such as in
a
high rise building. By providing one or more expansion compensators that will
expand or contract in length due to thermal heating and cooling of the piping
system, each fitting, e.g., a T-junction, may remain essentially static
thereby
increasing the reliability of the piping system and reducing the likelihood of
a leak
occurring.
[0018] Connectors that are compatible with typical thermoplastic piping
system components (e.g., pipe ends; fittings such as valves, tees, couplers,
elbows, and the like) may be provided at each end of the expansion compensator
to facilitate its installation. For example, the connectors may be configured
to
accept typical pipe end dimensions, and for joining and/or sealing using
typical
means. Also, the expansion compensator may have an inner plastic liner made
from the same (or similar) plastic material of the pipes to which it is to be
installed, so that a fluid flowing through a pipe and expansion compensator
will
be in contact with the same (or similar) material through both components.
[0019] In one broad aspect, there is provided a method for
manufacturing
an expansion compensator comprising an outer metal conduit and an inner
plastic liner wherein the inner plastic liner is secured to the outer metal
conduit
such that the outer metal conduit supports the inner plastic liner and absorbs
at
least some of the stresses imposed on the inner plastic liner due to thermal
- 6 -
CA 02847520 2014-03-25
cycling of the piping system. At least one, and preferably each end of the
outer
metal conduit and the inner plastic liner is provided with a connector that
may
secure the outer metal conduit and the inner plastic liner together to provide
a
unitary body (i.e., so that together the outer metal conduit and the inner
plastic
liner act as a single body).
[0020] In accordance with this broad aspect, there is provided a
method of
producing an expansion compensator, the method comprising:
a) providing an inner plastic liner having first and second spaced apart
ends, an inner surface, an outer surface, and an interior volume extending
from the first end to the second end;
b) positioning the inner plastic liner interior of an elongate metal
conduit, the elongate metal conduit having first and second spaced apart
ends, an inner surface, an outer surface, and an expansion/contraction
section;
c) heating the inner plastic liner;
d) applying pressure to a fluid positioned in the interior volume of the
inner plastic liner to expand the inner plastic liner whereby the expanded
inner plastic liner has an expansion/contraction section; and
e) cooling the inner plastic liner.
[0021] In some embodiments, the expansion/contraction section of the
elongate metal conduit may comprise a bellows having radial inner valleys and
radial outer peaks, the outer surface of the inner plastic liner has thicker
bands
and the method further comprises aligning the thicker bands with the radial
outer
peaks of the bellows prior to expanding the inner plastic liner, whereby the
expansion/contraction section of the inner plastic liner comprises a bellows.
- 7 -
CA 02847520 2014-03-25
[0022] In some embodiments, the method may further comprise selecting
a thickness of the thicker bands such that the bellows of the expanded inner
plastic liner has a generally uniform thickness.
[0023] In some embodiments, the inner plastic liner may be formed
with
the thicker bands.
[0024] In some embodiments, the inner plastic liner may be formed
with a
wall of generally uniform thickness and the thicker bands are provided after
formation of the inner plastic liner.
[0025] In some embodiments, the expansion/contraction section of the
elongate metal conduit may comprise a bellows having radial inner valleys and
radial outer peaks, and the inner plastic liner has a wall of generally
uniform
thickness whereby the expanded inner plastic liner has an
expansion/contraction
section having a non-uniform thickness.
[0026] In some embodiments, radial inner valleys of the
expansion/contraction section of the inner plastic liner may have a greater
wall
thickness than radial outer peaks of the expansion/contraction section of the
inner plastic liner.
[0027] In some embodiments, the method may further comprise providing
a first connector on the first ends of the inner plastic liner and the
elongate metal
conduit and providing a second connector on the second ends of the inner
plastic
liner and the elongate metal conduit.
[0028] In some embodiments, the first and second connectors may be
provided by overmolding.
[0029] In some embodiments, the first end of the elongate metal
conduit
may be provided with a plurality of openings and the method may further
comprise overmolding the first connector on the first ends of the inner
plastic liner
and the elongate metal conduit whereby the first connector comprises a first
- 8 -
CA 02847520 2014-03-25
portion on the outer surface of the elongate metal conduit, a second position
on
the inner surface of the inner plastic liner and connecting portions that
extends
through the plurality of openings.
[0030] In some embodiments, the method may further comprise providing
a plurality of openings at the first and second ends of the elongate metal
conduit
and overmolding a first connector on the first ends of the inner plastic liner
and
the elongate metal conduit and overmolding a second connector on the second
ends of the inner plastic liner and the elongate metal conduit.
[0031] In some embodiments, the method may further comprise trimming
each of the first and second ends of the inner plastic liner and the elongate
metal
conduit prior to overmolding the connectors on the ends.
[0032] In some embodiments, the method may further comprise providing
a gasket on the outer surface of the elongate metal conduit adjacent the first
end
of the elongate metal conduit prior to providing the first connector over the
first
ends of the inner plastic liner and the elongate metal conduit whereby the
gasket
is positioned between the elongate metal conduit and the first connector.
[0033] In some embodiments, the method may further comprise providing
a gasket on the outer surface of the elongate metal conduit adjacent the first
end
of the elongate metal conduit prior to overmolding the first connector over
the first
ends of the inner plastic liner and the elongate metal conduit whereby the
gasket
is positioned between the elongate metal conduit and the overmolded first
connector.
[0034] In some embodiments, the elongate metal conduit may comprise
at
least an inner and an outer elongate metal conduit and the method may further
comprise providing the inner plastic liner interior of the inner elongate
metal
conduit.
- 9 -
CA 02847520 2014-03-25
[0035]
In some embodiments, the method may further comprise providing
a protective layer intermediate the inner surface of the elongate metal
conduit
and the outer surface of the inner plastic liner.
[0036] In some embodiments:
a) the
protective layer may comprise a coating or a film applied to at
least one of the inner surface of the elongate metal conduit and the outer
surface of the inner plastic liner; or
b)
the inner plastic liner may comprise a co-extruded body having the
protective layer formed as an outer co-extruded layer; or
c) the
protective layer may comprise a separately formed sleeve
positioned between the inner surface of the elongate metal conduit and
the outer surface of the inner plastic liner.
[0037]
In some embodiments, providing the inner plastic liner having and
positioning the inner plastic liner interior of an elongate metal conduit may
comprise extruding the inner plastic liner into the elongate metal conduit.
[0038]
In some embodiments, heating the inner plastic liner may comprise
providing a heated fluid in the interior volume of the inner plastic liner.
[0039]
In some embodiments, applying pressure to the fluid positioned in
the interior volume of the inner plastic liner to expand the inner plastic
liner may
comprise applying pressure to the heated fluid after the inner plastic liner
has
been heated by the heated fluid.
[0040]
In some embodiments, an air gap may be located between the
outer surface of the inner plastic liner and the inner surface of the elongate
metal
conduit and applying pressure to the fluid positioned in the interior volume
of the
inner plastic liner to expand the inner plastic liner may include withdrawing
air
from the air gap while expanding the inner plastic liner.
-10-
CA 02847520 2014-03-25
[0041] In some embodiments, an air gap may be located between the
outer surface of the inner plastic liner and the protective layer and applying
pressure to the fluid positioned in the interior volume of the inner plastic
liner to
expand the inner plastic liner may include withdrawing air from the air gap
while
expanding the inner plastic liner.
[0042] In some embodiments, an air gap may be located between the
inner surface of the elongate metal conduit and the protective layer and
applying
pressure to the fluid positioned in the interior volume of the inner plastic
liner to
expand the inner plastic liner may include withdrawing air from the air gap
while
expanding the inner plastic liner.
[0043] In some embodiments, the air may be withdrawn by applying a
vacuum to the air gap.
[0044] In some embodiments, at least one of the inner surface of the
elongate metal conduit and the outer surface of the inner plastic liner may
have a
longitudinally extending recess, and the method may further comprise drawing
air
through the longitudinally extending recess while expanding the inner plastic
liner.
[0045] In some embodiments, the method may further comprise inserting
a
thin elongate member in the air gap prior to expanding the inner plastic
liner.
[0046] In some embodiments, the method may further comprise providing
a lubricant between the inner and outer elongate metal conduits.
[0047] In some embodiments, the method may further comprise a sleeve
having a generally longitudinally extending outer surface, wherein the
elongate
metal conduit is provided interior of the sleeve.
[0048] In some embodiments, the method may further comprise providing
a lubricant between the sleeve and the elongate metal conduit.
-11 -
CA 02847520 2014-03-25
[0049] It will be appreciated by a person skilled in the art that a
method or
apparatus disclosed herein may embody any one or more of the features
contained herein and that the features may be used in any particular
combination
or sub-combination.
[0050] These and other aspects and features of various embodiments will
be described in greater detail below. The apparatus and methods described
herein may be used to connect pipes and/or fittings of various materials (e.g.
metallic pipes, thermoplastic pipes) to create piping systems for transporting
various liquids or gasses. It will be appreciated that the piping system that
uses
the expansion compensator may be made from different materials (e.g., the
pipes may be made of PVC and/or CPVC and the fittings may be made of metal).
Alternatively, the piping system components (or at least their inner surfaces
through which fluid is conveyed) may be made of the same material.
[0051] Furthermore, the apparatus and methods may be applied to
different sizes of piping, and/or piping systems made of the same or different
materials, and therefore may be applicable to piping systems for domestic or
commercial uses, such as conveying potable water, non-potable or waste water,
or other liquids and/or gasses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] For a better understanding of the described embodiments and to
show more clearly how they may be carried into effect, reference will now be
made, by way of example, to the accompanying drawings in which:
[0053] Figure 1A is a cross section view of an expansion compensator
in
accordance with one embodiment;
[0054] Figure 1B is an enlarged view of the box 1B in Figure 1A of the
expansion compensator of Figure 1A;
[0055] Figure 2 is a cross section view of an end of the expansion
compensator of Figure 1A joined to a pipe end;
-12-
CA 02847520 2014-03-25
[0056] Figure 3A is a perspective view of an elongate metal conduit
and
an inner plastic liner in accordance with the embodiment of Figure 1A;
[0057] Figure 3B is an enlarged view of the box in Figure 3A;
[0058] Figure 3C is a perspective view of a two-layer elongate metal
conduit and an inner plastic liner in accordance with another embodiment;
[0059] Figure 3D is an enlarged view of the box in Figure 30;
[0060] Figure 3E is a perspective view of a two-layer elongate metal
conduit, a protective layer, and an inner plastic liner in accordance with
another
embodiment;
[0061] Figure 3F is an enlarged view of the box in Figure 3E;
[0062] Figure 3G is a perspective view of a two-layer elongate metal
conduit, a protective layer, and a two-layer inner plastic liner in accordance
with
another embodiment;
[0063] Figure 3H is an enlarged view of the box in Figure 3G;
[0064] Figure 4A is a perspective view of the expansion compensator of
Figure 1A with a sleeve;
[0065] Figure 4B is a perspective view of the expansion compensator
of
Figure 1A with an alternate sleeve;
[0066] Figure 5 is an exploded view of the expansion compensator of
Figure 4B;
[0067] Figure 6A is a perspective view of the expansion compensator
of
Figure 4B disposed between two pipe ends;
[0068] Figure 6B is a perspective view of the expansion compensator
and
pipe ends of Figure 6A with the pipe ends received in the connectors of the
expansion compensator;
[0069] Figure 7A is a cross section view of Figure 6B;
-13-
CA 02847520 2014-03-25
[0070] Figure 7B is an enlarged view of the box 7B in Figure 7A;
[0071] Figure 70 is a cross section view of an alternate expansion
compensator with pipe ends received in the connectors of the expansion
compensator;
[0072] Figure 7D is an enlarged view of the box 7D in Figure 70;
[0073] Figure 8A is a perspective view of a forming apparatus, a
metal
conduit, and a pre-formed plastic liner in accordance with one embodiment;
[0074] Figure 8B is a perspective view of Figure 8A with the pre-
formed
plastic liner positioned interior of the metal conduit;
[0075] Figure 80 is a perspective view of Figure 8B with the metal conduit
positioned in a cavity of one longitudinally extending body halves of the
forming
apparatus;
[0076] Figure 8D is a perspective view of Figure 80 with the
longitudinally
extending body halves of the forming apparatus in a closed configuration;
[0077] Figure 8E is a perspective view of Figure 8D with the upper support
frame of the forming apparatus partially inserted in the closed body halves;
[0078] Figure 8F is a perspective view of Figure 8E with the upper
and
lower support frames of the forming apparatus partially inserted in the closed
body halves;
[0079] Figure 9A is a cross section along line 9-9 in Figure 8F of the
metal
conduit and pre-formed plastic liner positioned in the forming apparatus;
[0080] Figure 9B is an enlarged view of the box 9B in Figure 9A;
[0081] Figure 10A is a cross section along line 9-9 in Figure 8F with
the
pre-formed plastic liner partially expanded against the metal conduit;
[0082] Figure 10B is an enlarged view of the box 10B in Figure 10A;
-14-
CA 02847520 2014-03-25
[0083] Figure 11A is a cross section along line 9-9 in Figure 8F
with the
pre-formed plastic liner further expanded against the metal conduit;
[0084] Figure 11B is an enlarged view of the box 11B in Figure 11A;
[0085] Figure 12A is a perspective view of a pre-formed plastic
liner in
accordance with one embodiment;
[0086] Figure 12B is a longitudinal cross section view of the pre-
formed
plastic liner of Figure 12A;
[0087] Figure 13A is a perspective view of a pre-formed plastic
liner in
accordance with another embodiment;
[0088] Figure 13B is a longitudinal cross section view of the pre-formed
plastic liner of Figure 13A;
[0089] Figure 14A is a perspective view of a pre-formed plastic
liner in
accordance with another embodiment;
[0090] Figure 14B is a longitudinal cross section view of the pre-
formed
plastic liner of Figure 14A;
[0091] Figure 15A is a perspective view of a pre-formed plastic
liner in
accordance with another embodiment;
[0092] Figure 15B is a longitudinal cross section view of the pre-
formed
plastic liner of Figure 15A;
[0093] Figure 16A is a perspective view of a pre-formed plastic liner in
accordance with another embodiment;
[0094] Figure 16B is a longitudinal cross section view of the pre-
formed
plastic liner of Figure 16A;
[0095] Figure 17 is a cross section view of ends of a two-layer
elongate
metal conduit and an inner plastic liner inserted into a molding apparatus;
- 15-
CA 02847520 2014-03-25
[0096] Figure 18A is a longitudinal cross section view of a metal
conduit, a
pre-formed plastic liner, and a thin elongate member disposed therebetween;
and,
[0097] .Figure 18B is a cross section along line 18B-18B in Figure
18A.
[0098] It will be appreciated that Figure 5 is for reference only, and that
it
may not be possible to assemble and/or disassemble expansion compensator
100 with the components in their illustrated configurations.
[0099] The drawings included herewith are for illustrating various
examples of articles, methods, and apparatuses of the teaching of the present
specification and are not intended to limit the scope of what is taught in any
way.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[00100] Various apparatuses, methods and compositions are described
below to provide an example of an embodiment of each claimed invention. No
embodiment described below limits any claimed invention and any claimed
invention may cover apparatuses and methods that differ from those described
below. The claimed inventions are not limited to apparatuses, methods and
compositions having all of the features of any one apparatus, method or
composition described below or to features common to multiple or all of the
apparatuses, methods or compositions described below. It is possible that an
apparatus, method or composition described below is not an embodiment of any
claimed invention. Any invention disclosed in an apparatus, method or
composition described below that is not claimed in this document may be the
subject matter of another protective instrument, for example, a continuing
patent
application, and the applicant(s), inventor(s) and/or owner(s) do not intend
to
abandon, disclaim, or dedicate to the public any such invention by its
disclosure
in this document.
[00101] The apparatuses, methods and compositions may be used with
piping systems made of various materials. The pipes and/or fittings to be
-16-
CA 02847520 2014-03-25
connected may be made of a plastic material and optionally a thermoplastic
material. The thermoplastic material may be one or more of acrylonitrile
butadiene styrene (ABS), PVC, CPVC, ethylene vinyl acetate (EVA),
polyethylene (PE) or the like. Preferably, the thermoplastic material is one
or
more of PVC and CPVC.
[00102] The drawings exemplify the use of an expansion compensator to
connect sections of pipe together. It will be appreciated that the same
expansion
compensator may be used to connect any parts of a piping system together. For
example, the expansion compensator may be used to connect a pipe with a
fitting such as a valve, tees, couplers, elbows, and the like, or to connect
one
fitting with another fitting.
[00103] Figures 1A to 7Dexemplify different embodiments of an
expansion
compensator 100, each of which may be made by the methods disclosed herein.
Expansion compensator 100 includes an elongate metal conduit, referred to
generally as 110, interior to which is positioned an inner plastic liner 120
that
provides a fluid flow path through the expansion compensator 100. Also, first
and
second connectors 130a,b may be provided at opposite ends of the metal
conduit and plastic liner. Connectors 130a,b may be used for coupling the
expansion compensator to a piping system, as will be discussed further
subsequently.
[00104] As shown in Figure 1A, each of elongate metal conduit 110 and
inner plastic liner 120 comprise a single layer, thereby forming a two-layer
expansion compensator 100. Expansion compensator 100 comprises a first end
102, a second end 104, and an expansion/contraction section 106.
Expansion/contraction section 106 allows for the axial length of expansion
compensator 100 to vary in response to an applied axial force (either
compressive or tensile). For example, if the position of first end 102 is
fixed, and
an axial force is applied to second end 104 in a direction towards first end
102,
expansion/contraction section 106 may contract in the axial direction,
reducing
-17-
CA 02847520 2014-03-25
the axial length of expansion compensator 100. Also, if the position of first
end
102 is fixed, and an axial force is applied to second end 104 in a direction
away
from first end 102, expansion/contraction section 106 may expand in the axial
direction, increasing the axial length of expansion compensator 100. While
expansion/contraction section 106 is illustrated as a bellows section having a
series of convolutions, it will be appreciated that other geometric
configurations
such as sinusoidal or otherwise articulated surface may be used. These
constructions permit the expansion compensator to temporarily deform (e.g.,
elastically deform) axially inwardly and outwardly during thermal expansion
and
contraction of the piping system, without fracture of the expansion
compensator.
[00105] The main body of expansion compensator 100 comprises elongate
metal conduit 110, within which is positioned inner plastic liner 120.
Preferably,
the opposite ends of metal conduit 110 and inner plastic liner 120 are coupled
together to provide a unitary body (i.e., so that the respective ends of the
outer
metal conduit and the inner plastic liner axial will have the same relative
displacement in response to an applied axial force). The elongate metal
conduit
110 and the inner plastic liner 120 may be coupled together by providing a
connector, which may be formed by overmolding, at one and preferably each end
of the expansion compensator. As shown in Figure 1B, metal conduit 110
(illustrated here as comprising an inner elongate metal conduit 116 and an
outer
elongate metal conduit 117) has an outer surface 112 and an inner surface 114.
Inner surface 114 is adjacent an outer surface 122 of inner plastic liner 120,
while
inner surface 124 of inner plastic liner 120 defines the interior volume of
expansion compensator 100 between connectors 130a,b.
[00106] Connectors 130a,b may be provided at one or both ends of
expansion compensator 100 and may be configured or adapted for coupling
expansion compensator 100 to other components of a piping system. For
example, connectors 130a,b may comprise exterior and/or interior surface
features (e.g. threads, grooves, ridges, tabs), and may be dimensioned to
-18-
CA 02847520 2014-03-25
receive (and/or be received within) a number of piping system components, such
as pipes, fittings, valves, and the like. Also, while connectors 130a,b in the
illustrated embodiments are substantially similar to each other, it will be
appreciated that in alternative embodiments different connectors (e.g. for
coupling to different sizes and/or types of components) may be provided on
opposite ends of the same expansion compensator.
[00107] The apparatus exemplified uses an insertion fit, i.e., one end
of one
part of a piping system is inserted into an open end of another part of the
piping
system. For example, connector 130a,b may be dimensioned to receive first and
second pipe ends inserted into first end 102 and second end 104, respectively,
of
expansion compensator 100. Connector 130 may be configured such that an end
of a pipe may be inserted only up to a predetermined distance into connector
130. This may assist in aligning one or more features (e.g. injection
passages,
grooves) of the connector and/or the pipe end with each other. Therefore, a
stop
member may be provided inside connector 130. For example, as exemplified in
Figure 1B, in some embodiments one or both connectors 130a,b may comprise
an interior ridge 138 that provides an abutment surface against which a pipe
end
inserted into the respective connector 130a,b will abut when inserted a
predetermined distance, to assist in coupling expansion compensator 100 to a
pipe end, as shown in Figure 2.1t will be appreciated that interior ridge 138
may
have a height that is similar to or the same as the thickness of the pipe
inserted
into end 104. Accordingly, the cross sectional area of flow through the pipe
and
the end of the expansion compensator is generally the same.
[00108] As exemplified in Figure 6A, expansion compensator 100 is
shown
disposed between and aligned with pipe ends 10a,b. More specifically,
connector
130a is aligned with pipe end 10a, and connector 130b is aligned with pipe end
10b. In the illustrated embodiment, connectors 130a,b are dimensioned to
receive therein, respectively, pipe ends 10a,b. Figure 6B shows expansion
compensator 100 once it has been coupled to pipe ends 10a,b. It will be
- 19-
CA 02847520 2014-03-25
appreciated that the ends of connectors 130a,b may be configured to be
connected to a pipe end 10a,b by any means known in the piping arts.
[00109] Figure 7A shows a cross section view of expansion compensator
100 coupled to pipe ends 10a,b. Expansion/contraction section 106 allows for
the
axial length of expansion compensator 100 to vary in response to an axial
force
(either compressive or tensile) applied by pipe end 10a and/or 10b. For
example,
if thermal expansion of one or both of the pipes 10 causes pipe ends 10a,b to
attempt to move towards each other, the pipe ends will exert a compressive
force
along the longitudinal axis of expansion compensator 100. Such a compressive
force may be exerted (or imposed) on expansion compensator 100 by a piping
system in response to water having a temperature of from about 55 C to about
85 C flowing through the piping system. In response to such an applied force,
expansion/contraction section 106 may contract in the axial direction,
reducing
the axial length of expansion compensator 100. The amount of contraction of
expansion compensator 100 will depend on the amount of the applied
compressive force, and the overall axial stiffness of expansion compensator
100.
Also, if the axial stiffness of the elongate metal conduit is greater than the
stiffness of the inner plastic liner, a greater portion of the applied
compressive
force will be borne (e.g. absorbed) by metal conduit 110 while expansion
compensator 100 is compressed, and the stress on plastic liner 120 may
accordingly be reduced.
[00110] As another example, if thermal contraction of one or both of
the
pipes 10 causes pipe ends 10a,b to attempt to move away from each other, the
pipe ends may exert a tensile force along the longitudinal axis of expansion
compensator 100. In response to such an applied force, expansion/contraction
section 106 may expand in the axial direction, increasing the axial length of
expansion compensator 100. Again, the amount of expansion of expansion
compensator 100 will depend on the amount of the applied tensile force and the
axial stiffness of expansion compensator 100. Also, if the axial stiffness of
the
- 20 -
CA 02847520 2014-03-25
elongate metal conduit is greater than the stiffness of the inner plastic
liner, a
greater portion of the applied tensile force will be borne by metal conduit
110
while expansion compensator 100 is expanded, and the stress on plastic liner
120 may accordingly be reduced.
[00111] It will be appreciated that the stiffness of expansion compensator
100 may vary based on the number of metal layers in metal conduit 110, the
particular metal or metals used, the thickness of each metal layer, and/or the
geometry of metal conduit 110. The stiffness of expansion compensator 100 may
also depend on the number of layers in inner plastic liner 120, the particular
plastic or plastics used, the thickness of each plastic layer, and/or the
geometry
of inner plastic liner 120.
[00112] It will also be appreciated that the overall stiffness of
expansion
compensator 100 may be selected based on the forces expected to be imposed
by a piping system into which it is installed, so as to reduce the stress in
the
piping system components. For example, an expansion compensator 100 with a
relatively lower overall stiffness may compress or expand more easily in
response to an applied force than an expansion compensator 100 with a
relatively higher overall stiffness. Providing a more pliant expansion
compensator
100 may allow greater axial deformation (e.g. expansion or contraction) of
piping
system components in response to expected thermal changes, which may
reduce the internal stress in these components.
[00113] Figures 8A to 16B exemplify methods and apparatus for
manufacturing expansion compensator 100. In general, the method includes
positioning a pre-formed plastic liner, referred to generally as 220, interior
of
elongate metal conduit 110 and using fluid under pressure to expand pre-formed
plastic liner 220 outwardly towards inner surface 114 of metal conduit 110,
whereby the expanded plastic liner forms inner plastic liner 120. Generally
speaking, the methods may be characterized as being analogous to
hydroforming pre-formed plastic liner 220 against metal conduit 110, using
inner
- 21 -
CA 02847520 2014-03-25
surface 114 of metal conduit 110 as a mold for pre-formed plastic liner 220.
After
forming, first and second connectors 130a,b may be provided at one or both
ends of the metal conduit and inner plastic liner.
[00114] Figure 8A illustrates a forming apparatus, referred to
generally as
300, which may be used when expanding pre-formed plastic liner 220. It will be
appreciated that, in variant embodiments, forming apparatus 300 may comprise
more or fewer components. Also, it will be understood by persons skilled in
the
art that one or more components (e.g. controllers, piping, wiring, etc.) have
been
omitted for clarity.
[00115] As exemplified in Figure 8A, forming apparatus 300 has first and
second body halves 310, 311, each having a complementary recess 318, 319,
respectively, for receiving and holding metal conduit 110 therebetween.
Accordingly, complementary recesses 318, 319 maybe dimensioned to receive
metal conduit 110 therebetween and to support metal conduit 110 during the
forming process. First and second body halves 310, 311 may be configured to
reinforce metal conduit during the forming process. For example, complementary
recess 318, 319 may be sized and shaped such that the outer surface of metal
conduit 110 abuts there against.
[00116] First and second body halves 310, 311 may be selectively
securable together and moveable between an open position as exemplified in
Figure 8A in which metal conduit 110 may be placed therein and a closed
forming position as exemplified by Figure 8F by any means known in the art. In
the Figures, the mechanism for moving one of both of first and second body
halves 310, 311 between the open and forming positions has not been shown. A
person skilled in the forming arts will be familiar with such mechanisms and
any
such mechanism may be used.
[00117] As exemplified in the Figures, mechanical engagement members
have been utilized to exemplify how forming apparatus 300 may be secured in
- 22 -
CA 02847520 2014-03-25
the forming position. As exemplified, first body half 310 has one or more
upper
engagement flanges 312a and one or more lower engagement flanges 312b that
may cooperate with one or more upper engagement flanges 313a and one or
more lower engagement flanges 313b on second body half 311, and/or with
upper and lower alignment pins 322a, 322b, as will be discussed subsequently.
Body halves 310, 311 may each also have one or more upper locking members
(314, 315, respectively) and lower locking members (316, 317, respectively),
for
engagement with upper locking ports 324, 325 on upper support frame 320 and
lower locking ports 326, 327 on lower support frame 321, as will be discussed
subsequently. It will be appreciated that other securing means, including
pneumatic means may be used and a person skilled in the forming arts will be
familiar with such mechanisms and any such mechanism may be used.
[00118] Prior to the forming step, pre-formed plastic liner 220 is
positioned
interior of metal conduit 110. As exemplified in Figure 8A, pre-formed plastic
liner
220 is inserted into metal conduit 110 in the direction indicated by arrow 8
such
that pre-formed plastic liner 220 is positioned in metal conduit 110 as
exemplified
in Figure 8B. Pre-formed plastic liner 220 may be positioned in metal conduit
100
prior to securing metal conduit 110 between complementary recesses 318, 319.
It will be appreciated that pre-formed plastic liner 220 may alternatively be
inserted into metal conduit 110 from the other direction, and/or positioned
interior
of metal conduit 110 during or after the securing first and second body halves
310, 311 together.
[00119] As exemplified, metal conduit 110 is provided as a pre-formed
construct (i.e., with the desired profile for the expansion/contraction
section 106).
Metal conduit 110 may be manufactured by any suitable process or processes,
such as tube drawing, hydroforming and the like.
[00120] Metal conduit 110 may be made from steel, copper, or other
iron
alloys, or any other metal used in the piping arts although it will be
appreciated
- 23 -
CA 02847520 2014-03-25
that other metallic materials may be suitable. Preferably, metal conduit 110
is
made from one or more layers of stainless steel, such as SS316L stainless
steel.
[00121] As exemplified in Figure 3A, metal conduit 110 comprises a
single
layer. For such an embodiment, the thickness of metal conduit 110 may be from
0.005 to 0.030 inches, preferably from 0.010 to 0.020 inches, and more
preferably from 0.012 to 0.016 inches.
[00122] Figures 12A and 12B exemplify a pre-formed plastic liner 220
having a first end 202, a second end 204, an inner surface 224, and an outer
surface 222. Pre-formed plastic liner 220 is dimensioned to be receivable
(e.g.,
slidably receivable) in metal conduit 110 and may be retained therein by any
means known in the forming arts. As exemplified in Figure 8B, first end 202
may
be dimensioned such that some or all of first end 202 remains outside of metal
conduit 110, i.e., axially outwardly of first end 111 of metal conduit 110.
For
example, first end 202 may be slightly conical in shape, or may have a stepped
profile so as to limit the extent to which pre-formed plastic liner is
insertable into
metal conduit 110. It will also be appreciated that metal conduit 110 may have
engagement members to secure pre-formed plastic liner 220 in a desired
position
and/or forming apparatus 300 may have a member to secure pre-formed plastic
liner 220 in a desired position. Alternatively, it will be appreciated that
all of first
end 202 may be received in metal conduit 110.
[00123] Pre-formed plastic liner 220 may have a length so as to extend
to
the opposed end of metal conduit and, optionally as shown in Figure 8B, the
extend axially past the opposed end of metal conduit 110. As exemplified in
Figure 8B, pre-formed plastic liner 220 may be dimensioned such that some or
all of second end 204 extends past second end 113 of metal conduit 110.
[00124] Pre-formed plastic liner 220 may be manufactured by any
suitable
process, such as injection molding and the like. As shown in Figures 12A and
12B, pre-formed plastic liner 220 may have a substantially uniform thickness.
- 24-
CA 02847520 2014-03-25
Alternatively, as will be discussed subsequently, pre-formed plastic liner 220
may
be provided with one or more regions of non-uniform wall thickness.
[00125] As exemplified in Figure 3A, inner plastic liner 120 may
comprise a
single layer. For such an embodiment, the thickness of inner plastic liner 120
may be from 0.005 to 0.125 inches, preferably from 0.020 to 0.1 inches, and
more preferably from 0.040 to 0.090 inches.
[00126] It will be appreciated that inner plastic liner 120 may
comprise two
layers. In such a case, two pre-formed plastic liners may be nested into metal
conduit 110 and the forming process then conducted. Alternatively, an outer
pre-
formed plastic liner may be individually placed in metal conduit 100 and the
forming process conducted. Subsequently, an inner pre-formed plastic liner may
then be placed in inner formed plastic liner and the forming process conducted
again.
[00127] In embodiments where inner plastic liner 120 comprises two
layers
(e.g., together forming a four-layer expansion compensator in two metal layers
are used as exemplified in Figure 3G), the thickness of each plastic layer
126,127 may be from 0.005 to 0.75 inches, preferably from 0.020 to 0.050
inches, and more preferably from 0.03 to 0.045 inches.
[00128] Once the pre-formed plastic liner 202 has been positioned
inside
metal conduit 110, forming apparatus 300 may be closed. Accordingly, as
exemplified in Figure 8C, metal conduit 110 (with pre-formed plastic liner 220
inserted therein) may be positioned in one of the complementary recesses,
e.g.,
recess 118. Subsequently, as exemplified in Figure 8D, body halves 310, 311
have been brought together so that complementary recesses 318, 319 define a
cavity surrounding metal conduit 110. Also, upper sockets 302a on upper
engagement flanges 312a have received upper projecting members 301a on
upper engagement flanges 313a and these are secured together by any means
known in the forming arts. Similarly, lower sockets 302b on lower engagement
- 25 -
CA 02847520 2014-03-25
flanges 312b have received lower projecting members 301b on lower
engagement flanges 313b and these are secured together by any means known
in the forming arts. The respectively coupled engagement members restrain any
relative vertical motion of body halves 310, 311, and also cooperatively
define
upper and lower alignment barrels 304a, 304b.
[00129] Upper support frame 320 is engaged with first and second body
halves 310, 311 (see Figure 8E). In doing so, upper alignment pins 322a are
received within upper alignment barrels 304a, and upper locking members 314,
315 are received by upper locking ports 324, 325, respectively. Preferably,
upper
alignment pins 322a are longer than upper locking members 314, 315, so that
upper alignment pins 322a engage upper alignment barrels 304a prior to upper
locking members 314, 315 engaging upper locking ports 324, 325. In this way,
the alignment pins and barrels act to constrain the horizontal alignment of
upper
support frame 320 as it is brought towards first and second body halves 310,
311, which may facilitate the engagement of upper locking members 314, 315
with upper locking ports 324, 325.
[00130] The engagement of upper support frame 320 with first and
second
body halves also results in upper plug 328 being received within first end 202
of
pre-formed plastic liner 220, which is itself positioned within first end 111
of metal
conduit 110.
[00131] Lower support frame 321 is engaged with first and second body
halves 310, 311 (see Figure 8F). In doing so, lower alignment pins 322b is
received within lower alignment barrels 304b, and lower locking members 316,
317 is received by lower locking ports 326, 327, respectively. Preferably,
lower
alignment pins 322b are longer than lower locking members 316, 317, so that
lower alignment pins 322b engage lower alignment barrels 304b prior to lower
locking members 316, 317 engaging lower locking ports 326, 327. In this way,
the alignment pins and barrels act to constrain the horizontal alignment of
lower
support frame 321 as it is brought towards first and second body halves 310,
- 26 -
CA 02847520 2014-03-25
311, which may facilitate the engagement of lower locking members 316, 317
with lower locking ports 326, 327.
[00132] The engagement of lower support frame 321 with first and
second
body halves also results in lower plug 329 being received within second end
204
of pre-formed plastic liner 220, which is itself positioned within second end
113 of
metal conduit 110.
[00133] It will be appreciated that these steps may be conducted in
any
order and may vary if different forming apparatus 300 is utilized.
[00134] As exemplified in Figure 9A, which is a cross section along
line 9-9
in Figure 8F, metal conduit 110 and pre-formed plastic liner 220 are
positioned in
the cavity defined by complementary recesses 318, 319 of first and second body
halves 310, 311.
[00135] It will also be appreciated that additional metal layers or
conduits
may be provided. In such a case, forming apparatus 300 and in particular first
and second body halves 310, 311 may be adapted to secure two metal conduits
in position in recesses 318, 319. For example, as shown in Figures 3C and
Figure 1B, elongate metal conduit 110 may comprise an inner elongate metal
conduit 116 and an outer elongate metal conduit 117, together with inner
plastic
liner 120 forming a three-layer expansion compensator. Where metal conduit 110
comprises more than one metal layer, it will be appreciated that the overall
axial
stiffness of metal conduit 110 may be approximated as the sum of the axial
stiffness for each metal layer. In such a case, inner elongate metal conduit
116
and outer elongate metal conduit 117 may have the same stiffness or they may
be different. In embodiments where metal conduit 110 comprises two layers, the
thickness of each metal conduit 116,117 may be from 0.005 to 0.025 inches,
preferably from 0.008 to 0.020 inches, and more preferably from 0.012 to 0.016
inches.
-27-
CA 02847520 2014-03-25
[00136] For example, in the embodiment illustrated in Figure 9B, metal
conduit 110 comprises inner elongate metal conduit 116 and outer elongate
metal conduit 117, and expansion/contraction section 115 of metal conduit 110
comprises an alternating series of radially outer peaks 160a,b,c and radially
inner
valleys 162a,b,c.
[00137] Pre-formed plastic liner 220 is heated and formed. Pre-formed
plastic liner 220 may be pre-heated. For example, once metal conduit 110 with
pre-formed plastic liner 220 is placed in recesses 118,119, pre-formed plastic
liner 220 may be heated and formed. It will be appreciated that pre-formed
plastic
liner 220 may be pre-heated prior to insertion into metal conduit 110 and/or
pre-
heated once placed in metal conduit 110 but prior to placement of metal
conduit
110 into forming apparatus 300. The pre-formed plastic liner 220 may be pre-
heated to a temperature above which the plastic becomes formable. Once
forming apparatus 300 is closed, the heating of pre-formed plastic liner 220
up to
a forming temperature may be conducted and pre-formed plastic liner 220 then
formed. Alternatively, the forming and the heating step may occur
concurrently.
Further, pre-formed plastic liner 220 may not be pre-heated and accordingly,
all
of the heating may occur once pre-formed plastic liner 220 is positioned in
forming apparatus 300.
[00138] The forming step is conducted by pressurizing the interior of pre-
formed plastic liner 220. Accordingly, once at a forming temperature, the
pressure will cause pre-formed plastic liner 220 to deform to produce the
desired
profile. Accordingly, prior to the forming step, a sealed volume is created
that
includes the interior of pre-formed plastic liner 220. For example, referring
to
Figure 9A, upper plug 328 and lower plug 329 may provide a sealed volume
within pre-formed plastic liner 220, into which a fluid is introduced. For
example,
conduit 330 may convey fluid into and/or out of the sealed interior volume of
pre-
formed plastic liner 220. Conduit 330 may be connected to a pump, compressor,
a high pressure fluid line that is available, e.g., high pressure steam or
other
- 28 -
CA 02847520 2014-03-25
source of pressurized fluid (not shown) for selectively introducing and/or
removing fluid from the sealed interior volume of pre-formed plastic liner
220.
[00139] Pre-formed plastic liner 220 may be heated in situ by the
forming or
working fluid. For example, the forming fluid may comprise a heated fluid,
preferably a heated liquid, such as water. Alternatively, or in addition, one
or
more heat sources (such as heating element 332 extending from lower plug 329)
may be provided in the sealed interior volume, to heat the fluid contained
therein.
Alternatively, or in addition, body halves 310, 311 may be provided with
heating
elements or a heating jacket may be provided.
[00140] In operation, once the interior volume of pre-formed plastic liner
220 has been sealed by upper and lower plugs 328, 329, a fluid (e.g. water)
may
be introduced into the interior volume, for example via conduit 330.
Preferably,
the fluid is introduced at an elevated temperature, so that pre-formed plastic
liner
220 is heated (and thus softened) by the fluid. Alternatively, or
additionally, the
fluid may be heated after introduction to the sealed interior volume, for
example
via heating element 332.
[00141] The forming temperature will depend upon the plastic that is
used
and the pressure that is applied. For example, for CPVC, the forming
temperature may be from 110 C to 150 C, preferably from 120 C to 140 C and
more preferably from 125 C to 135 C. For PVC, lower forming temperatures may
be used. Any forming temperature known in the forming arts may be used.
[00142] The forming fluid may be maintained in the sealed interior
volume
at a lower temperature for a period of time to partially or fully preheat the
pre-
formed plastic liner 220 prior to raising the pressure to a forming pressure.
Accordingly, after a sufficient time has elapsed for pre-formed plastic liner
220 to
be heated, and thereby softened, which may take from 1 to 30, preferably 2 to
10, more preferably 3 to 5 minutes, the pressure of the fluid in the interior
volume
may be increased, for example by introducing more fluid into the interior
volume
- 29 -
CA 02847520 2014-03-25
(e.g. via conduit 330) or pressurizing the fluid already in the interior. For
example, for CPVC, the forming pressure may be from 100 to 800 psi, preferably
from 250 to 600 psi and more preferably from 350 to 450 psi. Any forming
pressure known in the forming arts may be used. Increasing the pressure within
the sealed interior volume will increase the force exerted on the inner
surface
224 of pre-formed plastic liner 220, causing the walls of pre-formed plastic
liner
220 to expand towards inner surface 114 of metal conduit 110, as shown in
Figures 10A and 10B.
[00143] It will also be understood by a person skilled in the art
that the
forming fluid may be above the boiling point of the forming fluid, e.g., 120
to130 C so as to reduce the heating time for the plastic to reach, e.g., the
forming temperature. In such a case, forming apparatus 500 is operated so as
to
prevent the working fluid from boiling. For example, during the preheating
step,
the forming fluid may be an elevated pressure, such as 40 to 70 psi, to
prevent
the forming fluid from boiling.
[00144] Optionally, during expansion of pre-formed plastic liner 220,
fluid
(e.g. air) may be withdrawn ¨ continuously or intermittently ¨ from the
annular
volume between the outer surface 222 of pre-formed plastic liner 220 and the
inner surface 114 of metal conduit 110 (e.g., via vent port 334) and/or from
the
annular volume between the outer of metal conduit and the inner surface of
body
halves 310, 311. For example, one or more vent ports (such as port 334 in
first
body half 310) may be provided for selectively removing fluid from the annular
volume between the outer surface 222 of pre-formed plastic liner 220 and the
inner surface 114 of metal conduit 110, and/or from the annular volume between
the cavity defined by complementary recesses 318, 319 and outer surface 112 of
metal conduit 110. Vent port 334 may be connected to a pump or other vacuum
source.
- 30 -
CA 02847520 2014-03-25
[00145] Optionally, as shown in Figures 18A and 18B, one or more thin
elongate members 370 may be provided between inner surface 114 of metal
conduit 110 and outer surface 222 of pre-formed plastic liner 220 prior to
expanding pre-formed plastic liner 220. Such elongate members may provide a
longitudinal airflow path 375 (see e.g. Figure 18B) in the annular volume
between
the outer surface 222 of pre-formed plastic liner 220 and the inner surface
114 of
metal conduit 110, facilitating the abutment of outer surface 222 of pre-
formed
plastic liner 220 and the inner surface 114 of metal conduit 110 during
expansion
of the pre-formed plastic liner 220 by facilitating the escape of air from
between
metal conduit 110 and pre-formed plastic liner 220.
[00146] Optionally, one or more longitudinally extending grooves (not
shown) may be provided on inner surface 114 of metal conduit 110 and/or the
outer surface of the preformed plastic liner 220. Such grooves may provide a
longitudinal airflow path in the annular volume between the outer surface 222
of
pre-formed plastic liner 220 and the inner surface 114 of metal conduit 110,
facilitating the abutment of outer surface 222 of pre-formed plastic liner 220
and
the inner surface 114 of metal conduit 110 during expansion of the pre-formed
plastic liner 220. It will be appreciated that such a recess may be provided
on any
of all of the metal conduits illustrated herein.
[00147] As time elapses (during which the pressure and/or temperature of
the fluid may be maintained, increased, and/or decreased), pre-formed plastic
liner 220 may continue to expand until the outer surface 222 of pre-formed
plastic
liner 220 abuts the inner surface 114 of metal conduit 110, as illustrated in
Figures 11A and 11B and by the dotted lines (denoted 220') in Figure 18B.
Preferably, pre-formed plastic liner 220 is formed so as to develop a profile
that
conforms to the profile of the inner surface of metal conduit 110. As such
metal
conduit 110 may act as a mold. Therefore, it will be appreciated that, once
the
forming process is complete, metal conduit 110 and inner plastic liner 120 may
be abutting as exemplified in Figure 3B. However, it will be appreciated that
the
- 31 -
CA 02847520 2014-03-25
forming may be conducted, by controlling one or more of the time, pressure and
temperature such that such that the profile of plastic liner is similar to
that of the
interior surface of metal conduit 110 but does not completely conform thereto.
In
such a case, metal conduit 110 and inner plastic liner 120 may be spaced
apart.
[00148] Expansion/contraction section 106 is generally illustrated as a
bellows section having a series of convolutions. While the
expansion/contraction
sections of metal conduit 110 and inner plastic liner 120 are shown with
complementary profiles (e.g. each have a similar profile, and these profiles
are
aligned), it will be appreciated that that this need not be the case.
[00149] Alternatively, or additionally, while outer surface 122 of inner
plastic
liner 120 is illustrated as being in contact with (e.g. abutting) inner
surface 114 of
metal conduit 110, it will be appreciated that in some embodiments, an air gap
may be present along all or part of the length of expansion compensator 100.
This may be achieved by limiting the forming pressure, temperature and/or
time.
[00150] Once pre-formed plastic liner 220 has been expanded sufficiently to
form inner plastic liner 120, the plastic liner 120 may be cooled. This may
occur
by one or more of providing a cooling fluid to the interior volume,
withdrawing
water from the interior volume, applying cooling by the body halves 310, 311,
such as by passing a cooling fluid through cooling passages in body halves
310,
311, applying a cooling fluid to a thermal jacket around forming apparatus
300,
withdrawing the formed part from forming apparatus 300 and allowing it to cool
by exposing it to the ambient conditions or placing it in a cooling bath, or
any
other means known in the forming arts.
[00151] In some embodiments, in order to reduce friction a lubricant
may be
provided between metal conduit 110 and inner plastic liner 120. The lubricant
may be any lubricant that is compatible with the inner plastic liner and metal
conduit and may be talcum powder, powdered Teflon, powdered mica and the
like. The lubricant may be provided on the outer surface of pre-formed plastic
- 32 -
CA 02847520 2014-03-25
liner 220 and/or the inner surface of metal conduit 110 prior to the insertion
of
pre-formed plastic liner 220 in metal conduit and/or concurrently therewith
and/or
subsequent to the insertion step.
[00152] It will also be appreciated that, if metal conduit 110
comprises two
layers, then inner elongate metal conduit 116, outer elongate metal conduit
117
and inner plastic liner 120 may be abutting as exemplified in Figure 3D or
they
may be spaced apart. In some embodiments, in order to reduce friction a
lubricant may be provided between inner elongate metal conduit 116 and inner
plastic liner 120.
[00153] It will be appreciated that expansion compensator 100 may
comprise additional layers. These layers may be applied prior to the insertion
of
pre-formed plastic liner 220 in metal conduit 110 and/or concurrently
therewith
and/or subsequent to the insertion step.
[00154] For example, in Figure 3E a protective layer 170 is disposed
between metal conduit 110 (which itself comprises elongate metal conduits 116,
117) and inner plastic liner 120. Protective layer 170 may serve to reduce the
friction between metal conduit 110 and inner plastic liner 120 during
expansion
and/or contraction of expansion compensator 100. Also, protective layer 170
may
provide an additional cfailsafe' layer to prevent leakage of fluid from within
expansion compensator 100 (e.g. should one or more cracks develop in inner
plastic liner 120 and/or metal conduit 110).
[00155] Protective layer 170 is located between metal conduit 110 and
inner plastic liner 120 and may abut a surface or may be spaced from the
facing
surfaces. It will be appreciated that inner elongate metal conduit 116,
protective
layer 170 and inner plastic liner 120 may be abutting as exemplified in
Figures
3E and 3F or they may be spaced apart.
[00156] Protective layer 170 may be provided: as a coating on outer
surface
122 of inner plastic liner 120; as a coating on inner surface 114 of elongate
metal
- 33 -
CA 02847520 2014-03-25
conduit 110; and/or as a separate layer (not shown) positioned between metal
conduit 110 and pre-formed plastic liner 220 prior to expansion.
[00157] .For example, inner plastic liner 120 may comprise a co-
extruded
body having protective layer 170 formed as an outer co-extruded layer to inner
plastic liner 120.
[00158] Preferably, protective layer 170 is made
from
polytetrafluoroethylene (PTFE) or one or more other suitable fluropolymers,
although it will be appreciated that other materials may be used.
[00159] Figure 3G illustrates an embodiment where protective layer
170 is
disposed between metal conduit 110 (which itself comprises elongate metal
conduits 116, 117) and a two-layer inner plastic liner 120 (comprising inner
plastic layer 126 and outer plastic layer 127).
[00160] Optionally, after forming, portions of inner plastic liner
120 that
extend from metal conduit 110 may be trimmed or otherwise removed, resulting
in a two-layer expansion compensator, as exemplified in Figure 3A.
[00161] As noted previously, connectors 130a,b may be provided at one
or
both ends of expansion compensator 100, and may be configured or adapted for
coupling expansion compensator 100 to other components of a piping system.
[00162] As exemplified in Figure 1B, each connector 130 is secured to
each
of metal conduit 110 and inner plastic liner 120 to thereby secure metal
conduit
110 and inner plastic liner 120 together. As exemplified, connector 130 may
have
a first portion or arm 132 secured to the outer surface 112 of elongate metal
conduit 110, and a second portion or arm 134 secured to the inner surface 124
of
inner plastic layer 120. In the illustrated embodiment, first portion 132 and
second portion 134 are connected via an end portion 136, such that connector
130 defines a generally U-shaped cavity between portions 132, 134, and 136.
- 34 -
CA 02847520 2014-03-25
[00163] Connectors 130a,b may be provided by various means.
Preferably,
connectors 130 a,b are provided by molding a plastic component over the end of
metal conduit 110 and plastic liner 120 so as to secure the ends together and
essentially form a unitary body. For example, connectors 130 a,b may be formed
by overmolding portions 132, 134, and 136 of connector 130 onto the ends of
metal conduit 110 and inner plastic liner 120.
[00164] An advantage of forming connecting portions 133 by
overmolding,
is that portions 132, 134 of connector 130, connecting portions 133 and inner
liner 120 may be formed essentially as a unitary body (e.g., the plastic that
is
used to overmold will heat inner liner 120 and may melt a sufficient amount of
inner liner 120 to be secured thereto). Metal conduit 110 may therefore be
embedded therein and securely fixed in position and thereby be adapted to
incur
axial stresses applied by thermal cycling.
[00165] Alternatively, connectors 130 may be formed with projections
on
the inner surface of first portion 132 sized and located to be received in
openings
118 and act as connecting portions 133 when connector 130 is mounted (e.g.
press-fit or snapped on to) an end 102, 104 of metal conduit 110. In this
latter
case, the connecting portions 133 may be secured to inner plastic liner 120
by,
e.g., an adhesive, welding or the like. Optionally, inner plastic liner 120
may be
secured to portions 134 of connector 130 in a similar manner.
[00166] In some embodiments, as shown in Figure 2 and Figure 5, the
ends
of metal conduit 110 may be provided with a plurality of openings 118. These
openings may assist in securing connectors 130a,b to respective ends of
expansion compensator 100. Also, engagement of connector 130 and openings
118 in metal conduit 110 may allow a greater portion of an axial force applied
to
connector 130 to be transferred to metal conduit 110, rather than to inner
plastic
liner 120.
- 35 -
CA 02847520 2014-03-25
[00167] For example, openings 118 may allow a portion of first
portion 132
of connector 130 to project into metal conduit 110, which may provide a more
robust connection between metal conduit 110 and connector 130. These
connecting portions 133 extending through openings 118 may be provided by
overmolding portions 132, 134, and 136 of connector 130 onto the ends of metal
conduit 110 and inner plastic liner 120.
[00168] For example, as illustrated in Figure 17, the ends of metal
conduit
110 and inner plastic liner 120 may be inserted into and secured within a mold
body 350 that defines an annular cavity 360 into which a liquefied material
for
forming connector 130 may be injected (e.g. via one or more injection ports
355).Thus, portions 132, 134, and 136, and connecting portions 133 may be
molded substantially concurrently. It will be appreciated that, in variant
embodiments, mold body 350 may comprise more or fewer components. Also, it
will be understood by persons skilled in the art that one or more components
(e.g. controllers, piping, wiring, etc.) have been omitted for clarity. A
person
skilled in the molding arts will be familiar with such mechanisms and any such
mechanism may be used.
[00169] An advantage of connecting portions 133 is that connecting
portions 133 extend at about 90 to the axial forces that are expected to be
exerted on expansion compensator 100 by thermal cycling. Thus, the axial
forces
that are applied to expansion compensator 100 may be transferred to metal
conduit 110 via connectors 130a,b, and not via inner plastic liner 120.
[00170] As noted previously, Figures 3A and 30 depict, respectively,
two-
and three-layer expansion compensator bodies. If elongate metal conduit 110
comprises inner elongate metal conduit 116 and outer elongate metal conduit
117, then each metal conduit 116, 117 may be provided with openings 118.
Accordingly, even if two metal conduits 116, 117 are used, connecting portions
133 may extend from portion 132 through both metal conduits 116, 117 to be
- 36 -
CA 02847520 2014-03-25
secured to inner plastic liner 120, which itself may be secured to portion 134
of
connector 130, such as by heating to form a unitary body, an adhesive or the
like.
[00171] By securing metal conduit 110 and plastic liner together, such
as by
using connectors 130a,bõ metal conduit 110 and inner plastic liner 120 may be
characterized as springs acting in parallel. Thus, the overall axial stiffness
of
expansion compensator 100 (e.g. kEc) may be approximated as the sum of the
axial stiffness of metal conduit 110 (e.g. kmc) and the axial stiffness of
inner
plastic liner 120 (e.g. kipL):
kEc kmc + k/pL (1)
[00172] In some embodiments, the axial stiffness of the elongate metal
conduit may be greater than the stiffness of the inner plastic liner such that
a
greater portion (preferably a substantial portion, and most preferably
substantially
all) of an axial force applied to expansion compensator 100 will be borne
(e.g.
absorbed) by metal conduit 110, while inner plastic liner 120 will bear a
smaller
portion (preferably a significantly smaller portion) of the applied axial
force. Put
another way, to balance (e.g. reach equilibrium with) an axial force FEc
applied to
expansion compensator 100, and assuming a common axial displacement -x
(i.e. compression), the magnitude of the force exerted by each of metal
conduit
110 (FMC) and inner plastic liner 120 (F/pL)will be proportional to their
respective
stiffness:
FEC = Fitic F!PL
(kmc = ¨x) + (kipL = ¨x) (2)
= (kmc + kipL)(¨x)
- 37 -
CA 02847520 2014-03-25
[00173] For example, if the axial stiffness kmc is four times greater
than the
axial stiffness IcipL, metal conduit 110 will provide about 80% of the total
force
exerted by expansion compensator 100 in response to an applied axial force.
[00174] While the stiffer metal conduit 110 may absorb the majority of
an
applied axial force, inner plastic liner 120 may provide a barrier between the
metal conduit and a fluid flowing through expansion compensator 100. For
example, inner plastic liner 120 may protect metal conduit 110 from corrosive
or
otherwise reactive fluids, extending the lifespan of metal conduit 110 and/or
preventing portions of metal conduit 110 from leaching into fluids flowing
through
expansion compensator 100. Preferably, the expansion compensator has an
inner plastic liner made from the same (or similar) thermoplastic material of
the
pipes to which it is to be installed, so that a fluid flowing through a pipe
and
expansion compensator will be in contact with the same (or similar) material
through both components.
[00175] It will be appreciated that the stiffness of expansion compensator
100 may vary based on the number of metal layers in metal conduit 110, the
particular metal or metals used, the thickness of each metal layer, and/or the
geometry of metal conduit 110. The stiffness of expansion compensator 100 may
also depend on the number of layers in inner plastic liner 120, the particular
plastic or plastics used, the thickness of each plastic layer, and/or the
geometry
of inner plastic liner 120.
[00176] Where inner plastic liner 120 comprises more than one plastic
layer, it will be appreciated that the overall axial stiffness of inner
plastic liner 120
may be approximated as the sum of the axial stiffness for each plastic layer.
In
such a case, each plastic layer may have the same stiffness or they may be
different. As exemplified therein, outer elongate metal conduit 117, inner
elongate metal conduit 116, protective layer 170, inner plastic layer 126 and
- 38 -
CA 02847520 2014-03-25
outer plastic layer 127 may each be abutting as exemplified in Figure 3H or
one
or more may be spaced apart.
[00177] Optionally, the ends of metal conduit 110 may be provided with
one
or more surface features (e.g. radial ridges or grooves) to facilitate the
installation
of a gasket between metal conduit 110 and outer portion 132 of connector 130.
For example, as shown in Figures 1B and 5, a radial groove 119 may be
provided on outer surface 112 of an end of metal conduit 110, radial groove
119
being configured to receive a gasket such as an 0-ring 150. Such a gasket may
be provided to minimize the chance of fluid leaking from expansion compensator
100 via, e.g., a gap between inner surface 124 of inner plastic liner 120 and
second portion 134 of connector 130, between the ends of metal conduit 110 and
inner plastic liner 120 and end portion 136 of connector 130, and between
outer
surface 112 of metal conduit 110 and first portion 132 of connector 130.
Radial
groove 119 may assist in locating and retaining 0-ring 150 relative to the end
of
expansion compensator 100 as connector 130 is mounted and/or molded to an
end 102, 104 of metal conduit 110. It will be appreciated that a gasket may be
provided in the absence of a groove 119.
[00178] Accordingly, prior to overmolding (or otherwise providing) one
or
more connectors 130, one or more gaskets (e.g. 0-ring 150) may be installed on
the ends of metal conduit 110 (e.g. in one or more grooves 119) prior to
overmolding the connectors.
[00179] Additionally, or alternatively, the outer surface 112 of metal
conduit
110 (and/or the inner surface of inner plastic liner 120) at the ends of
expansion
compensator 100 may be subject to a surface treatment prior to overmolding, to
improve the connection between metal conduit 110 and/or inner plastic liner
120
and connectors 130.
[00180] As illustrated in Figure 4A, expansion compensator 100 may be
provided with a sleeve 140. Sleeve 140 may overlie some and preferably all or
- 39 -
CA 02847520 2014-03-25
essentially all of expansion/contraction section 106 to protect against
damage,
restrain deflection of expansion/contraction section 106 in a radial or
lateral
direction, and/or provide a distinctive aesthetic appearance to expansion
compensator 100. For example, expansion/contraction section 106 of expansion
compensator 100 may have a corrugated exterior surface. This surface might get
caught (which could cause damage to the expansion compensator) as a pipe
with the expansion compensator is slid into position. Providing a sleeve 140
over
some or all of expansion/contraction section 106 may assist the expansion
compensator being placed is position. In addition, when axially loaded,
expansion/contraction section 106 of expansion compensator 100 may tends to
deflect laterally instead of compress. Sleeve 140 may overlie some or all of
expansion compensator 100 so as to inhibit and, preferably, prevent, lateral
deflection under axial loading. In such a case, the inner diameter of sleeve
140 is
preferably proximate that of the outer diameter of expansion/contraction
section
106.
[00181] Sleeve 140 may have one or more tabs 144 or other engagement
means to retain it in a preset axial position about expansion compensator 100.
The engagement means permit sleeve 140 to be retained in position while still
allowing expansion compensator 100 to expand and contract. Accordingly, for
example, tabs 144 may be positioned axially outwardly from the axially opposed
ends of expansion/contraction section 106 so as to permit
expansion/contraction
section 106 to expand and contract its entire design distance without
restriction.
Accordingly, tabs 144 may be spaced sufficiently from the last ridge of
expansion/contraction section 106 (i.e. the ridge closes to the connector)
such
that, when fully expanded the ridge may at most abut tab 144.
[00182] Alternatively, or additionally, sleeve 140 may have one or
more
viewing ports 142 to allow for visual inspection of the outer surface 112 of
metal
conduit 110 in the expansion/contraction section 106. Figure 4B illustrates an
example sleeve 140 without viewing ports 142.
-40 -
CA 02847520 2014-03-25
[00183] Figure 5 illustrates a sleeve guard 146 that may be disposed
between the outer surface 112 of metal conduit 110 and the inner surface of
sleeve 140 such as to reduce friction and/or provide abrasion resistance
between
these components and/or to reinforce sleeve 140 and/or to provide a sliding
fit on
expansion/contraction section 106. It will be appreciated that more (as shown
in
Figure 7B) or fewer (as shown in Figure 4A) sleeve guards may be provided.
[00184] Sleeve 140 (and optionally one or more sleeve guards 146) may
be
provided after pre-formed plastic liner 220 has been expanded to form inner
plastic liner 120, and/or after providing one or more connectors 130. Inner
plastic
liner 120 may not have a uniform radial thickness. For example, as shown in
Figure 7B, where expansion/contraction section 106 comprises an alternating
series of radially outer peaks 160a,b,c and radially inner valleys 162a,b,c,
the
radial thickness Tp of inner plastic liner 120 at the radially outer peaks
160a,b,c
may be less than the radial thickness Tv of inner plastic liner 120 at the
radially
inner valleys 162a,b,c. Such variations in thickness may arise, for example,
where a plastic cylinder of substantially uniform thickness is positioned
within
metal conduit 110, heated, and then expanded outwards against inner surface
114 of metal conduit 110. Also, inner plastic liner 120 may be expected to
experience more erosion or wear at radially inner valleys 162a,b,c as compared
with portions of inner plastic liner 120 at radially outer peaks 160a,b,c, as
radially
inner valleys 162a,b,c may be exposed to higher velocity flows of fluid
through
expansion compensator 100. Accordingly, providing increased thickness at
portions of inner plastic liner 120 that are expected to experience higher
erosion
or wear may extend the operating lifespan of expansion compensator 100.
[00185] In some embodiments, the ratio of the radial thickness Tv to the
radial thickness Tp may be up to about 2:1, or up to about 3:1, or up to about
4:1.
For example, the radial thickness Tp of inner plastic liner 120 at the
radially outer
peaks 160a,b,c may be about 0.040 inches, and the radial thickness Tv of inner
- 41 -
CA 02847520 2014-03-25
plastic liner 120 at the radially inner valleys 162a,b,c may be about 0.080
inches
(i.e. the ratio of Tv to Tp is about 2:1).
[00186] Alternatively, as shown in Figures 7C and 7D, the radial
thickness
Tp of inner plastic liner 120 in radially outer peaks 160a,b,c may be
substantially
equal to the radial thickness Tv of inner plastic liner 120 in radially inner
valleys
162a,b,c. Such a uniform thickness for inner plastic liner 120 may be
achieved,
for example, by expanding a plastic cylinder of non-uniform thickness
outwardly
against inner surface 114 of metal conduit 110 or using the inner surface of
metal
conduit as an interior mold surface. Providing a generally uniform thickness
for
inner plastic liner 120 may assist in predicting and/or controlling the axial
stiffness of inner plastic liner 120, and thus the overall axial stiffness of
expansion compensator 100. For example, the radial thickness Tp of inner
plastic
liner 120 at the radially outer peaks 160a,b,c may be about 0.060 inches, and
the
radial thickness Tv of inner plastic liner 120 at the radially inner valleys
162a,b,c
may be about 0.060 inches (i.e. the ratio of Tv to Tp is about 1:1).
[00187] These profiles may be produced by using different pre-formed
plastic liners 120. As exemplified in Figures 13A and 13B, pre-formed plastic
liner
220 has an expansion/contraction region 215 that comprises one or more
annular ribs 230. As noted above with reference to Figure 7D, by expanding a
pre-formed plastic liner 220 of non-uniform thickness such as is exemplified
in
Figures 13A and 13B outwardly against inner surface 114 of metal conduit 110,
the radial thickness Tp of inner plastic liner 120 in radially outer peaks
160a,b,c
may be substantially equal to the radial thickness Tv of inner plastic liner
120 in
radially inner valleys 162a,b,c. Accordingly, by selecting the thickness of
ribs 230
a formed plastic liner 120 having a more or less uniform wall thickness may be
obtained.
[00188] Figures 14A and 14B exemplify another example of a pre-formed
plastic liner 220 also has an expansion/contraction region 215 with non-
uniform
wall thickness, however instead of forming pre-formed plastic liner 220 with a
- 42 -
CA 02847520 2014-03-25
series of ribs 230 (as in Figure 13A), the expansion/contraction region 215
illustrated in Figure 14A comprises one or more annular grooves 240 cut into a
pre-formed plastic liner 220 that was initially formed with a uniform wall
thickness.
[00189] In Figures
15A and 15B, another example pre-formed plastic liner
220 has an expansion/contraction region 215 that comprises one or more
annular ribs 230, and also has a longitudinally extending recess 250 on the
outer
surface 222. Such a recess may provide a longitudinal airflow path in the
annular
volume between the outer surface 222 of pre-formed plastic liner 220 and the
inner surface 114 of metal conduit 110, facilitating the abutment of outer
surface
222 of pre-formed plastic liner 220 and the inner surface 114 of metal conduit
110 during expansion of the pre-formed plastic liner 220. It will be
appreciated
that such a recess may be provided on any of all of the pre-formed plastic
liners
illustrated herein.
[00190] Figures 16A
and 16B illustrate another example pre-formed plastic
liner 220, having a uniform cylindrical profile and wall thickness. In this
example,
flared or enlarged outer ends are not provided. It will be appreciated that
pre-
formed plastic liners with other profiles may be used, depending on the
interior
profile of metal conduit 110 and/or the desired interior profile of inner
plastic liner
120.
[00191] As used
herein, the wording "and/or" is intended to represent an
inclusive - or. That is, "X and/or Y" is intended to mean X or Y or both, for
example. As a further example, "X, Y, and/or Z" is intended to mean X or Y or
Z
or any combination thereof.
[00192] While the
above description describes features of example
embodiments, it will be appreciated that some features and/or functions of the
described embodiments are susceptible to modification without departing from
the spirit and principles of operation of the described embodiments. For
example,
- 43 -
CA 02847520 2014-03-25
the various characteristics which are described by means of the represented
embodiments or examples may be selectively combined with each other.
Accordingly, what has been described above is intended to be illustrative of
the
claimed concept and non-limiting. It will be understood by persons skilled in
the
art that other variants and modifications may be made without departing from
the
scope of the invention as defined in the claims appended hereto. The scope of
the claims should not be limited by the preferred embodiments and examples,
but should be given the broadest interpretation consistent with the
description as
a whole.
- 44 -
