U.S. patent application number 09/812653 was filed with the patent office on 2002-11-21 for rupture-resistant fluid transport and containment system.
Invention is credited to Webber, Richard L..
Application Number | 20020170610 09/812653 |
Document ID | / |
Family ID | 25210238 |
Filed Date | 2002-11-21 |
United States Patent
Application |
20020170610 |
Kind Code |
A1 |
Webber, Richard L. |
November 21, 2002 |
Rupture-resistant fluid transport and containment system
Abstract
Fluid transport and containment systems are protected from
rupture related to an expanded volume within the systems. A fluid
transport system, such as a water supply pipe, has a relief channel
along its length configured for expanding outwardly when fluids
contained in the pipe freeze and expand. A unitary pipe
configuration including a pipe wall and an integral core structure
that can be sealed at each end provides a means for expansion
sufficient to resist freeze-induced rupture. Such pipe
configurations can be used with conventional pipes and pipe
fittings and with adapters adapted to fit both the improved pipes
and conventional pipes and pipe fittings.
Inventors: |
Webber, Richard L.;
(Clemmons, NC) |
Correspondence
Address: |
J. Michael Boggs
Kilpatrick Stockton LLP
1001 West Fourth Street
Winston-Salem
NC
27101-2400
US
|
Family ID: |
25210238 |
Appl. No.: |
09/812653 |
Filed: |
March 20, 2001 |
Current U.S.
Class: |
138/28 ; 138/109;
138/115; 138/164; 138/177; 138/178; 138/32 |
Current CPC
Class: |
F16L 9/006 20130101;
F16L 57/02 20130101; E03B 7/10 20130101; F16L 51/00 20130101 |
Class at
Publication: |
138/28 ; 138/32;
138/109; 138/115; 138/164; 138/177; 138/178 |
International
Class: |
E03B 007/10 |
Claims
What is claimed is:
1. A fluid transport system having an internal volume, the system
resistant to rupture due to expansion of the internal volume,
comprising: a pipe having a length and a pipe wall, the pipe wall
having an inside surface and an outside surface and two adjacent
edges along the length of the pipe forming an open seam; a core
structure connected to the inside surface of the pipe wall along
the length of the pipe and having an open seam contiguous with the
open seam in the pipe wall; and a hollow expansion channel along
the length of the pipe defined by the core structure, wherein the
pipe has a center along the length of the pipe and the pipe wall
and the core structure are expandable outwardly from the center of
the pipe in the direction of the open seams, and wherein when the
internal volume expands, the pipe wall and core structure expand
sufficiently to accommodate the expanded volume and resist rupture
of the system.
2. The fluid transport system of claim 1, wherein the pipe and the
core structure comprise an integral pipe unit.
3. The fluid transport system of claim 2, the integral pipe unit
having an original non-expanded position, and the expanded internal
volume is caused by freezing of fluid inside the pipe, wherein the
integral pipe unit comprises a configuration having elasticity
sufficient to expand outwardly greater than the expanded internal
volume caused by the freezing of the fluid and to contract to
approximately the original non-expanded position when the frozen
fluid thaws.
4. The fluid transport system of claim 3, wherein the fluid inside
the pipe is water and the integral pipe unit is sufficiently
expandable to accommodate an expanded volume of at least 10% when
the water freezes.
5. The fluid transport system of claim 1, the hollow expansion
channel having open ends adaptable for sealing, the system further
comprising a plug sealably contacting each end of the expansion
channel.
6. The fluid transport system of claim 5, wherein the plug is
solid.
7. The fluid transport system of claim 5, wherein the plug is
hollow.
8. The fluid transport system of claim 5, the pipe being
connectable to another pipe with pipe fittings each having an
internal volume, wherein the plug has a portion for inserting into
the end of the expansion channel and a compressible portion for
protruding into adjacent pipe fittings so that when the volume in
the pipe fittings expands, the compressible portion compresses to
accommodate the expanded volume and resist rupture of the
system.
9. The fluid transport system of claim 8, wherein the compressible
portion of the plug for protruding into adjacent pipe fittings is
tapered.
10. The fluid transport system of claim 5, the system further
comprising an adapter for fitting the pipe to a conventional pipe,
the adapter having a first end comprising a shape adapted to form a
sealable fit with the pipe and a second end comprising a shape
adapted to form a sealable fit with the conventional pipe.
11. The fluid transport system of claim 10, the pipe having an end,
wherein the first end of the adapter comprises an integral plug for
sealably contacting the end of the expansion channel and wherein
the first end of the adapter is larger than the pipe for sealably
fitting over the end of the pipe.
12. The fluid transport system of claim 10, the pipe being
connectable to another pipe with pipe fittings, wherein the second
end of the adapter comprises a shape adapted to form a sealable fit
with the pipe fittings, the second end further comprising a
compressible portion for protruding into adjacent pipe fittings so
that when the volume in the pipe fittings expands, the compressible
portion compresses to accommodate the expanded volume and resist
rupture of the system.
13. The fluid transport system of claim 1, wherein the pipe and the
core structure comprise a thermoplastic material.
14. The fluid transport system of claim 13, wherein the
thermoplastic material is polyvinyl chloride.
15. The fluid transport system of claim 1, wherein the pipe and the
core structure comprise a metallic material.
16. The fluid transport system of claim 1, wherein the pipe and the
core structure comprise a unitarily extruded material.
17. The fluid transport system of claim 1, wherein the pipe and the
core structure comprise an injection molded material.
18. The fluid transport system of claim 1, wherein the pipe, the
core structure, and the plug at each end of the expansion channel
comprise a smooth central passageway substantially free of surface
irregularities adapted to transport liquid with a minimum of
frictional losses.
19. The fluid transport system of claim 5, wherein the system
comprises a plurality of the plugs, further comprising a means for
packaging the plurality of plugs and inserting one of the packaged
plurality of plugs into each end of the expansion channel.
20. The fluid transport system of claim 19, wherein the means for
packaging and inserting plugs comprises a first length of the
plurality of plugs having each of the plurality of plugs connected
sequentially end to end by material adaptable for breaking, wherein
a plug at the end of the first length of plugs is inserted into the
end of the expansion channel and the inserted plug is broken away
from the first length of plugs at the connecting material to
provide a second length of plugs ready for repeating the insertion
and breaking away steps.
21. The fluid transport system of claim 1, wherein the fluid
transport system is a plumbing system.
22. The fluid transport system of claim 1, wherein the fluid
transport system is a fire sprinkler system.
23. The fluid transport system of claim 1, wherein the fluid
transport system is an irrigation system.
24. A fluid transport system having an internal volume, the system
resistant to rupture due to expansion of the internal volume,
comprising: a pipe having a length and a pipe wall, the pipe wall
having an inside surface and an outside surface and two adjacent
edges along the length of the pipe forming an open seam; a core
structure connected to the inside surface of the pipe wall along
the length of the pipe and having an open seam contiguous with the
open seam in the pipe wall; and a hollow expansion channel along
the length of the pipe defined by the core structure, wherein the
pipe and the core structure comprise an integral pipe unit, wherein
the pipe has a center along the length of the pipe and the integral
pipe unit is expandable outwardly from the center of the pipe in
the direction of the open seams, and wherein when the internal
volume expands, the integral pipe unit expands sufficiently to
accommodate the expanded volume and resist rupture of the
system.
25. The fluid transport system of claim 24, the hollow expansion
channel having open ends adaptable for sealing, the system further
comprising a plug sealably contacting each end of the expansion
channel.
26. The fluid transport system of claim 25, wherein the plug is
solid.
27. The fluid transport system of claim 25, wherein the plug is
hollow.
28. The fluid transport system of claim 25, the pipe being
connectable to another pipe with pipe fittings, wherein the plug
has a portion for inserting into the end of the expansion channel
and a compressible portion for protruding into adjacent pipe
fittings so that when the volume in the pipe fittings expands, the
compressible portion compresses to accommodate the expanded volume
and resist rupture of the system.
29. The fluid transport system of claim 28, wherein the
compressible portion of the plug for protruding into adjacent pipe
fittings is tapered.
30. The fluid transport system of claim 25, the system further
comprising an adapter for fitting the pipe to a conventional pipe,
the adapter having a first end comprising a shape adapted to form a
sealable fit with the pipe and a second end comprising a shape
adapted to form a sealable fit with the conventional pipe.
31. The fluid transport system of claim 30, the pipe having an end,
wherein the first end of the adapter comprises an integral plug for
sealably contacting the end of the expansion channel and wherein
the first end of the adapter is larger than the pipe for sealably
fitting over the end of the pipe.
32. The fluid transport system of claim 30, the pipe being
connectable to another pipe with pipe fittings each having an
internal volume, wherein the second end of the adapter comprises a
shape adapted to form a sealable fit with the pipe fittings, the
second end further comprising a compressible portion for protruding
into adjacent pipe fittings so that when the volume in the pipe
fittings expands, the compressible portion compresses to
accommodate the expanded volume and resist rupture of the
system.
33. The fluid transport system of claim 24, wherein the integral
pipe unit comprises a thermoplastic material.
34. The fluid transport system of claim 33, wherein the
thermoplastic material is polyvinyl chloride.
35. The fluid transport system of claim 24, wherein the integral
pipe unit comprises a metallic material.
36. The fluid transport system of claim 24, wherein the integral
pipe unit comprises an extruded material.
37. The fluid transport system of claim 24, wherein the in tegral
pipe unit comprises an injection molded material.
38. The fluid transport system of claim 25, wherein the integral
pipe unit and the plug at each end of the expansion channel
comprise a smooth central passageway substantially free of surface
irregularities adapted to transport liquid with a minimum of
frictional losses.
39. The fluid transport system of claim 25, wherein the system
comprises a plurality of the plugs, further comprising a means for
packaging the plurality of plugs and inserting one of the packaged
plurality of plugs into each end of the expansion channel.
40. The fluid transport system of claim 39, wherein the means for
packaging and inserting plugs comprises a first length of the
plurality of plugs having each of the plurality of plugs connected
sequentially end to end by material adaptable for breaking, wherein
a plug at the end of the first length of plugs is inserted into the
end of the expansion channel and the inserted plug is broken away
from the first length of plugs at the connecting material to
provide a second length of plugs ready for repeating the insertion
and breaking away steps.
41. The fluid transport system of claim 24, wherein the fluid
transport system is a plumbing system.
42. The fluid transport system of claim 24, wherein the fluid
transport system is a fire sprinkler system.
43. The fluid transport system of claim 24, wherein the fluid
transport system is an irrigation system.
44. A fluid container having an internal volume, the container
resistant to rupture due to expansion of the internal volume,
comprising: a plurality of sides, one of the plurality of sides
having a length and an inside surface and two adjacent edges along
the length of the one side forming an open seam; a core structure
connected to the inside surface and along the length of the one
side and having an open seam contiguous with the open seam in the
one side; and a hollow expansion channel along the length of the
one side defined by the core structure, wherein the one side and
the core structure comprise an integral unit, wherein the integral
unit is expandable outwardly in the direction of the open seams,
and wherein when the internal volume expands, the integral unit
expands sufficiently to accommodate the expanded volume and resist
rupture of the system.
45. The fluid container of claim 44, the integral unit having an
original non-expanded position, and the expanded internal volume is
caused by freezing of fluid inside the container, wherein the
integral unit comprises a configuration having elasticity
sufficient to expand outwardly greater than the expanded internal
volume caused by the freezing of the fluid and to contract to
approximately the original non-expanded position when the frozen
fluid thaws.
46. The fluid container of claim 45, wherein the fluid inside the
container is water and the integral unit is sufficiently expandable
to accommodate an expanded volume of at least 10% when the water
freezes.
47. The fluid container of claim 44, the hollow expansion channel
having open ends adaptable for sealing, the container further
comprising a plug sealably contacting each end of the expansion
channel.
48. The fluid container of claim 47, wherein the plug is solid.
49. The fluid container of claim 47, wherein the plug is
hollow.
50. The fluid container of claim 44, wherein the container
comprises a thermoplastic material.
51. The fluid container of claim 50, wherein the thermoplastic
material is polyvinyl chloride.
52. The fluid container of claim 44, wherein the container
comprises a metallic material.
53. The fluid container of claim 44, wherein the container
comprises an extruded material.
54. The fluid container of claim 44, wherein the container
comprises an injection molded material.
55. A fluid transport system having an internal volume, the system
resistant to rupture due to expansion of the internal volume,
comprising a pipe having a length and a pipe wall, the pipe having
a center along the length of the pipe, the pipe wall comprising at
least one depression toward the center and along the length of the
pipe, each of the at least one depression defining an external
expansion channel, wherein the pipe wall is expandable outwardly
from the center of the pipe in the direction of the at least one
depression, and wherein when the internal volume expands, the pipe
wall expands sufficiently to accommodate the expanded volume and
resist rupture of the system.
56. The fluid transport system of claim 55, the pipe wall having an
original non-expanded position, and the expanded internal volume is
caused by freezing of fluid inside the system, wherein the pipe
wall comprises a configuration having elasticity sufficient to
expand outwardly greater than the expanded internal volume caused
by the freezing of the fluid and to contract to approximately the
original non-expanded position when the frozen fluid thaws.
57. The fluid transport system of claim 56, wherein the fluid
inside the system is water and the pipe wall is sufficiently
expandable to accommodate an expanded volume of at least 10% when
the water freezes.
58. The fluid transport system of claim 55, the system further
comprising an adapter for fitting the pipe to a conventional pipe,
the adapter having a first end comprising a shape adapted to form a
sealable fit with the pipe and a second end comprising a shape
adapted to form a sealable fit with the conventional pipe.
59. The fluid transport system of claim 58, the pipe having an end,
wherein the first end of the adapter comprises an integral plug for
sealably contacting the end of the expansion channel and wherein
the first end of the adapter is larger than the pipe for sealably
fitting over the end of the pipe.
60. The fluid transport system of claim 58, the pipe being
connectable to another pipe with pipe fittings, wherein the second
end of the adapter comprises a shape adapted to form a sealable fit
with the pipe fittings, the second end further comprising a
compressible portion for protruding into adjacent pipe fittings so
that when the volume in the pipe fittings expands, the compressible
portion compresses to accommodate the expanded volume and resist
rupture of the system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to protection of fluid
transport and containment systems from rupture related to an
increased internal volume. In particular, the present invention
relates to a unitary pipe structure sufficiently expandable to
resist rupture due to freezing of fluids within the system.
BACKGROUND OF THE INVENTION
[0002] It is well known that when water freezes to solid ice it
undergoes an expansion in volume of about 9%. This physical change
causes increased pressure within a water containment system or
transport passage and has been the cause of many instances of
bursting of water pipes. There have been many attempts to solve
this problem. In residential housing the typical practice is to
insulate water pipes or otherwise keep them from exposure to
freezing temperatures by putting the pipes under ground or inside
houses where a heating system maintains temperatures above
freezing.
[0003] Another approach to protect pipes from freezing is covering
pipes with heating coils or other means to keep the temperature of
the water above freezing. This approach is impractical for general
use purposes due to the expense of added heating materials and the
need for an energy supply to operate the heating coils.
[0004] Another approach to protect pipes from freezing is
introducing an antifreeze solution into the water to change the
temperature at which water freezes. As an illustration, U.S. Pat.
No. 4,664,181 describes a method wherein heating pipes are not
filled all the way and a solvent is added to reduce the freezing
temperature of the water. In plumbing systems, this practice is
usually limited to situations where a system remains dormant for a
period of time, such as in a vacation home or on a recreational-use
boat. Use of an antifreeze solution generally makes a water supply
unusable for human consumption until the pipes are cleared of the
solution. In addition, discharge of antifreeze solutions from a
plumbing system may be hazardous to the environment.
[0005] Still other means have been attempted in the past to prevent
freeze damage to pipes containing water or other liquids.
Compressible compartments within branches or reservoirs connected
to the outside of water pipes have been used in plumbing systems,
such as that described in U.S. Pat. No. 1,672,393. Such systems
require extra piping which may not fit in crowded spaces and which
adds much extra expense.
[0006] Compressible, air-filled compartments placed within the
water flow path inside a pipe are disclosed, for example in U.S.
Pat. Nos. 2,409,304, 3,480,027, and 4,649,959. A central
compressible core placed inside a pipe containing water is designed
to provide an internal expansion volume to accommodate the volume
needed when the water freezes. Such internally disposed
compressible compartments have a number of disadvantages. For
example, the turns, couplings, and other fittings in modern piping
do not lend themselves to having a continuous length of
compressible core as shown in these patents. Furthermore, the
pressure of liquids inside pipes is such that compressible cores
might be so compressed that little safety volume would remain for
that needed when the water freezes. Moreover, the compressible core
may tend to move away from its desired position due to velocity
changes of water flowing in the pipe. Additionally, compressible
cores add the expense of extra materials and increased installation
costs and are subject to stress fatigue and leakage.
[0007] In attempt to overcome disadvantages of air-filled
compartments, some pipe freeze protection systems use solid
compressible bodies inserted within water pipes, such as described
in U.S. Pat. No. 2,360,596. However, these types of insertable
bodies are still subject to movement out of position with the flow
of water through the pipe. Also, compressible inserts made with
rubber and inserts having rubber flanges for holding them in place
in the center of the pipe are ineffective. Rubber flanges of
adequate size and compressibility cannot be used around bends, such
as found near outside faucets where protection is critical and
where pipe dimensions vary because of faucets and couplings. As
well, rubber deteriorates with age and thus cannot provide
permanent freeze protection.
[0008] A different approach to insertable compressible bodies for
absorbing expansion of freezing water is disclosed in U.S. Pat. No.
4,773,448. This patent describes a pipe having a rigid outer shell,
a smooth flexible inner shell spaced inwardly from the outer shell,
and a flexible foam material, such as foamed polyethylene, filling
the space between the outer and inner shells. The flexible inner
shell is sufficiently elastic to expand the internal volume of the
pipe about 10% to accommodate freezing water. A disadvantage of
such a design is that the use of two different materials which must
be bonded together creates additional manufacturing costs.
Operation of such an insert is also plagued with reliability and
durability concerns.
[0009] Another system for freeze-protecting an aqueous fluid
conduit using a compressible material is disclosed in U.S. Pat. No.
6,119,729. In this system, an elongated compressible elastomeric
material is disposed within the conduit along its length. The
conduit includes a rigid wall and a substantially liquid
impermeable membrane disposed adjacent to the compressible
elastomeric material. The conduit may also include rigid structural
supports between the membrane and the rigid wall. The compressible
elastomeric material, such as silicone foam, foamed butyl rubber,
foamed neoprene, silicone sponge rubber, and urethane foam,
accommodates expansion caused by freezing. This device is disclosed
as particularly suitable for heat transfer applications, such as a
solar thermal collector or photovoltaic cells. As noted above, such
a system incurs the added expense of materials and manufacturing
for separate inner membranes, outer walls, and compressible
materials. Furthermore, a flexible fluid-conducting membrane is
susceptible to weakening and leakage during prolonged use.
[0010] Rather than rigidly fixing compressible inserts inside the
entire length of a pipe, other approaches allow an inner body to
move within a pipe. For example, U.S. Pat. No. 4,321,908 discloses
an apparatus to prevent freeze damage to a pipe conducting a
pressurized liquid by attaching one end of an inner tube to the
pipe so as to prevent linear axial movement of the tube and
maintaining the other end concentrically within the pipe so as to
permit limited linear axial expansion of the tubing inside the
pipe. The tube comprises a linear section of tubing which is sealed
at each end and contains an inert gas under pressure in excess of
the pressure of the liquid in the pipe. When the water begins to
freeze and expand, it then compresses the central core. Such a
device is unsatisfactory because a continuous length of the
compressible core tube does not easily fit within the angles of
bends and couplings, fixing the tube in place during installation
is complex, the pressurized tube may rupture and thus fail in
action, and material and installation costs are excessive.
[0011] U.S. Pat. No. 5,058,627 discloses yet another water pipe
anti-rupture system for preventing freeze damage in which a string
of hollow cups spaced apart by a common connecting rod are placed
within the interior of a pipe such that the cups provide for
compression within the pipe. The connecting rod frictionally
engages the inside of a water pipe to hold the cups in place
substantially in the center and along a length of water pipe with
hollows oriented downward so that the cups can entrap air. When
water freezes and expands within the pipe, air trapped in the
hollow chambers compresses to absorb the expansion of freezing
water.
[0012] This type of pipe freeze protection system has several
disadvantages. One disadvantage is that the spaced cups must be
oriented in a downward direction in order to entrap air, thus
requiring different configurations for each length of pipe placed
at different angles. For example, for hollows to be oriented
downwardly, cups must be oriented one direction in a
horizontally-placed pipe and in a different direction in a
vertically-placed pipe. Another disadvantage is that to prevent
pipe rupture by absorbing expansion of freezing water with air,
such a pipe system must entrap a sufficient volume of air to be
effective. Yet another disadvantage is that such pipe freeze
protection systems are designed for selective use in lengths of
pipe in critical areas exposed to freezing, such as from an outside
faucet into the interior of a house, rather than along the entire
length of a plumbing system.
[0013] In addition, previous approaches to protecting pipes from
rupture due to freezing have not addressed in the same design
protecting pipes from rupture related to other causes. For example,
an increase in temperature and/or pressure of a fluid beyond a
pipe's normal elastic limit may not be sufficiently accommodated by
air-filled compartments or compressible inserts as in prior
designs.
[0014] Until now there has not been a fluid transport or
containment system designed to protect such a system from rupture
due to an expanding internal volume, particularly rupture due to
freezing of fluid, in which the system structure itself is adapted
to expand and contract.
[0015] Prior pipe freeze-protection approaches have not combined
advantages of a unitary configuration that is sufficiently
expandable and contractible to resist rupture during repeated
cycles of freezing and thawing with those of a system that allows
use of standard-sized pipes with standard pipe fittings, that are
economical to manufacture and use, that can be used in virtually
any fluid containment and/or fluid transport system, and that
overcome disadvantages of systems using separate internal
components. It is to these perceived needs that the present
invention is directed.
SUMMARY OF THE INVENTION
[0016] The present invention protects fluid transport and
containment systems from rupture related to an expanded volume
within the systems. In particular, the present invention provides a
system for containing and/or transporting fluids having a means for
sufficiently expanding when fluids contained therein freeze,
thereby resisting freeze-induced rupture.
[0017] In embodiments of the present invention, freeze-damage
resistance is provided by pipes having a hollow expansion channel,
or relief groove, which runs longitudinally along the pipes. As
water inside a pipe freezes and changes from liquid state to a
solid ice state, the increase in volume due to such expansion
exerts an outward pressure on pipe walls. The pipe walls are able
to expand, or move outwardly, in an elastic process, and relieve
the stress caused by such volume expansion. In this way, rupture of
the pipes can be prevented. Such outward elastic movement of pipe
walls in response to expansion caused by freezing fluids is
reversible. As such, pipes of the present invention allow pipe
walls to contract back, or move inwardly, to substantially their
original position when frozen fluid within the pipes thaws. Pipe
systems of the present invention include plugs which sealingly fit
into each end of the hollow, expansion channels to allow pipes to
be utilized in conventional ways including with a variety of
fittings, such as elbows, tees, caps, adapters, expanders,
reducers, collars, and the like.
[0018] More particularly, embodiments of a fluid transport system
resistant to rupture due to expansion of freezing fluid contained
within the system as in the present invention include a pipe having
an open seam along the length of the pipe and a core structure
connected to the inside surface of the pipe along its length. The
core structure also has an open seam that is contiguous with the
open seam in the pipe wall, and defines a hollow expansion channel
along the length of the pipe. The expansion channel has open ends
adaptable for sealing with a plug at each end. The pipe and core
structure are expandable outwardly in radial fashion from the
longitudinal center of the pipe in the direction of the open seams.
The pipe wall and core structure of the present invention are
expandable, or outwardly moveable, and contractible, or inwardly
moveable, so that when fluid contained within the system freezes
and expands, the pipe wall and core structure expand, or move
outwardly, to accommodate an increased volume, thereby resisting
rupture of the system.
[0019] In embodiments, the pipe and the core structure of the
present invention comprise an integral pipe unit. The integral pipe
unit comprises a configuration having elasticity sufficient to
expand greater than an increased volume, for example, the increase
in volume caused by freezing of fluid within the pipe system, and
to contract to approximately an original non-expanded position, as
when frozen fluid within the system thaws.
[0020] In embodiments in which the fluid contained within the pipe
system is water, the present invention comprises a pipe and core
structure that are sufficiently expandable to accommodate an
increased volume of at least 10% when the water freezes.
[0021] Pipes of the present invention can be constructed with any
material suitable for transporting fluids that is sufficiently
elastic to allow a pipe structure to expand and contract in
response to freezing and thawing fluid. Preferably the material is
a strong, hard material, such as thermoplastic polymeric materials,
including polyvinyl chloride (PVC).
[0022] Embodiments of pipes and pipe systems of the present
invention are readily manufactured as the pipe and core structure
can be extruded as a single, integral pipe unit. Alternatively,
pipes and pipe systems of the present invention can be made by
injection molding and by forming a cast of selected material.
Preferably, pipe walls and core structures in embodiments of the
present invention are made from the same material.
[0023] In preferred embodiments, the pipe, core structure, and plug
at each end of the expansion channel comprise a smooth central
passageway substantially free of surface irregularities adapted to
transport liquid with a minimum of frictional losses.
[0024] Other embodiments of the present invention comprise a fluid
container resistant to rupture from an increase in internal volume,
for example, from expansion due to freezing of fluid within the
container. In such embodiments, a side of the container has an open
seam along its length, a core structure connected to the inside
surface of the side along its length also having an open seam that
is contiguous with the open seam in the side, and a hollow
expansion channel, defined by the core structure, along the length
of the side.
[0025] Similar to embodiments comprising pipes, in a fluid
container of the present invention, the expansion channel has open
ends adaptable for sealing with a plug at each end. In other
embodiments, fluid containers of the present invention are
configured without plugs. The container side and core structure are
expandable and contractible so that when fluid contained within the
system freezes and expands, the side and core structure expand, or
move outwardly, to accommodate an increased volume, thereby
resisting rupture of the container. The container side and core
structure may further comprise an integral unit having elasticity
sufficient to expand outwardly greater than the increased volume
caused by freezing of fluid within the container and to contract
inwardly to approximately the original non-expanded position when
frozen fluid within the container thaws.
[0026] Features of pipes, pipe systems, and containers of the
present invention resistant to freeze-induce rupture may be
accomplished singularly, or in combination, in one or more of the
embodiments of the present invention. As will be appreciated by
those of ordinary skill in the art, the present invention has wide
utility in a number of applications as illustrated by the variety
of features and advantages discussed below.
[0027] For example, the present invention advantageously provides a
system resistant to rupture related to freezing of fluids contained
within pipes and containers that is effective, reliable, and
durable. Embodiments of pipes, pipe systems, and containers of the
present invention have a configuration that is sufficiently
expandable and contractible to resist rupture during repeated
cycles of freezing and thawing.
[0028] Embodiments of the present invention provide advantages over
previous approaches to freeze protection of pipes and containers by
utilizing a unitary, or integral, structure that overcomes the
disadvantages of inserts and compressible compartments positioned
within pipes. The present invention avoids the limitations of prior
systems using internal components that may become dislodged,
rupture during normal use, require precise positioning, limit use
of pipes with conventional fittings, and add expense for extra
materials and complex installation.
[0029] Pipe systems of the present invention are advantageous in
that standard-sized pipes are utilized in conventional ways
including with standard pipe fittings such as elbows, tees, caps,
collars, adapters, reducers, expanders, and the like.
[0030] Another advantage is that pipes, pipe systems, and
containers of the present invention can be constructed with any
material suitable for transporting and/or containing fluids that is
sufficiently elastic to expand and contract in response to a
predetermined increase in internal fluid volume, such as caused by
freezing and thawing fluid.
[0031] Another advantage is that embodiments of the present
invention can be economically manufactured using currently
available equipment and techniques. Pipes of the present invention
can be extruded in a single integral unit, and can be made by
injection molding. As such, pipes, pipe systems, and containers of
the present invention are simple and cost-effective to manufacture,
as well as to maintain.
[0032] Still another advantage is that the present invention
provides a freeze-rupture resistant system that can be used in
virtually any fluid containment and/or fluid transport system in
which freezing of the fluid is a risk. For example, pipes and pipe
systems of the present invention are useful in new construction and
for retrofitting, in domestic and industrial settings, in settings
where pipes are likely to be exposed to freezing temperatures and
monitoring for freezing is limited, in transportation systems, in
water-borne vessels, in fire sprinkler systems, and in agricultural
irrigation systems. In addition, the present invention can be used
in containers for storing and/or transporting liquids, such as
water.
[0033] In addition, the present invention may be advantageously
used in pipes and pipe systems susceptible to rupture from causes
other than freezing. For example, pipes and pipe systems according
to the present invention that contain and/or transport fluids under
high-temperature and/or high-pressure conditions would resist
rupture due to internal volume expansion from even higher
temperatures and/or pressures. Applications in such
high-temperature and/or high-pressure conditions avoid the
disadvantages of the expense and safety issues of systems using
relief valves to prevent pipe rupture.
[0034] As will be realized by those of skill in the art, many
different embodiments of a pipe and pipe system resistant to
freeze-induced rupture according to the present invention are
possible. Additional uses, objects, advantages, and novel features
of the invention are set forth in the detailed description that
follows and will become more apparent to those skilled in the art
upon examination of the following or by practice of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a diagrammatic view of a cross-section of a pipe
used in a pipe stress analysis illustrating a channel cut in the
pipe wall and the relative movement of the pipe wall during
expansion.
[0036] FIG. 2 is a cut-away view of a diagram illustrating the
dimensions of a two inch section of a pipe used in a pipe stress
analysis.
[0037] FIG. 3 is a cross-sectional view of a pipe having a core
structure defining a relief channel in an embodiment of the present
invention.
[0038] FIG. 4 is another cross-sectional view of the pipe in FIG. 3
illustrating the relative movement of the core structure and the
pipe wall during expansion in an embodiment of the present
invention.
[0039] FIG. 5 is a perspective view of a length of pipe having an
integral core structure along the length of the pipe and
illustrating a plug for sealing the end of the core structure in an
embodiment of the present invention.
[0040] FIG. 6 is a perspective view of the length of pipe in FIG. 5
illustrating the end of the core structure sealed with the plug in
an embodiment of the present invention.
[0041] FIG. 7 is a view of an alternative plug for use in
embodiments of the present invention.
[0042] FIG. 8 is a perspective view of a fluid container having an
integral core structure along the length of the container side and
illustrating a plug for sealing the end of the core structure in an
embodiment of the present invention.
[0043] FIG. 9 is perspective view of a length of plugs in an
embodiment of the present invention.
[0044] FIG. 10 is a perspective view of an embodiment of an adapter
for fitting a pipe of the present invention to a conventional
circular pipe.
[0045] FIG. 11 includes cross-sectional views of four embodiments
of the present invention. FIG. 11A shows an embodiment of a core
structure defining one closed expansion channel. FIG. 11B shows an
embodiment of a core structure defining two closed expansion
channels. FIGS. 11C and 11D show embodiments having more than one
core structure.
[0046] FIG. 12 is a cross-sectional view of a pipe having a
depression in the pipe wall in an embodiment of the present
invention.
DETAILED DESCRIPTION
[0047] The present invention provides a fluid transport system
resistant to rupture due to an internal volume expansion. In
particular, embodiments of the present invention provide a fluid
transport system resistant to rupture due to expansion of freezing
fluid contained within the system. Referring to FIGS. 3-6,
embodiments of the present invention comprise a pipe 20, having a
length 27, and a pipe wall 21. Pipe wall 21 has an inside surface
22 and an outside surface 23 and two adjacent edges 25 along length
27 of the pipe forming an open seam 26. A core structure 30 is
connected at area 33 to inside surface 22 of pipe wall 21 along
length 27 of the pipe. Core structure 30 has an open seam 31
contiguous with open seam 26 in pipe wall 21. A hollow expansion
channel 40 is disposed along length 27 of the pipe and is defined
by core structure 30. Expansion channel 40 has ends 41 that are
open and adaptable for sealing. Each of the open ends 41 of
expansion channel 40 is sealed with a plug 50, shown in FIGS. 5 and
6, to prevent leakage of fluid from pipe lumen 28 during operation.
Pipe wall 21 and core structure 30 of the present invention are
together expandable and contractible so that when fluid contained
within the system freezes and expands, pipe wall 21 and core
structure 30 expand outwardly to accommodate an increased volume,
thereby resisting rupture of the system.
[0048] In the present invention, embodiments of pipe 20 have a
center 29 along length 27 of pipe 20, wherein pipe wall 21 and core
structure 30 are expandable outwardly from center 29 of pipe 20 in
radial fashion in the direction of open seams 26 and 31. Such
outwardly radial forces caused by freezing fluid, for example,
cause pipe wall 21 and core structure 30 to expand outwardly and
open channel 40 to relieve the attendant pressure.
[0049] In embodiments of the present invention, pipe 20 and core
structure 30 comprise an integral pipe unit. The movement of an
integral pipe unit due to expansion and contraction, for example
from freezing and thawing of fluid, respectively, is shown in FIG.
4, where pipe wall inside surface 22, core structure 30, and
channel 40 are shown in an original non-expanded position. The
integral pipe unit comprises a configuration having elasticity
sufficient to expand greater than the increased volume caused by
outwardly expanding forces, such as by freezing of fluid within the
system. Thus, when fluid inside pipe 20 freezes, the integral pipe
unit expands, or moves outwardly. FIG. 4 shows expanded positions
for the pipe wall inside surface at 24, for the core structure at
32, and for the channel at 42. The elasticity modulus is sufficient
for the integral pipe unit to contract, or move inwardly, to
approximately the original non-expanded position when frozen fluid
within the system thaws.
[0050] An optimal configuration for an integral pipe unit according
to the present invention was determined by testing and modeling, as
described. In the example below, an optimal configuration, or
design, has an appropriate size, shape, and placement of core
structure 30 relative to pipe wall 21 for adequate movement due to
expansion and contraction without rupture as would occur, for
example, during repeated cycles of freezing and thawing. As an
example, when the fluid contained within the system is water, pipe
wall 21 and core structure 30 are configured to be sufficiently
expandable and contractible to accommodate an increased volume of
at least 10% when the water freezes. Optimal configuration for an
integral pipe unit may also change in relation to variables in
addition to an expanded volume caused by freezing of a particular
fluid inside the pipe. For example, as ambient temperature
decreases, such as in outer space or extreme laboratory conditions,
pipe materials generally become more brittle, or less flexible. As
a consequence, an optimal configuration of an integral pipe unit
accommodates not only an internal freeze-induced volume expansion
but also less flexibility of pipe material due to lower
temperatures.
[0051] As described above, pipe systems of the present invention
include plugs 50 which sealingly fit into each end 41 of hollow
expansion channels 40 to allow pipes to be utilized in conventional
ways including with standard pipe fittings (not shown) such as
elbows, tees, caps, collars, expanders, reducers, adapters, and the
like.
[0052] Plugs 50 are permanently fixed inside ends 41 of channel 40,
and core structure 30, so that the points of contact between plugs
50 and core structure 30 do not move during expansion of fluid
against inner surface 22 of pipe wall 21, as during freezing, or
during contraction, as with thawing of the frozen mass inside pipe
20. As such, the integrity of the contact between core structure 30
and plugs 50 is maintained, and fluid contained within pipe lumen
28 continues to be contained within pipe lumen 28 during movement
of pipe wall 21 related to expansion and contraction. In the
present invention, constrained movement related to plugs 50 fixed
at both ends 41 of channel 40 is insufficient to restrict
expandability, or outward movement, of pipe wall 21 along length 27
of the pipe beyond that necessary to accommodate expansion caused
by freezing fluids.
[0053] Pipe systems of the present invention include embodiments of
plugs that have elastic compressibility and provide further relief
of pipe volume expansion due to freezing of fluids. For example,
plugs can be shaped so as to protrude into adjacent fittings, which
generally are not flexible, so as to accommodate freeze-induced
expansion in fittings. In preferred embodiments, plugs 50 are
solid. Alternatively, plugs 50 comprise a hollow core. In other
embodiments, pipe systems of the present invention include
flexible, tapered plugs 52, as seen in FIG. 7, that are permanently
fixed inside ends 41 of channel 40 and core structure 30. Insert
portion 54 of plug 52 is inserted into channel 40, allowing taper
53 to extend into a fitting placed on the end of pipe 20. Such
flexible, tapered plugs 52 provide a further relief, or cushion,
means for expansion, for example, by ice pressing against flexible
plug taper 53 such that taper 53 flexes inwardly, thereby allowing
more room for freeze-related expansion, particularly in connections
between pipes where plugs are located.
[0054] As shown in FIG. 10, pipes of the present invention can be
fit to existing, conventional pipes, for example circular pipes, by
using an adapter 80. In an embodiment, adapter 80 has a first end
81 and a second end 82 for fitting the pipe to a standard circular
pipe 84. First end 81 is larger than pipe 20 for fitting over the
end of pipe 20. First end 81 includes an integral plug 50 for
sealably contacting end 41 of expansion channel 40. Second end 82
has a circular shape 83 and is further shaped for fitting the end
of a circular pipe, for example, in a tapered design, as shown in
FIG. 10, to fit inside conventional pipe 84. Alternatively, second
end 82 can be designed to fit over the end of standard circular
pipe 84 (not shown).
[0055] The present invention comprises a means for efficiently
packaging and inserting plugs into the ends of expansion channels.
Referring to FIG. 9, in an embodiment, a means 70 for packaging and
inserting plugs comprises a series of individual plugs 71 joined
from end to end in a length 72 of plugs by a small amount of
material 73 between each plug 71 adapted to allow the length of
plugs to be easily broken away from an inserted plug. As such, a
number of plugs are packaged together in one unit that is
conveniently stored and more readily portable for easier insertion
of individual plugs into the ends of expansion channels. In
operation, a plug at the insertion end 74 in length 72 of breakaway
plugs is inserted into end 41 of expansion channel 40 (as seen in
FIG. 5). After plug 75 is inserted into end 41 of channel 40,
length 77 of breakaway plugs is then bent by the operator so as to
break length 77 of plugs away from plug 75 at breakaway point 76
adjacent plug 75. The insertion and break away steps are repeated
to sequentially place plugs at the insertion end in a length of
breakaway plugs into the ends of expansion channels. In this
manner, an operator can more easily and quickly insert plugs into
expansion channels and avoid unnecessary contact with adhesives
used to secure the plugs in place. Embodiments of a length of
breakaway plugs according to the present invention comprise plugs
sized to fit various sizes of expansion channels.
[0056] In other embodiments, pipes of the present invention
comprise configurations having one or more expansion channels that
are closed, rather than "hollow," as described above. For example,
as shown in FIG. 11, a core structure 30 may define one closed
expansion channel 90 (FIG. 11A), as well as two closed expansion
channels 90 (FIG. 11B). Embodiments having closed expansion
channels operate without the use of plugs. Moreover, embodiments of
the present invention comprise more than one core structure 30, as
seen in FIGS. 11C and 11D.
[0057] In other embodiments of the present invention, a fluid
transport system resistant to rupture due to expansion of the
internal fluid volume, as seen in FIG. 12, comprises a pipe 20
having at least one depression 91 in pipe wall 21 toward the
cross-sectional center 29 of the pipe 20 and along the length of
the pipe. Each of the one or more longitudinal depressions 91
defines an external expansion channel 40. Such an embodiment is
designed so that pipe wall 21 is expandable outwardly from the
center 29 of the pipe in the direction of the one or more
depressions 91. When the internal fluid volume expands, pipe wall
21 expands sufficiently to accommodate the expanded volume and
resist rupture of the system. For example, when the internal fluid
volume expands due to freezing of fluid inside pipe 20, pipe wall
21 is sufficiently elastic to expand outwardly greater than the
expanded internal fluid volume caused by the freezing and to
contract to approximately an original non-expanded position when
the frozen fluid thaws. In particular, when the internal fluid is
water, the pipe wall in such embodiments is sufficiently expandable
to accommodate an expanded volume of at least 10% when the water
freezes.
[0058] Pipes, pipe systems, and fluid containers of the present
invention can be constructed with any material suitable for
transporting and/or containing fluids that is configured to be
sufficiently elastic to expand outwardly in response to a
particular increase in internal volume, such as caused by freezing,
and contract inwardly when the volume decreases, as with thawing.
Preferably the material is a strong, hard material, such as
thermoplastic polymeric materials. Most preferably, pipes and
containers of the present invention are made from polyvinyl
chloride (PVC). Pipes, pipe systems, and containers of the present
invention made from PVC and PVC composites are advantageous as
compared to copper and other like materials because PVC and PVC
composites are less expensive and are more resistant to damage and
leaking. Other embodiments comprise pipes and containers made from
ABS copolymers, composites, and other like materials.
[0059] In preferred embodiments, pipe 20, core structure 30, and
plugs 50 at each end of expansion channel 40 comprise a smooth
central passageway substantially free of surface irregularities
adapted to transport liquid with a minimum of frictional losses. In
embodiments, a core structure and expansion channel can have
configurations other than the typical circular pipe shape.
Embodiments of pipes of the present invention have a capacity to
transport a volume of fluid that is less than a pipe of the same
inside diameter without a core structure, but the decrease in
volume capacity is insignificant. As an optional compensation for a
decreased capacity in volume due to the presence of a core
structure, fluid pressure may be increased slightly. Alternatively,
a pipe as in the present invention can be manufactured in larger
than standard sizes to compensate for any loss of volume capacity
due to presence of a core structure.
[0060] Embodiments of pipes and pipe systems of the present
invention are readily manufactured, as pipe 20 and core structure
30 can be extruded as a single, integral pipe unit. Preferably,
pipe walls 21 and core structures 30 in embodiments of the present
invention are made from the same material. In an alternative
manufacturing approach, pipes and pipe systems of the present
invention can be made by injection molding. In addition, pipes and
pipe systems of the present invention can be made by forming a cast
of the material, as well as by other methods suitable for forming
an integral pipe unit. As such, embodiments of the present
invention can be economically manufactured using currently
available equipment and techniques.
[0061] As illustrated in FIG. 8, other embodiments of the present
invention include a fluid container 60 resistant to rupture due to
an expanded internal volume, such as caused by freezing of fluid
within the container, in which a side 61 of container 60 has an
open seam 62 along its length 63 and a core structure 64 connected
to the inside surface of side 61 along its length 63. Core
structure 64 also has an open seam (not shown) that is contiguous
with open seam 62 in side 61, and a hollow expansion channel 65,
defined by core structure 64, along length 63 of side 61.
[0062] As shown in FIG. 8, in embodiments of fluid containers of
the present invention, expansion channel 65 has open ends 66
adaptable for sealing with a plug 67 at each end 66. Plugs 67 may
be hollow; however, plugs 67 are preferably solid. Container side
61 and core structure 64 are outwardly expandable and inwardly
contractible so that when fluid contained within the system freezes
and expands, side 61 and core structure 64 expand to accommodate an
increased volume, thereby resisting rupture of the container.
Container side 61 and core structure 64 may further comprise an
integral unit having elasticity sufficient to expand greater than
the increased volume caused by freezing of fluid within container
60 and to contract to approximately the original non-expanded
position when frozen fluid within container 60 thaws. In preferred
embodiments of fluid containers, core structure 64 and container
top 68 comprise an integral unit such that fluids are contained
within container 60, and plugs are not used.
[0063] Similar to pipes and pipe systems described above,
embodiments of fluid containers of the present invention can be
manufactured from thermoplastic polymeric materials, such as
polyvinyl chloride, and comprise extruded material, injection
molded material, and/or a cast of material.
[0064] As mentioned above, the pipe and pipe system of the present
invention that provide protection against rupture, such as caused
by freezing, have numerous applications. For example,
freeze-rupture resistant pipes of the present invention can be used
in domestic and industrial settings, both in new construction and
for retrofitting in existing plumbing systems. Such pipes and pipe
systems can readily be used in mobile homes and pre-manufactured
buildings, which often have less insulation than conventional-built
structures. Freeze-protected pipes of the present invention are
particularly useful in settings where pipes are likely to be
exposed to freezing temperatures and monitoring for freezing is
limited, such as in a vacation home of a non-resident owner. Other
applications for freeze-rupture resistant pipes of the present
invention in which monitoring for freezing may be limited is in
motor homes, campers, and recreational vehicles. The present
invention can be used in plumbing of transportation systems,
including airplanes, trains, buses, and ferries, as well as in
other water-borne vessels such as ships, yachts, and houseboats.
Pipes of the present invention, resistant to freeze rupture, are
especially beneficial in dedicated, special purpose fluid transport
systems in which integrity and patency of the system is critical
for safety and/or catastrophe prevention. Special purpose fluid
transport systems that can benefit from such pipes include, for
example, fire sprinkler systems, particularly self-draining fire
sprinkler systems, and irrigations systems in nurseries, farming,
and agriculture. In addition, embodiments of the present invention
can be used in other plumbing applications, such as in liquid
effluent drains.
[0065] In addition, the present invention provides a system that
resists freeze-induced rupture that can be used in fluid
containment and/or fluid transport applications other than
plumbing. For example, embodiments of the present invention could
provide freeze-rupture resistance to containers used to store
and/or transport potable liquids, such as water. Another
application of the present invention is in containers used to store
and/or transport liquids having a freezing point near the
temperature range of a working environment, such as in extreme
temperature laboratory conditions and in space vehicles. A
freeze-rupture resistant system of the present invention could be
used in virtually any fluid containment and/or fluid transport
situation in which freezing of the fluid is a risk.
[0066] Moreover, pipes, pipe systems, and containers of the present
invention resist rupture from causes other than freezing. For
example, pipes, pipe systems, and containers according to the
present invention that contain and/or transport fluids under
high-temperature and/or high-pressure conditions resist rupture due
to internal volume expansion from even higher temperatures and/or
pressures.
[0067] In embodiments of the present invention, a fluid transport
system, having an internal volume, resistant to rupture due to
expansion of the internal volume comprises: a pipe having a length
and a pipe wall, the pipe wall having an inside surface and an
outside surface and two adjacent edges along the length of the pipe
forming an open seam; a core structure connected to the inside
surface of the pipe wall along the length of the pipe and having an
open seam contiguous with the open seam in the pipe wall; and a
hollow expansion channel along the length of the pipe defined by
the core structure, wherein the pipe has a center along the length
of the pipe and the pipe wall and the core structure are expandable
outwardly from the center of the pipe in the direction of the open
seams, and wherein when the internal volume expands, the pipe wall
and core structure expand sufficiently to accommodate the expanded
volume and resist rupture of the system.
[0068] In embodiments of a fluid transport system of the present
invention, the pipe and the core structure comprise an integral
pipe unit. In such a fluid transport system, the integral pipe unit
has an original non-expanded position, and the expanded internal
volume is caused by freezing of fluid inside the pipe, wherein the
integral pipe unit comprises a configuration having elasticity
sufficient to expand outwardly greater than the expanded internal
volume caused by the freezing of the fluid and to contract to
approximately the original non-expanded position when the frozen
fluid thaws. In embodiments wherein the fluid inside the pipe is
water, the integral pipe unit is sufficiently expandable to
accommodate an expanded volume of at least 10% when the water
freezes.
[0069] A fluid transport system of the present invention can have a
hollow expansion channel having open ends adaptable for sealing,
wherein the system further comprises a plug sealably contacting
each end of the expansion channel. In embodiments, such plugs are
solid. Alternatively, embodiments of such plugs are hollow.
[0070] In embodiments of a fluid transport system of the present
invention, the pipe is connectable to another pipe with pipe
fittings each having an internal volume, wherein the plug has a
portion for inserting into the end of the expansion channel and a
compressible portion for protruding into adjacent pipe fittings so
that when the volume in the pipe fittings expands, the compressible
portion compresses to accommodate the expanded volume and resist
rupture of the system. The compressible portion of the plug for
protruding into adjacent pipe fittings can be tapered.
[0071] In embodiments, the fluid transport system further comprises
an adapter for fitting the pipe to a conventional pipe, the adapter
having a first end comprising a shape adapted to form a sealable
fit with the pipe and a second end comprising a shape adapted to
form a sealable fit with the conventional pipe. In other
embodiments, the pipe has an end, wherein the first end of the
adapter comprises an integral plug for sealably contacting the end
of the expansion channel and wherein the first end of the adapter
is larger than the pipe for sealably fitting over the end of the
pipe. In still other embodiments, the pipe is connectable to
another pipe with pipe fittings, wherein the second end of the
adapter comprises a shape adapted to form a sealable fit with the
pipe fittings, the second end further comprising a compressible
portion for protruding into adjacent pipe fittings so that when the
volume in the pipe fittings expands, the compressible portion
compresses to accommodate the expanded volume and resist rupture of
the system.
[0072] In the present invention, embodiments of a fluid transport
system include a pipe and a core structure that comprise a
thermoplastic material. The thermoplastic material may be polyvinyl
chloride. In other embodiments, the pipe and the core structure
comprise a metallic material.
[0073] Embodiments of the fluid transport system of the present
invention include a pipe and a core structure that comprise a
unitarily extruded material. In other embodiments, the pipe and the
core structure comprise an injection molded material.
[0074] In embodiments of a fluid transport system of the present
invention, the pipe, the core structure, and the plug at each end
of the expansion channel comprise a smooth central passageway
substantially free of surface irregularities adapted to transport
liquid with a minimum of frictional losses.
[0075] In the present invention, a fluid transport system comprises
a plurality of plugs, further comprising a means for packaging the
plurality of plugs and inserting one of the packaged plurality of
plugs into each end of the expansion channel. Embodiments of the
means for packaging and inserting plugs comprise a first length of
the plurality of plugs having each of the plurality of plugs
connected sequentially end to end by material adaptable for
breaking, wherein a plug at the end of the first length of plugs is
inserted into the end of the expansion channel and the inserted
plug is broken away from the first length of plugs at the
connecting material to provide a second length of plugs ready for
repeating the insertion and breaking away steps.
[0076] In embodiments of the present invention, the fluid transport
system is a plumbing system. In other embodiments, the fluid
transport system is a fire sprinkler system. In still other
embodiments, the fluid transport system is an irrigation
system.
[0077] In embodiments of the present invention, a fluid transport
system, having an internal volume, resistant to rupture due to
expansion of the internal volume, comprises: a pipe having a length
and a pipe wall, the pipe wall having an inside surface and an
outside surface and two adjacent edges along the length of the pipe
forming an open seam; a core structure connected to the inside
surface of the pipe wall along the length of the pipe and having an
open seam contiguous with the open seam in the pipe wall; and a
hollow expansion channel along the length of the pipe defined by
the core structure, wherein the pipe and the core structure
comprise an integral pipe unit, wherein the pipe has a center along
the length of the pipe and the integral pipe unit is expandable
outwardly from the center of the pipe in the direction of the open
seams, and wherein when the internal volume expands, the integral
pipe unit expands sufficiently to accommodate the expanded volume
and resist rupture of the system.
[0078] In embodiments wherein the pipe and the core structure
comprise an integral pipe unit, the hollow expansion channel has
open ends adaptable for sealing, and the system further comprises a
plug sealably contacting each end of the expansion channel. In such
embodiments of the present invention, the plug is solid.
Alternatively, embodiments of such plugs are hollow.
[0079] In a embodiments of a fluid transport system of the present
invention wherein the pipe and the core structure comprise an
integral pipe unit, the pipe is connectable to another pipe with
pipe fittings, wherein the plug has a portion for inserting into
the end of the expansion channel and a compressible portion for
protruding into adjacent pipe fittings so that when the volume in
the pipe fittings expands, the compressible portion compresses to
accommodate the expanded volume and resist rupture of the system.
The compressible portion of the plug for protruding into adjacent
pipe fittings can be tapered.
[0080] In embodiments wherein the pipe and the core structure
comprise an integral pipe unit, the fluid transport system further
comprises an adapter for fitting the pipe to a conventional pipe,
the adapter having a first end comprising a shape adapted to form a
sealable fit with the pipe and a second end comprising a shape
adapted to form a sealable fit with the conventional pipe. In
embodiments, the pipe has an end, wherein the first end of the
adapter comprises an integral plug for sealably contacting the end
of the expansion channel and wherein the first end of the adapter
is larger than the pipe for sealably fitting over the end of the
pipe. In other embodiments wherein the pipe and the core structure
comprise an integral pipe unit, the pipe is connectable to another
pipe with pipe fittings each having an internal volume, wherein the
second end of the adapter comprises a shape adapted to form a
sealable fit with the pipe fittings, the second end further
comprising a compressible portion for protruding into adjacent pipe
fittings so that when the volume in the pipe fittings expands, the
compressible portion compresses to accommodate the expanded volume
and resist rupture of the system.
[0081] In the present invention wherein the pipe and the core
structure comprise an integral pipe unit, embodiments the integral
pipe unit comprise a thermoplastic material. The thermoplastic
material may be polyvinyl chloride. In other embodiments wherein
the pipe and the core structure comprise an integral pipe unit, the
integral pipe unit comprises a metallic material.
[0082] Embodiments of an integral pipe unit of the present
invention comprise an extruded material. In other embodiments, the
integral pipe unit comprises an injection molded material.
[0083] In embodiments of a fluid transport system of the present
invention, the integral pipe unit and the plug at each end of the
expansion channel comprise a smooth central passageway
substantially free of surface irregularities adapted to transport
liquid with a minimum of frictional losses.
[0084] In the present invention wherein the pipe and the core
structure comprise an integral pipe unit, a fluid transport system
comprises a plurality of plugs, further comprising a means for
packaging the plurality of plugs and inserting one of the packaged
plurality of plugs into each end of the expansion channel.
Embodiments of the means for packaging and inserting plugs comprise
a first length of the plurality of plugs having each of the
plurality of plugs connected sequentially end to end by material
adaptable for breaking, wherein a plug at the end of the first
length of plugs is inserted into the end of the expansion channel
and the inserted plug is broken away from the first length of plugs
at the connecting material to provide a second length of plugs
ready for repeating the insertion and breaking away steps.
[0085] In embodiments of the present invention, the fluid transport
system comprising an integral pipe unit is a plumbing system. In
other embodiments, the fluid transport system comprising an
integral pipe unit is a fire sprinkler system. In still other
embodiments, the fluid transport system comprising an integral pipe
unit is an irrigation system.
[0086] In embodiments of the present invention, a fluid container,
having an internal volume, resistant to rupture due to expansion of
the internal volume, comprises: a plurality of sides, one of the
plurality of sides having a length and an inside surface and two
adjacent edges along the length of the one side forming an open
seam; a core structure connected to the inside surface and along
the length of the one side and having an open seam contiguous with
the open seam in the one side; and a hollow expansion channel along
the length of the one side defined by the core structure, wherein
the one side and the core structure comprise an integral unit,
wherein the integral unit is expandable outwardly in the direction
of the open seams, and wherein when the internal volume expands,
the integral unit expands sufficiently to accommodate the expanded
volume and resist rupture of the system.
[0087] In embodiments of the fluid container of the present
invention, the integral unit has an original non-expanded position,
and the expanded internal volume is caused by freezing of fluid
inside the container, wherein the integral unit comprises a
configuration having elasticity sufficient to expand outwardly
greater than the expanded internal volume caused by the freezing of
the fluid and to contract to approximately the original
non-expanded position when the frozen fluid thaws. In embodiments
wherein the fluid inside the container is water, the integral unit
is sufficiently expandable to accommodate an expanded volume of at
least 10% when the water freezes.
[0088] A fluid transport system of the present invention can have a
hollow expansion channel having open ends adaptable for sealing,
the container further comprising a plug sealably contacting each
end of the expansion channel. In embodiments, the plug is solid. In
other embodiments, the plug is hollow.
[0089] In the present invention, embodiments of an container
comprise a thermoplastic material. The thermoplastic material may
be polyvinyl chloride. In other embodiments, the container
comprises a metallic material.
[0090] Embodiments of a container of the present invention comprise
an extruded material. In other embodiments, the container comprises
an injection molded material.
[0091] In embodiments of the present invention, a fluid transport
system, having an internal volume, resistant to rupture due to
expansion of the internal volume, comprise a pipe having a length
and a pipe wall, the pipe having a center along the length of the
pipe, the pipe wall comprising at least one depression toward the
center and along the length of the pipe, each of the at least one
depression defining an external expansion channel, wherein the pipe
wall is expandable outwardly from the center of the pipe in the
direction of the at least one depression, and wherein when the
internal volume expands, the pipe wall expands sufficiently to
accommodate the expanded volume and resist rupture of the
system.
[0092] In embodiments of the present invention wherein the pipe
wall comprises at least one depression, the pipe wall has an
original non-expanded position, and the expanded internal volume is
caused by freezing of fluid inside the system, wherein the pipe
wall comprises a configuration having elasticity sufficient to
expand outwardly greater than the expanded internal volume caused
by the freezing of the fluid and to contract to approximately the
original non-expanded position when the frozen fluid thaws. In
embodiments wherein the pipe wall comprises at least one depression
and wherein the fluid inside the system is water, the pipe wall is
sufficiently expandable to accommodate an expanded volume of at
least 10% when the water freezes.
[0093] In embodiments wherein the pipe wall comprises at least one
depression, the fluid transport system further comprises an adapter
for fitting the pipe to a conventional pipe, the adapter having a
first end comprising a shape adapted to form a sealable fit with
the pipe and a second end comprising a shape adapted to form a
sealable fit with the conventional pipe. In embodiments of a fluid
transport system of the present invention wherein the pipe wall
comprises at least one depression, the pipe has an end, wherein the
first end of the adapter comprises an integral plug for sealably
contacting the end of the expansion channel and wherein the first
end of the adapter is larger than the pipe for sealably fitting
over the end of the pipe. In other embodiments wherein the pipe
wall comprises at least one depression, the pipe is connectable to
another pipe with pipe fittings, wherein the second end of the
adapter comprises a shape adapted to form a sealable fit with the
pipe fittings, the second end further comprising a compressible
portion for protruding into adjacent pipe fittings so that when the
volume in the pipe fittings expands, the compressible portion
compresses to accommodate the expanded volume and resist rupture of
the system.
EXAMPLE
[0094] This example is set forth by way of illustration and is not
intended to limit the scope of the invention. As described above,
material testing and experimental modeling were conducted to
determine at least one configuration for pipes having an expandable
channel to provide structural relief and thus resistance to
rupture, as, in this instance, when water contained within the
pipes freezes. One objective of such testing and modeling is to
determine configuration(s) that are optimal for resistance to pipe
rupture related to expansion of internal pipe volume. In this
example of determining appropriate pipe configurations in
embodiments of the present invention, stress analysis was performed
for polyvinyl chloride (PVC), which was assumed to be linearly
elastic over the range of pressures considered. Results of the
stress analysis were then utilized in design optimization modeling
considering a single standard cylindrical piping size. Such stress
analysis and design optimization methodology can be applied to
pipes of various sizes and materials.
[0095] First, wall stress analysis was conducted for PVC pipe
according to standard design specifications for PVC pipe provided
by the American Society for Testing of Materials (ASTM
specification D1785-85). For example, types 1120, 1220, 4116, 2112,
2116, and 2120 of a standard one inch nominal size PVC pipe have
the wall thickness, diameter, weight, and bursting pressures given
by ASTM as listed in Table 1 below. See, Marks' Standard Handbook
for Mechanical Engineers, Ninth Edition, pages 8-198.
1TABLE 1 ASTM Specifications of Commercial Size PVC Pipe Nominal
Size (inches) 1.0 Schedule 40 Wall thickness (inches) 0.113 OD
(inches) 1.315 ID (inches) 1.049 Theoretical weight (lb/ft) 0.305
Calculated min. bursting pressure (lb/in.sup.2): 1,440 PVC 1120,
1220, 4116 Calculated min. bursting pressure (lb/in.sup.2): 1,130
PVC 2112, 2116, 2120
[0096] The fundamental equation for calculation of circumferential
or tangential stress in a thick-walled cylindrical vessel is given
as
.sigma..sub.t=p.sub.i(b.sup.2 +a.sup.2)/(b.sup.2 +a.sup.2),
[0097] where .sigma..sub.t is the tangential stress at the inner
surface, p.sub.i is the internal pressure, and a and b are the
inner and outer radii, respectively. In this analysis, a 2% safety
margin beyond the elastic limit for the known value of tensile
stress of rigid PVC is given as 6,000 psi. Using minimum burst
pressure values and the known tensile strength of PVC, it is
possible to model new designs for PVC pipe with similar factors of
safety.
[0098] As water freezes in pipes, it expands the pipe walls
orthogonally, i.e., at right angles, or outwardly in radial
fashion, producing an anisotropic stress. Referring to the
cross-section in FIG. 1, when a circular pipe, such as test pipe
10, has a seam 14, or relief channel, along its length, and water
freezes inside the pipe, pipe wall 11 reshapes to force open seam
14 to accommodate expansion caused by freezing. In FIG. 1, the
inside surface of pipe wall 11 is shown in its normal, unexpanded
position 12, and in expanded position 13. Outward movement of pipe
wall 11 during expansion causes seam 14 to move from its normal,
unexpanded position 15 to an expanded position 16. Because elastic
modulus is a function of temperature, this elastic process is
reversible when temperature increases. Thus, as temperature rises
and ice inside pipe 10 thaws, pipe wall 11 moves from expanded
position 13 toward its normal, pre-expansion position 12. Inward
movement of pipe wall 11 during contraction causes seam 14 to move
from expanded position 16 to its normal, pre-expansion position
15.
[0099] Since test pipe 10 has a seam 14 and is therefore movable in
response to freeze-induced expansion, pipe wall 11 experiences
different stresses than a pipe without a seam. Instead of the
typical uniform tangential stresses in a closed circular
cross-section, bending stress is formed in a region of the pipe
wall 17 diametrically opposite seam 14. As such, analysis of pipe
wall stresses in test pipe 10 include calculations for deformation
caused by bending. Bending stress is calculated from such
deformation using a flexure formula, taking into consideration an
otherwise symmetrical structure. (Calculations for a curved beam
may also be used.) It is known that when water freezes, its volume
expands 9%. As a margin of safety, this analysis considers the
amount of cross-sectional deformation required for a 10% volume
expansion.
[0100] As an example, pipe wall stress analysis was performed on a
section of one inch nominal size, schedule 40, commercial PVC pipe,
according to the specifications in Table 1. FIGS. 2A and 2B show
cut-away views of a diagram illustrating the dimensions, listed in
Table 2, of a two inch section of the pipe used in the following
analysis.
2TABLE 2 Test Pipe Section Dimensions Inside Radius (a) 0.5245
inches Outside Radius (b) 0.6575 inches Length (1) 2.0 inches Angle
.theta. 70.degree.
[0101] (1) Lateral deflection: Lateral deflection at the free end
of pipe section 10 necessary to increase the volume of the section
by 10% is next determined. Since results of this stress analysis
will be used to design an optimal configuration for radial
expansion of a pipe, determination of lateral deflection (and
volume increase) assumes that volume expansion will cause an
increase in the cross-sectional area only and not in the axial
length. Increase in cross-sectional area correlates to an increase
in the radius of curvature.
[0102] Luminal area of the pipe section is calculated as:
A.sub.initial=1/4.PI.a.sup.2+(0.1944).PI.a.sup.2(0.444)=0.3841
in.sup.2.
[0103] The volume of water contained within the two inch section of
the pipe after 10% expansion is approximated as:
V.sub.final=.PI.a.sup.2
(0.444)(1)=.PI.(0.5245).sup.2(0.444)(2.0)=0.7675 in.sup.3.
[0104] Solving for the new radius of curvature after 10% expansion
gives:
A=[V /.PI.(2.01)].sup.1/2=[(0.7675
in.sup.3)/.PI.(2.01)].sup.1/2=0.5504 in.
[0105] Finally, lateral deflection of the end of pipe 10 caused by
10% volumetric expansion is determined by subtracting the old
radius of curvature from the new radius of curvature to give:
0.5504-0.4225=0.1279 in.
[0106] (2) Maximum load to cause deflection: Next, the maximum load
required to create this deflection of the free end of pipe section
10 is determined using the lateral deflection calculated above. The
cross-sectional moment of inertia (I) must first be determined, as
follows:
I={fraction (1/12 )}bh.sup.3 ={fraction
(1/12)}(2.0)(0.6575-0.5245).sup.3=- 3.92.times.10.sup.-4
in.sup.4.
[0107] Deflection for cantilever beams is calculated using the
formula:
v=P1.sup.3/3EI,
[0108] where v is lateral deflection, P is applied load, and E is
elastic modulus.
[0109] At room temperature, the elastic modulus for rigid PVC is
400,000 psi, and at -20.degree. F. the modulus increases to
approximately 450,000 psi. Using the cold temperature stiffness for
the present calculation, with all variables known except P, the
maximum load required to create the lateral deflection caused by
10% volumetric expansion is:
P=3EIv/1.sup.3=3(450,000)(3.92.times.10.sup.-4)(0.1279)/(1.0174).sup.3=64.-
27 pounds.
[0110] (3) Maximum bending stress: The maximum bending stress in
pipe section 10 (a beam) is then determined using the flexure
formula to give:
.sigma.=My/I=Ply/I=(57.14)(0.0665)(3.92.times.10.sup.-4)=10,903
psi.
[0111] (4) Comparison of maximum bending stress to tensile
strength: The tensile strength of high-impact rigid PVC is known to
be
[0112] 6,000 psi at room temperature and approximately 9,500 psi at
-20.degree. F. Medium-impact rigid PVCs have tensile strengths
given in a range between 10,000 and 11,500 psi. See, L. I. Nass,
Encyclopedia of PVC, volume 3, chapter 30.
[0113] The lower tensile strength value at -20.degree. F. is
compared to the maximum bending stress due to a 10% volumetric
expansion in test pipe section 10. This comparison (9,500
psi/10,903 psi=87%) indicates that the maximum bending stress when
water freezes in test pipe 10 exceeds the pipe tensile strength at
-20.degree. F. by 13%. Therefore, a design configuration for the
pipe used in this analysis must accommodate a cross-sectional
expansion of approximately 13% to allow for expansion of freezing
water and avoid freeze-induced rupture.
[0114] (5) Design modeling: Results of the pipe wall stress
analysis were then used to perform computer-assisted geometric and
finite element modeling of pipe designs that would accommodate such
an expansion. Models employed symmetry about longitudinal midline
18 of pipe 10. The pipe wall region 17 diametrically opposite seam
14, or relief channel, was held in a rigidly fixed position, while
nodes in the middle half-plane of the pipe were allowed to move
only in the direction toward the relief channel. Pressure was
applied to the inside lumen surface 12. In all cases, enough
pressure was applied so as to create a deflection consistent with
the previously determined bending calculations. The elastic modulus
was selected to be 450,000 psi and the tensile strength was
selected to be 9,500 psi. Both figures are conservative, as elastic
modulus may be as high as 480,000 psi and tensile strength may be
as high as 11,500 psi.
[0115] The Rankine failure criteria was used in which maximum
principal stress was compared to the known tensile strength of the
material at -20.degree. F. After several iterations, a design was
found which supported a 40,000 psi load, which is 20 times greater
than the published minimal burst pressure for a commercial,
one-inch nominal size PVC pipe at room temperature. For this
cross-section, a 40,000 psi load imparts a bending stress to the
pipe that is at or near the elastic limit for PVC at -20.degree.
F.
[0116] Stress analysis and modeling experiments, such as those
described above, can be similarly applied to other sizes of pipes
of various materials to achieve design optimization objectives.
Optimal configuration for an integral pipe unit as in the present
invention also relates to variables in addition to a volume of
expansion caused by freezing of a particular fluid inside the pipe,
such as decreased pipe material flexibility due to decreased
ambient temperatures.
[0117] (6) Empirical testing: Although the numerical model
predicted some regions of stress slightly above the published
tensile strength of rigid PVC, freeze-thaw experiments with a
similar cross-section of pipe showed the integral pipe structure
expanded outwardly during freezing and contracted inwardly during
thawing in reliable fashion. After repeated cycles of freezing and
thawing, there was no permanent plastic deformation or bursting.
Thus, under freeze-thaw conditions as in actual use, pipes
according to the present invention do not rupture as would ordinary
pipes under similar conditions. Consequently, such a pipe
configuration is useful in embodiments of the present invention to
resist freeze-induced rupture.
[0118] Although the present invention has been described with
reference to particular embodiments, it should be recognized that
these embodiments are merely illustrative of the principles of the
present invention. Those of ordinary skill in the art will
appreciate that the pipes, pipe systems, and containers of the
present invention may be constructed and implemented in other ways
and embodiments. Accordingly, the description herein should not be
read as limiting the present invention, as other embodiments also
fall within the scope of the present invention.
* * * * *