Double-containment pipe assembly with conical-shaped internal anchor

An anchor support is provided for a double-containment piping assembly having at least one outer piping component defining a first diameter, and at least one inner piping component received within the at least one outer piping component and defining a second diameter less than the first diameter and forming an approximately annular space between the inner and outer piping components. The anchor support has a cylindrical outer-component support section defining a first approximately annular support surface having a first diameter approximately equal to the first diameter of the at least one outer piping component for contacting and supporting the outer piping component. An approximately cylindrical inner-component support section of the anchor support is spaced laterally relative to, and located approximately at an opposite end of the anchor support relative to the outer-component support section. The inner-component support section defines a second approximately annular support surface having a second diameter which is less than the first diameter and approximately equal to the second diameter of the inner piping component for anchoring and supporting the inner piping component within the outer piping component. A tapered connecting section of the anchor support defines a conical-tapered surface extending between the outer-component support section and the inner-component support section and tapering inwardly from one end adjacent to the outer-component support section to another end adjacent to the inner-component support section.

FIELD OF THE INVENTION 
The present invention relates to double-containment pipe assemblies having 
inner, primary or carrier pipes or components located within outer, 
secondary or containment pipes or components, and more particularly, to 
internal anchors for supporting and anchoring the inner pipes or 
components within the outer pipes or components. 
BACKGROUND INFORMATION 
Hazardous fluids are routinely conveyed within enclosed pipes or conduits. 
Recognizing that such pipes and conduits can leak due to any of numerous 
causes, such as manufacturing defects, excessive pressure, corrosion, 
joint defects, and other defects created by thermal stresses, 
double-containment piping systems have been developed in which an inner 
pipe system (also referred to as the "carrier" or "primary" pipe system) 
is located within an outer pipe system (also referred to as the 
"containment" or "secondary" pipe system). An axially-extending space, 
typically in the form of an annulus, is defined between the inner and 
outer pipe systems for receiving and containing any fluids that might leak 
from the inner or carrier piping components. The inner pipes are typically 
supported by either resting on a lower, inside wall of the outer pipes, or 
alternatively, by intermediate supports mounted between the inner pipes 
and the outer pipes for supporting the inner pipes in spaced relation to 
the outer pipes and thereby forming an annulus between the inner and outer 
pipes. 
Intermediate supports are typically designed to permit axial movement, but 
tend to constrain lateral movement of the inner pipes relative to the 
outer pipes in order to maintain the inner and outer pipes in an 
approximately coaxial relationship (these types of supports have been 
referred to as "centering supports"). However, other types of intermediate 
supports are designed to permit both axial and lateral movement of the 
inner pipes relative to the outer pipes in order to accommodate 
differential thermal expansion. Exemplary prior art intermediate supports 
for double-containment pipe systems are illustrated in U.S. Pat. Nos. 
5,141,184; 5,018,260; 4,751,945; 3,863,679; and U.S. Pat. No. 3,417,785. 
Double-containment pipe fittings, such as elbow fittings, tee fittings, 
lateral and/or reducing fittings, tee-wye branch fittings, etc., may be 
also provided with supports for centralizing, and often anchoring the 
inner pipes connected to the fittings. Exemplary prior art fitting and 
anchor support assemblies of this type are shown in U.S. Pat. Nos. 
4,886,305; 5,186,502; and 5,398,973. 
For double-containment pipe systems subject to relatively moderate 
differential thermal expansion, the problem has been addressed in the 
prior art by employing the above-described fitting and anchor support 
assemblies with intermediate centering supports spaced relative to each 
other between the anchor supports. In these types of systems, the outer or 
containment pipes are typically anchored within the soil in underground 
installations, and otherwise are anchored with suitable supports in 
aboveground installations. Thus, the above-described fitting and anchor 
support assemblies restrain and substantially prevent any axial expansion 
of the carrier pipes, and the intermediate supports are designed and 
positioned to prevent buckling of the carrier pipes between the fitting 
and anchor support assemblies. Since any thermal expansion is restrained, 
the inner pipes or carrier components are subjected to compressive stress. 
If the magnitude of this stress, and the resulting strain within the 
system is held within specified limits, then this type of arrangement can 
effectively control and compensate for any thermal expansion of the 
carrier pipe system. This type of arrangement is particularly effective 
for controlling thermal expansion in double-containment pipe systems 
employing materials that do not perform well in bending, such as certain 
types of piping made of reinforced thermosetting resin that employ 
adhesively-bonded joints, and piping made of certain types of 
thermoplastics that employ solvent-cemented joints. In these types of 
systems, the magnitude of bending that may occur in a flexible system can 
cause a failure, typically at a joint, and therefore a restrained system 
is often a better choice. 
One of the drawbacks of the prior art fitting and anchor support assemblies 
is that they typically must be joined to the respective carrier and 
containment pipes and other components by adhesive bonding (in RTRP or 
thermoplastic systems), solvent cementing (in thermoplastic systems), hot 
gas welding (in thermoplastic systems), or welding (in metallic systems). 
The welding/bonding processes, which are often difficult to perform due to 
the complexities of the assemblies, can require substantial construction 
and assembly time and thus involve substantial costs. The welding/bonding 
processes also typically require that the supports be made of the same 
material as either the inner and/or the outer pipes so that they can be 
properly welded or bonded to the respective pipes. Accordingly, any 
flexibility in selecting the materials of the anchor supports is typically 
limited by the materials of the inner and/or outer pipes. 
In addition, the configurations of the prior art fitting and anchor support 
assemblies typically require a different geometry depending upon the type 
of fitting to be joined (e.g., 90.degree. elbow, 45.degree. elbow, tee, 
lateral, etc.). Furthermore, the prior art designs typically require a 
different internal anchor design for each given pipe size, thereby 
increasing the number of parts required on hand and the overall costs of 
the double-containment pipe systems. 
Accordingly, it is an object of the present invention to provide anchor 
supports for double-containment pipe assemblies which overcome one or more 
of the drawbacks and disadvantages of the prior art. 
SUMMARY OF THE INVENTION 
The present invention is directed to support for a double-containment pipe 
assembly. The double-containment pipe assembly includes at least one outer 
piping component defining a first diameter, and at least one inner piping 
component received within the at least one outer piping component and 
defining a second diameter less than the first diameter and forming an 
approximately annular space between the inner and outer piping components. 
The anchor support comprises an outer-component support section including 
a first approximately annular support surface defined at least in part by 
a first diameter approximately equal to the first diameter of the at least 
one outer piping component for anchoring and supporting the outer piping 
component. An inner-component support section of the anchor support is 
spaced laterally relative to, and located approximately at an opposite end 
of the anchor support relative to the outer-component support section. The 
inner-component support section includes a second approximately annular 
support surface defined at least in part by a second diameter which is 
less than the first diameter and approximately equal to the second 
diameter of the inner piping component for anchoring and supporting the 
inner piping component within the outer piping component. A tapered 
connecting section of the anchor support defines a tapered surface 
extending between the outer-component support section and the 
inner-component support section and tapering inwardly from approximately 
the first diameter at one end adjacent to the outer-component support 
section to approximately the second diameter at another end adjacent to 
the inner-component support section. 
In a preferred embodiment of the invention, the outer-component support 
section defines an approximately cylindrical shape, the inner-component 
support section defines an approximately cylindrical shape, and the 
tapered connecting section defines an approximately conical shape. The 
outer-component support section is adapted to be received within a socket 
of, or otherwise may abut or be stacked against, an outer piping 
component, such as an elbow fitting, branch fitting, or pipe coupling. 
Similarly, the inner-component support section is adapted to receive an 
inner pipe or like carrier component, and further is adapted to abut or be 
stacked against one end of an inner piping component, such as an elbow 
fitting, branch fitting or pipe coupling, to anchor the inner piping 
components relative to the outer piping components. 
One advantage of the anchor supports of the invention is that they may be 
assembled with other double-containment components without employing 
welding or bonding processes as required by the prior art. 
Another advantage of the anchor supports of the invention is that they may 
be made of different materials than the other double-containment 
components with which they are assembled. 
These and other advantages of the invention will become apparent in view of 
the following detailed description and accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIGS. 1 and 2, an anchor support embodying the present invention is 
indicated generally by the reference numeral 10. As described in further 
detail below, the anchor support 10 is designed for use in a 
double-containment pipe assembly having at least one outer piping 
component, and at least one inner piping component received within the 
outer piping component and defining an approximately annular space between 
the inner and outer components. The term double-containment pipe system or 
assembly is used herein to describe without limitation any of numerous 
systems or assemblies wherein inner, primary or carrier pipes and/or other 
components are contained within outer, secondary or containment pipes 
and/or other components, and an approximately annular space is formed 
between the inner and outer piping components for receiving and containing 
any fluids carried by the inner piping components in the event of a leak. 
As described in further detail below, the anchor supports of the invention 
are used to anchor and support the inner pipes or components within the 
outer pipes or components in substantially restrained double-containment 
piping systems. Alternatively, the anchor supports of the invention may be 
employed to limit, direct and/or control thermal expansion towards, for 
example, elbows and expansion loops in internally flexible 
double-containment piping systems. 
As shown in FIGS. 1 and 2, the anchor support 10 comprises an 
outer-component support section 12 located at one end of the support for 
contacting and supporting an outer pipe or containment component. An 
inner-component support section 14 is spaced laterally relative to, and 
located approximately at the opposite end of the anchor support relative 
to the outer-component support section 12 for anchoring and supporting an 
inner pipe or carrier component within the outer pipe or containment 
component. A tapered connecting section 16 extends between the 
outer-component support section 12 and the inner component support section 
14, and tapers inwardly from an outer diameter D1 at one end adjacent to 
the outer-component support section 12, to an inner diameter D2 at the 
opposite end adjacent to the inner-component support section 14. As shown 
in FIG. 2, the tapered connecting section 16 defines an outer tapered 
surface 18, and an inner tapered surface 20 located on the opposite side 
of, and oriented approximately parallel to the outer tapered surface. As 
also shown best in FIG. 2, the tapered connecting section 16 tapers 
inwardly from the outer-component support section to the inner-component 
support section at an angle of approximately 45.degree. relative to the 
central axis of the support. However, as will recognized by those skilled 
in the pertinent art based on the teachings herein, the angle of taper may 
be selected as desired depending upon the requirements of a particular 
design or system, or as otherwise desired in order to provide adequate 
stress transition between the outer and inner component support sections. 
Accordingly, although a taper angle of 45.degree. is currently preferred, 
another taper angle within the range of approximately 15.degree. to 
75.degree. may be equally sufficient depending upon other characteristics 
of the double-containment piping system. 
The outer-component support section 12 defines one or more annular support 
surfaces for anchoring and supporting an outer or containment piping 
component. As shown in 2, a first annular support surface 22 is defined by 
the first diameter D1 and extends along the external periphery of the 
outer-component support section 12 in the axial direction thereof, and a 
second annular support surface 24 extends inwardly from the first annular 
support surface on the respective end of the support. As described further 
below, the first annular support surface 22 is typically received within a 
socket of an outer or containment component, such as an outer elbow or 
branch fitting, and the diameter D1 is selected to allow the support 
surface 22 to be slidably received within the socket. The second annular 
support surface 24, on the other hand, typically abuts or is "stacked" 
against either an adjacent outer pipe or containment component slidably 
received within the socket of the carrier or containment fitting, or a 
containment extension, such as an extension ring, seated between the 
anchor and the containment component. 
The inner-component support section 14 also defines one or more annular 
support surfaces for anchoring and supporting an inner or carrier piping 
component. As shown in FIG. 2, a first annular support surface 26 is 
defined by the second diameter D2 and extends along the internal periphery 
of the inner-component support section 14 in the axial direction thereof, 
and a second annular support surface 28 extends outwardly from the first 
annular support surface on the respective end of the support. As described 
further below, the diameter D2 is typically selected to allow the first 
annular support surface 26 to slidably receive an inner or carrier pipe or 
containment component. The second annular support surface 28, on the other 
hand, typically abuts or is "stacked" against either an adjacent inner 
fitting or containment component, such as the end surface of a socket for 
receiving the inner piping component, or the end surface of a carrier 
extension, such as an extension ring, seated between the anchor and the 
socket. 
As shown in FIGS. 1 and 2, the tapered connecting section 18 may define a 
plurality of apertures 30 formed through the support for permitting any 
fluid (liquid and/or gas) to flow through the support. Although four 
apertures are shown spaced approximately 90.degree. relative to each 
other, a different number of apertures, having different shapes and/or 
spacing relative to each other, may be equally employed. For example, it 
may be desirable to have only a single aperture located at the 6 o'clock 
position when the anchor support is mounted within a double-containment 
assembly in order to permit any fluid to drain through the assembly. 
Depending upon the expected loads to be applied to the anchor support, and 
the resulting stress calculations, it may be necessary for the wall 
thickness of the outer-component support section 12 to be approximately 
equal to the wall thickness of the adjacent outer or containment piping 
component, or to have some other defined relationship with respect to the 
outer or containment piping component. In addition, it may be desirable 
for the wall thickness of the inner-component support section 14 to be 
approximately equal to, or at least closer to the wall thickness of the 
adjacent inner or carrier piping component. Accordingly, as shown 
typically in FIG. 2, the outer-component support section 12 may have a 
different wall thickness than the inner-component support section 14. In 
the embodiment of FIG. 2, the outer-component support section 12 defines a 
greater wall thickness than does the inner-component support section 14 
since the larger diameter outer piping components will typically define 
greater wall thicknesses than the smaller diameter inner piping 
components. Also in the embodiment of FIG. 2, the wall thickness of the 
tapered connecting section 16 preferably tapers down from a wall thickness 
approximately equal to that of the outer-component support section 12 at 
one end, to a wall thickness approximately equal to that of the 
inner-component support section 14 at the other end. However, as will be 
recognized by those skilled in the pertinent art based on the teachings 
herein, it may be unnecessary to vary the wall thicknesses, and therefore 
the anchor support 10 may define an approximately uniform wall thickness 
throughout. In addition, if the anchor support is made of a material that 
is stronger than that of the other piping components (e.g., if the anchor 
support is made of steel, aluminum, titanium or other metal and is mounted 
in a thermoplastic double-containment piping system), then the wall 
thickness(es) of the anchor support may be significantly thinner than 
those of the corresponding pipes or containment components. 
In FIGS. 3 and 4, another embodiment of the anchor support of the invention 
is indicated generally by the reference numeral 110. The anchor support 
110 is substantially the same as the anchor support 10 described above 
with reference to FIGS. 1 and 2, and therefore like reference numerals 
preceded by the numeral 1 are used to indicate like elements. 
The primary difference of the anchor support 110 in comparison to the 
anchor support 10, is that the anchor support 110 comprises means for 
interlocking or otherwise aligning the anchor support with one or more 
other inner and/or outer piping components. In the preferred embodiment of 
FIGS. 3 and 4, this means includes one or more tabs or like pilots 132 
which are dimensioned to be received within corresponding apertures or 
recesses formed in the adjacent inner and/or outer piping or like 
components (not shown) to thereby fix the angular position of the anchor 
support relative to the other components within the double-containment 
piping system. One advantage of this feature of the invention is that it 
permits the anchor support, and thus the apertures 130 of the support to 
be mounted in a predetermined angular position within the 
double-containment piping system. For example, it is frequently desirable 
to ensure that one of the apertures 130 is located at the 6 o'clock 
position when assembled in the double-containment piping system to ensure 
that any fluid within the annulus is permitted to flow through the support 
and, if necessary, drain from the system. 
As shown in FIGS. 3 and 4, the anchor support 110 includes four pilots 132 
equally spaced relative to each other on the annular surface 124 of the 
outer-component support section 112; four pilots 132 equally spaced 
relative to each other on the external conical-tapered surface 118 of the 
connecting section 116; and four pilots 132 equally spaced relative to 
each other on the external surface of the inner-component support section 
114. As shown in FIG. 3, each of the pilots 132 is defined by a raised 
protuberance having either a cylindrical or semi-cylindrical 
cross-sectional configuration, and therefore is shaped to be received 
within a correspondingly-shaped recess or aperture in the adjacent pipe or 
component. However, as will be recognized by those skilled in the 
pertinent art based on the teachings herein, the pilots or protuberances 
132 may take any of numerous different shapes and/or configurations, may 
be formed in any of numerous different ways, and any desired number of 
such protuberances may be employed. For example, it may be desirable to 
form the pilots on the adjacent inner or outer piping components, and to 
form the corresponding recesses or apertures for receiving the pilots on 
the anchor support. Similarly, the pilots may be formed by dowel pins, or 
other types of pins or interlocking members received on each end within 
corresponding apertures formed within the anchor support and the adjacent 
carrier and/or containment components. In each case, the pilots and 
corresponding recesses or apertures will prevent the adjacent parts from 
rotating relative to each other to thereby align the anchor support 10, 
110, and the aperture(s) 30, 130 of the anchor support within the 
double-containment piping system. 
Turning to FIGS. 5 and 6, two anchor supports 110 of the invention are 
shown mounted within a 90.degree. elbow fitting for centralizing and 
supporting a carrier elbow 34 within a containment elbow 36, and for 
anchoring at least two carrier pipes 38 connected to the carrier elbow. As 
shown in FIG. 6, one end of each inner pipe 38 is slidably received 
through an inner-component support section 114 of a respective anchor 
support 110, and in turn is slidably received within a socket 40 formed on 
a respective end of the carrier elbow 34. As also shown FIG. 6, the 
annular surface 128 of each inner-component support section 114 abuts, or 
is stacked against the adjacent outer surface of the respective inner 
elbow socket 40. The pilots 132 formed on each inner-component support 
section 114 of the anchors are received within corresponding apertures 
formed on the external peripheries of the sockets 40 of the inner elbow 
fitting 32 to interlock the anchors and inner elbow. 
The outer-component support section 112 of each anchor support 110 is 
slidably received within a respective socket 42 of the containment elbow 
36. Two outer or containment pipes 44 are each slidably received within a 
respective socket 42 of the containment elbow 36 with the ends of the 
outer pipes abutting or stacked against the respective annular surfaces 
124 of the outer-component support sections 112. As shown typically in 
FIG. 6, pilots 132 may be formed on the outer-component support sections 
112 and received within corresponding apertures formed within the annular 
end faces of the outer pipes 44 to interlock the outer pipes and anchor 
supports. However, since the pilots 132 of the inner-component support 
sections 114 are interlocked with the carrier fitting, it may be deemed 
unnecessary to interlock the outer-component support sections with the 
adjacent containment components. Similarly, if the pilots of the 
outer-component support sections are interlocked with the adjacent 
containment components, it may be deemed unnecessary to interlock the 
inner-component support sections with the carrier fitting. In addition, if 
one or more pilots formed on the tapered connecting sections are 
interlocked with adjacent containment components, then it may be deemed 
unnecessary to include any other pilots. Thus, if a conservative approach 
is desired, both the carrier and containment pilots 132 of FIGS. 3 and 4 
may be used. Alternatively, a lesser number of pilots may be used to 
interlock each anchor support with at least one of the adjacent carrier 
and containment components. One advantage of forming the pilots with 
separate dowel pins or like interlocking members as described above, is 
that the anchor supports and adjacent containment or carrier components 
may be provided with apertures to receive any number of pilots. However, 
the pilots need only be installed where desired. Thus, a single type of 
anchor support may be used with any desired number of pilots by simply 
inserting the dowel pins where desired. 
As can be seen, the two anchor supports 110 centralize and support both the 
carrier elbow 34 within the containment elbow 36, and the carrier pipes 38 
within the containment pipes 44. Once the containment pipes 44 are stacked 
against the outer-component support sections 112 within the outer elbow 
sockets 42, the inner and outer elbow fittings and inner pipes are 
anchored in place. In addition, if the fittings (not shown) at the other 
ends of the inner and outer pipes 38 and 44, respectively, are similarly 
anchored with additional anchor supports 10 or 110, the pipes extending 
between the anchored fittings will become anchored as well. As shown 
typically in FIG. 5, the outer elbow fitting 36 may take the form of a 
two-piece closure fitting defining axially-extending seams 43 on opposite 
sides of the fitting (only one shown) forming lines of joinder for 
connecting the two halves of the fitting together and thereby enclosing 
the double-containment assembly. The seams 43 may be joined together in 
any of numerous different ways known to those of ordinary skill in the 
pertinent art, such as by electro-fusion, adhesive bonding, hot gas 
welding, or mechanical fasteners. 
One advantage of the present invention is that the anchor supports may be 
installed without welding, bonding, fusing, cementing or otherwise 
attaching or fastening the anchor supports to the fittings or to the inner 
and outer pipes. Rather, the anchor supports are locked in place by 
stacking one end of each anchor between the adjacent carrier fitting and 
pipe, and by stacking the other end of each anchor between the adjacent 
containment fitting and pipe. As a result, the entire assembly can be 
rapidly installed, either by prefabricating the assembly, or by assembling 
all components in the field. In each case, the parts simply need to be 
slipped together, without the need for welding, bonding or otherwise 
attaching or fastening one part to the other. 
Another advantage of the anchor supports of the invention is that because 
they do not have to be bonded, welded, fused, or cemented into a 
double-containment pipe assembly, they can be made from any desired 
material without regard to the materials of the other components with 
which they will be assembled. For example, the anchor supports can be made 
of aluminum, steel, or other desired metal, and still be used in 
thermoplastic double-containment piping systems. As a result, the anchor 
supports can be made with relatively thin wall thicknesses in comparison 
to the thermoplastic or other double-containment components, with 
significantly higher strength. In addition, if desired, the metal anchor 
supports can be coated with a thermoplastic, thermosetting resin, or like 
coating to increase the corrosion resistance of the support. Thus, the 
anchor supports of the invention can be made from virtually any material, 
and can be fabricated in virtually any manner permitted by the selected 
material. As a result, the anchor supports of the invention may 
significantly enhance design flexibility with respect to material 
selection, and may reduce material and installation costs. 
In FIGS. 7 and 8, two anchor supports 110 of the invention are shown 
mounted within a 90.degree. elbow fitting for centralizing the inner elbow 
and piping components within the outer elbow and piping components, and 
for anchoring the components relative to each other. The elbow fitting and 
anchor assembly of FIGS. 7 and 8 is substantially the same as that of 
FIGS. 5 and 6, and therefore the same numbers are used to indicate the 
same or corresponding components. As shown best in FIG. 8, the outer elbow 
is a fabricated-type elbow, and therefore is indicated generally by the 
reference numeral 36'. In addition, as shown best in FIG. 8, the carrier 
elbow 34 defines a plurality of pairs of protuberances 146, wherein the 
protuberances in each pair are spaced relative to each other to define a 
groove or recess therebetween. The protuberance pairs 146 are spaced about 
90.degree. relative to each other on the outside surface of the socket 40 
of the carrier elbow, and therefore each pair is located to receive within 
its groove or recess a corresponding pilot 132 projecting outwardly from 
the inner-component support section 112 of the respective anchor 110. 
Accordingly, the pilots 132 and corresponding protuberance pairs 146 
interlock the anchor supports 110 with the carrier elbow 34 to thereby 
prevent the parts from rotating relative to each other. As also shown 
typically in FIG. 7, the pilots and corresponding recesses are preferably 
located to cause one of the apertures 130 to be located at the 6 o'clock 
position when assembled in the double-containment piping system. 
In FIGS. 9 and 10, the anchor supports 10, 110 of the invention are shown 
mounted within a double-containment piping assembly comprising two 
90.degree. elbow fittings with sections of straight containment and 
carrier pipes 44 and 38, respectively, connected with the anchors at the 
ends of the elbow fittings. As can be seen, each of the elbow fitting and 
anchor support assemblies are constructed in the same manner as described 
above in connection with FIGS. 5-8. In addition, a plurality of centering 
and/or axial-guiding supports 51 are mounted at predetermined spacings 
relative to each other between the inner and outer sections of pipe 38 and 
44 to center, and axially guide the containment within the carrier pipes. 
The centering or axial-guiding supports 51 may be any of numerous supports 
known to those of ordinary skill in the pertinent art, and the 
predetermined spacings between the supports may be set in accordance with 
the teachings of U.S. Pat. No. 5,482,088, which is hereby expressly 
incorporated by reference as part of the present disclosure. 
The arrows in FIG. 9 show the approximate force distribution within the 
double-containment pipe assembly when the carrier components undergo 
thermal expansion, which may be caused, for example, when the carrier 
pipes contain a relatively warm fluid. As can be seen, the anchors 
substantially prevent axial or longitudinal movement of the straight 
sections of pipe connected between them. As a result, and as indicated by 
the arrows in FIG. 9, when the carrier components expand, compressive 
forces are created within the carrier components and tensile forces are 
created within the containment components. The stresses are substantially 
equal and opposite, and therefore when the carrier system is in axial 
compression, the containment system is subjected to a substantially equal 
degree of axial tension. 
The arrows in FIG. 10, on the other hand, show the approximate force 
distribution within the double-containment pipe assembly when the carrier 
components undergo thermal contraction, which may be caused, for example, 
when the carrier pipes contain a relatively cool fluid. As can be seen, 
the anchors substantially prevent axial or longitudinal movement of the 
straight sections of pipe connected between them. As a result, and as 
indicated by the arrows in FIG. 10, when the carrier components contract, 
tensile forces are created within the carrier components and compressive 
forces are created within the containment components. When the carrier 
system is in axial tension, the containment system is subjected to an 
approximately equal amount of compressive stress. In either case, the 
anchors of the invention substantially prevent any axial or longitudinal 
movement of the inner and outer components relative to each other. 
In FIG. 11, three anchor supports of the invention, 10A, 10B, and 10C, are 
shown mounted within a 45.degree. lateral branch connection fitting 
assembly for supporting an inner 45.degree. lateral branch fitting 48 and 
inner pipes 38A-38D within an outer 45.degree. lateral branch fitting 50 
and outer pipes 44 (only two shown), and for anchoring the parts of the 
assembly relative to each other. As shown in FIG. 11, the inner pipe 38A 
is slidably received through the inner-component support 14 of the anchor 
support 10A and a carrier extension 52A, and in turn is received within a 
respective socket 54A of the inner branch fitting 48. Accordingly, the 
annular support surface 28 of the anchor support 10A abuts, or is stacked 
against one side of the carrier extension 52A, and the other side of the 
carrier extension is stacked against the outer face of the socket 54A. As 
can be seen, the carrier extension 52A defines a width dimensioned to fill 
any gap between the anchor support 10A and the socket 54A in order to 
permit the parts to abut one another and thereby anchor themselves in 
place. The carrier extension 52A is preferably a ring-shaped member which 
may be made, for example, by cutting or otherwise trimming a piece of 
piping to the desired width necessary to fill the gap between the anchor 
support and the adjacent carrier fitting. However, as will be recognized 
by those skilled in the pertinent art based on the teachings herein, the 
carrier extension may equally take any of numerous different shapes and/or 
configurations for purposes of performing its functions described herein. 
As also shown in FIG. 11, the inner pipe 38B is slidably received through 
the inner-component support 14 of the anchor support 10B and a carrier 
extension 52B, and in turn is received within a respective socket 54B of 
the inner branch fitting 48. Accordingly, the annular support surface 28 
of the anchor support 10B abuts, or is stacked against one side of the 
carrier extension 52B, and the other side of the carrier extension is 
stacked against the outer face of the socket 54B. As can be seen, the 
carrier extension 54B defines a width slightly greater than the width of 
the carrier extension 54A in order to fill the gap between the anchor 
support 110B and adjacent socket 54B and thereby permit the adjacent 
components to abut one another. 
As also shown in FIG. 11, the anchor support 10C is inverted in the Figure 
relative to the other two anchor supports 10A and 10B in order to anchor 
and support the inner pipes 38C and 38D, and the corresponding outer pipe 
44. The inner pipe 38C is slidably received on one end within the 
respective carrier branch socket 54C, and is slidably received on the 
other end through the inner-component support section 14 of the anchor 
support 10C and within one end of a standard pipe coupling 56. One end of 
the inner pipe 38D is slidably received within the other end of the pipe 
coupling 56 to form a stacked and anchored assembly. In addition, the 
outer-component support section 12 of the anchor support 10C is slidably 
received within the respective socket 58C of the outer branch fitting 50, 
and the corresponding outer pipe 44 is stacked against the annular surface 
on the other side of the outer-component support section to anchor the 
support and related parts in place. 
If desired, rather than the anchor supports 10, the anchor supports 110 
having pilots or like means may be used in the branch fitting assembly of 
FIG. 11 instead. In this case, the pilots 132 formed on the 
outer-component support section 114 (FIG. 4), or the pilots 132 formed on 
the tapered connecting section 116, are used to interlock the 
outer-component support section 112 to the containment socket 58C or the 
containment pipe 44. 
Another advantage of the present invention is that a single type of anchor 
support can be used for each size combination of inner and outer pipes or 
other containment components (e.g., nominal 2 inch inside nominal 4 inch 
outside, nominal 3 inch inside nominal 6 inch outside, etc.). For each 
size combination, the outer-component support section of the anchor 
support corresponds to the respective outer pipe size, and the 
inner-component support section corresponds to the respective inner pipe 
size. Accordingly, in contrast to the prior art anchor supports, and as 
illustrated by the example of FIG. 11, each anchor support of the 
invention can be used for any arrangement involving its given size 
combination. Thus, a family of anchor supports of the invention, each 
corresponding to a respective inner/outer pipe size combination, can be 
provided to anchor and support virtually any double-containment piping 
assembly involving one of the standard size combinations. As also shown in 
the example of FIG. 11, the anchor supports of the invention may be 
combined with carrier and/or containment extensions, if required, in order 
to fill any gaps between the anchors and the adjacent carrier and/or 
containment components. Alternatively, if it is unnecessary to use 
standard, or "off-the-shelf" components, the axial length of the 
outer-component support section and/or the inner-component support section 
of an anchor can be selected to obviate the need for an extension ring or 
like extension coupling. In addition, as described above, the angle of 
taper of the connecting section of an anchor can be selected as desired in 
order to adjust the axial length of the connecting section for each given 
inner/outer pipe size combination, and therefore adjust the overall axial 
length of the anchor support. 
In FIG. 12, the 45.degree. lateral branch connection fitting and anchor 
assembly of FIG. 11 is shown assembled to a floor cleanout to create a 
mid-line cleanout assembly. As can be seen, a plurality of anchor supports 
10, each identical to the others, are combined to anchor the entire 
assembly by slipping the components together and without having to fasten 
or otherwise join the other components to the anchors. In addition, each 
of the components of the assembly may be a standard, or "off-the-shelf" 
component. 
As shown in FIG. 12, a floor cleanout assembly 60 is connected through a 
containment assembly, including two inner pipes 38 and a standard pipe 
coupling 56, to one end of a 45.degree. elbow fitting 62. A corresponding 
straight containment pipe 44 is connected between the floor cleanout 60 
and the 45.degree. elbow 62, and an axial-guiding or centering support 51 
is mounted between one of the inner pipes 38 and the containment pipe 44 
to further support the inner and outer pipes in spaced relation to each 
other. As also shown, the 45.degree. elbow fitting 62 includes anchor 
supports 10 or 110 of the invention mounted at each end of the fitting in 
the same manner as described above with reference to FIGS. 5-8 in order to 
anchor each of the components connected to the 45.degree. elbow fitting 
relative to each other. 
As also shown in FIG. 12, three inner pipes 38 are connected together with 
pipe couplings 56 between the anchor 10 at one end of the 45.degree. elbow 
62 and the corresponding anchor 10 of the 45.degree. lateral branch 
fitting 48. Two straight sections of containment pipe 44 are each stacked 
against the same anchors, and a tubular closure fitting 64 is connected 
between the two straight sections of containment pipe 44 to enclose the 
assembly. 
Turning to FIGS. 13A and 13B, two mid-line internal anchor assemblies 
incorporating the anchor supports 10, 110 of the invention are indicated 
generally by the reference numerals 66A and 66B, respectively. In FIG. 
13A, the mid-line internal anchor assembly 66A comprises two anchor 
supports 10 or 110 of the invention, and the outer-containment component 
section 12, 112 of each anchor support is received within one end of a 
respective containment pipe coupling 68. Three straight sections of 
containment pipe 44 are received between, and within each end of the 
containment couplings 68 to thereby form a stacked and anchored 
containment assembly. Two straight sections of containment pipe 38 are 
each received through a respective inner-component support section 14, 114 
of the anchor supports 10, 110, and in turn are each received within a 
respective end of the carrier pipe coupling 56 to form a stacked and 
anchored carrier assembly. In FIG. 13B, the midline internal anchor 
assembly 66B comprises one containment pipe coupling 68 with the 
outer-component support sections 12, 112 of each anchor support 10, 110 
received within a respective end of the containment pipe coupling, and two 
carrier pipe couplings 56, each stacked against a respective 
inner-component support section 14, 114 of the anchor supports. 
As can be seen, the anchor supports of the invention may be employed with 
other standard, or off-the-shelf components to easily and relatively 
inexpensively construct mid-line internal anchor assemblies. Mid-line 
internal anchor assemblies of this type are particularly suitable for use 
in internally flexible double-containment piping systems, and may be 
mounted, for example, between flexible fittings (i.e., fittings that 
permit axial and/or lateral movement of the inner piping components 
relative to the outer piping components) to anchor the inner piping 
components relative to the outer piping components. In these types of 
applications, the mid-line anchor assemblies are provided to limit, 
control and direct thermal expansion towards flexible elbow fittings, 
expansion loops, and like flexible fitting assemblies. 
In FIGS. 14 and 15, another embodiment of the anchor support of the 
invention is indicated generally by the reference numeral 210. The anchor 
support 210 is substantially the same as the anchor support 110 of FIGS. 3 
and 4, and therefore like reference numerals preceded by the numeral "2" 
instead of the numeral "1" are used to indicate like elements. The primary 
difference of the anchor support 210 in comparison to those described 
above is that the axial lengths of the inner-component support section 214 
and outer-component support section 212 are substantially less that of the 
corresponding sections described above. If necessary, carrier and/or 
containment extensions, such as extension rings, may be stacked against 
the ends of the inner and/or outer component support sections to provide 
suitable overall axial lengths. In addition, the annular surface 222 of 
the outer-component support section 212 is spaced radially outwardly from 
the adjacent end of the tapered connecting section 216 to, in effect, form 
a flange at the end of the support. This type of outer-component support 
section may be particularly suitable for mounting within the socket of a 
typical containment coupling of the type shown in the mid-line anchor 
assembly of FIG. 13. 
In FIGS. 16 and 17 another anchor support embodying the invention is 
indicated generally by the reference numeral 310. The anchor support 310 
is substantially the same as the anchor support 210 described above with 
reference to FIGS. 14 and 15, and therefore like reference numerals 
preceded by the numeral "3" instead of the numeral "2" are used to 
indicate like elements. The primary difference between the anchor support 
310 and the anchor support 210 is that the anchor support 310 is a 
two-part support that may be connected together with bolts, screws or 
other suitable fasteners. As shown in FIG. 16, the anchor support 310 is 
split in half along a seam 366. Each half of the support defines two 
axially-extending joinder surfaces (each forming a respective seam 366), 
and further defines a respective half of the outer-component support 
section 312, inner-component support section 314, and tapered connecting 
section 316. As can be seen, the first and second parts of the support 310 
are engageable along the opposing axially-extending joinder surfaces to 
join the first part to the second part and thereby form the anchor 
support. As shown in FIG. 16, two pairs of mating flanges or tabs 368 are 
formed on the inner tapered surfaces 320, and two pairs of mating flanges 
or tabs 368 are formed on the outer tapered surfaces 318 of each half of 
the support. As shown in FIGS. 16 and 17, each respective pair of opposing 
tabs 368 are aligned with each other, and depending upon the manner in 
which the anchor support is installed within a double-containment 
assembly, the inner tabs and/or the outer tabs may be connected together 
to join the two halves and thereby form an integral support. In the 
illustrated embodiment, each tab defines an aperture 370 extending through 
the tab for receiving a fastener 372 to fixedly secure the tabs, and thus 
the two halves of the support together. As will be recognized by those 
skilled in the pertinent art based on the teachings herein, however, any 
of numerous different means for joining the two halves of the anchor 
supports together may be employed. For example, any of numerous different 
fasteners may be employed. Alternatively, the two halves may be adhesively 
bonded, cemented, welded, or fused together. 
One advantage of the two-piece anchor support 310 is that the anchor may be 
fixedly secured to the primary, carrier or inner pipe or component to 
prevent rotation of the parts relative to each other. Another advantage of 
this embodiment of the invention, is that if molded, the two-piece 
construction may reduce the size and cost of a fabricating mold in 
comparison to the mold required for forming the same type of anchor 
support as a single part. 
As will be recognized by those skilled in the pertinent art based on the 
teachings herein, numerous changes and modifications may be made to the 
above-described and other embodiments of the invention without departing 
from its scope as defined in the appended claims. For example, the anchor 
supports of the invention can be used with virtually any type of inner and 
outer piping components in double-containment piping systems. As a further 
example, the anchor supports of the invention may be assembled with split 
outer piping components (i.e., two-part components) which may be assembled 
together to enclose the double-containment assembly by fasteners, 
electro-fusion, or other suitable joining mechanism. Exemplary closure 
fittings of this type suitable for use with the anchor supports of the 
invention for purposes of creating, for example, mid-line anchor 
assemblies in internally flexible double-containment piping systems, are 
shown in U.S. Pat. No. 5,690,148, which is hereby expressly incorporated 
by reference as part of the present disclosure. 
The anchor supports of the invention also may take any of numerous 
different shapes and/or configurations. For example, the tapered 
connecting section may be defined by any of various surface configurations 
that gradually or otherwise decrease in diameter or width between, and in 
the direction from the outer-component support section toward the 
inner-component support section. Accordingly, it may be desirable to form 
the tapered connecting section with any of various taper angles, or to 
form the tapered surfaces with unique curvatures, ridges, or other linear 
or non-linear surface contours. One advantage of the substantially 
conical-tapered connecting sections of the preferred embodiments, however, 
are that they provide a relatively smooth transition of forces and 
stresses between the inner and outer-component support sections. 
In addition, it may be desirable to form the inner-component support 
section and/or the outer-component support section in a different shape or 
configuration than those shown and described above. For example, the 
annular support surfaces may define a curvature different than a circular 
curvature if necessary to conform to a particular type of carrier or 
containment component. In addition, the inner-component and/or 
outer-component support sections may include flanges or other structures 
for facilitating assembly to other double-containment piping components. 
Accordingly, this detailed description of preferred embodiments is to be 
taken in an illustrative, as opposed to a limiting sense.