Abstract:
A casing spacer comprised of high strength plastic includes two complementary nut and bolt connected members each having an arcuate inner portion adapted for tight-fitting engagement with a pipe&#39;s outer surface and plural linear ribs (risers) extending radially outwardly from the arcuate inner portion and adapted to engage an inner surface of an outer casing maintains the pipe in fixed position within the casing. The arcuate inner portion of each member is flexible so that its entire inner surface contacts the pipe&#39;s outer surface for a range of pipe diameters, permitting only two members of fixed size to be used with variously sized pipes. Each casing spacer member includes an aperture in its flexible, arcuate inner portion which is disposed between aligned risers and is adapted to receive and retain a non-slip member frictionally engaging the pipe&#39;s outer surface for maintaining the casing spacer in fixed position on the pipe.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to fluid carrying pipe arrangements and is particularly directed to apparatus for maintaining fixed spacing between inner fluid carrying pipes having a wide range of diameters and a concentrically disposed outer casing. 
   BACKGROUND OF THE INVENTION 
   A pipeline is frequently in the form of an inner liquid carrying pipe disposed within a rigid outer casing. In some cases, plural liquid carrying pipes are disposed within a single rigid outer casing. The carrier pipe, or pipes, disposed within an outer casing is frequently provided for water and sewer mains within highway and railroad crossing pipe casings to maintain carrier pipe alignment, restrain the carrier pipe against flotation or other movement, or maintain the carrier pipe in a fixed position and orientation such as per grade requirements in the case of a gravity sewer. In the case of a single carrier pipe, a single spacer is frequently disposed about the carrier pipe and between the carrier pipe and the outer casing to maintain stationary positioning and fixed spacing of the carrier pipe relative to the outer casing. 
   Earlier approaches to maintaining positioning of an inner carrier pipe within an outer casing made use of wooden skids banded to the outer periphery of the carrier pipe with steel strapping. Not only is it difficult and time consuming to install the wooden skids, but the wooden skids also frequently catch on welded beads resulting in rotation of the carrier pipe and destabilizing of its joints. Moreover, the wooden skids and steel straps are susceptible to breakage, requiring removal and reinstallation. 
   The wooden skid approach to positioning a carrier pipe within an outer casing has generally been replaced with casing spacers comprised of stainless steel, galvanized steel, or epoxy coated steel. This type of casing spacer employs two or more shell members each including an inner portion disposed about and engaging the inner carrier pipe and an outer portion engaging the inner surface of the outer casing. The plural shell members are securely coupled together and attached about the inner carrier pipe by means of plural nut and bolt combinations, with each shell member&#39;s inner portion being arcuate in shape and its outer portion including plural spaced ribs attached to and extending outwardly from the inner portion and engaging the outer casing&#39;s inner surface. These spaced ribs are commonly called “risers”. 
   An example of this later type of casing spacer can be found in U.S. Pat. No. 6,571,832, issued on Jun. 3, 2003 and assigned to the assignee of the present application. The individual sections of this type of casing spacer are sized to fit a specific carrier pipe diameter. To accommodate an inner carrier pipe having a different diameter, at least one casing spacer segment must be replaced with another segment of a different size. In some cases, both casing spacer segments must be replaced when used with an inner carrier pipe of a different diameter. This approach requires a large casing spacer inventory to accommodate a wide range of carrier pipe sizes. In addition, while incorporating non-slip members for more securely engaging the inner carrier pipe, the location of these non-slip members on the casing spacer segments limits their frictional engagement with the carrier pipe reducing the likelihood for fixed attachment to the carrier pipe. In addition, these non-slip members are subject to impact damage because of their position on the inner portion of the casing spacer. 
   The present invention addresses the aforementioned considerations of the prior art by providing a flexible casing spacer comprised of two complementary segments which are adapted for tight-fitting engagement with inner carrier pipes having a wide range of diameters for securely maintaining the carrier pipe in fixed position within an outer casing. The inventive casing spacer eliminates the requirement for a large inventory of casing spacers of different sizes to accommodate inner carrier pipes of various diameters. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide secure, fixed positioning of an inner carrier pipe within an outer, concentrically disposed casing. 
   It is another object of the present invention to provide a spacer disposed between an inner fluid carrying pipe and an outer casing having high strength, spaced risers radially extending outwardly from a pair of connected flexible, arcuate inner portions which are adapted for tight-fitting positioning on inner pipes having a wide range of diameters. 
   Yet another object of the present invention is to provide first and second complementary spacer elements for maintaining fixed concentric positioning of an inner fluid carrying pipe within an outer casing, where the spacers are adapted for use with pipes and casings having a range of diameters. 
   A further object of the present invention is to provide a pair of interconnected pipe spacer elements conformable in shape to tightly engage the outer surface of inner carrier pipes having a wide range of circumferences and maintain the carrier pipes securely and fixedly in position within an outer concentric casing. 
   A still further object of the present invention is to provide a non-metallic casing spacer such as comprised of a high strength plastic which is equally applicable for use in water distribution systems and natural gas pipelines, as well as for use with an outer casing and an inner carrier pipe containing virtually any type of gas or liquid material. 
   The present invention contemplates a spacer disposed within an outer casing for engaging and maintaining an inner carrier pipe in fixed position within the outer casing which comprises first and second shell members each having respective flexible, arcuate inner portions disposed about and engaging 180° or less of an outer circumference of the inner carrier pipe and plural rigid risers disposed on and extending radially outward from the inner portion of the shell member, wherein the distal ends of the risers engage an inner surface of the casing and each of the risers includes plural spaced tapered apertures; plural couplers inserted through aligned apertures in the first and second shell members, wherein the flexible, arcuate inner portions of the shell members allow the shell members to be drawn tightly about carrier pipes having a range of diameters when the couplers are tightened and the tapered apertures allow the couplers to assume various orientations relative to the shell members depending upon the carrier pipe&#39;s diameter; and first and second friction members disposed within and extending through the flexible, arcuate inner portions of the first and second shell members, respectively, for engaging the carrier pipe and maintaining the spacer in fixed position thereon, wherein the friction members are disposed between and protected from impact damage by adjacent risers on each of the shell members. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
       FIG. 1  is a perspective view of a two-piece casing spacer in accordance with the principles of the present invention, without the nut and bolt connector combinations; 
       FIG. 2  is an end-on view of the two-piece casing spacer of  FIG. 1  shown partially in phantom disposed on an inner carrier pipe; 
       FIG. 3  is a perspective view of one segment of the two-piece casing spacer of the present invention; 
       FIG. 4  is a top plan view of the casing spacer segment shown in  FIG. 3 ; 
       FIG. 5  is an end-on view of the casing spacer segment shown in  FIG. 3 ; 
       FIG. 6  is a side elevation view of the casing spacer segment shown in FIG.  3 . 
       FIG. 7  is an end-on view showing a two-piece casing spacer in accordance with the present invention positioned on an inner carrier pipe and within an outer casing; 
       FIG. 8  is an end-on view of the inventive two-piece casing spacer similar to that shown in  FIG. 7 , where the casing spacer is attached to an inner carrier pipe of smaller diameter; and 
       FIG. 9  is a perspective view of a non-slip member for use in a casing spacer of the present invention for securely maintaining the casing spacer in fixed position on an inner carrier pipe. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , there is shown a perspective view of a casing spacer  10  in accordance with the principles of the present invention.  FIG. 2  is an end-on view shown partially in phantom of the inventive casing spacer  10  positioned on an inner carrier pipe  44 .  FIGS. 3 and 4  are respectively perspective and top plan views of a first shell member  12  of the casing spacer of the present invention, while  FIGS. 5 and 6  are respectively end-on and side elevation views of the casing spacer&#39;s first shell member. 
   Casing spacer  10  is comprised of first and second shell members  12 ,  14  which are preferably identical in size and configuration. First shell member  12  includes a flexible, arcuate inner portion  16  and plural radial ribs, or risers,  20   a - 20   d . The first and fourth risers  20   a ,  20   d  are disposed on opposed ends of the first shell member&#39;s flexible, arcuate inner portion  16 . The second and third risers  20   b ,  20   c  are disposed on an outer, central portion of the first shell member&#39;s flexible, arcuate inner portion  16  and are arranged in common alignment. Disposed between the second and third risers  20   b ,  20   c  is a preferably circular aperture  46  which extends through the first shell member&#39;s flexible, arcuate inner portion  16 . Aperture  46  is adapted to receive a first non-slip member  40  as described in detail below. 
   First and second apertures  32   a ,  32   b  are disposed within the first riser  20   a . Similarly, a pair of spaced apertures  34   a ,  34   b  are disposed in the fourth riser  20   d . First and second apertures  32 ,  32   b  in the first riser  20   a  and third and fourth apertures  34   a ,  34   b  in the fourth riser  20   d  are each adapted to receive a respective coupler for securely attaching the first and second shell members  12 ,  14  to an inner carrier pipe  44  which is shown in dotted line form in FIG.  2 . Each of the paired apertures  32   a ,  32   b  and  34   a ,  34   b  in the first and fourth risers  20   a ,  20   d  is tapered along the length thereof as shown for the case of apertures  32   a ,  34   a  and  36   a ,  38   a  in FIG.  2 . The tapered apertures in the first and fourth risers of the first and second shell members  12 ,  14  allow the orientation of a coupler element, such as a bolt, connecting a pair of shell members to change with the size of the diameter of the inner carrier pipe  44  as described in detail below. In accordance with another aspect of the present invention, the arcuate inner portions  16 ,  18  of the first and second shell members  12 ,  14  are flexible, while each of the first through fourth risers of the shell members is hard and rigid. In a preferred embodiment, each of the first and second shell members  12 ,  14  is comprised of a high strength plastic such as polyurethane, where the flexible, arcuate inner portions are thin enough so as to be capable of undergoing a change in shape, while the risers are sufficiently thick so as to be of high strength and remain rigid even when exposed to large applied forces. The nut and bolt combinations for connecting the first and second shell members are also preferably comprised of a high strength plastic such as polyurethane or nylon. 
   The first shell member  12  further includes first through fourth connector projections  21   a - 21   d  which are disposed on the outer surface of the first shell member  12  at the juncture of its flexible, arcuate inner portion  16  and its first riser  20   a . Similarly, fifth through eighth connector projections  24   a - 24   d  are disposed on the outer surface of the shell member at the juncture of its flexible, arcuate inner portion  16  and its fourth riser  20   d . As shown in  FIG. 4 , adjacent pairs of connector projections are disposed on opposed sides of each of the connector apertures  32   a ,  32   b ,  34   a  and  34   b . Each pair of connector projections disposed adjacent a respective one of the aforementioned connector apertures is adapted to engage a nut in a nut and bolt combination used to connect the first and second shell members  12 ,  14  for maintaining the nut in position over the aperture and preventing the nut from rotating during insertion and tightening or loosening and removal of a bolt within the nut. 
   The second shell member  14  is similarly configured and includes four risers, where the first, second and fourth risers are shown in the various figures as elements  22   a ,  22   b  and  22   d . The second shell member  14  similarly includes four coupling apertures, with two in its first riser  22   a  and two in its fourth riser  22   d . Three of the four coupling apertures in the second shell member  14  are shown as elements  36   a ,  38   a  and  38   b  in FIG.  1 . The second shell member  14  further includes eight connector projections, where four connector flanges are disposed at the juncture of its first riser  22   a  and its flexible, arcuate inner portion  18  and four connector projections are disposed at the juncture of its fourth riser  22   d  and its arcuate inner portion. Two of these connector projections are shown as elements  26   a  and  28   a  in the various figures. The second shell member  14  further includes an aperture extending through its flexible, arcuate inner portion  18  between its second riser  22   b  and its third riser, which is not shown in the various figures. This aperture is adapted to receive a second non-slip member  42  which engages an outer surface of the inner carrier pipe  44 . Inner portions of each of the first and second shell members  12 ,  14  are provided with respective circular recessed portions  48  and  50  which are shown in the various figures in dotted line form. Circular recessed portion  48  is adapted to receive an inner, disc-like pad portion of the first non-slip member  40 , while circular recessed portion  50  is adapted to receive an inner, disc-like pad portion of the second non-slip member  42  which also engages a surface portion of the inner carrier pipe  44 . These circular recessed portions provide secure, fixed positioning of the inner pad portions of the non-slip members within the shell members. 
   Referring to  FIG. 9 , there is shown a perspective view of a non-slip member  80  used in a preferred embodiment of the inventive casing spacer. Non-slip member  80  includes a disc-shaped base  86  attached to which are first and second retaining members  82  and  84 . First and second retaining members  82 ,  84  are preferably integrally formed with the disc-shaped base  86 . Non-slip member  80  is preferably comprised of a material which is pliable and possesses a relatively high surface coefficient of friction. The disc-shaped base  86  of each non-slip member  80  is inserted in the aforementioned generally circular recessed portions  48  and  50  of the first and second shell members  12 ,  14  respectively. The non-slip members disposed in the shell members of casing spacer  10  of the present invention prevent displacement of the casing spacer on the inner carrier pipe, thus maintaining the casing spacer in fixed position between the carrier pipe and an outer casing. This arrangement maintains the carrier pipe in fixed position within the outer casing. 
   Casing spacers in accordance with the present invention are preferably spaced within two (2) feet of each end of the outer casing, with the remaining casing spacers spaced every eight (8) feet along the length of the carrier pipe. Non-slip member  80  is preferably comprised of a material such as plastic or leather which is adapted to frictionally engage pipes having a wide range of compositions and which is particularly adapted for securely engaging pipes comprised of polyvinyl chloride PVC). Each of the first and second retaining members  82 ,  84  of the non-slip member  80  includes a respective projection  82   a  and  84   a  on its distal end as shown in the perspective view of FIG.  9 . With the non-slip member  80  comprised of a flexible, pliant material, the first and second retaining members  82 ,  84  may be displaced toward or away from one another by engaging them with one&#39;s fingers. In this manner, the first and second retaining members  82 ,  84  may be moved towards one another when removing the non-slip member  80  from an aperture within a casing spacer&#39;s shell member to permit passage of the retaining members  82   a ,  84   a  through the aperture. With the non-slip member&#39;s disc-shaped base disposed in contact with an inner surface of the casing spacer shell member and with retaining member projections  82   a  and  84   a  disposed on an opposed side of the shell member, the two retaining members may then be released, allowing the retaining member projections  82   a ,  84   a  to engage the opposed side of the shell member to prevent removal of the non-slip member  80  from the casing spacer&#39;s shell member. While the retaining member&#39;s base  86  is described herein as being disc-shaped, the base is not limited to this shape and may assume virtually any geometric shape. 
   Referring to  FIG. 7 , there is shown an end—end view of a casing spacer  60  in accordance with the present invention disposed about and engaging a first carrier pipe  70 . Casing spacer  60  is also shown disposed within a first casing  52 . As in the previously described embodiment, casing spacer  60  includes first and second shell members  62  and  64  which are connected together by plural nut and bolt combinations, where first and second nut bolt combinations are shown as elements  66  and  68 . The first carrier pipe  70  is shown as having an outer diameter D 1 . As shown in  FIG. 7 , the size of the first carrier pipe  70  is such that a gap exists between adjacent end portions of the first and second shell member  62 ,  64 . The gaps between the first and second shell members  62 ,  64  are spanned by the first and second nut and bolt combinations  66  and  68 . 
   Referring to  FIG. 8 , there is shown an end-on view of the same casing spacer  60  disposed about a second carrier pipe  72 . In  FIG. 8 , casing spacer  60  is also shown disposed within an outer second casing  54 . The second carrier pipe  72  is shown as having a diameter D 2 , where D 2 &lt;D 1 . Because of the smaller diameter of the second carrier pipe  72 , there is no gap between adjacent end portions of the casing spacer&#39;s first and second shell members  62  and  64 . Moreover, it can be seen that the orientation of the nut and bolt combinations  66  and  68  within the aligned apertures in the first and second shell members  62  and  64  is different in the installations shown in  FIGS. 7 and 8 . In the configuration of  FIG. 8 , each of the first and second nut and bolt combinations  66  and  68  is aligned generally at right angles to the end risers of the first and second shell members  62 ,  64 . In the configuration of  FIG. 7 , the first and second nut and bolt combinations  66  and  68  are oriented at an acute angle relative to the end risers of the first and second shell members  62  and  64 . It is the tapered shape of the connector apertures in each of the first and second shell members  62 ,  64  which allows each of the connecting elements (bolts) to assume a different orientation and position relative to the two casing spacer shell members depending upon the outer diameter of the inner carrier pipe. The two bolts in the nut and bolt combinations  66 ,  68  are shown as having distal ends in dotted line form. The length of the two bolts is such that the illustrated bolts could not be used with the illustrated combination of carrier pipe  72  and outer casing  54 . The two bolts are too long. Thus, the distal ends of the two bolts (shown in dotted line form) have been removed so that the bolts do not contact the outer casing  54 . By using plastic bolts of substantial length, the same bolts may be used to connect two shell members about a carrier pipe of large diameter (where long bolts are required) as well as to connect two shell members about a carrier pipe of small diameter (where short bolts are required) by removing the ends of the bolts in the latter case. 
   While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.