US 3860742 A
There is provided a filament wound plastic pipe in which conductive wires are embedded. In one embodiment of the invention the ends of the pipe are scarfed by selective abraiding so as to expose portions of the conductive wire means. A metallic sleeve is secured to the scarfed ends of the pipe and contacts the exposed conductive wire means. Two adjacent pipe sections are mechanically and electrically joined to each other by a connecting member that is a conductor which is in electrical contact with both adjacent sleeves.
Claims available in
Description (OCR text may contain errors)
United States Patent Medney 1 1 Jan. 14, 1975  CONNECTION OF PLASTIC PIPES WITH 2,577,049 12/1951 Ulinc 138/127 X GROUND WIRES EMBEDDED THEREIN 3,189,676 6/1965 Muller 174/47 Inventor: Jonas Medney, 3504 Woodward St.,
Oceanside, N.Y. 11572 Filed: Apr. 4, 1973 Appl. No.2 347,871
US. Cl. 174/84 S, 138/127, 174/47, 174/78, 285/305, 285/369 Int. Cl H02g 15/08 Field of Search 174/68 C, 36, 84 R, 84 S, 174/355 M, 78, 47, 88 C; 339/14; 138/120, 127, 123, 124, 133, 134, 155; 285/305, 369, 404, 417, 423
References Cited UNITED STATES PATENTS 6/1950 Hollingsworth et al 138/127 Primary ExaminerDarrell L. Clay Attorney, Agent, or Firm-Leonard H. King  ABSTRACT There is provided a filament wound plastic pipe in which conductive wires are embedded. In one embodiment of the invention the ends of the pipe are scarfed by selective abraiding so as to expose portions of the conductive wire means. A metallic sleeve is secured to the scarfed ends of the pipe and contacts the exposed conductive wire means. Two adjacent pipe sections are mechanically and electrically joined to each other by a connecting member that is a conductor which is in electrical contact with both adjacent sleeves.
14 Claims, 6 Drawing Figures CONNECTION OF PLASTIC PIPES WITH GROUND WIRES EMBEDDED THEREIN The aforementioned Abstract is neither intended to define the invention of the application which, of
course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to filament wound resin bonded pipes and more particularly to electrically non-conductive pipes having electrically conductive means.
2. Description of the Prior Art There is a long standing need for a rugged, light weight pipe that is basically non-conductive but which can still provide a continuous electrical path with grounding available. One use for such a pipe is in a coal mine where the pipe is used to carry limestone for dusting the mine in order to prevent explosions. The powder passing through the pipe can generate a high electrostatic charge which can cause explosions. By providing a continuous electrical path in the wall of the pipe, grounding wires or the like may be used to discharge the pipe and not allow the charge (i.e. voltage) to build up.
SUMMARY OF THE INVENTION In providing a non-conductive plastic pipe which can be grounded there are two basic problems that must be solved. One of the problems is forming a continuous conductive path from one end of the pipe to the other and the second problem is to remove any built up charge in the pipe wall. One means for providing a continuous conductive path is to embed wires in the wall of the pipe. In the present invention the pipe is comprised of a resin bonded glass fiber wall in which conductive wires are embedded. Aluminum may be used for the conductive wire and has the advantage of having the same modulus of elasticity as the glass and will have the smallest limiting factor as far as tensile strength or stress for pressure carrying capabilities are concerned. Other wires that may be used on a cost preference basis would be copper, magnesium and steel. During the course of winding the glass fiber pipe, the number of ends of wire are usually less than the finite number of the glass fibers and are included in the winding operation.
When the pipe is fully cured the ends are cut and scarfed by selective abrading so as to expose some of the conductive wires. An electroplatic operation can be performed at this point to further build up the conductive ends of the wire over the ground surface of the scarfed end of the pipe to increase insurance of contact with metallic ends. A metallic sleeve is then secured to each end of the pipe in electrical contact with the exposed conductive wires and then a coupling member that provides a conductive path is used to join adjacent sleeves both mechanically and electrically.
It is desirable that the pipe be translucent so that any blockage of the material therein may be readily located and removed. Another desirable feature of the present invention is use of epoxy coated conductive wires that are insulated from each other where they cross during the winding operation. An additional feature of the present invention is the use of a conductive adhesive where the conductive sleeves are secured to the scarfed ends of the pipe. Alternatively, the conductive wire means that are exposed by scarfing may be solder dipped or electroplated.
In one embodiment of the present invention the conductive lead wires are wound close to the outside diameter of the pipe and the scarfing of that embodiment is done on the outside diameter. Another embodiment of the invention that is useful where heat is to be applied to the material flowing through the pipe provides that the conductive wires are wound substantially closer to the inside diameter of the pipe and in the second embodiment, of course, the inside diameter would be scarfed and the sleeve applied thereto. In the second embodiment the two sleeves that are adjacent to each other are also mechanically and electrically coupled to each other.
In order to provide still further conductivity to the pipe it is possible to use fillers such as aluminum powders, conductive carbon such as acetylene black, or other compatible conductive fillers in the gel coat. The same material could be included in the winding resin and can also be deposited on the outer layer of the pipe in order to decrease the electrical resistance of the glass fiber resin system between the conductive wires. The fillers may be included in local areas of the pipe rather than in the whole pipe, in order not to reduce the transparency of the pipe which is advantageous in identifying obstructions in the pipe system.
Accordingly, it is an object of the present invention to provide an improved filament wound resin bonded pipe.
Another object of the present invention is to provide an improved filament wound resin bonded pipe having conductive wires wound integrally therewith.
A further object of the present invention is to provide an improved filament wound resin bonded pipe, as described above, wherein the conductive wires are wound relatively close to the outside diameter of the pipe.
Yet another object of the present invention is to provide an improved conductive filament wound resin bonded electrical pipe, as described above, wherein the conductive wires are wound relatively close to the inside diameter of the pipe.
An advantage of the present invention is that the pipe may be translucent.
A feature of the present invention is that a continuous electrical path is provided from one end of the pipe to the other.
These and other objects, features and advantages of the invention will, in part, be pointed out with particularity, and will, in part, become obvious from the following more detailed description of the invention, taken in conjunction with the accompanying drawing which forms an integral part thereof.
BRIEF DESCRIPTION OF THE DRAWINGS In the various figures of the drawing like reference characters designate like parts.
In the drawing:
FIG. 1 is a longitudinal elevational view, partially broken away illustrating one embodiment of a conductive pipe system comprising the present invention;
FIG. 2 is an exploded, fragmentary view, partially in section, illustrating constructional features of the pipe system shown in FIG. I;
FIG. 3 is an enlarged, fragmentary transverse sectional view illustrating the wall structure of one embodiment of the present invention;
FIG. 4 is an enlarged view, similar to FIG. 3, illustrating an alternative embodiment of the present invention;
FIG. 5 is an enlarged, fragmentary, longitudinal, sectional view taken along line 5-5 of FIG. 1; and
FIG. 6 is a fragmentary view of a pipe end illustrating another feature of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, and in particular to FIG. 1, there is shown a pipe system 10 comprising the present invention. The pipe system 10 comprises several coaxial, adjacent lengths of pipe designated by the reference characters 12, 14 and 16. Each length of pipe, as shown in FIG. 2, comprises a resin bonded glass fiber tubular section 18 having a wall portion 20 and two end sections 22 and 24. Conductive wires 26 which are preferably coated with an insulating material such as an epoxy resin 27 (FIGS. 3 and 4) are wound integrally with the glass fibers, for example in the helical pattern shown in FIG. 2. When the ends 22 and 24 are scarfed as shown in FIG. 2, the glass fibers and the resin binder therefor will be selectively abraded away and the wires 26 in these sections will be exposed. It is preferred to use coated wire as better bonding between the resin of the pipe system and the wire is obtained preventing the formation of leakage paths and resulting in a stronger pipe.
A metallic sleeve 28 is secured to each scarfed end 22 and 24. The sleeve 28 is electrically conductive and is provided with a first annular groove 30 for receiving an O-ring 32 (FIG. 5) and a second annular, generally V-shaped groove 34 for receiving a conductive coupling member 36 (FIG. 1 and FIG. 5). An ohm meter 37 may be connected across the coupling members 36 at each end of each pipe section to test the resistivity thereof.
The cross section of the wall section 20 can best be appreciated by reference to FIG. 3. It will be seen that, in one embodiment of the invention, the conductive wires 26 are wound closer to the outside diameter of the tubular section 18. Further, it will be seen in FIG. 3 that by virtue of their own epoxy coating 27 the wires 26 are insulated from each other at their cross over points.
Reference now may be had to FIG. 2 and FIG. 3 for a better understanding of the means for exposing the wires 26. It will be seen that the wires 26 are wound in a generally helical pattern and when the end sections 22 and 24 are scarfed, the angular cut will intersect the plane of the wires 26. Thus, by selective abrasion of the glass fibers and the resinous binder, a short length of the ends of the wires 26 will be exposed so as to be contacted by the metallic sleeve 28. The selective abrasion results from the scarfing operation to improve the electrical path. A conductive adhesive may be used between the outside diameter of the scarfed ends 22 and 24 and the inside diameter of the sleeves 28 which are tapered at the same angle as the scarfed ends 22 and 24. Another method of increasing the electrical contact area is to metallize the scarfed ends of the pipe, such as by metal spraying, electroplating, die soldering or the like. Metallizing will further raise the conductive ends above the conical surface of the scarfed insulator insuring better contact. A typical metallized end is schematically represented by the reference character 25, as shown in FIG. 6.
As shown in FIG. 4, an alternative embodiment of the present invention contemplates the positioning of the conductive wires 26' closer to the inside diameter of the wall section 20' than in the previous embodiment. The conductive wires 26 may be formed of Nichrome or other resistive material and may be used for heating the material flowing through the pipe. As in the previous embodiment, the conductive wires 26 may be coated with an epoxy material 27 for insulation purposes. It will be appreciated from FIG. 4 that greater heat transfer is available by placing the wires 26 closer to the inside diameter of the pipe section 18' and, in addition, the mass of glass fiber material radially outward of the heating wires 26' constitute a heat insulation means.
By referring to FIG. 1, together with FIG. 5, a better understanding may be had of the means for both me-' chanically and electrically coupling adjacent pipe sections. The member 36 may be a stainless steel cable, that is threaded through two pairs of coaxial and chordally oriented openings 38a, 38b, and 38c, 38d that are formed in a sleeve 40. For a complete understanding of the principle of operation of this type of coupling, reference may be had to my issued U.S. Pat. No. 3,606,402. Briefly, the cable 36 is engaged in the grooves 34 of two adjacent sleeves 28 and takes up the end load of the piping system in addition to providing electrical continuity. It should be noted at this time that the sleeve 40 also serves to compress the O-rings 32.
In some installations a single metal coupling may be used as where the pipe is to be connected to a ground.
If desired, the metallic coupling member may be threaded-to permit joining sections together. If both ends are male members then a conventional metal female sleeve would be employed as the coupling member. Generally, if threaded coupling members are employed, one end would be a male and the other end a female coupling.
There has been disclosed heretofore the best embodiment of the invention presently contemplated. However, it is to be understood that various changes and modifications may be made thereto without departing from the spirit of the invention.
What I claim as new and desire to secure by Letters Patent is:
1. An electrically conductive insulator plastic pipe.
a. at least two rigid adjacent tubular sections made of resin bonded glass fibers each being defined by an elongated, non-conductive wall including a central portion having axially spaced apart first and second ends;
b. conductive wire means completely embedded within each said wall along said central portion thereof and extending between said first and second ends, said conductive wire means being exposed only proximate each said tirst and second ends; and
c. external, axially elongated, annular coupling means mechanically coupling two adjacent ones of said tubular sections and electrically coupling said exposed conductive wire means to said two adjacent ends of said tubular sections, said annular coupling means extending at least partially over said two adjacent tubular sections, wherein said annular coupling means comprises an electrically conductive sleeve positioned about each said first and said second end, said conductive sleeve being in electrical contact with said exposed conductive wire means, a tubular member extending over said sleeves of said two adjacent ones of said tubular sections, and a conductor in engagement with said tubular member and said sleeves, said conductor being in electrical contact with said two adjacent ones of said sleeves whereby there is electrical continuity between said two adjacent ones of said tubular sections.
2. The pipe system in accordance with claim 1 wherein said tubular sections are translucent.
3. The pipe system in accordance with claim 1 wherein said conductive wire means are copper.
4. The pipe system in accordance with claim 1 wherein said conductive wire means are aluminum.
5. The pipe system in accordance with claim 1 wherein said conductive means are resistance wires.
6. The pipe system in accordance with claim 1 wherein said conductive means are steel.
7. The pipe system in accordance with claim 1 wherein there is further included an insulator coating on said conductive wire means.
8. The pipe system in accordance with claim 1 wherein said conductive wire means are positioned proximate the outside diameter of said tubular sections.
9. The pipe system in accordance with claim 1 wherein said conductive wire means are positioned proximate the inside diameter of said tubular sections.
10. The pipe system in accordance with claim 9 wherein said conductive wire means are resistance wires.
11. The pipe system in accordance with claim 1 wherein each said sleeve has at least one annular groove formed on the outside diameter thereof, said tubular member having two pairs of coaxial, substantially chordally oriented openings in axial alignment with said grooves on said sleeve, said conductor extending through the aligned openings in said tubular member whereby said conductor is positioned in the grooves of two said adjacent sleeves.
12. The pipe system in accordance with claim 11 wherein each said sleeve includes a second annular groove and there is further provided an O-ring in each said second groove.
13. The pipe system in accordance with claim 1 wherein there is further provided a conductive adhesive intermediate each said sleeve and said first and second ends.
14. The pipe system in accordance with claim 1 wherein there is further included a metallized coating over said exposed portions of said conductive wire means.