HK1141763B - Conduit, manufacture thereof and fusion process therefor - Google Patents

Description

Conduit and its manufacture and fusion process of conduit

Technical Field

The present invention relates generally to systems for fusing or joining conduit or pipe sections, such as polyvinyl chloride conduit or pipe, and more particularly to a process for effectively and permanently fusing a first conduit section to a second conduit section, as well as fused conduit, fused joint area, and methods of manufacturing conduit.

Background

Conduit systems are widely used throughout the world to transport or convey materials such as water and other fluids from one location to another for distribution throughout the system. In addition, conduit systems are also used as structural enclosures for communication wiring, power wiring, data wiring, fiber optic cables, and the like. Typically, such conduits or piping are located underground (since pipes above the ground are neither good looking nor easily invaded). However, there are after all also devices above ground. Further, it should be noted that the terms "conduit" and "pipe" are used interchangeably herein and may be used to refer specifically to structures (typically tubular) that convey liquids, contain materials, contain wires or other conduits/pipes, and the like.

The logistics of transporting the pipes and conduits to the installation site is often difficult because only short sections of pipe can be efficiently shipped. Once these short sections of pipe or conduit are delivered to the installation site, these sections must be attached or connected together according to known processes and installation techniques. Accordingly, various joining or connecting processes have been developed, and in particular, they utilize mechanical joints, embedding wires at or near the ends to create fused joints, resistive heating elements to fuse joined conduit sections together, or solvent welding using chemical adhesives to join conduit sections using conventional bell and spigot structures. For example, see U.S. patent 6,398,264 to Bryant, III; U.S. patent 6,394,502 to Andersson; U.S. patent 6,156,144 to Lueghamer; U.S. patent 5,921,587 to Lueghamer; U.S. patent 4,684,789 to Eggleston; and us patent 4,642,155 to Ramsey. Ethylene pipe (PE or HDPE) has been conventionally fused for many years using well known joining techniques. For example, see U.S. patent 3,002,871 to Tramm et al; U.S. patent 4,987,018 to Dickinson et al; U.S. patent 4,963,421 to Dickinson et al; and U.S. patent 4,780,163 to Haneline, jr. et al; and genoi, U.S. patent publication No. 2003/0080552. Thus, preexisting fusion equipment can be utilized.

Furthermore, fusion of polyvinyl chloride conduits is known and practiced as described and claimed in U.S. patent No. 6,982,051 to st. The assignee and owner of this patent is the assignee and owner of the present invention and application. Further, the disclosure of the referenced patents and their contents are hereby incorporated by reference.

One disadvantage of the prior art is the formation of internal welds extending from the inner wall of the fused pipe. In particular, as the melting and fusing conduit requires heat and pressure, when the terminal ends of two pipe sections are melted and joined, the pressure of the joint causes a weld to form in the joint area extending from the inner and outer walls of the now fused pipe. The inner weld seam encroaches slightly into the interior region of the fused pipe and reduces the cross-section and passage of the conduit. Moreover, the presence of such an internal weld may interfere with and affect certain objects inserted therein, such as, for example, communication wiring, power and data wiring, and the like. For example, the weld may damage the insulation of the wire, which may adversely affect the wire signal, or cause a short circuit of the wire.

Currently, such internal welds can be eliminated in various ways. In one variation, the internal weld is removed with a manual or mechanical tool or structure. However, such manual/mechanical removal can result in incomplete or excessive removal of the weld, removing the internal weld increasing the time of the installation process. Moreover, in many cases, the removal of such welds is simply forgotten during the installation process. Furthermore, removal of the weld may become impossible due to the pipe and fitting structure, e.g., fusion of bends and the like. In another variation, some mechanical structure is used to join the pipe sections, as opposed to using fused pipe. For example, a hand hole box may be used, but this may result in additional threaded or clamped "joints" in the conduit, which creates more potential for leakage and separation between the connected conduit sections. Also, the use of metal fittings to restrain the joint typically results in corrosion and other degradation over time, which in turn increases maintenance costs and associated costs. Furthermore, in many special applications, mechanical and solvent welded joints cannot be used, for example, trenchless applications and applications requiring high joint strength.

Disclosure of Invention

It is therefore an object of the present invention to provide a fusion process for conduits that overcomes the deficiencies of the prior art. It is another object of the present invention to provide a fusion process for conduits that requires the connection of many lengths in the field. It is another object of the present invention to provide a fusion process for conduit that provides a single conduit system with a joint of sufficient strength so that the conduit can be installed by multiple trenchless and open-trench methods in long lengths, which also precludes leakage through the joint. It is another object of the present invention to provide a shaped and fusible thermoplastic conduit that can be fused and used without removing internal welds and without risking any objects inserted therein, such as communication wiring, power wiring, data wiring, etc. It is yet another object of the present invention to provide a method of fusion forming a conduit. It is another object of the present invention to provide a method of making a shaped, fusible conduit.

Accordingly, in one embodiment, a method of fusing a first conduit section to a second conduit section is provided wherein each of the conduit sections includes at least one bell portion with a first end and a second end, and an inside bell portion dimension at the second end of the bell portion is greater than an inside bell portion dimension at the first end of the bell portion. The method comprises the following steps: heating and melting at least a portion of each of the second end of the bell portion of the first conduit section and the second end of the bell portion of the second conduit section; and fusing the first conduit section and the second conduit section by joining the second end of the bell portion of the first conduit section with the second end of the bell portion of the second conduit section, thereby forming a fused conduit having a fused joint area.

In another aspect and embodiment, the present invention is directed to a method of fusing a first conduit section to a second conduit section in situ, each section including a linear portion and at least one bell portion with a first end and a second end, and the bell portion inside dimension at the second end of the bell portion being greater than the bell portion inside dimension at the first end of the bell portion. The method comprises the following steps: moving at least one fusing device to the site, and the fusing device is adapted to: (i) heating and melting at least a portion of each of the second end of the bell portion of the first conduit section and the second end of the bell portion of the second conduit section; and (ii) fusing the first conduit section and the second conduit section by joining the second end of the bell portion of the first conduit section with the second end of the bell portion of the second conduit section, thereby forming a fused conduit having a fused joint area.

In yet another embodiment, a method of manufacturing a conduit section in situ is provided. The method includes engaging at least one terminal end of the conduit section with a forming mandrel, thereby forming a bell portion on the at least one terminal end of the conduit section.

In yet another embodiment, the present invention is directed to a conduit section. The conduit section comprises: a catheter body having a first terminal end and a second terminal end; and a bell portion located on at least one of the first and second terminal ends. Further, the conduit body is fabricated from a thermoplastic material having properties sufficient to allow the bell portion to be fused to the bell portion of the next conduit section.

The above and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

Drawings

FIG. 1 is a side cross-sectional view of one embodiment of a catheter in accordance with the principles of the present invention;

FIG. 2 is a side view of another embodiment of a catheter in accordance with the principles of the present invention;

FIG. 3 is a side view of yet another embodiment of a catheter in accordance with the principles of the present invention;

FIG. 4 is a side cross-sectional view of a fused conduit made in accordance with one embodiment of a method according to the principles of the present invention;

FIG. 5 is a side view of a fused conduit made in accordance with another embodiment of a method in accordance with the principles of the present invention;

FIG. 6 is a side cross-sectional view of a catheter in an intermediate manufacturing step in one embodiment according to the principles of the present invention;

fig. 7 is a side cross-sectional view of a catheter in an intermediate manufacturing step in another embodiment according to the principles of the present invention.

Detailed Description

For purposes of the following description, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall refer to the invention as oriented in the drawing figures. It is to be understood, however, that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting.

Various numerical ranges are disclosed in this patent application. Because these ranges are continuous, they include values between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations.

In one aspect of the present invention, a catheter 100 is provided, as shown in the various embodiments of fig. 1-5. In a preferred but non-limiting embodiment, conduit 100 refers to a straight extended length of conduit 100, both before and after the fusion process described below. However, the catheter 100 and the method of making the catheter 100 of the present invention may be used to provide a variety of different forms, arrangements, shapes, sizes and configurations. For example, the conduit 100 (or a segment thereof) may be in the form of a substantially straight length conduit, an elbow, an arced tube, a non-straight length of conduit, or the like. Thus, the present invention is not limited to any particular shape, configuration, geometric form, etc. Further, as discussed above, the term "conduit" is interchangeable with the term "pipe," and generally refers to a tubular body having a circular cross-section. However, any shape, configuration, or geometric cross-section is contemplated as being within the scope and ambit of the present application.

In a preferred but non-limiting embodiment, as shown in FIG. 1, the conduit 100 includes a linear portion 102 having a linear inner diameter 104. Further, the conduit 100 includes at least one bell portion 106 having a first end 108 and a second end 110. The bell portion 106 has a bell portion inside diameter 112, the diameter 112 being greater at the second end 110 of the bell portion 106 than at the first end 108 of the bell portion 106. Further, in a preferred but non-limiting embodiment, the inner diameter 112 at the first end 108 is substantially equal to the inner diameter 104 of the linear portion 102 and gradually increases toward the middle portion 109 of the bell portion 106. The inner diameter 112 remains substantially constant from the middle portion 109 to the second end 110 of the bell portion 106, thereby providing a square face at the second end 110 of the bell portion 106. It is this varying inner diameter 112 that provides or forms the "bell shape" of the bell portion 106 of the conduit 100. Further, when used in connection with a conduit 100 or bell portion 106 that does not include a circular cross-section, at least one internal dimension (e.g., width) at the second end 110 of the bell portion 106 is greater than the internal dimension (e.g., width) at the first end 108 of the bell portion 106.

Although the bell portion 106 is shown only on one end 115 of the conduit 100 in fig. 1, it is also contemplated that the bell portion 106 may be formed, located, or positioned on both terminal ends 114, 115 of the conduit 100. Such a structural arrangement is shown in fig. 2. Additionally, lengths of such conduit 100 may be fused together by placing the bell portions 106 on each end 114, 115 of the conduit 100, as will be discussed in detail below. Further, as described above and shown in FIG. 3, any desired shape or shape of the conduit 100 may be fused together using the bell portion 106 at one or both ends 114, 115 of the conduit 100. For example, the conduit 100 of fig. 3 is in the form of an elbow with a bell portion 106 at each terminal end 114, 115.

As discussed above, in a preferred but non-limiting embodiment, the conduit 100 and/or components thereof, e.g., the linear portion 102, the bell portion 106, etc., are fabricated from a polyvinyl chloride composition. In particular, the conduit 100 and/or any portion 102, 106 of the conduit 100 may be manufactured using an extruded polyvinyl chloride composition in a well-known extrusion process. In addition, any number of compositions may be used to maximize the ability to successfully fuse the sections of conduit 100 together, as will be discussed in detail below.

In another aspect, the present invention is directed to a method of fusing a first conduit section 116 to a second conduit section 118. As discussed above, each conduit section 116, 118 includes at least one bell portion 106 and may (but need not) include a linear portion 102. In a preferred but non-limiting embodiment, the first conduit section 116 and the second conduit section 118 are fused as follows. First, the second end 110 of the bell portion 106 of the first conduit section 116 is positioned in an opposing relationship to the second end 110 of the bell portion 106 of the second conduit section 118. Next, the second ends 110 of the bell portions 106 of each conduit section 116, 118 are aligned. At least a portion of the second end 110 of each bell portion 106 of the conduit sections 116, 118 is melted. In addition, the melted ends 110 are joined to each other, and pressure is maintained between the joined ends 110, thereby forming a fused conduit 119 having a fused joint area 120. In one embodiment, the pressure and engagement of the melted end 110 is maintained until the melted end 110 of each conduit section 116, 118 cools sufficiently to provide a fused conduit 119 having a fused joint area 120 of the desired strength.

Another example of a fusion conduit 119 using the fusion process of the present invention is shown in fig. 5. As shown in this non-limiting embodiment, the first conduit section 116 is in the form or shape of an arc, while the second conduit section 118 is in the form or shape of an elbow. Further, while the second conduit section 118 includes a bell portion 106 on each terminal end 114, 115, the first conduit section 116 has a bell portion 106 only on the second terminal end 115. The fusing of the first terminal end 114 (non-bell portion end) of the first conduit section 116 to a subsequent length or section of conduit or pipe having no bell portion 106 thereon may be accomplished according to the fusing process and method shown and described in U.S. patent No. 6,982,051.

As discussed above, in a preferred but non-limiting embodiment, the first conduit section 116, the second conduit section 118, the linear portion 102 of the first conduit section 116, the linear portion 102 of the second conduit section 118, the bell portion 106 of the first conduit section 116, and/or the bell portion 106 of the second conduit section 118 may be manufactured from a polyvinyl chloride composition. However, the first conduit section 116 and the second conduit section 118 may be extruded from a variety of thermoplastic materials, such as plastic, polyethylene, high density polyethylene, and the like, wherein the thermoplastic material exhibits or includes properties sufficient to allow the bell portion 106 of the first conduit section 116 to fuse to the bell portion 106 of the second conduit section 118. Thus, as discussed above in fig. 1-5, one or both of the first and second conduit sections 116, 118 includes the bell portion 106 positioned or formed on one or both ends 114, 115 of the conduit sections 116, 118.

To fuse the additional length of conduit, the process may be used for successive segments of conduit 100 having a bell portion 106 at least one terminal end 114, 115. Specifically, the positioning, aligning, melting, and joining steps discussed above may be used to continue adding successive lengths or lengths of conduit 100 (regardless of shape or size), thereby forming a longer fused conduit system 119. It should be noted, however, that the fusion process described above requires only a melting and joining step in order to provide a fused conduit system 119 and fused joint region 120. Further, since these conduit sections 116, 118 may be formed in a variety of shapes, sizes, forms, configurations, etc., a fused conduit system 119 may be provided when fused together at the second end 110 of the respective bell portion 106 of each conduit section 116, 118 (and other or subsequent conduits 100). The fused conduit system 119 may be used to form any desired length of conduit, casing, pipeline, or other above ground or below ground system.

In a preferred but non-limiting embodiment, the second end 110 of one or both of the bell portions 106 may be surfaced prior to the aligning step. Specifically, the use of a surfacing mechanism (as described in U.S. Pat. No. 6,982,051) may provide parallel, smooth, flush and opposing edges prior to the second end 110 of the bell portion 106 being melted and engaged. In particular, the facing mechanism (i.e., the facing blade or device) grinds or machines the ends 110 until there is a minimum distance between the machined ends 110 (typically the thickness of the facing blade or device), or a predetermined stop associated with the device that clamps or secures the ends 110.

Further, as discussed above in connection with the fusion of two opposing conduit sections 116, 118, the melting step of this embodiment may include simultaneously heating the second end 110 of the bell portion 106 of the first conduit section 116 and the second end 110 of the bell portion 106 of the second conduit section 118. To provide suitable heating and melting of the second end 110, a plurality of heating zones may be provided and applied to the second end 110 of the bell portion 106 of the conduit section 116, 118. In particular, a heating plate (as described in U.S. Pat. No. 6,982,051) may be utilized to provide such zone heating, for example, with different portions of the heating surface differing in temperature, such as the upper and lower surfaces. This provides more uniform heating of the end 110 due to the natural physical characteristics of the heating process.

After the conduits 116, 118 and, in particular, the bell portions 106 of the conduits 116, 118 are fused, an outer weld 122 and an inner weld 124 are formed. Also, as the second end 110 of the bell portion 106 of each conduit 116, 118 is heated and at least partially melted, such welds 122, 124 are formed. After the ends 110 are pressed and joined together, the molten material is compressed to form these welds 122, 124. See, for example, fig. 4. It is with respect to the particular use of the conduit to house wires, cables, etc. that these possible adverse effects of forming welds 122, 124 are greatly reduced or mitigated by the described conduits 100, 116, 118, 119 and fusion process.

In another preferred but non-limiting embodiment, sufficient pressure is maintained, and thereafter allowed to cool down at the second end 110 of the bell portion 106 of each conduit section 116, 118 to form a fused joint area 120 of a desired strength. Further, to provide a fused joint area 120 exhibiting at least 50% tensile strength (or even substantially the same strength) of one or both of the conduit sections 116, 118, any of the following parameters may be selected and used during the fusion process: a bonding interface pressure, a bonding gauge pressure, a bonding time, a heated interface pressure, a heated gauge pressure, a heating temperature, and/or a heating time. For example, in one embodiment, the gage pressure of the engagement is calculated using the following equation:

where MGp is the gauge pressure of the machine, π is the 3.1416 circumference ratio, OD²Is the square of the outside diameter (in inches) of the straight line section, ID²Is the square of the internal diameter (in inches) of the straight section, Ip is the interfacial pressure, and Ca is the cylindrical area (in inches) of the machine. Further, the "OD" and "ID" referred to are any of the following: without bellsThe outside and inside diameters of the conduit or tube of section 106; or the outside and inside diameters of the bell portion 106 itself. Since the cross-sectional area is preferably the same for each, any set of diameters may be used. Furthermore, if the bell portion 106 includes a different cross-section, such as a square, the equation can be modified to replace the portion included in the fractional numerator with a "cross-sectional area of the bell portion end". In another embodiment, the interface pressure of the bonding is between about 50psi and about 250psi, the heating pressure is between about 5psi and about 50psi, and the time period between heat melting and bonding can be up to about 10 seconds.

By using the polyvinyl chloride compound discussed above, as well as the bell portion 106 of the conduit 100, a fused conduit system 119 and fused joint area 120 may be formed. Due to the shape of the fused bell portion 106, the inner weld 124 formed during the fusion process does not encroach into the area defined by the straight portion inner diameter 104 (or the "non-bell" portion of the conduit 100). Other dimensions may be modified and maximized for effective use, such as the combined flow characteristics, intended use of the fused conduit 119, and the like. These dimensions, for example, the length of the bell portion 106 and the offset from the linear portion 102 of the conduit 100, may be set to minimize the overall length of the fused bell portion 106 outside the area formed by the linear portion inner diameter 104 of the inner weld bead 124. In particular, by minimizing the overall length of the bell portion 106, the likelihood of wires and cables sagging into the bell portion 106 (thereby compromising the integrity of the protective coating on the wire or cable by contacting or rubbing against the inner weld 124) is minimized or eliminated. Also, the length and offset of the bell portion 106 may vary for effective use and implementation in certain specific or necessary applications.

As noted above, in a preferred but non-limiting embodiment, the conduits 100, 116, 118 (or any portion thereof) may be manufactured using a polyvinyl chloride compound. According to this embodiment, as shown in fig. 6, in manufacturing the conduit 100, a straight portion 126 of the conduit is provided, the straight portion 126 including at least one terminal end 128. It should be noted that the linear portion 126 may be at the terminal end 128 of any size, shape or configuration of the conduit 100, such as an elongated linear length, bend, curved segment, etc. Next, the terminal end 128 is engaged with a shaped mandrel 130, the mandrel 130 is abutted against the terminal end 128, and the linear portion 126 is deformed, thereby forming the bell portion 106 described above at the terminal end 128 of the linear portion 126. Accordingly, the mandrel 130 should be sized and shaped to impart the desired bell portion 106 of the appropriate form, profile, shape and size to the linear portion 126 of the conduit 100.

The present invention contemplates various methods of forming the bell portion 106. In a preferred but non-limiting embodiment, as shown in FIG. 6, the terminal end 128 is heated prior to the terminal end 128 being engaged to the forming mandrel 130. Specifically, the terminal end 128 is heated to a temperature sufficient to allow the end 128 to form and take the shape of the forming mandrel 130. For example, the terminal end 128 may have reached or be near a sufficient temperature after extrusion so that the bell portion 106 may be formed during or immediately after extrusion and prior to cooling. In another preferred but non-limiting embodiment, the forming mandrel 130 is heated to a suitable temperature to at least partially melt the terminal end 128 of the catheter 100, as opposed to heating the terminal end 128 of the straight portion 106. Such a structural arrangement is shown in fig. 7. In order to achieve the desired melting temperature of the forming mandrel 130, a suitable heat source 132 may be provided. Of course, the heat source 132 may be controlled to a specified temperature range to maximize the efficiency and effectiveness of the heating process.

After the bell portion 106 is formed at the terminal end 128 of the conduit 100, the newly formed bell portion 106 is allowed to cool down. Finally, after the bell portion 106 cools and solidifies, it is disengaged from the forming mandrel 130. This same manufacturing technique and process may be used for each terminal end 128 of the straight portion 126 as desired. As such, the conduit 100 is formed with a bell portion 106 at one or both of the terminal ends 128.

Although specific methods of manufacturing the inventive conduit 100 have been discussed, any manner of positioning or forming the bell portion 106 on the conduit 100 is contemplated. For example, forming sleeves, forms, dies, and other configurations may be used as compared to using forming mandrel 130. For example, the bell portion 106 may be formed on the conduit 100 during an initial extrusion or molding process, or by various methods of preparing and manufacturing shaped plastic products known in the art.

In another preferred but non-limiting embodiment, the bell portion 106 may be formed using transportable and/or portable (mobile) equipment in the field or worksite. For example, a fusing device such as the device described in U.S. Pat. No. 6,982,051 may be modified to be used to form the bell portion 106 on a straight length of extruded conduit 100. In addition, a forming mandrel 130, for example in the form of a modified heater mechanism, heated plate, or the like, may be used on or in conjunction with the fusing apparatus. Thus, the bell portion 106 may be formed on one or both ends of the conduit 100 as "desired" in the field.

The present invention may be used in conjunction with a variety of applications in both underground and above-ground installations. For example, the conduit 100, fused conduit system 119 and fusion method of the present invention may be used in a variety of applications where, according to the prior art, and in order to transport and insert a liner into a main conduit, the liner must be manufactured in sections or portions that are typically much shorter in length than the final and desired length of liner to be formed. In particular, the conduit sections 116, 118 may be fused at the installation site according to changing needs and requirements of the pipeline laying process. Also, the catheter 100, fused catheter system 119, and fusion method of the present invention may be used in sliding line (slipping) applications, where a slightly smaller diameter fused catheter is inserted into a larger tube, i.e., for repair or for transporting or carrying other materials. Another variation of the sliding pipeline process for conduits requires pulling a "bundle" of multiple conduits simultaneously, which can result in multiple conduits being incorporated into a casing or main pipe.

The conduit 100 and fused conduit system 119 may be implemented in a variety of other applications in which a fused joint is used in conjunction with a horizontal directional drilling process. According to this process, a pilot hole is drilled in the ground and the drilled hole can be steered in a precise manner to control depth and alignment. After the pilot hole is completed, the borehole is reamed to a larger diameter and filled with drilling mud to keep the enlarged hole open and provide lubrication. The pipe 100, fused pipe system 119 or bundled pipe is then pulled through the drilling mud, bringing the pipe or pipe bundle into position.

In addition, the fused conduit system 119 may be used in pipe bursting applications. Pipe bursting uses a cutter head, e.g., a large hydraulic or pneumatic cutter head, to break open the old pipe and force the debris into the surrounding earth. This allows a new tube or tube bundle of the same or larger diameter to be pulled into the resulting space. This process is typically used when new pipeline capacity must be increased. Also, the conduit 100 and fused conduit system 119 may be used in a direct-bury application, wherein an at least partially open conduit aperture is formed into which the fused conduit system 119 is inserted and positioned. Another variation of the direct-bury application requires the use of a plow to cut cuts and pipe openings in the ground, while pulling the conduit 100 or fused conduit system 119 behind. This is typically a simultaneous process. The conduit 100, fused conduit system 119, and fusing method of the present invention may be adapted to be effectively implemented and utilized in any of a number of applications and installations, all such applications and installations should be considered within the scope and ambit of the present invention.

In this manner, this aspect of the invention eliminates the potential effects of the inner weld 124 formed during the fusion process. In addition, this effect is minimized and eliminated without the need for additional process steps, increasing the cost or time of the fusion and installation process. In this way, any fusion process occurring at the site is not altered, and the overall joining time is not extended in the process. Furthermore, this aspect of the invention does not require any equipment to remove the weld, and the fused conduit system 119 and fused joint region 120 do not exhibit the disadvantages associated with mechanical or solvent welded joints described above.

Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

Claims (18)

1. A method of butt fusing a first conduit section to a second conduit section, the method comprising:

providing a first conduit section manufactured from a polyvinyl chloride composition, the first conduit section comprising a first straight portion and a first bell portion formed at an end of the first straight portion, the first bell portion comprising: a first portion having an inner diameter substantially the same as the first straight portion of the first conduit section; a second portion extending from the first portion and having a gradually increasing inner diameter; and a third portion extending from the second portion to an end of the first conduit section and having a substantially constant inner diameter, the inner diameter of the third portion being greater than the inner diameter of the first portion;

providing a second conduit section manufactured from a polyvinyl chloride composition, the second conduit section including a second linear portion and a second bell portion, the second bell portion formed at an end of the second linear portion, the second bell portion including: a first portion having an inner diameter substantially the same as the second linear portion of the second conduit section; a second portion extending from the first portion and having a gradually increasing inner diameter; and a third portion extending from the second portion to an end of the second conduit section and having a substantially constant inner diameter, the inner diameter of the third portion being greater than the inner diameter of the first portion;

heating and melting at least a portion of the end of the first conduit section and the end of the second conduit section; and

butt fusing the first conduit section and the second conduit section by joining the end of the first bell portion of the first conduit section with the end of the second bell portion of the second conduit section to form an inside weld between the end of the first bell portion of the first conduit section and the end of the second bell portion of the second conduit section, thereby forming a butt fused conduit system having a butt fused joint area;

wherein the butt fusion conduit system is used as a containment structure for wires and/or cables; and

wherein the butt-fusion joint region has substantially the same strength as the conduit.

2. The method of claim 1, wherein at least one of: the first conduit section, the second conduit section, the butt-fused conduit, or any combination thereof, in the form of at least one of: substantially straight length conduits, elbows, arced tubes, non-straight length conduits, or any combination thereof.

3. The method of claim 1, wherein prior to the heating and melting, the method further comprises:

surfacing the end of the first conduit section and the end of the second conduit section; and

aligning the end of the first conduit section with the end of the second conduit section.

4. The method of claim 1, wherein the heating comprises simultaneously heating the end portion of the first conduit section and the end portion of the second conduit section.

5. The method of claim 1, wherein the time period between the heating and melting and the bonding is up to 10 seconds.

6. The method of claim 1, further comprising maintaining a joined interfacial pressure between the end of the first linear portion of the joined first conduit section and the end of the second linear portion of the second conduit section until the melted end of each conduit section cools sufficiently to provide a fused joint area of a desired strength.

7. The method of claim 1, wherein the interface pressure of the joint is between 50psi and 250 psi.

8. The method of claim 1, wherein the heated interface pressure is between 5psi and 50 psi.

9. A butt fusion joint region made as described in claim 1.

10. The method of claim 1, wherein prior to the heating and melting, the method further comprises: moving at least one fusing device to a site on a site, the fusing device configured to: (i) heating and melting at least a portion of each of the second end of the bell portion of the first conduit section and the second end of the bell portion of the second conduit section; and (ii) butt fusing the first conduit section and the second conduit section by joining the second end of the bell portion of the first conduit section with the second end of the bell portion of the second conduit section, thereby forming a butt fused conduit system having a butt fused joint area.

11. The method of claim 1, wherein the method further comprises:

inserting the wire and/or cable into the catheter.

12. The method of claim 1, wherein the method further comprises:

heating and melting at least a portion of the other end of the first conduit section and at least a portion of the end of the conduit section thereafter; and

joining said other end of said first conduit section with said end of said subsequent conduit section, thereby forming a subsequent butt-fusion joint region.

13. The method of claim 1, wherein the method further comprises:

heating and melting at least a portion of the other end of the second bell portion of the first conduit section and at least a portion of the end of the bell portion of the conduit section thereafter; and

joining said other end of said first conduit section with said end of said subsequent conduit section, thereby forming a subsequent butt-fusion joint region.

14. The method of claim 1, wherein the method further comprises:

burying the conduit in the ground;

inserting the wire and/or cable into the catheter.

15. The method of claim 1, wherein the method further comprises:

pulling the conduit into the space created by the pipe burst application.

16. The method of claim 15, wherein the method further comprises:

inserting the wire and/or cable into the catheter.

17. A method of forming a bell conduit, the method comprising:

mating at least one terminal end of a conduit section made of a polyvinyl chloride composition with a shaped mandrel, the shaped mandrel being connected to a controlled heat source, thereby forming a bell portion, the bell portion comprising: a first portion having an inner diameter substantially the same as a straight portion of the conduit section; a second portion extending from the first portion and having a gradually increasing inner diameter; and a third portion extending from said second portion to an end of said conduit section and having a substantially constant inner diameter, thereby providing a square face at the end of said conduit section, and said inner diameter of said third portion being greater than the inner diameter of said first portion;

allowing the bell to cool; and

after the bell portion has cooled and solidified, releasing the bell portion from the shaped mandrel;

wherein the bell conduit is used as a containment structure for wires and/or cables; and

wherein the butt-fusion joint region has substantially the same strength as the conduit.

18. A bell conduit made as set forth in claim 17.