Patent Application
20060076775
None.
Not Applicable.
Not Applicable.
This invention relates to the lining of sewers, water mains, culverts, tunnels, conduits, pipes, and other passageways (generically referred to herein as passages), and especially but not exclusively to the lining of underground passages. Lining in this context is intended to include both rehabilitation and using the pipe of the present invention as new pipe for burial. It is anticipated that the process is particularly suited for rehabilitation, including the relining of sewers. It is more particularly directed to slipline pipe for passages.
As sewers and other passages age, they deteriorate in many ways. Cracks appear and joints separate. Infiltration through these cracks and joints creates external voids, accelerates structural deterioration and can overload collection systems and treatment plants. Many passages can be successfully rehabilitated using what is called the soft-lining or cured in place method. This method is illustrated in U.S. Pat. Nos. 4,009,063 and 4,064,211. Most deteriorating sewers can be rehabilitated economically in this way.
Other rehabilitation projects, particularly those involving larger passages, may require a different method, one using a hard liner inside the existing passage. Inserting a hard liner in an existing passage poses several problems. Typically, there is a limited amount of space available in such passages, so manipulating the liner to place it in the passage and/or assemble it in place can be difficult. Moreover, the lining of such passages should not excessively reduce the cross-sectional area of the passage, since otherwise the flow rate through the passage will be unduly restricted.
One known manner of inserting a hard liner inside an existing passage is called sliplining. In this type of remediation, a new liner pipe is pushed or pulled into the existing pipe, creating a slight decrease in the inside diameter of the pipe. Sliplining is normally used with pipes ranging from 8 to 96 inches in diameter. Sliplining can be performed rapidly, without disturbing adjacent services or requiring bypass pumping. It makes it possible to repair long lengths of pipe with minimal disruption. Because the liner is structurally sound, it solves problems relating to leakage and structural deterioration.
It is known that sections of slipline pipe may be joined together with an elastomeric gasket therebetween to form a seal between the sections of the pipe. For example, U.S. Pat. No. 6,176,523 shows such a pipe with a gasket 80 disposed in a recess 66 for creating a seal between two sections of pipe. This involves considerable handling and machining of the pipe, however, since the recess (and in fact the various shaped surfaces of the ends of the pipe sections) are formed by sawing, routing, lathing, or the like. See col. 5, lines 24-31, for example. These machine steps are expensive, and can result in damage to the pipe sections. U.S. Pat. No. 5,547,230 shows a similar system.
Similar pipe sections are made by winding a construction material, such as polyethylene, around suitably sized mandrels. See U.S. Pat. No. 5,261,461, particularly
Various connectors have been proposed for pipe sections for slipline pipe. For a particularly complicated one see U.S. Pat. No. 6,113,158.
In the following application, the process is described in connection with sliplining, but it should be understood that the present process is not limited to sliplining or slipline pipe. Sliplining, as a process, is not limited to passages that are circular in cross section. Such passages can be oval, elliptical, circular, or any modification of these shapes. Sliplining is equally applicable to those passages. See U.S. Pat. No. 5,458,155 which discloses (see
The slipline pipe discussed above could be improved. It would be desirable to have a simple, gasketed joint between pipe sections that does not require expensive machining steps. The gasketed joints provide a tight joint between pipe sections that can accommodate some deflection of the pipe sections. But forming complicated shapes or machining the final product raises the cost substantially.
It would also be desirable to have the pipe sections formed as single sections, rather than multi-part sections as shown in U.S. Pat. No. 5,458,155 above. Multi-part sections are more expensive to fabricate. This is particularly true in connection with non-circular pipes.
Finally, it would be desirable to avoid the external and internal mandrel methods of construction, because of the inherent variation in product produced in that way.
Among the various objects and features of the present invention is the provision of an improved pipe.
Another object is the provision of such a pipe that facilitates the placement and assembly of the pipe in a passage.
A third object is the provision of such a pipe that is closed molded to its substantially final shape.
A fourth object is the provision of such a pipe that may be formed in non-circular shapes if desired.
A fifth object is the provision of such a method that it is relatively simple and inexpensive.
Other objects and features will be in part apparent and in part pointed out hereinafter.
In one aspect of the present invention, a pipe for lining a pre-existing passage includes at least a first pipe section having a bell at one end and at least a second pipe section having a spigot at one end. The spigot is adapted to mate with the bell of the first pipe section. The first and second pipe sections are both closed molded. At least one of the bell of the first pipe section or the spigot of the second pipe section has a circumferential groove molded therein to substantially its final shape. An elastomeric gasket sized to fit in said groove forms a compression seal between the first pipe section and the second pipe section.
In a second aspect of the present invention, a pipe section for a pipe includes a pipe body having a groove closed molded therein at one end of the pipe body, the pipe body having one end that is closed molded to have a predetermined outer size and a second end that is closed molded to have a predetermined inner size, the inner size of the second end being larger than the outer size of the first end, the pipe body having an inner size, except at said second end, that is less than the outer size of the first end.
Similar reference characters indicate similar parts throughout the several views of the drawings.
Turning to the drawings,
Specifically,
As can be seen, bell 21 has an inner size large enough to accept the corresponding spigot of the next section of pipe, in this case section 17. (In the case of circular pipe, the inner size corresponds to the inner diameter of the pipe. In the case of non-circular pipe, the inner size corresponds to the various dimensions of the opening inside the pipe.) An elastomeric gasket 25 is disposed in a groove 27 of each spigot 23, so as to form a seal between the pipe sections. Gasket 25 may be made in accordance with U.S. Pat. No. 6,719,302, although the actual gasket used is not a feature of the present invention. Groove 27 extends circumferentially around its corresponding spigot, so that the gasket disposed therein can provide a suitable seal around the periphery of each pipe section. The use of an elastomeric gasket also allows for some misalignment between the pipe sections. Optionally, some compression packing 29 (of any suitable material) may be disposed between the pipe sections as shown. The compression packing also extends around the circumference of the pipe. As can be seen in
It is preferred that the pipe sections be closed molded to substantially their final dimensions, including the groove 27 and the chamfer 31, to eliminate or at least drastically reduce the necessity of any machining of the pipe sections. A suitable closed molding process is disclosed in co-assigned U.S. patent application Ser. No. 10/364,096, the disclosure of which is incorporated herein by reference. The molding process is called “closed” to distinguish the open molding process in which material is sprayed upon the interior or exterior of a mandrel, or similar processes.
The closed molding process may involve a mold with one or more openings to allow the injection or other insertion of material, and the escape of gases, but the final shape of the molded object, in this case the sections of slipline pipe, is determined by the interior and exterior shape of the mold. It is of particular importance that the circumferential groove 27 be closed molded in the pipe sections to substantially its final shape. This greatly reduces cost and eliminates the possibility of subsequent damage to the spigot during machining which would otherwise be required to create the groove.
Although the slipline pipe of the present invention may have any cross-section, it should be realized that such pipe formed in a closed mold process is especially well suited for non-circular shapes such as that shown in
The pipe of the present invention may be used for any application for lining passages. Sizes of eight inches to 96 inches would be conventional. The pipe sections themselves may be many feet in length, limited primarily by the restrictions imposed by shipping or by the passage being lined.
In view of the above, it will be seen that all the objects and features of the present invention are achieved, and other advantageous results obtained. The description of the invention contained herein is illustrative only, and is not intended in a limiting sense.
