Pipes and tubular conduits – Repairing – Patches
Reexamination Certificate
2001-05-14
2002-12-17
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Repairing
Patches
C138S110000, C138S157000, C138S155000
Reexamination Certificate
active
06494232
ABSTRACT:
FIELD OF THE INVENTION:
This invention relates to protective sleeves for underground utilities, and particularly to modular protective sleeves which can be put into place by being hauled or dragged through a utility duct which runs between two adjacent manholes, so as to be positioned within the duct and to protect the utility which the modular protective sleeve surrounds while the casing in which the duct is placed is broken.
BACKGROUND OF THE INVENTION
Most countries in the world, developed and developing, western and eastern, including third world countries, may have many underground utilities that have been put into place or will be put into place in the near future. This is especially true in urban areas of nearly every country, and in many suburban areas particularly of European, North American, Southeast Asian, Australasian, some South American, and some Asian subcontinent cities. Such underground utilities include electrical power distribution utilities, telephone and cable television distribution utilities, other high speed data distribution utilities including particularly optical fibre transmission and distribution systems, and gas distribution systems. All of those utilities are typically buried underground in urban and many suburban areas for reasons of safety, convenience, so as to avoid tampering, so as to avoid urban visual blight, and so on.
Typically, such underground utilities are referred to as buried utilities, and typically they are installed in plastic ducts which are, themselves, surrounded and protected by a concrete casing or barrier. Such ducts are buried at depths from several centimeters up to several meters below the surface, and they range in diameter from, say, 10 cm up to 40 cm or more.
Also, buried utilities that are run in ducts are typically found in ducts which extend in straight lines between adjacent manholes. This provides an opportunity to “fish” a line or fishtape, or the like, from one manhole to the next adjacent manhole, a feature which the present invention takes advantage of.
It will also be noted that, in most instances, there is some clearance around any utility cables, wiring, or piping, that is carried through a duct—in other words, the duct is not packed full—and that is also a feature of which the present invention takes advantage, as will be described hereafter.
However, any buried utility of the sort described above is liable at some time or another to have a fault, whereby wires may short together or insulation may break down, a pipe may collapse, and so on; and in any such instance, it is necessary to dig into the ground at the point where the fault has occurred so as to correct it.
Moreover, it very often occurs that a repair such as a splice or a branch must be installed in or taken from the underground utility, at a particular location. This again requires digging into the ground so as to reach the buried utility at the desired spot.
However, as it has been noted, most such underground utilities are encased in a concrete protective casing which requires to be broken such as by jackhammers or sledge hammers. Typically, jackhammers are used for that purpose.
Obviously, however, the use of a jackhammer in the immediate region of a utility duct creates considerable danger to the utility duct because it is possible that, as the last few centimeters of concrete are broken through by the jackhammer, the point of the jackhammer might pierce into the utility duct. It will be borne in mind that the utility duct is, itself, typically made of plastic such as PVC or the like, having relative hardness and stiffness, but not nearly enough to withstand the slightest impact of a jackhammer.
The purpose of the present invention is to provide a modular protective sleeve which can be positioned inside the underground utility duct at the point where the concrete casing surrounding the duct is to be broken. Then, as the last few centimeters of concrete are broken away and the point of the jackhammer approaches the duct, even if it pierces the plastic material of the duct it will simply glance or bounce or slide off the hard metallic protective sleeve which has been put into position in the place where the jackhammer work is to be done. This protects the utility, so that it may continue to work in an operative manner delivering whatever commodity it is that is within the utility duct.
Thus, a very particular need arises for a modular protective sleeve which can be put into position at a place where the concrete casing which surrounds a buried utility duct is to be broken so as to gain access to the utility within that duct, without disturbing the delivery of the utility commodity.
Typically, a modular protective sleeve in keeping with the present invention may have a length of 30 cm or 40 cm and up to several meters, depending on the nature of the digging and concrete breaking activity that is to be undertaken. The purposes for varying lengths of modular protective sleeve are manifold, including the fact that if a fault has occurred it may not be possible to precisely locate its position within, say, a few centimeters. Moreover, it may sometimes occur that a length of duct of several meters or more may be required to be exposed in order to permit utility workers to gain access to the specific utility so as to repair it, splice into it, take a branch from the utility, or whatever other task is required.
However, manholes are typically not very large. A manhole having room for two or three workers may be all that is available, or even smaller, and as such the manhole may have a diameter of not more than 1.5 meters or so. Accordingly, in order to install a protective sleeve somewhere along the length of the duct stretching from that manhole to an adjacent manhole, requires modularity so that the required length of sleeve may be put into place—even though the working space within the manhole might be quite small.
On the other hand, because ducts between adjacent manholes generally run in a straight line, and the distance between the manholes is known; and also because it is possible to fish a tape or line through the duct from one manhole to the adjacent manhole, it is possible to quite accurately position a modular protective sleeve in keeping with the present invention by the use of lanyards which extend from each end of the modular protective sleeve to a respective one of the adjacent manholes, in the manner described hereafter.
It should also be noted that the modular protective sleeve in keeping with the present invention may be assembled without the necessity for any special tools, and without the necessity for hinged structures and the like. The disassembly of modular protective sleeves in keeping with the present invention, when required and appropriate, may be carried out at the site where the utility repair is to take place, because in any event it is necessary to remove the modular protective sleeve away from the utility which it has been protecting after the surrounding concrete casing has been broken away. Of course, it may also be possible to pull the modular protective sleeve back into one or the other of the adjacent manholes which define the length of duct into which the modular protective sleeve has been placed, if necessary or appropriate.
Any modular protective sleeve in keeping with the present invention must be sufficiently strong and rugged to withstand handling in a manhole, and particularly to withstand the shock of a sledge hammer or jackhammer striking it during the course of breaking away the concrete casing which surrounds the utility duct. Accordingly, modular protective sleeves in keeping with the present invention are generally constructed of a strong metal such as case hardened steel, although they may be constructed of aluminum in some circumstances as well.
On the other hand, because a modular protective sleeve in keeping with the present invention does not represent a particularly high capital cost, there are some circumstances—such as when it is necessary to protect a splice or bypass on a gas line or elect
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