Pipes and tubular conduits – With flow regulators and/or baffles – Restrictors
Reexamination Certificate
2000-06-12
2001-12-11
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
With flow regulators and/or baffles
Restrictors
C138S093000, C138S045000, C137S118040
Reexamination Certificate
active
06328072
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally concerns devices of the type represented by automatically triggered safety valves used in gas distribution systems, as well as a process for protecting such systems.
More precisely, a first aspect of the invention concerns a safety device selectively inserted into a fluid pipeline to protect it from an excessive flow of the fluid running through it, this device comprising a chamber having an upstream end and a downstream end, controlled admission means sensitive to a pressure loss in the pipeline between the upstream and downstream ends of the chamber, so as to selectively allow or prevent the establishment of a flow of fluid through the upstream end of the chamber, and retaining means for holding the chamber in place inside the pipeline.
Many devices of this type are known in the prior art, for example as shown by the valve described in U.S. Pat. No. 5,551,476.
Certain fluid distribution systems justify specific safety measures, imposed by the nature of the fluid transported and by the potential risk of damage to the pipes of which these systems are constituted.
For example, gas distribution systems in urban areas generally run under the roads and sidewalks, i.e., under public works subject to various interventions, and especially digging operations.
If a gas pipe is accidentally torn out or breached during such an operation, the resulting gas leak immediately causes a high risk of fire or explosion.
In this context, safety valves have been developed for shutting off gas pipes as soon as an abnormally high flow of gas through them is detected.
However, at present, safety valves can only be installed in new systems under construction, or possibly in existing systems, but only during their renovation.
In essence, given that the pipes of existing networks may have been built at different times and in accordance with different standards, that they do not necessarily have diameters defined with very high precision, that along their lengths they have obstacles, burrs, dents or various constrictions, and that the installation of a safety valve requires a perfect fitting of the valve body to the pipe, the insertion of safety valves into existing systems requires an intervention at the exact point of the insertion, i.e., an excavation that provides access to the chosen point in the system, a shutoff of the system, and a local adaptation of the system to the valve at the insertion point itself.
Thus, although it is known to insert devices of limited size, particularly for detection purposes, into a system under pressure through an access point outside the branch without having to perform a complicated intervention on the system, this technique, like catheterization for medical examinations, is currently unfeasible for installing safety valves.
The object of the invention, which falls within this context, is to offer a safety device capable of being installed in a system, without excavation, by being inserted into a branching point of this system.
To this end, the device of the invention, in keeping with the generic definition given in the above preamble, is essentially characterized in that it comprises a rigid core joined to the retaining means, and an inflatable envelope supported by the rigid core, this envelope having a lateral wall that at least partially delimits the chamber, and that faces one wall of the pipeline, in that the controlled admission means are calibrated to selectively allow the establishment of the flow of fluid through the upstream end of the chamber, at least until it allows an inflation of the envelope when the pressure loss is greater than a first predetermined threshold, and in that the inflatable envelope selectively seals off the pipeline, at least partially, by radially displacing its lateral wall toward the wall of the pipeline.
As a result of these characteristics, the safety device of the invention, once installed in a pipeline, performs a completely automatic monitoring of the flow of the fluid running through it, and uses this fluid's own energy to protect the pipeline from any potential excessive flow.
Although several prior documents already describe devices comprising a body, a valve, and an inflatable tubular envelope for sealing off a passage, none of these devices is designed to solve the problem of the invention.
Thus, for example, although the patents U.S. Pat. No. 2,856,002, DE 3 339 572 and GB 2 155 080 disclose sealing devices comprising an inflatable envelope, all of these devices are designed to be exclusively controlled by a fluid intentionally and selectively injected at a specifically controlled pressure in order to actuate them, none of these devices being equipped with a valve subject to a pressure loss to which it would be sensitive.
Preferably, the core extends along a longitudinal axis and the retaining means comprise a plurality of claws, each claw having one connecting end integral with the rigid core and one free end, and selectively assuming a folded position in which its free end is relatively close to the longitudinal axis, and an open position in which its free end is relatively distant from the longitudinal axis, each claw also being able to be elastically stressed toward its open position.
Given that the length of the claws must be adapted to the diameter of the pipeline and that the core of the device must have, relative to the diameter of the pipeline, a transverse diameter that allows it to be easily inserted into the pipeline, it may for example be advantageous to provide for one or more of its claws to have a length greater than half the diameter of the core.
In a first possible embodiment, the rigid core comprises for example a body delimited by a tubular wall and having an upstream end and a downstream end, the controlled admission means comprise a valve sensitive to pressure loss, supported by the body and disposed between the upstream and downstream ends of the body, and the inflatable envelope is outside the body and impermeably encloses a section of effective length of the tubular wall into which at least one first opening is cut, having for example the shape of a longitudinal slot.
This safety device can therefore comprise, on at least one of the upstream and downstream ends of the body, a corresponding upstream or downstream end piece carrying corresponding upstream or downstream retaining means and having at least one first assembly tab elastically inserted into the first opening.
Preferably, this device comprises, on the upstream and downstream ends of the body, respective upstream and downstream ends pieces having respective upstream and downstream shafts inserted into the body.
In one simple and effective embodiment of the invention, the valve comprises a helical spring attached to the downstream shaft, an upstream valve seat formed by an internal end of the upstream shaft, and a ball elastically stressed against the upstream valve seat by the helical spring.
The valve therefore comprises, for example, a downstream valve seat formed by an internal end of the downstream shaft, and cooperating with the ball.
At least one of the upstream and downstream shafts can also be bordered, outside the body, by a corresponding annular flange, to the periphery of which the corresponding upstream or downstream claws are attached by their connecting ends.
In the advantageous case where the device comprises both upstream claws and downstream claws, the latter preferably open like an umbrella in respective movements in opposing directions.
Likewise, in the advantageous case where the device of the invention comprises both an upstream shaft and a downstream shaft, the envelope preferably has upstream and downstream collars, respectively projecting past the upstream and downstream ends of the body and respectively fitting tightly around the upstream and downstream shafts.
According to a second embodiment of the invention, the rigid core essentially comprises for example a barrel, while a downstream end of the inflatable envelope delimiting the downstream end of the
Drouvin Robert
Giraud Daniel
Leme David
Mahe Jean-Luc
Brinson Patrick
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Gaz de France-(GDF) Service National
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