Abstract:
An apparatus for squeezing pipes, comprising a first jaw having a first squeezing surface and a second jaw having a second squeezing surface. The first jaw and the second jaw are interconnected for relative displacement at proximal ends through a first shaft of the apparatus and at distal ends through a second shaft of the apparatus. The first squeezing surface and the second squeezing surface are separated by a gap adapted to receive a pipe therein. The first jaw is rotatable with respect to the first shaft and engageable with the second shaft such that the apparatus is mountable about a pipe with the pipe being positioned in the gap between the first and the second shaft. Actuation means are provided for axially displacing the first shaft to reduce the gap to squeeze the pipe between the first squeezing surface of the first jaw and the second squeezing surface of the second jaw to block at least partially fluid flow in the pipe, wherein at least one of the first and second jaws bends at a given level of squeezing of the pipe whereby greater pressure is applied on cross-sectional ends of the pipe being squeezed.

Description:
TECHNICAL FIELD  
         [0001]    The present invention generally relates to a pipe-squeezing apparatus for reducing a flow of fluid in a pipe and more particularly, but not exclusively, to shut off at least substantially a natural gas distribution pipe in pipe network for safety purposes.  
         BACKGROUND ART  
         [0002]    In a natural gas distribution system, resilient pipes, such as polyethylene pipes, are frequently used for the underground distribution of natural gas.  
           [0003]    Leaks in natural gas lines must be attended to quickly as natural gas is flammable. Furthermore, as the natural gas in such lines is under pressure, a leak of is natural gas (e.g., as a result of a breach in the line due to third party damages or other reasons) must be attended to quickly to limit the spreading of the natural gas.  
           [0004]    U.S. Pat. No. 5,152,497, issued to Bissell on Oct. 6, 1992, and No. 5,219,146, issued to Thompson on Jun. 15, 1993, each disclose tools for squeezing resilient pipes in order to reduce the flow of natural gas upstream of the leaks or breaches. These tools are manually actuated, as it would be hazardous to use any electrical source in the vicinity of a natural gas leak. Also, an operator of these tools must be close to the mechanism to operate the tool. However, for safety reasons, the operator is often precluded from entering the excavated hole in which the natural gas leak has occurred. Accordingly, pipe access holes must be excavated upstream and/or downstream of the leak to safely reduce the fluid flow through the pipe. This results in an increase in the time of intervention. It is pointed out, however, that squeezing tools are not limited to being used for emergency leak blocking operations on pipes, whereby an operator may be in the vicinity of a pipe for the squeezing thereof.  
           [0005]    Squeezing tools must provide given performances of blocking to the pipes they are squeezing. For instance, the blocking of a pipe to reduce a fluid flow below 300 L/hour is a known safety practice in the industry. In designing squeezing tools apt to perform such blocking of pipes, opposed design factors are taken into account. The tools must be as light as possible to be readily maneuverable. On the other hand, they must often squeeze pipes of relatively large diameter, for instance above four inches, whereby they must be rigid and sturdily built.  
         SUMMARY OF INVENTION  
         [0006]    Therefore, it is a feature of the present invention to provide an apparatus for squeezing pipes and which is manually operable at a distance from the pipe.  
           [0007]    It is a further feature of the present invention to provide a method of use of the apparatus of the present invention for squeezing pipes.  
           [0008]    It is a still further feature of the present invention to provide an apparatus for squeezing pipes optimizing the above described design factors.  
           [0009]    According to the above feature of the present invention, and from a broad aspect thereof, the present invention provides an apparatus for squeezing pipes, comprising a first jaw having a first squeezing surface and a second jaw having a second squeezing surface. The first jaw and the second jaw are interconnected for relative displacement through at least a first shaft. The first squeezing surface and the second squeezing surface are separated by a gap adapted to receive a pipe therein. The first jaw has a proximal end portion fixed to the first shaft. The second jaw has a proximal end portion at least slidingly connected to the first shaft. A handle is provided for positioning the gap about the pipe. The handle is substantially distant from the first and the second jaw such that the gap may be manually positioned about the pipe by an operator distantly located from the pipe. Actuation means are provided for axially displacing the first shaft to reduce the gap to squeeze the pipe between the first squeezing surface of the first jaw and the second squeezing surface of the second jaw to block at least substantially fluid flow in the pipe.  
           [0010]    According to a further broad aspect of the present invention there is provided a method for squeezing a pipe comprising the steps of i) providing an apparatus having a first jaw and a second jaw being adapted to receive a pipe therebetween, the first jaw and the second jaw being interconnected at proximal ends for relative displacement through a first shaft of the apparatus and at distal ends through a second shaft of the apparatus, the first jaw being fixed to the first shaft, the second jaw being slidingly and rotatably connected to the first shaft and being slidably engaged to the second shaft, the first jaw being rotatable with the first shaft with respect to the second jaw so as to detachably engage the second shaft; ii) positioning the second jaw against the pipe and between the first and the second shaft; iii) rotating the first jaw to engage the first jaw to the second shaft, such that the pipe is between the first and the second jaw; iv) displacing the first jaw toward the second jaw by axially displacing the shafts so as to squeeze the pipe between the jaws.  
           [0011]    According to a still further broad aspect of the present invention there is provided an apparatus for squeezing pipes, comprising a first jaw having a first squeezing surface and a second jaw having a second squeezing surface. The first jaw and the second jaw are interconnected for relative displacement at proximal ends through a first shaft of the apparatus and at distal ends through a second shaft of the apparatus. The first squeezing surface and the second squeezing surface are separated by a gap adapted to receive a pipe therein. The first jaw is rotatable with respect to the first shaft and engageable with the second shaft such that the apparatus is mountable about a pipe with the pipe being positioned in the gap between the first and the second shaft. Actuation means are provided for axially displacing the first shaft to reduce the gap to squeeze the pipe between the first squeezing surface of the first jaw and the second squeezing surface of the second jaw to block at least partially fluid flow in the pipe, wherein at least one of the first and second jaws bends at a given level of squeezing of the pipe whereby greater pressure is applied on cross-sectional ends of the pipe being squeezed. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0012]    A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 is a schematic view of the pipe-squeezing apparatus constructed in accordance with the present invention;  
         [0014]    [0014]FIG. 2 is a perspective view of the pipe-squeezing apparatus having a lower jaw open for mounting to a pipe;  
         [0015]    [0015]FIG. 3 is a perspective view of the pipe-squeezing apparatus with the lower jaw closed for capturing the pipe from opposed sides;  
         [0016]    [0016]FIG. 4 is a perspective view of the pipe-squeezing apparatus partially squeezing the pipe;  
         [0017]    [0017]FIG. 5 is a perspective view of the pipe-squeezing apparatus fully blocking the pipe;  
         [0018]    [0018]FIG. 6 is a perspective view of pipe squeezing apparatus.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]    Referring now to the drawings, and more particularly to FIG. 1, a pipe-squeezing apparatus in accordance with the present invention is generally shown at  10 . The pipe-squeezing apparatus is illustrated mounted to a pipe P. The pipe P consists of a resilient material, such as polyethylene. The pipe P is typically used to convey a fluid, such as natural gas. The pipe-squeezing apparatus  10  has a lower jaw  12  and an upper jaw  14 . The lower jaw  12  and the upper jaw  14  are interconnected by a pair of parallel shafts  16  and  18 . More particularly, the lower jaw  12  is fixed at a first end  20  thereof to a bottom end of the shaft  16 .  
         [0020]    As best seen in FIG. 3, a slot  24  is positioned in a second end  22  of the lower jaw  12 . As will be explained hereinafter, the shaft  16  rotates and, therefore, the lower jaw  12  rotates or swings about an axis of the shaft  16 . The slot  24  is positioned in the second free end  22  of the lower jaw  12  so as to clip onto a bottom end of the shaft  18 . A flange  25  is fixed to the shaft  18  and has a top surface thereof coplanar with a bottom surface of the jaw  12  when the latter is clipped to the shaft  18 .  
         [0021]    A pin  26  has a first free end thereof (not shown) protruding in the slot  24 , and is biased toward the slot  24 . A corresponding bore  28  (FIG. 2) on the shaft  18  is positioned opposite to the pin  26  when the shaft  18  is received in the slot  24 , such that the pin  26  snaps into the bore  28  to lock the lower jaw  12  to the shaft  18 , and this position is referred to as the locked position. A second end of the pin  26 , as clearly seen in FIG. 3, protrudes outwardly from the second end  22  of the lower jaw  12 . The second end of the pin  26  protrudes out from the second end  22  enough to be pulled manually upon the removal of the apparatus  10  from the hole.  
         [0022]    Cylinders  36  and  38  extend upwardly from the upper jaw  14 . As seen in FIG. 1, the shafts  16  and  18  are part of the cylinders  36  and  38 , respectively, and hence an actuation of the cylinders  36  and  38  displaces the shafts  16  and  18  vertically, respectively. The cylinders  36  and  38  are typical cylinders each having a piston therein displaceable axially in the cylinders  36  and  38  according to fluids inserted into inlets of the cylinders. More precisely, the cylinders  36  and  38  are shown having pistons  16 A and  18 A, respectively. The pistons  16 A and  18 A are fixed to the shafts  16  and  18 , respectively, and each separate inner cavity of their respective cylinders in chambers A and B, as best shown in FIG. 1. The cylinder  36  has an upward displacement inlet  46 A open to the chamber A thereof and a downward displacement inlet  46 B open to the chamber B thereof. Similarly, the cylinder  38  has an upward displacement inlet  48 A open to the chamber A thereof and a downward displacement inlet  48 B open to the chamber B thereof.  
         [0023]    In a typical operation of the cylinder  36 , a fluid is inserted into the chamber A thereof through the inlet  46 A for displacing upwardly the shaft  16 . During an upward displacement of the shaft  16 , the inlet  46 B serves as an outlet for fluid accumulated in the chamber B thereof. The operation of the cylinder  38  is similar to the operation of the cylinder  36 . It is pointed out that the downward displacement inlets  46 B and  48 B are blocked with plugs  40 . A supply line  42  is connected to both the upper displacement inlets  46 A and  48 A so as to supply the cylinders  36  and  38  with a fluid to displace the shafts  16  and  18 , respectively, in an upward direction. The hydraulic supply line  42  is connected to a fluid source, such as a hydraulic pump (not shown), capable of supplying a fluid in the chambers A of the cylinders  36  and  38 , and holding the fluid under pressure therein. It is obvious that a manually operated pump is preferred over electrically powered pumps, for safety reasons due to the leak of natural gas. If the pump is electrically powered, the supply line  42  must be long enough for the electrically powered pump to be operated at a safe distance.  
         [0024]    Referring to FIG. 1, the shaft  16  extends upwardly from the cylinder  36  and has a handle  44  projecting perpendicularly from a top end thereof. The handle  44  is rotatable so as to control the rotation of the lower jaw  12  through the shaft  16 . As seen in FIGS. 1 and 6, adjustable abutment pins  50  are positioned on both ends of the upper jaw  14 ., facing toward the lower jaw  12 , and limit the displacement of the upper jaw  14  toward the lower jaw  12 , as will be explained hereinafter. Tapped holes  52  in the lower jaw  12  and the upper jaw  14  are in register, such that locking bolts  54  may be used to ensure that the jaws  12  and  14  remain in a given position with respect to one another when squeezing a pipe, for safety precautions. Finally, a positioning ring  56  is positioned on the upper jaw  14  and is provided such that an operator can use a perch or pole (not shown), to position the apparatus  10  on a pipe. It is pointed out that the adjustable abutment pins  50  and the locking bolts  54 , although preferred, are optional to the apparatus  10 .  
         [0025]    Now that the various parts of the pipe-squeezing apparatus  10  have been described in detail, an operation thereof for blocking pipes will be explained. Referring to FIG. 2, the pipe-squeezing apparatus  10  is shown as being mounted to the pipe P. More precisely, the handle  44  (not visible in FIG. 2) is rotated such that the lower jaw  12  (not visible in FIG. 2) is far enough from the shaft  18  to allow the pipe-squeezing apparatus  10  to have a bottom surface of the upper jaw  14  abut against the pipe P. Once the upper jaw  14  is abutted against the pipe P, the handle  44  (not shown in FIG. 2) is rotated such that the lower jaw  12  clips onto the shaft  18 . An operator may use a perch or a pole engaged in the positioning ring  56  to facilitate the positioning of the apparatus  10  on the pipe P. The pin  26  snap-fits into the corresponding bore of the shaft  18 , whereby the lower jaw  12  is in the locked position, as shown in FIG. 3. It is pointed out that the shaft  16  is long enough such that an operator rotating the handle  22  can be positioned at a safe distance above the pipe P. If the pipe P attended to is breached as a result of excavation, the shaft  16  is long enough for the operator to actuate the lower jaw  12  from outside the excavated hole.  
         [0026]    Referring to FIG. 3, once the lower jaw  12  is in the locked position, the cylinders  36  and  38  are actuated so as to displace upwardly the lower jaw  12  to squeeze the pipe P between the jaws  12  and  14 . More precisely, a fluid such as a hydraulic oil is supplied to the cylinders  36  and  38  by a hydraulic pump (not shown) via the line  4 . 2  connected to the upward displacement inlet couplings  46 A and  48 A, respectively. Accordingly, the lower jaw  12  moves in an upward direction. The flange  25  is solidly fixed to the shaft  18  so as to support the second end  22  of the lower jaw  12  during the squeezing of the pipe P. As the downward displacement inlet couplings  46 B and  48 B are blocked with plugs  40 , air captured in the chambers B of the cylinders  36  and  38  is compressed by the upward movement of the pistons  16 A and  18 A.  
         [0027]    Referring now to FIG. 4, the pipe P is shown partially blocked by the jaws  12  and  14 . The pipe-squeezing apparatus  10  has not yet finished its upward travel to block the pipe P. It is pointed out that the pipe-engaging surfaces of the jaws  12  and  14  that are in contact with the pipe P have smooth surfaces to prevent further damage to the pipe P.  
         [0028]    Referring to FIG. 5, the pipe P is shown blocked by the jaws  12  and  14 . At that point, the fluid conveyed in the pipe P is substantially prevented from circulating therethrough, i.e., the flow of fluid is below safety levels allowed by the industry. It is pointed out that the abutment pins  50  limit the squeezing of the pipe P, by preventing the lower jaw  12  from being brought closer to the upper jaw  14 . This is to ensure that the pipe P is not damaged by a squeeze. When the pipe P is blocked by the pipe-squeezing apparatus  10 , the pipe P may be attended to for repairs. The operator may insert the locking bolts  54  in the tapped holes  52  in order to ensure that the jaws  12  and  14  remain in position.  
         [0029]    Once the repairs are done, the pipe-squeezing apparatus  10  is disconnected by releasing the fluid pressure that keeps the jaws  12  and  14  blocking the pipe P. When the pressure is released by the hydraulic pump (not shown), the compressed air in the chambers B of the cylinders  36  and  38  will cause the lower jaw  12  to be displaced outwardly, whereby the pipe P will no longer be squeezed between the jaws  12  and  14 . Once the pipe P has regained its shape, the pipe-squeezing apparatus  10  may be removed. The pin  26  engaged in the bore  28  must be disengaged for the lower jaw  12  to be rotated away from the shaft  18 . At this point, it is no longer dangerous for an operator to approach the pipe P, as the leaks have been attended to. Therefore, the pin  26  may be pulled away from the bore  28  and, thereafter, the handle  44  is rotated such that the lower jaw  12  is separated from the shaft  18 . Accordingly, the pipe-squeezing apparatus  10  may be removed from the pipe P.  
         [0030]    Although the preferred embodiment proposes using the shafts  16  and  18  such that the first jaw  12  is adequately supported at both ends thereof, it is obvious that the apparatus  10  may be provided with only one shaft, such that the pipe is positioned between the first jaw  12  and the second jaw  14  laterally. This saves the step of rotating the first jaw  12  into engagement with the second shaft  18 .  
         [0031]    In a preferred embodiment of the present invention, the lower jaw  12  and the upper jaw  14  are bendable, such that they bend at some point during the squeezing of a pipe. The reason for such bending of the lower jaw  12  and the upper jaw  14  is that a pipe being squeezed forms ears in opposed ends of its cross section. Ears are formed at these opposed ends as there is more pipe material at these two areas. Therefore, it has been known to make the jaws  12  and  14  more rigid, and to increase the squeezing pressure of squeezing tools for substantially blocking these ears and ensure the fluid flow through the blocked pipe is below allowed levels by the industry. However, this requires more rigid jaws, which results in an increase of weight of the squeezing tools, and this must be avoided in order to have an easily maneuverable tool.  
         [0032]    If the jaws  12  and  14  are relatively resilient such that they bend when the ears are formed, they will be applying more pressure on opposed ends of the cross-section of the pipe, i.e. the ears, than in the middle of the pipe where the jaws will bow outwardly as that section is furthest from the shafts and more flexible. Fluid flow is substantially reduced through the ear sections of the pipe. This is possible because of the configuration of the apparatus  10 , wherein the jaws  12  and  14  are actuated from opposed ends thereof. Accordingly, the apparatus  10  constructed in accordance with the present invention does not require more rigid jaws for effectively squeezing pipes to block them, and this results in significant weight minimization, especially in an apparatus  10  sized for squeezing pipes of diameters above four inches. It is pointed out that only one of the jaws  12  and  14  is required to be relatively resilient, although it is preferred that both the jaws  12  and  14  are bendable.  
         [0033]    It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.