Shut-off device for pipe

A shut-off device for a pipe in a pipeline for operation in response to ingress of water, has a valve for installation in a pipe of the pipeline. The valve has a valve member moving between an open position, when the valve is open, to permit passage of fluid through the pipe, and a closed position, when the valve is closed, to shut off a passage extending through the pipe. A buoyant member associated with the valve member moves the valve member to the closed position automatically in the presence of ingress water in the vicinity of the buoyant member.

The present invention relates to a shut-off device for pipe for use in a pipeline for operation in response to ingress of water.

BACKGROUND OF THE INVENTION

Pipelines or pipe networks for transmission and supply of gaseous fuels, such as town gas or natural gas, are often built underground and are therefore vulnerable to ingress of water in the case of accidents (e.g. leakage caused by nearby underground work and in particular damage by impinging water jets from burst water mains) or unexpected circumstances (e.g. soil/earth movement, and cracking or faulty condition of pipe fittings). Underground water leaking into the system may find its way spreading very quickly over a long distance down the pipeline. Such water will take considerable time to clear, subsequent to rectification of the leak or faulty condition. To worsen the problems, water carrying soil or dirt, etc. may reach and foul or cause damage to gas equipment/apparatus at the customers' premises.

As present, measures safeguarding or catering for the ingress of water into underground pipelines are rare or complicate.

The invention seeks to eliminate or at least to mitigate such a problem by providing a new or otherwise improved shut-off device for pipe for use in a pipeline for operation in response to ingress of water.

SUMMARY OF THE INVENTION

According to the invention, there is provided a shut-off device for pipe for use in a pipeline for operation in response to ingress of water, comprising a valve for installation in a pipe of said pipeline. The valve comprises a valve member supported for movement between an open position when the valve is open to permit passage through said pipe and a closed position when the valve is closed to shut off passage through said pipe. Included is a buoyant member associated with the valve member for moving the valve member to the closed position automatically in the presence of ingress water in the vicinity of the buoyant member.

Preferably, the valve member is arranged, upon movement from the open position to the closed position, to move into the passage through said pipe.

More preferably, the valve member is arranged to stay clear of the passage through said pipe when it is in the open position.

It is preferred that the valve member is arranged to move along a non-linear path from the open position to the closed position.

It is preferred that the valve member has a planar body and is arranged, in the open position, to extend along the direction of the passage through said pipe and, in the closed position, to extend transverse to the direction of the passage through said pipe.

It is preferred that the valve member normally stays in the open position and is adapted to return automatically to the open position upon removal of said ingress water.

In a preferred embodiment, the shut-off device includes a connecting mechanism provided between the valve member and the buoyant member such that the valve member is directly movable by or with the buoyant member.

More preferably, the connecting mechanism has a configuration which enables the buoyant member to move the valve member from the open position to the closed position along a relatively longer path compared to the path of the movement of the buoyant member causing the movement of the valve member.

It is preferred that the connecting mechanism comprises a linkage having a first link pivotably inter-connecting the valve member and the buoyant member for simultaneous movement.

It is further preferred that the linkage includes a base and a second link pivotably connecting the buoyant member to the base, with the first link pivotably connecting the valve member to the buoyant member.

It is yet further preferred that the linkage includes a pair of said second links of equal length and extending in parallel with each other such that the buoyant member is pivotable about the base at a constant angular position relative to the base.

Preferably, the valve member is pivotably connected to the base for angular movement about the base between the open position and the closed position.

More preferably, the linkage includes a third link fixed with and supporting the valve member, by means of which third link the valve member is pivotably connected to the base and to the buoyant member via the first link.

It is preferred that the buoyant member is pivotable at a constant angular position, and the valve member has a sealing surface and is arranged to be pivoted by the buoyant member from the open position with the sealing surface extending perpendicular to the angular position to the closed position with the sealing surface extending parallel to the angular position.

In a preferred embodiment, the valve includes a valve seat from which the valve member disengages in the open position and with which the valve member engages in the closed position.

More preferably, the valve member and the valve seat have respective sealing parts for inter-engagement to close the valve, and at least one of the sealing parts is provided with a magnet or magnets for magnetic attraction with the other sealing part to hold the valve member in the closed position.

In a specific construction, the buoyant member comprises a plurality of buoys connected together by means of a bracket.

In a preferred embodiment, the shut-off device includes a housing in which the valve and the buoyant member are provided, the housing having opposite open ends which include pipe jointing means.

More preferably, the housing has a main chamber for acting as part of the passage through said pipe and includes a bottom chamber immediately underneath the main chamber, accommodating the buoyant member and for collecting ingress water, and the buoyant member is arranged to float on collected ingress water to rise outwardly of the bottom chamber and in turn move the valve member towards or to the closed position.

Further more preferably, the bottom chamber has a lower part which is openable for removal of ingress water collected in the bottom chamber.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawings, there is shown a shut-off device10for pipe, embodying the invention, for use in a pipeline for operation in response to ingress of water into the pipeline. The pipeline is for the supply of gas fuel from the gas production plant and/or storage of a gas company to customers at a specific supply location or zone protected by the shut-off device10. The shut-off device10includes a valve100installed in a pipe P of the pipeline and a buoyant member200for operating the valve100. The pipe P has two adjoining sections P1 and P2, between which the shut-off device10is connected and at a lowermost position of the pipe P or preferably the entire pipeline.

The valve100includes a valve member110supported for movement between a horizontal open position (FIG. 2) in which the valve100is open to permit passage Q through the pipe, and a vertical closed position (FIG. 4) in which the valve100is closed to shut off the passage Q. The buoyant member200is associated with the valve member110for moving the valve member110to the closed position automatically in the presence of ingress water in the vicinity of the buoyant member200, when such water leaking into the pipe P builds up to sufficient quantity.

The buoyant member200may be associated with the valve member110in a number of ways for simultaneous movement, such as simply bearing against or abutting each other, being fixed relative to each other for movement as one rigid piece, or as in this particular embodiment being connected together by means of a connecting mechanism300for simultaneous movement in different directions. The use of the connecting mechanism300between the valve member110and the buoyant member200ensures that the valve member110is directly movable by, or with, the buoyant member200.

In operation, the valve member110is arranged, upon movement from the open position to the closed position, to move into the passage Q for shutting off the pipe against flow of gas through the passage Q. While it is in the open position, the valve member110is arranged to stay clear of the passage Q, without obstructing the flow of gas through the passage Q.

The specific construction of the shut-off device10of this particular embodiment is now described in detail. It has a metallic housing500(e.g. made of cast iron) in which the valve100and the buoyant member200are installed. The housing500has opposite right and left cylindrical openings501and502which act as inlet and outlet respectively and include respective pipe jointing means in the form of integral flanges501F and502F, by means of which the shut-off device10is connected in the pipe P between the pipe sections P1 and P2. The housing500also includes upper and lower openings503and504which are likewise cylindrical.

Internally, the housing500defines a main chamber510which acts as part of the passage Q through the pipe P and in which the valve100is housed, and also a bottom chamber520immediately underneath the main chamber510, in which the buoyant member200is accommodated. The main chamber510has a generally cylindrical shape and is in axial alignment with, and of the same cross-sectional size or footprint as, the inlet and outlet openings501and502on opposite sides thereof, together forming a right straight through passage Q. The bottom chamber520is situated immediately underneath the passage Q.

The valve100includes a valve seat120for co-operation with the valve member110, from which the valve member110disengages in the open position and with which the valve member110engages in the closed position. The valve member110has a circular planar body. The valve seat120has an annular configuration and is provided by an inner end of the cylindrical outlet opening502. The valve member110and the valve seat120have respective generally planar sealing parts or surfaces for inter-engagement, i.e. bearing against each other, to close the valve100.

To enhance the sealing effect, a rubber seal ring121is embedded almost fully in the sealing surface of the valve seat120. To further enhance the sealing effect, at least one of the sealing parts or the sealing part of the valve member110in this particular embodiment is provided with an annular series of magnets111(or a ring magnet). These magnets111are used to provide magnetic attraction with the other sealing part of the valve seat120for holding or maintaining the valve member110in the closed position, when the valve100is closed.

The bottom chamber520accommodates the buoyant member200, and is arranged to collect water that leaks into the pipe P. The main chamber510is accessible from outside the housing500via the upper opening503, which is normally sealed off by means of a round top lid531attached co-axially thereto by bolts532. The bottom chamber520is provided by the cavity within the lower opening504as closed by a pot-like lower part or cover521underneath it. The cover521is secured co-axially to the lower opening504by bolts522.

The bottom chamber520is at the lowermost position of the housing500as well as the pipe P or preferably the entire pipeline, such that water leaking into the pipeline will flow into the pipe P and be collected in the bottom chamber520. The buoyant member200is arranged to float on ingress water collected in the bottom chamber520and hence rise outwardly of the bottom chamber520while simultaneously moving the valve member110towards and eventually to the closed position, whereby the valve100is closed. The cover521is openable and may be detached by undoing the bolts522for removal or draining of water collected in the bottom chamber520, or for maintenance purposes.

The buoyant member200is provided by a set of four upright cylindrical buoys210that are connected together by means of a flat bracket220. The bracket220is formed by four inter-connected horizontal rings224each surrounding a respective buoy210, with a central hinge connection221amongst the rings224. The buoys210may be hollow plastic or made of polystyrene material.

As to the connecting mechanism300provided between the valve member110and buoyant member200, it is a linkage300L which is formed by a first link310, a pair of second links320, a third link330and a base340supporting the overall linkage300L. The base340is mounted vertically on the wall internally of the housing's bottom chamber520at a position right below the outlet opening502. The first link310pivotably inter-connects, by its opposite ends, the valve member110and the buoyant member200together for simultaneous movement. An upper end of the first link310is pivotably connected to the valve member110via the third link330, and a lower end thereof is connected to the central hinge connection221of the buoyant member200.

The second links320pivotably connect the buoyant member200to the base340, with the first link310pivotably connecting the valve member110to the buoyant member200. The second links320are of equal length and extend in parallel with each other, together forming opposite sides of a parallelogram linkage, such that the buoyant member200is pivotable about the base340at a constant angular position relative to the base340, as it moves upwards out of and downwards into the bottom chamber520. In this arrangement, the buoyant member200will stay with its buoys210upright at all time, either during movement or at rest.

The valve member110is pivotably connected to the base340, by means of the third link330, for angular movement about the base340between the horizontal open position and the vertical closed position. Hence, in particular, the valve member110is arranged to move along a non-linear path from the open position to the closed position.

More specifically, the third link330has one end fixed with a central part110C of the valve member110and the other end hinged to the uppermost end of the base340.

While extending radially of, and parallel to, the circular planar body of the valve member110, the third link330provides support for the valve member110. By means of the third link330, the valve member110is pivotably connected to the base340for pivotal movement between its open and closed positions and also to the buoyant member200via the first link310for operation (i.e. movement) by the buoyant member200. The first link310is hinged to the third link330at a position along the third link330about one-third of its length from the valve member110and two-third of its length from the base340.

In general, the base340acts as a mount for the valve member110and the buoyant member200as articulated together by the linkage300L, by means of which linkage300L the valve member110is positioned normally, when the valve100is open, horizontally flat across the mouth of the bottom chamber520in the housing500(FIG. 2). In the valve-open position, the valve member110stays completely clear of the passage Q through the pipe P, without obstructing the flow of gas through the passage Q, and hence the supply of gas can proceed as usual.

The valve member110is arranged, in the open position, to extend along or substantially parallel to the direction of the passage Q and, in the closed position, to extend transverse or substantially perpendicular to the direction of the passage Q.

As mentioned above, the buoyant member200is pivotable about the base340at a constant angular position (relative to the base340), and the buoyant member200will stay with its buoys210upright at all time. The constant angular position is thus an upright position. It follows that the valve member110is to be pivoted by the buoyant member200from the horizontal open position with its sealing surface extending perpendicular to the said upright position to the vertical closed position with the sealing surface extending parallel to the said upright position.

In the case of accidental ingress of water, which may be caused by for example impinging water jets from burst underground water mains damaging a part of the pipeline nearby, water leaking or entering into the pipeline will eventually reach the shut-off device10and be collected in the bottom chamber520.

As water builds up in the bottom chamber520, the buoyant member200will eventually be reached and displaced by the rising water, thereby floating and rising with the water together. The buoyant member200rises to push and pivot the valve member110upwards, causing the latter to depart from the horizontal open position and swing up towards the vertical closed position (FIG. 3). Before the bottom chamber520is filled up, the valve member110will reach and bear tight against the valve seat120, whereby the valve100is closed (FIG. 4) automatically to shut off the passage Q and in turn the supply of gas to the customers in the associated supply location or zone.

It is noted that the connecting mechanism300or linkage300L has a configuration which enables the buoyant member200to move the valve member110from the open position to the closed position along a relatively longer path compared to the path of the movement of the buoyant member200causing the movement of the valve member110. For example, as measured comparingFIG. 4withFIG. 2, whilst the buoyant member200has risen over a vertical distance of about 40 mm, the valve member110has been pivoted thereby over an arcuate distance of about 55 mm (measured at its central part110C).

The supply of gas via the passage Q is terminated. More importantly, the customers' side of the pipeline downstream of the tripped shut-off device10is sealed off by the closed valve100and hence protected against invasion by the water leaking into the pipeline on the gas supply side.

The shut-off device10should be reset in order to prepare for resuming of the supply of gas via the passage Q after the leakage has been rectified, for example a damaged pipe section and/or fitting (e.g. joint) of the pipeline having been repaired or replaced. To reset the shut-off device10, the water collected inside should be drained and the valve100re-opened.

Detaching the bottom cover521by undoing the bolts522will open up the bottom chamber520and allow the water collected in the housing500and beyond to drain out or otherwise be removed or disposed of. Detaching the top lid531by undoing the bolts532will reveal the interior of the main chamber510and permit access to the valve member110. It is then possible to release manually the valve member110from the valve seat120, for example, by using a screwdriver to pry off the valve member110against the magnetic attraction force applied by the magnets111. The valve member110will fall back down to the original open position under its own weight and the weight of the linkage300L and the buoyant member200. Detaching the top lid531may also permit the insertion of a dewatering tool, e.g. suction tube, to remove water from the bottom chamber520, instead of detaching the bottom cover521. With the cover521and/or the lid531re-attached, the shut-off device10is reset and subsequently the supply of gas via the passage Q can be resumed.

In operation, the valve member110is held tight against the valve seat120primarily by the force of floatation upon the buoyant member200as displaced by the water in the bottom chamber520. The magnitude of this force may be adjusted or enhanced in a number of ways, e.g. by increasing cross-sectional size of the buoys210and/or Mechanical Advantage of the linkage300L. This force will subsist for as long as water remains inside the shut-off device10, i.e. prior to resetting of the same.

The magnets111are fitted to provide additional holding force for the valve member110in the closed position, as may be necessary, is optional though preferred. Without such or equivalent magnets, the valve member110may or is adapted to return automatically to the open position upon removal of ingress water from the shut-off device10, in which case resetting of the shut-off device10may become simpler.

It is envisaged that the supply of gas may come in either one of the two opposite directions, e.g. in the direction opposite to the passage Q (i.e. opposite to direction Q), without affecting the operation of the shut-off device10. In addition, the shut-off device10will still work even if the leakage is on the opposite side and ingress water comes in via the pipe section P1 (i.e. opposite to direction Q), as the water will flow past the valve100(which is open before tripping) and then be collected in the bottom chamber520and then close the valve100.

A supply location/zone for key customers, e.g. shopping malls or restaurants, may be served by a ring-circuit pipeline for uninterrupted gas supply. In that case, gas may continue to be delivered to the customers from the remaining side of the shut-off device10, which has been tripped to seal off the leaking side fouled by water.

The invention has been given by way of example only, and various other modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

For example, the valve may instead be a sliding valve including a valve member that slides vertically upwards by a buoyant member (which may be rigidly connected to the valve member from below) into the path of supply of gas in order to close the valve. To accommodate such a value, the bottom chamber may have to be made deeper. In addition, the sliding valve may incorporate a pair of valve members facing in opposite directions to cater specifically for water leaking on either side of the valve.