Technical Field

The present invention relates to techniques and equipment for stopping flow of fluids within pipes.

Background

Fluid distribution networks for conveying fluids (such as, natural gas, LPG, or water) often require maintenance, modification, or repair. As such, it is often required that fluid flow within a portion of a network is prevented thereby isolating that portion of the network for subsequent works to be undertaken. A common technique used to prevent fluid flow within a pipe is to use a flow stop device comprising an inflatable plug. The inflatable plug is inserted within the pipe and inflated until it is sufficient in size to block the pipe. In this way, inflatable plugs can be used to isolate portions of fluid distribution networks thereby allowing works to be performed downstream.

Whilst inflatable plugs can be effective at stopping flow in many settings, they are not suited for use in, high pressure pipework such as small diameter pipework. This is due to the fact that the high fluid pressure associated with such pipework can generate sufficient force to either burst or dislodge the inflatable plug. Further, such plugs may have to be inserted through fittings such as isolation valves with relatively small internal diameters thereby placing stringent dimension constraints on the inflatable plug.

In the interest of health and safety, particularly when performing works on a gas network, it is of paramount importance to eliminate as far as possible any risk of fluid escaping. As such, when work is required on small diameter pipework, such as above ground gas distribution pipework located near end points of the network where gas is consumed, inflatable flow stop devices are not used. Instead, operatives must expose a larger section of pipe (such pipe often buried underground) and clamp or ‘pinch’ the section off to allow work, downstream, on the smaller diameter pipework. This process is lengthy, disruptive, and expensive. Summary of the Invention

In accordance with a first aspect of the invention there is provided a flow stop device for inserting in a pipe and blocking fluid flow through the pipe, the flow stop device comprising: an inflatable element located at a distal end of the device and inflatable by inflation means, positionable at a proximal end of the device, such that when said inflatable element is inflated, the inflatable element blocks the pipe; and, a collar fitted around a proximal end of the inflatable element; wherein, said collar comprises a plurality of elongate elements which radially splay as the inflatable element is inflated thereby forming a brace that resists displacement of the inflatable element in a direction towards the proximal end of the device induced by fluid flow in the pipe.

Optionally, the elongate elements are resilient such that the elongate elements return to their original form when the inflatable element is deflated.

Optionally, the elongate elements are disposed around a circumference of the collar.

Optionally, the elongate elements are evenly spaced around the circumference of the collar.

Optionally, the collar is formed as a closed ring.

Optionally, the collar is formed from a flat piece of material by rolling and welding said flat piece of material.

Optionally, the flat piece of material has a thickness of approximately 0.86mm.

Optionally, the welding is performed in accordance with a ‘latch and tag’ technique.

Optionally, the collar is made from steel.

Optionally, the collar is made from OS 70 spring steel.

Optionally, the elongate elements each have the same length and width with respect to one another.

Optionally, the length of the elongate elements is approximately 15.85mm. Optionally, the width of the elongate elements is approximately 2.5mm.

Optionally, the elongate elements are fingers, said fingers extending in a direction towards the distal end of the device.

In accordance with a second aspect of the invention there is provided a collar for a flow stop device in accordance with the first aspect of the invention, said collar configured to be fitted around a proximal end of an inflatable element of a flow stop device; wherein, said collar comprises a plurality of elongate elements which radially splay as the inflatable element is inflated thereby forming a brace that resists displacement of the inflatable element in a direction towards the proximal end of the device induced by fluid flow in a pipe in which the flow stop device has been inserted.

In accordance with embodiments of the invention there is provided a flow stop device for inserting into a pipe and blocking fluid flow through the pipe. The flow stop device comprises an inflatable plug and a collar which is fitted around the inflatable plug. The collar comprises a plurality of resilient elongate elements configured to be mechanically biased towards a first position which is such that, when inflatable plug is deflated, the collar can be inserted through a small diameter opening. The collar is further configured to change shape in correspondence with the inflatable plug, such that, when the inflatable plug is inflated, the elongate elements are urged outwards by the inflatable plug such that, collectively, they radially splay outwards thereby forming a brace configured to prevent the inflatable plug from bursting or being dislodged as a result of fluid pressure within the pipe.

As such, by virtue of the brace formed by the elongate elements of the collar, the inflatable plug can withstand high pressure. Further, by virtue of the resilient nature of the elongate elements and their mechanical bias, when the inflatable plug is in a deflated state, the collar is sufficiently compact to allow the flow stop device to be inserted into (and retracted from) small diameter pipework. That is, by virtue of the collar, the flow stop device can withstand high pressure and is compact enough to be deployed within small diameter pipework such as that of small diameter pipe found at end points of gas networks. In this way, works, such as maintenance, repair, or modification can be performed on such pipework without the requirement to expose a larger section of pipe, further upstream, thereby minimising disruption and costs associated with the works.

Various further features and aspects of the invention are defined in the claims. Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings where like parts are provided with corresponding reference numerals and in which:

Figure 1a provides a simplified schematic diagram of a flow stop device arranged in accordance with certain embodiments of the invention;

Figure 1 b provides a simplified schematic diagram of a cross section of the flow stop device shown in Figure 1a;

Figure 2a provides a simplified schematic diagram of a collar from the flow stop device shown in Figures 1a and 1 b;

Figure 2b provides a simplified schematic diagram of a collar from the flow stop device shown in Figures 1a and 1 b when viewed from a proximal end;

Figure 3a provides a simplified schematic diagram of the flow stop device shown in Figures 1a and 1 b inserted within a pipe when the inflatable plug is in a deflated state, and

Figure 3b provides a simplified schematic diagram of the flow stop device shown in Figures 1a and 1 b inserted within a pipe when the inflatable plug is in an inflated state.

Detailed Description

Figure 1a provides a simplified schematic diagram of a flow stop device 101 arranged in accordance with certain embodiments of the invention. Figure 1b provides a simplified schematic diagram of a cross section of the flow stop device 101 shown in Figure 1a.

The flow stop device 101 is configured to be inserted into a pipe of a fluid distribution network (such as, a natural gas, LPG, or water distribution network), and inflated to block fluid flow through the pipe.

The flow stop device 101 comprises a flexible hose 103, an inflatable plug 102, and a collar 105. The flow stop device 101 has a proximal end 101a from which the inflatable plug 102 is inflated and a distal end 101b which is the leading end when the flow stop device 101 is inserted into a pipe to be blocked.

The collar 105 comprises a plurality of fingers 114 which are resilient elongate elements that are mechanically biased to run parallel with the length of the flow stop device 101.

The inflatable plug 102 and the flexible hose 103 are substantially cylindrical tubes. The internal diameter of the inflatable plug 102 is similar to the external diameter of the flexible hose 103 such that the inflatable plug 102 can be passed over the flexible hose 103, as can be seen in Figures 1a and 1 b.

The collar 105 is formed in the shape of a closed ring with an internal diameter that is similar to the external diameter of the inflatable plug 102. The collar 105 is secured around the inflatable plug 102 by an interference fit. This can be seen in Figure 1a where the collar 105, including the fingers 114, fits snugly around the outer surface of the inflatable plug 102 at the proximal end 101a.

The inner volume of the flexible hose 103 forms a chamber 109.

Fitted at the proximal end of the flexible hose 103 is a valve 108 (shown covered by a removable dust cap 106 in Figures 1a and 1b) through which air can be pumped in to the chamber 109.

A terminating insert 110 is located at the distal end of the chamber 109 formed within the flexible hose 103. The terminating insert 110 forms a fluid tight seal between the insert 110 and the flexible hose 103 such that air pumped into the chamber 109 of the flexible hose 103 does not escape through the distal end of the flexible hose 103. As such, the chamber 109 is sealed.

A support ring 111 is fitted, by an interference fit, over the insert 110 and the distal end of the flexible hose 103. An end cap 107 is fitted, by an interference fit, over both the support ring

111 and the insert 110.

The inflatable plug 102 is clamped to the flexible hose 103 by a first ring 104a and a second ring 104b. This forms a fluid tight seal at either end of the inflatable plug 102 between the inside of the inflatable plug 102 and the outside of the flexible hose 103.

The fixing rings 104a and 104b can be clamped to the flexible hose 103 in any suitable way sufficient to provide a fluid tight seal at either end of the inflatable plug 102 between the inside of the inflatable plug 102 and the outside of the flexible hose 103 (for example, by a crimped connection).

A plurality of apertures 112 are provided through the wall of the flexible hose 103. The apertures 112 are positioned along a portion of the length of the flexible hose 103 bounded by the first ring 104a and the second ring 104b such that the apertures 112 provide a fluid connection between the chamber 109 and an internal wall 113 of the inflatable plug 102. As such, when air is pumped into the chamber 109, the pressure within the chamber 109 increases thereby forcing air through the apertures 112 against the internal wall 113 of the inflatable plug 102 causing it to inflate.

In use, the inflatable plug 102 is inserted, end cap 107 first, into a pipe to be blocked, the dust cap 106 is removed, and the valve 108 is connected to a pump system. The pump system pumps air in to the chamber 109 through the valve 108. As the air is pumped into the chamber 109, the pressure within the chamber 109 increases thereby forcing air through the apertures

112 against the internal wall 113 of the inflatable plug 102 causing it to inflate.

The inflatable plug 102 is inflated until it reaches a size sufficient to create a fluid tight seal between the inflatable plug 102 and the internal wall of the pipe.

By virtue of the interference fit between the collar 105 and the flexible hose 103 described above, the fingers 114 of the collar 105 fit snugly against the outer surface of the inflatable plug 102. Consequently, as the inflatable plug 102 is inflated, the fingers 114 are urged outwards such that, collectively, they radially splay outwards. The length of the fingers are such that when the inflatable plug 102 is fully inflated, the radially splayed fingers 114 form a brace which acts to support and surround the proximal end of the inflated inflatable plug 102. This support reduces the risk that the inflatable plug 102 is dislodged in direction ‘A’ by the pressure of the fluid in the pipe and reduces the risk that the that the inflatable plug 102 bursts.

Once the seal is no longer required, the air is released from the chamber 109 via the valve 108 thereby deflating the inflatable plug 102. Correspondingly, the fingers 114 of the collar 105 return to substantially their original form.

The flexible hose 103 can be made from any suitable flexible material (such as nylon) within which an air-tight chamber can be formed. Further, the flexible hose 103 can be made to any suitable length such that the inflatable plug 102 can be inserted to the required depth within a pipe to be blocked.

The inflatable plug 102 can be made from any suitable material such that the plug can be inflated to a sufficient size to block pipes which are required to be blocked by the flow stop device 101 (for example, a nitrile rubber for use in pipes conveying gas or an EPDM for use in pipes conveying water).

The valve 108 is shown as a Schrader valve however any suitable valve can be used provided that the valve can be used as an input point through which a fluid (such as air) can be driven into the chamber 109 such that the inflatable plug 102 is inflated.

Any suitable pump system capable of inflating the inflatable plug 102 by driving a fluid (such as air) into the chamber 109 can be used (for example a manual pump or a compressor).

Figure 2a provides a simplified schematic diagram of the collar 105 from the flow stop device 101 shown in Figures 1a and 1b. Figure 2b provides a simplified schematic diagram of the collar 105 from the flow stop device 101 shown in Figures 1a and 1 b when viewed along its length from a proximal end.

The collar 105 is formed in the shape of a closed ring with a proximal end 105a and a distal end 105b. As can be seen from Figures 2a and 2b, the collar 105 is cylindrical with a circular profile. The collar 105 comprises ten fingers 114, evenly spaced around the circumference of the collar, which extend from partway along the length of the collar 105 towards the distal end 105b. The fingers 114 are of equal length and width with respect to one another and each comprise a rounded portion at the distal end 105b; the length of each finger is approximately 15.85mm; the width of each finger is approximately 2.5mm; and, the radius of the rounded portion of each finger is approximately 1 ,25mm. These dimensions are particularly suitable for small diameter pipes of up to two inches in diameter. However, any suitable collar dimensions (for example alternative collar radius, collar thickness, finger length, or finger width) can be used, for example, to fit different sizes of flow stop device for use in pipework of different diameters. Further, more or fewer fingers can be used and the fingers can be arranged with alternative spacing, provided that they radially splay to form a suitable brace when the inflatable plug is inflated.

The collar 105 is formed by cutting (for example, by stamping or laser cutting) a flat piece of CS 70 spring sheet steel at a thickness of approximately 0.86mm then rolling it into a cylindrical form and welding the rolled piece of steel at welded joint 115 shown in Figure 2. The welded joint 115 is a ‘latch and tag’ joint.

As described above, the fingers 114 are resilient such that they radially splay when the inflatable plug 102 is inflated, but such that they return to their original form when the inflatable plug 102 is deflated. In this way, the collar 105 is reusable.

In the above embodiments, the collar 105 is described as being made from CS 70 spring sheet steel. However, any suitable material can be used provided the material has the requisite stiffness and resilience such that the fingers, both, act as a brace when the inflatable plug 102 is inflated and return to their original form when the inflatable plug 102 is deflated.

Alternatively, in accordance with certain embodiments of the invention, a collar can be provided that is made from a suitable material and dimensioned such that when the inflatable plug is inflated the fingers are urged outwards such that, collectively, they radially splay outwards to form a brace as described above with the exception that when the inflatable plug is deflated the fingers do not return to their original form. In such embodiments of the invention, after deflation of the inflatable plug, the fingers remain pointing outwardly and forwardly towards the distal end of the flow stop device. However, the fingers are sufficiently pliable such that the collar (and therefore the flow stop device) can still be removed from a pipe within which it inserted. Such a collar would be suitable for single use applications.

Figure 3a provides a simplified schematic diagram of the flow stop device 101 inserted within a pipe 301 when the inflatable plug 102 is in a deflated state. Figure 3b provides a simplified schematic diagram of the flow stop device 101 inserted within a pipe 301 when the inflatable plug 102 is in an inflated state.

The pipe 301 represents part of a fluid distribution network for conveying fluids (such as, natural gas, LPG, or water). The inner volume of the pipe 301 forms a chamber 302 bounded by an internal wall 303 of the pipe 301. When the chamber 302 is unobstructed, a fluid ‘F’ flows through it in the direction of the arrows shown in Figure 3a.

When work (for example, maintenance, modification, or repair) is required to be undertaken, on a part of the network that is downstream from the pipe 301 , the flow stop device 101 is inserted (whilst the inflatable plug is in a deflated state), distal end 101b first, into the chamber 302. As can be seen from Figure 3a, whilst deflated, the inflatable plug 102 does not fully block the chamber 302.

Air is then driven in to the flexible hose 103 thereby inflating the inflatable plug 102, as can be seen in Figure 3b, such that it is brought into contact with the internal wall 303 to form a fluid tight seal. As such, the fluid is ‘F’ is prevented from flowing past the inflatable plug 102 and thereby exerts a force, in substantially the direction of the arrows shown in Figure 3b, on the flow stop device 101. However, advantageously, the fingers 114 radially splay to form a brace (as described with respect to Figures 1a and 1b) which acts to support and surround the proximal end of the inflated inflatable plug 102. This support reduces the risk of the inflatable plug 102 bursting or being dislodged in the direction of the arrows shown in Figure 3b. That is, were the collar 105 not present, there would be an increased likelihood of the force from the fluid ‘F’ bursting the inflatable plug 102 or ejecting it from the chamber 302 in the direction of the arrows shown in Figure 3b.

Whilst the fluid ‘F’ is prevented from flowing past the inflatable plug 102, the required work can be undertaken downstream from the inflatable plug 102. When the work is complete and therefore the seal is no longer required, the air is released from the chamber 109 thereby deflating the inflatable plug 102 and, correspondingly, the fingers 114 of the collar 105 return to substantially their original form.

Advantageously, by providing a collar 105 as described above the fingers 114 form a brace which acts to support the inflatable plug 102 such that it can withstand high pressure such as that associated with fluid flow in small diameter pipework. Further, by virtue of the resilient nature of the fingers 114 and their bias to the position shown in Figure 3a where they fit snugly against the inflatable plug 102, when the inflatable plug 102 is in a deflated state, the collar 105 is sufficiently radially compact to allow the flow stop device 101 to be inserted into (and retracted from) small diameter pipework. As such, by virtue of providing the collar 105, the flow stop device 101 can be used to block fluid flow through high pressure pipework such as the small diameter pipework found at end points of gas networks. In this way, works, such as maintenance, repair, or modification can be performed on such pipework without the requirement to expose a larger section of pipe, further upstream. This minimises disruption and costs associated with the works.

As described above, by virtue of providing a flow stop device comprising a collar as described above, the flow stop device is suitable for blocking fluid flow through high pressure pipework such as the small diameter pipework found at end points of gas networks. However, it will be understood that flow stop devices arranged in accordance with certain embodiments of the invention can be used to block fluid flow of other fluids (such as water). Further, it will be understood that flow stop devices arranged in accordance with certain embodiments of the invention can be used to block fluid flow in larger diameter pipework and pipework in which the fluid pressure is low.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations).

It will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope being indicated by the following claims.