GB2383831A

GB2383831A - Cleaning of a pipeline system

Info

Publication number: GB2383831A
Application number: GB0224591A
Authority: GB
Inventors: Walter Robert Suttie
Original assignee: Aubin Ltd
Current assignee: Aubin Ltd
Priority date: 2001-10-26
Filing date: 2002-10-23
Publication date: 2003-07-09
Anticipated expiration: 2022-10-23
Also published as: GB0224591D0; GB0125805D0; GB2383831B

Abstract

A pipeline system including a pump, valve means and other apparatus for drawing product or substance from a store and feeding it to a delivery line. So that product or substance in the pipeline can be reclaimed at the end of a production run, and so that conventional pigs need not be used, the apparatus referred to includes a launching trap for a pipeline slug of gel.

Description

Cleaning and other apparatus for pipelines The invention relates to cleaning and other apparatus for pipelines, that is to say apparatus for the cleaning of the internal surfaces of pipelines and also apparatus for providing moving seals to separate different fluids or substances being pumped through pipelines.

It has in the past been well known to use so-called pipeline pigs both for the cleaning of the interior surfaces of pipelines and for providing moving seals for separating different fluids or substances being pumped through them, such pipeline pigs usually being made at least in part of a resilient material and being of spherical or cylindrical form. When, for example, a cleaning operation is carried out by the use of a pipeline pig, the pig is generally propelled through the pipelines concerned under gas or liquid pressure, and, being slightly oversize initially, that is to say being made of a diameter slightly greater than the bore diameter of the pipelines through which it is to be traversed, it will clean the pipelines to a standard largely dependent upon the condition of the pipelines and the condition of the peripheral surfaces of the pig and its fit within the pipelines concerned.

Pipeline cleaning apparatus for reclaiming product which would otherwise be degraded or wasted by being drained or purged from the pipeline is increasingly being employed in process industries. The reasons for this include recent legislation limiting the production of waste together with other environmental

considerations, cost of waste disposal (including increased water charges) and also operational considerations, for example to reduce downtime resulting from removal of waste product from pipes which are to be used for conveying a different product; also the introduction of more stringent quality control measures. In pipework installations where there is a substantial length of pipeline between a product store and a production machine using the product, a considerable cost saving can be made if the product in the length of pipeline can be reclaimed on completion of a production run. This can be a particularly important consideration in those installations where frequent changes of product are made and where the products concerned are of relatively high value However, in the foodstuffs manufacturing and pharmaceutical industries in particular, it is important that the apparatus concerned should be able to be cleansed to a very high standard, and preferably in a short space of time. (In this connection, it may be noted that for the purpose of being able to make the entire apparatus hygienically clean it is preferred that any valve means should be butterfly valves rather than, say, ball valves but it will be understood that a conventional pipeline pig cannot be passed through a butterfly valve). Also, when the apparatus includes pipeline pigs, it is equally important that no fragment of such a pig should ever break off to contaminate a product and this is virtually impossible to guarantee, especially in view of the undeniable fact that the resilient surfaces of a pig, in sliding along the internal surfaces of the pipelines, do eventually wear away to some extent. A further disadvantage

when using a pigging system is that pigs commonly used require a relatively high propulsion pressure, this sometimes resulting in pigs being propelled at high velocities. This has in the past been the cause of severe damage to pipework and operators also are at serious risk of injury if pigs exit the pipework by accident.

According to the invention, there is provided a pipeline system for conveying a product or substance, the system including a product pump for drawing the product or substance from a store and feeding it to a delivery line; a first valve means openable to allow the flow of product or substance from said delivery line; a second valve means openable to allow the flow of CIP (clean in place) fluid into said delivery line when the flow of product or substance has ceased; a launching trap for a pipeline slug of gel, a pipeline for conveying the product or substance; and a slug receiving trap and means for detecting or for determining the arrival of the slug within said receiving trap, the latter having third valve means openable to allow the exit of said pipeline slug from the system and having fourth valve means, openable in sequence to the opening of said third valve means, to allow the flow of product or substance from said slug receiving trap to a loading point where the product or substance is packaged or used.

The gel material will preferably have the characteristic of having a particular affinity to itself whereby, having been divided, it will readily re-combine, and in this case the first, third and fourth valve means referred to will preferably be butterfly valves. The second valve means, provided for admitting CIP (clean in place) fluid to the delivery line in order to propel the slug of gel along the

pipeline when recovering the product therein, will preferably also be constituted by a butterfly valve.

The launching trap may be provided with a plunger slidably located in a barrel within which a quantity of gel can be contained, means being provided for causing an appropriate movement of said plunger when a slug of gel is required. In this case, the means provided for causing movement of the plunger may include a compressed air cylinder a piston rod of which is connected to the plunger located in the barrel of the launching trap; there may be a cover piece pivotally connected to the barrel and carrying the compressed air cylinder, said cover piece being pivotable away from said barrel when a sachet of gel within the barrel has become depleted and needs to be replaced. In this case also, the launching trap may be provided with a latch device which when in use acts to limit the stroke of the plunger in the barrel.

Alternatively, the launching trap may be connected to a gel conveying line extending from a gel container, a gel pump being provided for maintaining the gel in said conveying line under pressure during the operation of the system, valve means being provided for allowing a flow of gel into a flow passage through the launching trap, thereby forming a slug of gel within said launching trap. In this case, the valve means may include a poppet valve element closable onto a valve seat formed at the point where the gel conveying line communicates with the product flow passage through the launching trap, said poppet valve element being carried by the piston rod of a pneumatic cylinder.

Alternatively, the valve means may include a cut-off valve having a spool type valve element slidably mounted in a bore which communicates with the flow passage through the launching trap, the arrangement being such that when located in one position said valve element blanks off the gel conveying line and simultaneously closes off the bore in which it is located at the wall of the flow passage, and when displaced to another position said valve element uncovers the end of the gel conveying line to allow gel to flow into the flow passage and to form a pipeline slug of gel.

A compressed air line may be connected into the upper end of the gel container to provide a top pressure of air in said container to assist in the feeding of gel to the gel conveying line.

The first valve means, openable to allow the flow of product or substance from the delivery line, and the launching trap for a pipeline slug of gel, may be constituted by a 3-way valve including a housing with three flow passages extending from it and a valve member which has a flow passage extending through it, said valve member being adjustable to bring different pairs of flow passages of the housing into communication, the arrangement being such that, in normal operation, the valve member will be adjusted so that product or substance can flow freely from the store to the delivery line and, at the end of a production run, said valve member can be adjusted so that gel can flow from the gel conveying line to form a pipeline slug. In this case, the valve member may be rotatable in the housing to bring the required pairs of flow passages into communication. Alternatively, it could be slidable linearly in the housing to

bring the required pairs of flow passages into communication. There may be a plurality of separate transfer lines for fluids or substances, said separate transfer lines being served by a single gel container.

The or each slug detector device may includes a sight glass window and a colour sensor adjacent said window and be connected to an electronic circuit, the arrangement being such that the device can detect the arrival of a slug of gel by a colour change at the sight glass window.

In the accompanying drawings, which illustrate, by way of example only, particular embodiments of the invention, Figure I is a schematic view of a product transfer line embodying the invention, Figures 2 to 4 are more detailed views of items forming part of the transfer line of Figure 1, Figure 5 is a schematic view illustrating a modification of the product transfer line of Figure 1, and Figures 6 to 15 illustrate further possible modifications which will presently be referred to.

Referring now in particular to Figure 1, the product transfer line there illustrated includes a product pump 10 for drawing product from a product store (not shown) and feeding it to a delivery line 12; a butterfly valve 14; a launching trap 16 for a pipeline slug of gel; a first slug detector device 18; a pipeline 20; a second slug detector device 22; and a slug receiving trap 24. A CIP (clean in place) fluid inlet line 26 communicates with the delivery line 12 by way of a valve 28 (which may well also be a butterfly valve). As shown,

the slug receiving trap 24 communicates, by way of a butterfly valve 30, with a drain connection 32 and also, by way of a butterfly valve 34, with a product flow line 36, the latter leading to a loading point, that is to say, to a machine or machines where the product is used to fill bottles, cans, jars or the like (not shown). It will be understood that the pipeline 20 is shown in chain-dotted lines and describing a circuitous route to indicate that it may well extend in circuitous fashion across the roof space of premises in which the transfer line is installed.

Referring now to Figure 2, this illustrates the construction of the launching trap 16. The trap includes an upstanding cylindrical barrel 38 which has flanged connection with a pipe section 40 with pipe connections 15 at its opposite,

ends. As shown, the pivot spindle for a manually operable butterfly valve 42 is located between the flanged connections 39, 41 of the barrel 38 and pipe section 40.

At its upper end the barrel 38 is provided with a cover piece 43, this being secured to the barrel by means of a clamp type fastener 44. Secured to said cover piece, co-axially with the barrel, is an upstanding compressed air cylinder 46 containing a piston 48. A piston rod 50, connected to the piston 48, extends downwards through the cover piece 43 and carries at its lower end a plunger 52 which is slidably located in the barrel. There is provided a latch device by means of which a downward stroke of the piston 48 can be limited, said latch device being constituted by a thumb screw 54 which engages a screwthread extending through a spigot portion 56 welded to the wall of the cylinder 46. As

drawn in Figure 2, the thumb screw is in an inoperative position where it does not affect the piston in its travel. When screwed further in, however, it acts as an abutment to limit the travel of said piston (and it will be understood that there could be more than one such abutment provided at different spacings along the length of the barrel and that such an abutment member need not necessarily be in the form of a screwthreaded member).

A sachet of gel 58 is shown to have been loaded into the barrel (by opening the clamp type fastener 44 and detaching the cover piece 43 and connected items).

Beneath the sachet of gel, and in a tapering lower portion of the barrel, there is located an upwardly facing sachet piercer 60 in the form of a knife blade with an upstanding central spike. At the closed upper end of the compressed air, cylinder a compressed air line 62 communicates with the cylinder space overlying the piston 48.

In the operation of the apparatus, when the butterfly valve 42 has been opened and compressed air is admitted through the air line 62, downward movement of the plunger 52 presses the sachet of gel downwards so that its lower end is pierced and gel can be forced into the pipe section 40. If only a limited amount of gel is to be dispensed into the pipe section, the latch device will have been brought into use to limit the travel of the piston 48 in its cylinder.

Referring now to Figures 3 and 4, these illustrate the construction of each of the slug detector devices 18 and 22. As shown, each one is constituted by a length of pipe 64 with pipe connections 15 at its opposite ends (by means of which it can be located as required in the product transfer line) and a sight glass

window 66 intermediate its ends. A colour sensor 68 for detecting a change in colour of substance flowing through the device is located at the outside of the window. The colour sensor is connected in an electronic circuit (not shown) by wires 70. It will be understood that the gel which is used for forming the pipeline slugs will be dyed a distinctive colour in comparison with the colour of the product or substance with which it is to be used.

In the normal operation of the product transfer line illustrated in Figure 1, butterfly valve 14 will be open, valve 28 and butterfly valve 30 will be closed and butterfly valve 34 will be open. Consequently, when pump 10 is running, product is pumped from the product store to the loading point. However, at the end of a production run, the pump will be stopped and the product in the pipeline 20 (which may well be a substantial amount) can be retrieved by injecting a slug of gel at the launching trap and opening butterfly valve 28. In this way, CIP (clean in place) fluid is admitted under pressure to the transfer line and, acting behind the pipeline slug, forces the product along the pipeline 20 and along the flow line 36 to where it can be used up at the loading point or, for example, be collected in a holding tank (not shown) from where it can be returned in due course to the product store. The retrieval of product continues in this way until the second slug detector device 22 senses the passage of the pipeline slug, whereupon the butterfly valve 30 is caused to open and butterfly valve 34 is caused to close so that the slug exits the apparatus through the drain connection 32. When the slug has been ejected, the butterfly valve 30 can be re-closed and butterfly valve 34 re-opened so that the CIP (clean in place)

fluid can continue to flow through the pipeline 20 and through the product flow line 36 to clean them of all traces of the previous product. At the completion of the cleaning process, the CIP (clean in place) fluid can be allowed to drain from the system or, alternatively, a further pipeline slug of gel can be launched to be pushed through the pipeline by the succeeding product. Having traversed the pipeline, said further slug can be exited from the system in the same manner as the first slug, the product flow line, which is relatively short, then being cleaned by the passage of said succeeding product, the wastage of the latter through contamination during this final cleaning process being a minimal and insignificant amount.

Referring now to Figure 5, this illustrates a product transfer line very similar to that illustrated in Figure 1 in that it includes a product pump 10 for drawing product from a store (not shown) and feeding it to a delivery line 12; a butterfly valve 14 ; a launching trapl6 for a pipeline slug ; a first slug detector device 18; a pipeline 20 (which in this case, for purposes of simple illustration, is shown to be straight but which in fact will almost certainly extend in circuitous fashion across the roof space of the premises in which the transfer line is installed); a second slug detector device 22; a slug receiving trap 24; a CIP (clean in place) fluid inlet line 26 communicating with the delivery line 12 by way of a butterfly valve 28; a butterfly valve 30 by means of which the slug receiving trap can communicate with a drain connection 32; and a butterfly valve 34 by means of which the slug receiving trap can communicate with a product flow line 36.

However, in this case the launching trap for a pipeline slug does not

incorporate any kind of storage means for a quantity of the gel of which the pipeline slugs are formed. Instead there is provided a container 72 (which may be located some distance from the launching trap) this being capable of containing a substantial quantity of the gel. The container 72 is connected into a gel conveying line 74, extending to the launching trap, by way of a gel pump 76 which maintains the gel in said conveying line under pressure during pumping operations. (As shown in the drawing, the conveying line extends in opposite directions from the gel pump, this being to indicate that the container may be arranged to simultaneously serve at least one further transfer line similar to that illustrated, if required). A compressed air line 78 is shown to be connected into the upper end of the container, this providing a top pressure of air to facilitate the free flow of gel when the pump is feeding the gel to the conveying line 74. As shown, a bleed valve 80 is provided in the gel conveying line, immediately adjacent the launching trap. Air can thus be bled from said conveying line when the system is first being charged with gel, this being to guard against any inclusions of air in the pipeline slugs as they are being formed in the launching trap..

The launching trap 16 in this case includes a poppet valve element 82 which is carried by the piston rod 84 of a pneumatic ram generally indicated 86. The poppet valve element is closable onto a valve seat 88 formed at the point where the gel conveying line communicates with the product flow passage through the launching trap.

The arrangement is such that during the normal operation of the transfer line the poppet valve element 82 is held tightly on the valve seat 88 by the pneumatic ram 86 and product can be pumped through the transfer line by the pump 10 (the flow of product through the launching trap taking place around the piston rod 84 which carries the poppet valve). However, when a production run has come to an end, the pump 10 will be stopped and the poppet valve will be opened to allow the flow of gel into the flow passage where it can form a pipeline slug of gel completely filling a section of said flow line. When the first slug detector device senses the presence of the slug, this causes the re-closure of the poppet valve element 82 and causes the valve 28 to open so that CIP (clean in place) fluid is admitted to the delivery line 12. Consequently, the pressure of said fluid, acting behind the slug, traverses the latter through the pipeline 20 to recover the product contained therein. As in the previously described arrangement, when the slug reaches the slug receiving trap 24, it is caused to be exited from the line through the drain connection 32 whereupon the CIP (clean in place) fluid can continue to flow through the pipeline 20 and through the product flow line 36 until the entire transfer line is perfectly clean.

It will be understood that the transfer line arrangement just described has certain advantages over the arrangement illustrated in Figure 1. For example, because the launching trap does not include any storage facility for gel, its construction is greatly simplified. Also, if lack of space in the immediate vicinity of the transfer line is a problem, it is advantageous to locate the gel container in a more convenient part of the premises. The capacity of the gel

container can be made to suit whatever number of transfer lines are to be served by it. In addition, it can be made sufficiently large to ensure that infrequent loading is required and this in itself is advantageous because hygiene is thereby improved.

Referring now to Figures 6,7 and 8, these illustrate a modification of the arrangement just described with reference to Figure 5. As shown in Figure 6, the arrangement still includes a gel container 72 and a gel pump 76 by means of which gel in a conveying line 74 can be pressurised. However, as shown, in this case the gel in the gel conveying line flows into the flow passage through the launching trap by way of a cut-off valve generally indicated 90. As shown in Figures 7 and 8, the cut-off valve includes a spool type valve element 92 slidably mounted in a bore 94 which communicates with the flow passage. An enlarged piston portion 96 of said valve element is located in a counterbore portion 98 to the opposite ends of which air lines 100 and 102 are connected, as shown. The arrangement is such that, depending on which air line is pressurised, the valve element is displaced upwards or downwards. When displaced downwards, as shown in Figure 7, the valve element blanks off the end of the gel conveying line 74 and simultaneously closes off the bore 94 at the wall of the flow passage. (This is the position of the valve element when either product or CIP fluid is flowing through the transfer line). When displaced upwards, as shown in Figure 8, the valve element uncovers the end of the gel conveying line 74 which allows the gel to flow into the flow passage and form a pipeline slug of gel. (This is the position of the valve element when

a production run of product has been reached and the product in the pipeline is to be recovered and the transfer line cleaned in readiness for use with a different product).

Referring now to Figures 9 to 11, these illustrate a possible modification of the product transfer line illustrated in Figure 5, the modification being made by the substitution of the butterfly valve 14 and pipeline slug launching trap 16 of the Figure 5 construction by the 3-way valve generally indicated 104. As shown, the 3-way valve includes a cylindrical housing 106 with three equally spaced flow passages 108,110 and 112 extending radially outwards from it. Located within the housing 106 is a rotatable valve member 114 which has a flow passage 116 extending through it, as shown, the opposite ends of said flow passage conveniently being spaced apart, circumferentially, through 120 degrees.

When the 3-way valve has been installed in substitution for the butterfly valve and launching trap in the Figure 5 arrangement, the flow passage 108 will be connected to the delivery line 12, the flow passage 110 will be connected to the flow passage in advance of the first slug detector device 18, and the flow passage 112 will be connected to the gel conveying line 74.

In normal operation, the valve will be adjusted, as shown in Figure 9, so that product or substance can flow freely to the pipeline 20. At the end of the production run, the valve will be adjusted, as shown in Figure 10, so that gel can flow from the gel conveying line 74 to form a pipeline slug 200 (which in Figure 10 is shown to have started to push the product in the flow passage 110

along the transfer line). When the slug reaches the location of the first slug detector device 18, this will trigger the re-adjustment of the valve back to its original state, and simultaneously open the valve 28 to the flow of CIP (clean in place) fluid from the fluid inlet line 26. The pipeline slug will thus be acted upon by the flow of CIP fluid, as indicated in Figure 11, and the product recovery and pipeline cleaning operation will proceed in the manner previously described.

The arrangement just described with reference to Figures 9 to 11 may itself be modified. For example, since there are only two required positions of the valve member 114 it is not essential for the flow passages to be arranged at the angles shown in the drawings. Furthermore, it is not essential for the valve member to be rotationally adjustable in the housing. The valve could be replaced by the kind of valve which has a valve member linearly adjustable in a housing to effect different communications between flow passages. Such a valve could in fact be easier to maintain in a hygienically clean condition as required in foodstuffs manufacturing for example.

Various other modifications may be made. For example, several ways in which the launching trap of Figure 1 may be modified are shown in Figures 12 to 15.

In Figure 12 there is illustrated a launching trap similar to that of Figure 2 in that it includes an upstanding cylindrical barrel 38 having flanged connection with a pipe section 40 and having also a butterfly valve located between the flanged connections of the barrel and pipe section. It also has a cover piece 43 secured to the barrel by means of a clamp type fastener 44 and a sachet piercer

60 which in this case is shown as a simple knife blade element. However, in this case, the plunger 52 has sealing engagement with the interior wall of the barrel by means of an O-ring seal 53 and a compressed air line 113 is connected through the cover piece 43 so that air under pressure acts in the space overlying the plunger and forces the gel into the flow line for forming a pipeline slug. A spindle 115 upstanding from the plunger extends slidably through a sleeve 117 which is mounted on the cover piece 43. The sleeve is provided with a series of horizontal cut-outs 118 which are connected, as shown, by vertical slots 119, the arrangement being such that a peg element 121 projecting from the upper end of the spindle 115 can be brought into engagement with any one of the horizontal cut-outs 118. This constitutes a stroke limiting mechanism, that is to say limits the stroke of the plunger 52 and thereby limits the amount of gel which is forced into the flow line to form a pipeline slug.

In Figure 13 there is illustrated a somewhat different form of launching trap, this including an upstanding tubular body 120 which, by means of a screwed connection 122, mates with a branch pipe 124 welded to the pipe section 40.

As shown, the tubular body and branch pipe together form a resevoir for the gel and contain a plunger 126 by means of which the gel can be forced into the pipe section when required. In the position of the plunger shown in fuD tines in the drawing, gel has been injected into the pipe section, and a length of metal rod 128 with a screwthreaded lower end has been inserted through an aperture 130 in an end cover portion 132 of the tubular body and connected to the plunger. As shown, the upper end of said rod has a tee handle 134 and the

arrangement is such that, when the tubular body has been removed from the pipe section, said body can be re-charged with gel by drawing the plunger to its upper end (as shown in chain-dotted lines) by means of said handle. On the reconnection of the body part with the pipe section, the rod 128 can be disconnected from the plunger so that a connector for a compressed air line (shown in chain-dotted lines) can be fitted to the end cover portion, for which purpose the aperture therein is shown to be screwthreaded. The new charge of gel can then be forced into the flow line, when required, by the pressure of compressed air acting above the plunger.

Referring now to Figures 14 and 15, the launching trap there illustrated is similar to that illustrated in Figure 2 in that it includes a cylindrical barrel 38 upstanding from a pipe section 40 with pipe connections 15 at its opposite ends; it has a cover piece 43 to which is secured, co-axially with the barrel, an upstanding compressed air cylinder 46 containing a piston 48; it also has a piston rod 50 connected to the piston and extending downwards through the cover piece 43, said piston rod carrying at its lower end a plunger 52 which is slideable in the barrel 38. However, in this case the cover piece 43 is pivotally connected to the barrel 38 by a pivot pin 136 so that the cover piece and the parts fixed to it can be pivoted to the position shown in chain-dotted lines when the gel sachet 58 has become depleted and needs to be replaced. When returned to its operative position, as shown in full lines in Figure 14, the cover piece is retained in that position by a finch pin 138 which, as shown in Figure 15, can be located through lugs 140 formed on the wall of the barrel and

extending through a lug 142 formed on the cover piece. When removed from its operative position, the linch pin is captive on the end of a length of chain 144.

At its underside, and co-axial with the barrel, the pipe section 40 is provided with a downwardly projecting pneumatic cylinder 146 an upstanding piston rod 148 of which extends through a hygienic seal 149 in the lower wall of the pipe section. The upper end of the piston rod 148 carries a closure member 150 for the aperture through which the gel is dispensed from the barrel 38, said closure member itself incorporating a hygienic seal element 152.

Various other modifications may be made to the transfer lines described and illustrated and to the components which they include. Features forming parts of several illustrated components may be capable of being incorporated in other similar components.

During the operation of any of the transfer lines referred to there may be occasions when there is no need to clean the line with CIP (clean in place) fluid during a change over of product (for example, if the products concerned are very similar types of jam). In such a case, the delivery line can simply be reconnected to the required new product store and a slug of gel can be inserted into the line to divide the two products. Bottling can proceed as normal and those bottles of product found to be mixed to any degree, which will be a very small number, can be discarded.

Modifications may be made to the way in which the apparatus is operated. For example, instead of using the pipeline slug detectors it would be possible to

accurately determine the position of a pipeline slug as it nears the end of its travel along a pipeline by metering the flow of the CIP (clean in place) fluid or of the following product if the slug is being propelled by the following product at the time. (It has already been proposed to determine the size of a pipeline slug by metering the flow of gel; this method could be used instead of the slug detector 18 in the Figure 5 embodiment for example).

Claims

Claims 1. A pipeline system for conveying a product or substance, the system including a product pump for drawing the product or substance from a store and feeding it to a delivery line, a first valve means openable to allow the flow of product or substance from said delivery line; a second valve means openable to allow the flow of CIP (clean in place) fluid into said delivery line when the flow of product or substance has ceased; a launching trap for a pipeline slug of gel; a pipeline for conveying the product or substance; a slug receiving trap and means for detecting or for determining the arrival of the slug within said receiving trap, the latter having third valve means openable to allow the exit of said pipeline slug from the system and having fourth valve means, openable in sequence to the opening of said third valve means, to allow the flow of product or substance from said slug receiving trap to a loading point where the product or substance is packaged or used
2. A pipeline system according to claim 1, in which the gel material of which the slug is formed has the characteristic of having a particular affinity to itself whereby, having been divided, it will readily re-combine, and the first, third and fourth valve means referred to being butterfly valves.
3. A pipeline system according to claim 2, in which the second valve means, provided for admitting CIP (clean in place) fluid to the delivery line in order to propel the slug of gel along the pipeline when recovering the product therein, is also constituted by a butterfly valve

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4. A pipeline system according to any one of the preceding claims, in which the launching trap is provided with a plunger slidably located in a barrel within which a quantity of gel can be contained, means being provided for causing an appropriate movement of said plunger when a slug of gel is required.
5. A pipeline system according to claim 4, in which the means provided for causing movement of the plunger include a compressed air cylinder a piston rod of which is connected to the plunger located in the barrel of the launching trap.
6. A pipeline system according to claim 5, in which a cover piece pivotally connected to the barrel and carrying the compressed air cylinder can be pivoted away from said barrel when a sachet of gel within the barrel has become depleted and needs to be replaced.
7. A pipeline system according to any one of claims 4 to 6, in which the launching trap is provided with a latch device which when in use acts to limit the stroke of the plunger in the barrel.
8. A pipeline system according to any one of claims 1 to 3, in which the launching trap is connected to a gel conveying line extending from a gel container, a gel pump being provided for maintaining the gel in said conveying line under pressure during the operation of the system, valve means being provided for allowing a flow of gel into a flow passage through the launching trap, thereby forming a slug of gel within said launching trap.
9. A pipeline system according to claim 8, in which the valve means include a poppet valve element closable onto a valve seat formed at the point where the gel conveying line communicates with the product flow passage through the

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launching trap, said poppet valve element being carried by the piston rod of a pneumatic cylinder.
10. A pipeline system according to claim 8, in which the valve means include a cut-off valve having a spool type valve element slidably mounted in a bore which communicates with the flow passage through the launching trap, the arrangement being such that when located in one position said valve element blanks off the gel conveying line and simultaneously closes off the bore in which it is located at the wall of the flow passage, and when displaced to another position said valve element uncovers the end of the gel conveying line to allow gel to flow into the flow passage and to form a pipeline slug of gel.
11. A pipeline system according to any one of claims 8 to 10, in which a compressed air line is connected into the upper end of the gel container to provide a top pressure of air in said container to assist in the feeding of gel to the gel conveying line.
12. A pipeline system according to any one of claims 8 to 11, in which the first valve means, openable to allow the flow of product or substance from the delivery line, and the launching trap for a pipeline slug of gel, are constituted by a 3-way valve including a housing with three flow passages extending from it and a valve member which has a flow passage extending through it, said valve member being adjustable to bring different pairs of flow passages of the housing into communication, the arrangement being such that, in normal operation, the valve member will be adjusted so that product or substance can flow freely from the store to the delivery line and, at the end of a production

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run, said valve member can be adjusted so that gel can flow from the gel conveying line to form a pipeline slug.
13. A pipeline system according to claim 12, in which the valve member is rotatable in the housing to bring the required pairs of flow passages into communication.
14. A pipeline system according to claim 12, in which the valve member is slidable linearly in the housing to bring the required pairs of flow passages into communication.
15. A pipeline system according to any one of claims 8 to 14, including a plurality of separate transfer lines for fluids or substances, said separate transfer lines being served by a single gel container.
16. A pipeline system according to any one of the preceding claims, in which the or each slug detector device includes a sight glass window and a colour sensor adjacent said window and connected to an electronic circuit, the arrangement being such that the device can detect the arrival of a slug of gel by a colour change at the sight glass window.
17. A pipeline system constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by Figures 1 to 4, or Figure 5, or Figures 6 to 8, or Figures 9 to 11, or Figure 12, or Figure 13, or Figures 14 and 15 of the accompanying drawings.