WO2014062077A1

WO2014062077A1 - A pig for cleaning and/or inspecting a pipeline as well as a method for operating such pig

Info

Publication number: WO2014062077A1
Application number: PCT/RU2012/000841
Authority: WO
Inventors: Vitaly Vladimirovich Malinin; Ivan Vladimirovich Nikolin
Original assignee: Siemens Aktiengesellschaft
Priority date: 2012-10-18
Filing date: 2012-10-18
Publication date: 2014-04-24

Abstract

The invention relates to a pig (24) for cleaning and/or inspecting a pipeline (26), comprising at least one housing element (28), on which at least one support element (40) is held, via which the pig (24), which is movable through the pipeline (26) in a direction of movement, is supportable on an inner circumferential shell surface (42) of the pipeline (26), wherein the support element (40) on the housing element (28) between at least one extended and at least one retracted position, in which the support element (40) in comparison with the extended position in a direction of movement extending perpendicularly to the direction of movement is arranged closer to the housing element (28), is held in a way movable relative to the housing element (28), as well as a method for operating such pig (24).

Description

A pig for cleaning and/or inspecting a pipeline as well as a method for operating such pig

The invention relates to a pig for cleaning and/or inspecting a pipeline according to the preamble of patent claim 1 as well as a method for operating such pig according to the preamble of patent claim 11.

From the general prior art pipelines are known which commonly are used to transport fluids such as liquids or gases. Further in such pipelines capsules can be conveyed pneumatically, wherein within the capsules goods can be transported. For moving the capsules within the pipelines for instance pressurized air is used. With regard to gas and liquid at least essentially any chemically stable substance can be transported through a pipeline. Further, it is known from the general prior art to use so- called pigs for inspecting and/or cleaning the pipeline. Such a pig can move in a direction of movement within the pipeline along same and for example clean and/or inspect the pipeline from within, i.e. check it for example for damages. Such pig commonly is used for inspecting and/or for cleaning the pipeline, however, its function is not limited to cleaning and/or inspecting.

For moving the pig within the pipeline relative to same the fluid flowing within the pipeline and to be transported via the pipeline is used. In other words, the pig is moved within the pipeline by means of the pressure of the fluid. Thereby it is possible to employ the pig and move it along within the pipeline, whilst the fluid flows through the pipeline and is correspondingly transported. An interruption of this

transport of the fluid is not required, so that costs and financial losses resulting from the transport failure can be avoided. In order to insert the pig into the pipeline, for example an essentially Y-shaped pipeline section with a secondary branch is provided, with the pig being inserted via the secondary branch into the actual pipeline.

The fluid keeps pushing the pig along within the pipeline for instance until the pig reaches a corresponding end or reception station, at which the pig can be removed from the pipe- line.

In order to adjust the through flow of the fluid through the pipeline, valve elements may be arranged within the pipeline. Such a valve element may for instance be a so-called ball valve, which has a ball for adjusting the through flow.

Such a valve element alternatively may also be a so-called butterfly valve, an example of which is shown in FIG 1. FIG 1 shows a butterfly valve as a whole bearing the reference 10, which in the present case is arranged in a pipe segment 12 of a pipeline. The butterfly valve 10 comprises a flap 14, which is received within the pipe segment 12 and is pivotable relative to the pipe segment 12 about a pivot axis 16 extending in radial direction of the pipe segment 12

The flap 14 can be pivoted between at least one closing position and at least one open position, wherein a flow cross section 18 of the pipe segment 12, through which the fluid can flow, in the closing position at least in a subportion is blocked by the flap 14. In the open position the flow cross section 18 is deblocked in the subportion, so that the fluid can flow through the pipe segment 12 in the open position in comparison with the closing position with a greater volume or mass flow rate.

In order to pivot the flap 14 between the closing position and the open position, the butterfly valve 10 also comprises an actuation element, in the present case in the form of a rotatable actuation wheel 20.

Ball valves with regard to the movement of the pig through the pipeline do not represent an obstacle, since the diameter of the ball can be adjusted to a diameter of the pipeline, so that the pig can pass smoothly through the ball valve, i.e. be conveyed through the ball valve. As can be seen from FIG 1, however, the butterfly valve 10 represents a considerable obstacle for a pig, as the flap 14 constricts the flow cross section 18 also in its open position and for example divides it into two parts. Thus, the pig cannot be moved through the butterfly valve and cannot pass same.

Rather, upstream of the butterfly valve 10 the pig needs to be removed from the pipeline and be reinserted into the pipeline downstream of the butterfly valve 10. This is very labo- rious as well as time-consuming and cost-intensive. Moreover, commonly known pigs require complex measures for inserting the pig into the pipeline and removing it from same. Besides, in the case of commonly known pigs there is invariably a relatively high likelihood that the pig becomes stuck in the pipeline, which could result in an interruption of the flow of the fluid and corresponding financial losses.

It therefore is the task of the present invention to provide a pig of the initially mentioned kind as well as a method for operating such a pig, which allow for a simple, time and cost-efficient as well as safe operation of the pig.

This task is solved by a pig having the features of patent claim 1 as well as by a method for operating such a pig, the method having the features of patent claim 11. Advantageous embodiments with expedient and non-trivial further developments of the invention are indicated in the remaining claims. Such a pig for cleaning and/or inspecting a pipeline has at least one housing element, on which at least one support element is held. Via the support element the pig, which is movable through the pipeline in a direction of movement, is sup- portable on an inner circumferential shell surface of the pipeline .

For realizing a simple, time and cost-efficient as well as safe operation of the pig according to the invention it is envisaged that the support element is held on the housing element in a way movable between at least one extended position and at least one retracted position relative to the housing element, wherein the support element in the retracted position in comparison with the extended position in a direction extending perpendicularly to the direction of movement is arranged closer to the housing element.

This means that the pig in the retracted position of the support element has a smaller outer circumference and in partic- ular a smaller outer diameter than in the extended position of the support element. Thus the pig can also be moved through such cross sections of the pipeline that are smaller in comparison with further cross sections adjacent to these cross sections.

For this purpose the support element in a simple way is moved from its extended position, in which the pig could not be moved through the corresponding cross sections, into its retracted position, so that the pig then can be moved through the corresponding cross sections. Thus, the pig needs not be removed from the pipeline upstream of the cross sections and be reinserted into the pipeline downstream of the cross sections . As a consequence of the mobility of the support element between the extended position and the retracted position the pig has a variable outer circumference and in particular a variable outer diameter, so that the pig with regard to its outer circumference can be adjusted as required to different flow cross sections of the pipeline, through which for instance a fluid can flow. Thereby the likelihood of the pig becoming stuck whilst moving through the pipeline can be min- imized. Moreover, the pig can be used for different flow cross sections as well as for different pipelines with different flow cross sections.

The pig according to the invention in particular also allows for passing butterfly valves possibly arranged in the pipeline, which leads to a simple, time and cost-efficient as well as safe operation of the pig.

By means of the pig according to the invention the pipeline thus can be examined and for instance inspected and/or cleaned in a cost-effective, reliable, sustainable, and environmentally friendly manner, as the pipeline need not be opened for removing and inserting the pig. The pig in this connection preferably allows for detecting damages and/or a undesired tapping of the fluid from the pipeline and/or of leakages, via which the fluid flowing through the pipeline possibly might leak from the pipeline. By means of the pig it is preferably possible to quickly lo- cate such incidents and/or spots.

The pig further can be used for various purposes and/or for various facilities such as for instance mixing and/or storing and/or filling facilities that comprise at least one pipe- line. The pig moreover can be used for any kind of pipeline. For instance it is possible to employ the pig in pipelines for conveying oil, paints, chemicals, sewages, cosmetic products, food, and/or other goods. The pig for instance can also be made use of for cleaning and discharging the pipeline into a tank.

Further, the pig can be employed in any sections of the pipeline, such as for example in a beginning section, an end sec- tion, and an interim section and accordingly can move within the pipeline. Further applications of the pig are for instance the detection of corrosion within the pipeline and/or the capture of a wall thickness of the pipeline. Not least can the pig be used for separating various goods from each other in a so-call multiple goods pipeline.

In a particularly advantageous embodiment of the invention for moving the support element between the extended position and the retracted position two first lever elements that are spaced apart from each other in the direction of movement are provided. These first lever elements are held on the housing element in a way pivotable about a respective pivot axis relative to the housing element and whilst forming a four joint assembly are connected with each other via a further lever element that is connected with the first lever elements in a way pivotable about a respective pivot axis relative to the first lever elements. The lever elements thus move at least essentially in the fashion of a parallelogram, in order to thereby move the support element between the positions in a particularly space- saving way. In other words, the lever elements form parallelogram rod assembly, which allows for a particularly advanta- geous and space-saving movement of the support element.

At the same time the support element is supported on the housing element in a particularly firm and stable way, so that the pig as a whole can be supported on the inner circum- ferential shell surface of the pipeline and move along the inner circumferential shell surface through the pipeline. In this connection the direction of movement corresponds with the direction of the extension of the pipeline, in which the fluid flows through the pipeline.

Preferably, the further lever element has a longitudinal extension direction, which at least essentially extends in the direction of movement. Further, it is advantageously envis- aged that the lever elements at least essentially are movable in the direction of movement, so that the pig in particular in -the retracted position of the support element requires only very little space.

It may be envisaged that the support element is formed integrally with the further lever element. In other words, the further lever element is the support element. For this purpose the further lever element for instance is formed from a plastic, which preferably has very good sliding properties, so that the pig can slide via the support element along the inner circumferential shell surface of the pipeline.

In a particularly advantageous embodiment of the invention the support element is held on the further lever element.

This means that the support element and the lever element are formed separate from each other, with the support element being arranged on a further lever element. Hereby a simple manufacture and easy mounting of the pig are realizable.

The support element in this connection can be provided as coating, in particular as slide coating, of the further lever element, via which the pig is supportable on the inner circumferential shell surface.

To keep an actuation and/or driving force for moving the pig within the pipeline relative to the pipeline particularly small, in a further advantageous embodiment it is envisaged that the support element comprises at least one roll that is held on a further lever element in a way rotatable about a rotation axis relative to the further lever element. The pig thus can roll via the roll on the inner circumferential shell surface of the pipeline and thus be moved along within the pipeline by means of an only very small actuation effort.

It has turned out to be particularly advantageous, if the pig comprises at least one pump, by means of which a fluid is conveyable for moving the support element. In other words, the support element is movable between the positions by conveying the fluid by means of the pump. The support element is thus hydraulically and/or pneumatically movable between the positions. Thereby the support element whilst requiring for instance only a very small amount of energy and force of the pump can be moved with high actuation forces from the retracted position into the extended position. Further, a raised safeguarding against failure is realizable. In the case of a further advantageous embodiment of the invention the pump is fluidically connected with a surroundings of the pig via at least one channel. Via the channel a fluid flowing through the pipeline can be sucked in by means of the pump for moving the support element into the extended posi- tion. Accordingly, for moving the support element into the retracted position by means of the pump the fluid can be conveyed back into the pipeline.

This embodiment envisages that for moving the support element from the retracted position into the extended position the fluid flowing through the pipeline is used, which by means of the pump is sucked into the channel out from the pipeline and conveyed through the channel. In this way it is not required to carry a fluid along with the pig for moving the support element, so that the its required space can be kept particularly small. Moreover, it is thus also possible to keep actuating elements of the pig on the whole to a minimum with regard to the constructed space. This leads to a reduced constructed space as well as to an only very small weight of the pig.

In a further embodiment of the invention at least one sensor of the pig is provided, which is movable along with the sup- port element. Thereby it can be done without separate actuating elements, which are associated with the sensor and serving for moving the sensor, which leads to a small constructed space required and a low weight of the pig. This facilitates a simple, time and cost-effective operation. Moreover, this renders it possible that the sensor in the extended position is positioned particularly close to the pipeline or touches the pipeline, so that the pipeline can be examined by means of the sensor. The sensor is for instance a sensor for detecting corrosion and/or capturing the wall thickness of the pipeline and/or a leakage of the pipeline.

For realizing a simple and particularly cost-effective moving of the pig along within the pipeline the pig comprises at least one capture element for capturing a fluid flowing through the pipeline and for driving the pig as a consequence of the capturing. Due to the capturing of the fluid through the capture element a momentum or movement energy is trans- ferred from the fluid to the capture element and from the latter to the pig as a whole, so that thereby the pig is moved within the pipeline relative to same. The capture element in this connection for instance acts in the manner of a sail and in particular in the manner of a parachute.

For realization of a particularly small constructed space required by the capture element this is made from a flexible material, for instance from an at least essentially pliable textile. Thereby the capture element can be stowed in a way occupying particularly little space. Further, it is possible that the flexible, in particular pliable, capture element of its own accord adjusts to different, varying flow cross sections and thus of its own accord enlarges its capture surface, for instance in the case of an expanding cross section, and correspondingly reduces the surface in the case of a narrowing or decreasing cross section, without an active control element being required for this purpose.

The invention also includes a method for operating a pig for cleaning and/or inspecting a pipeline. The method involves moving the pig comprising at least one housing element and at least one support element held on the housing element for supporting the pig on an inner circumferential shell surface of the pipeline in a direction of movement through the pipeline .

For realizing a simple, time and cost effective as well as particularly safe operation of the pig it is envisaged according to the invention that the support element held on the housing element in a way movable relative to the housing element between at least one extended position and at least one retracted position is moved between the retracted position and the extended position.

In this connection the support element in the retracted position in comparison with the extended position is positioned closer to the housing element in a direction extending per- pendicularly to the direction of movement. Thereby the pig in the retracted position of the support element has a smaller outer circumference and in particular a smaller outer diameter than in the extended position of the support element, so that the pig can be moved also through particularly small and in particular variable flow cross sections of the pipeline.

Further it is possible to adapt the pig as required to different flow cross sections, in particular to different inner diameters of the pipeline, and to move it through cross sec- tion diameters that are merely in a subportion particularly small, without having to remove the pig from the pipeline and reinsert it into the pipeline.

Advantageous embodiments of the pig according to the inven- tion are to be regarded as advantageous embodiments of the method according to the invention and vice versa.

Advantages, features, and details of the invention derive from the following description of preferred embodiment exam- pies as well as from reference to the drawing. The features and feature combinations afore-mentioned in the description as well as the features and feature combinations shown in the following in the description of the figures and/or in the figures alone are usable not only in the respective indicated combination, but also in any combination or taken alone, without leaving the scope of the invention. The drawing shows in: a schematic front view of a butterfly valve for a pipeline according to the prior art; a schematic perspective view of a segment of a pig for cleaning and/or inspecting a pipeline, comprising a housing element, on which support elements are held, with the support elements being movable relative to the housing element between a respective extended position and a respective retracted position and with the support elements being in the extended position; a schematic perspective view of the segment according to FIG 2, with the support elements being in the retracted position; a partial schematic and sectional view of a pipeline, in which a pig having three segments according to FIGS 2 and 3 is received, with the support elements being in the extended position; a further partial schematic and sectional perspective view of the pipeline with the pig received within the pipeline, with the support elements being in the retracted position;

FIG 6a a schematic cross-sectional view of the pipeline according to FIG 5, with the pig received within the pipeline being shown from the front; and FIG 6b a schematic cross-sectional view of the pipeline according to FIGS 5 and 6a, with the pig being shown in a rear view. In the figures same elements or elements of the same function are equipped with the same references.

FIG 2 shows a pig segment 22 of a pig for cleaning and/or inspecting a pipeline 26 (FIG 4), the pig as a whole bearing the reference 24 (FIG 4) . The pig 24 shown in FIGS 4 and 5 comprises three pig segments 22. The respective pig segment 22 comprises a housing element 28 as well as a plurality of parallelogram rod assemblies 30. The parallelogram rod assemblies 30 in the present case are at least largely positioned outside the housing element 28 and preferably evenly distributed in the circumferential direction of the pig segment 22 across its circumference.

The parallelogram rod assemblies 30 each comprise two first lever elements 32, 34, which in a longitudinal direction of the first pig segment 20 are spaced from each other. The longitudinal direction in this setup in FIG. 2 is suggested by a directional arrow 38 and corresponds at least essentially with a direction of movement, in which the pig 24 is movable within the pipeline 26 relative to the pipeline 26.

The lever elements 32, 34 each are held on the housing element 28 in a way pivotable about a respective pivot axis relative to the housing element 28.

The respective parallelogram rod assemblies 30 moreover comprise a further lever element 36, via which the lever elements 32, 34 are connected with each other. As can be seen from FIG 2, the further lever element 36 extends at least es- sentially in the longitudinal direction (directional arrow 38) of the pig segment 22 and thus of the pig 24. Besides, the further lever element 36 on the one side is connected with the lever element 32 in a way pivotable about a pivot axis relative to the lever element 32.

On the other side, the further lever element 36 is connected with the lever element 34 in a way pivotable about a pivot axis relative to the lever element 34. In other words, the lever elements 32, 34 are coupled with the housing element 28 as well as connected with each other in an articulated manner via the further lever element 36.

Through the respective parallelogram rod assembly 30 thus a so-called four joint assembly is created, with the lever elements 32, 34, 36 being movable in the fashion of a parallelogram.

Thereby it is possible to move the respective parallelogram rod assemblies 30 between a respective extended position - shown in FIG 2 - and at least one respective retracted position - shown in FIG 3.

In the retracted position the respective further lever element 36 - relative to a direction extending perpendicularly to the longitudinal direction and thus to the direction of movement - is positioned closer to the housing element 28 than in the extended position. In other words, the further lever elements 36 in the extended position in the radial direction are spaced further apart from the housing element 28 than in the retracted position. Respective support elements in the form of rolls 40 are held on the respective further lever elements 36. The rolls 40 therein are held on the corresponding further lever element 36 in a way rotatable about a respective rotation axis relative to the corresponding lever element 36 and consequently in a way movable along with the corresponding further lever element 36 between the retracted position and the extended position. This means that thus also the rolls 40 are movable relative to the housing element 28 between a respective ex- tended position shown in FIG 2, and at least one respective retracted position shown in FIG 3. In the retracted position the rolls 40 in this setup relative to the direction extending at least essentially perpendicularly to the longitudinal direction are positioned closer to the housing element 28 than in the extended position.

The pig segment 22, i.e. the pig 24 on the whole, thus in the respective retracted position of the rolls 40 in comparison with the extended position has a considerably smaller outer circumference and in particular a considerably smaller outer diameter.

Thereby it is possible to adjust the pig 24 as required to different, i.e. for example variable flow cross sections of the pipeline 26 through which a fluid flowing through the pipeline can flow.

Via the rolls 40 the pig 24 can be supported on an inner cir- cumferential shell surface 42 of the pipeline 26 in such a way that the pig 24 can roll via the rolls 40 on the inner circumferential shell surface 42 and thus be smoothly moved at a very low driving force along within the pipeline 26 and relative to the latter.

Instead of rolls 40 also other support elements can be employed, which for instance are arranged on the respective further lever element 36 and are movable along with the latter. Such support element for instance could be a sliding el- ement coated with an abrasion-resistant and low-friction material. This, too, helps to keep the friction between the pipeline 26 and the pig 24 particularly low, so that the pig 24 can be moved along at an only very low driving force or driving energy. Furthermore, the wear of the support element can be minimized, as the material is abrasion-resistant.

The housing element 28 in its interior may comprise at least one receptacle for the arrangement of a further component such as for instance an electronic and/or electric component of the pig 24. This component can be for instance a positioning system for determining a position of a pig 24 within the pipeline 26 relative to the latter. As further components in the housing element 28 for instance an energy supply device may be comprised, which serves for providing at least one component of the pig 24 with energy, with this component being driven by means of energy. Moreover, as component in the housing element 28 at least one sensor and/or a receiver, a data processing device, as well as a data storage device may be comprised.

Moreover, as component a capture element that can be seen from FIGS 4 and 5 in the present case in the form of a para- chute 44 in a stowed position of the parachute 44 can be received in the housing element 28. The parachute 44 therein is adjustable from a stowed position into a use position shown in FIGS 4 and 5. In the use position the parachute 44 serves for capturing a fluid flowing through the pipeline, wherein the fluid is for example a liquid or a gas. As a consequence of the capturing, a momentum of the fluid is transferred to the parachute 44 and further to the pig 24 as a whole, as the parachute 44 is coupled via ropes 46 to the housing element 28. By way of this transfer of the momentum the pig 24 by means of the fluid in the pipeline 26 can be moved relative to the latter, without a separate drive being provided.

As further component in the housing element 28 also at least one pump can be arranged, by means of which for moving the rolls 40 between the retracted position and the extended position a fluid is conveyable.

In the present case the fluid for moving the rolls 40 between the retracted position and the extended position is the fluid flowing through the pipeline 26, as will be explained in the following. The pump, which is not shown in the figures, is fluidically connected with a surroundings of the pig 24 via at least one channel. Via the channel the pump can suck in the fluid that is flowing through the pipeline, in order to thereby move the further lever elements 36 and thereby the rolls 40 from the retracted position into the extended position.

For moving the further lever elements 36 between the extended position and the retracted position the respective, elastic or flexible volume elements in the present case in the form of bellows 48 are provided. One of the bellows 48 each therein is arranged between two of the lever elements 36 and supported on both sides each on one of the lever elements 36. In the retracted position shown in FIG 3 the respective bellows 48 are folded up and accordingly have a small volume. In order to now move the rolls 40 into the extended position, by means of the pump fluid is sucked in from the pipeline 26 and thus from surroundings of the pig 24 via the channel and con- veyed into the respective bellows 48. As a consequence the respective bellows 48 are filled with the fluid, thereby unfolded and accordingly enlarged in the size of their volume. Thereby the movement of the lever elements 36 and together with these of the rolls 40 from the retracted position into the extended position is caused.

In order to move the further lever elements 36 from the extended position back into the retracted position, the pump is reversed in its conveying direction in comparison with the moving of the further lever elements 36 from the retracted position into the extended position, so that by means of the same pump now the fluid is conveyed out from the bellows 48 and via the channel back into the pipeline 26. As thereby the bellows 48 no longer are filled or only slightly filled with fluid, a pressure prevailing in the pipeline 26 and thus in the surroundings of the pig 24 and caused by the fluid can fold up the bellows 48 via the further lever elements 36, so that thereby a movement of the further lever elements 36 and with these of the rolls 40 from the extended position into the retracted position is caused.

To the respective lever elements 36 also one sensor plate 50 each is attached, on which in turn sensors 52 are held.

Thereby the sensors 52 are movable along with the respective further lever element 36 between the extended and the retracted position. In the extended position the sensors 52 in comparison with the retracted position are positioned considerably closer to the inner circumferential shell surface 42 of the pipeline 26 or even touch the inner circumferential shell surface 42, so that for instance through the sensors 52 a wall thickness of the pipeline and/or a corrosion on the inner circumferential shell surface 42 can be determined. As the sensors 52 are held on the further lever elements 36 and can be moved along with them, an additional separate drive for moving the sensors 52 is not required.

With the pig 24 thus for moving the rolls 40 as well as the sensors 52 a pneumatic-mechanical drive comprising the pump, the channel, the bellows 48, and the parallelogram rod assemblies 30 is provided, by means of which the rolls 40 are mov- able in a simple, space-saving as well as time and cost- efficient way.

The sensors 52 may comprise touch-sensitive sensors and/or cameras, which are arranged outside of the housing element 28 and in the present case are attached to the respective lever element 36. Alternatively, the sensors 52 can also be arranged inside the housing element 28.

The sensors 52 are connected via corresponding lines with a data recording device, a data processing device, and a data storage device, which in the present case are housed as further components of the pig 24 preferably within the housing element 28. These lines may be fibre glass and/or metallic wires. Alternatively or additionally the sensors 52 can also be connected otherwise with the data recording device, the data processing device, and the data storage device. Such connection can be effected for instance by radio waves and/or an optical signal transfer system.

As can be seen from FIGS 4 and 5, the pig 24 in the present case comprises three pig segments 22, which can comprise each the described components, in particular the pneumatic- mechanical drive for moving the rolls 40. Preferably, in each of the housing elements of the pig segments 22 the above- described components are housed, so that the pig segments can be exchanged as desired. The pig segments 22 in this setup are connected in a flexible, i.e. articulated way, so that the interconnected pig segments 22 can be moved relative to each other. Thereby, the pig 24 can also be passed through bends and curves of the pipeline 26.

The bellows 48 are formed for instance from a flexible, i.e. elastic material such as a plastic, in particular rubber. The bellows 48 each may be formed also from a thin-walled metal sheet. The enlarging of the respective volume of the bellows leads to the fanning out or unfolding of the parallelogram rod assemblies 30, whilst the conveying of the fluid out from the bellows 48 causes the shutting or folding up of the par- allelogram rod assemblies 30 towards the housing element 28.

The functional principle of the pig 24 is demonstrated in particular in FIGS 4 to 6b. The pig 24 is inserted for instance by means of an insertion device at an insertion loca- tion into the pipeline 26. In this connection the parallelogram rod assemblies 30 to start with are in the retracted position. After insertion the pump conveys fluid into the bellows 48, so that the rolls 40 move into the extended position, and so that the rolls 40 come to bear against the inner circumferential shell surface 42. In this process the pump is operated in a first conveying direction, in which it conveys the fluid from the pipeline 26 into the bellows 48. Thereby the pig 24 can be supported via the rolls 40 on the inner circumferential shell surface 42. The pump then is deactivated, so that it conveys no further fluid into the bellows 48. Up to that point in time the parachute 44 preferably is still in its stowed position.

Once the rolls 40 have been moved into a position in which they bear against the inner circumferential shell surface 42, the parachute 44 serving as the drive element is opened and thereby moved from its stowed position into its use position. In the use position the parachute 44 captures the fluid flowing through the pipeline 26, whereby the pig 24 is drawn by means of the parachute 44 along the pipeline 26. This means in this process the flow of the fluid in the pipeline 26 is used for driving the pig 24. In this state a main operating state is given. This means that in the main operating state the parallelogram rod assemblies 30 are unfolded and the rolls 40 are in direct contact with the inner circumferential shell surface 42. In this main operation state the pig 24 is arranged at least essentially coaxially to the pipeline 26, wherein the housing element 28 at least essentially is positioned in the center of the pipeline 26. This can be seen from FIG 4. The drive element in the form of the parachute 44 is formed for instance from a flexible plastic or from a thin-walled metal sheet. Furthermore, the parachute 44 can be formed from an at least essentially pliable textile with flexible ribs for stretching out the textile. The corresponding construc- tion of the parachute 44 allows for the parachute 44 to pass even very narrow, locally arranged flow cross sections of the pipeline 26, so that the parachute 44 can move through such narrow flow cross sections. Owing to its flexibility the parachute 44 of its own accord can adjust to different flow cross sections of the pipeline 26, i.e. to cross sections of different sizes. At the same time the corresponding design of the parachute 44 avoids its complete collapse. For this purpose for instance elastic ribs are provided, which are elastically bendable and can accordingly adapt to narrow flow cross sections, and which, whilst elastically springing back, can unfold the parachute 44 again in larger flow cross sections. Thereby the parachute 44 is invariably in a position to capture fluid and as a consequence to move the pig 24 through the pipeline 26.

The parachute 44 in the present case has an at least essen- tially central passage 54, through which the fluid can flow. The passage 54 lends additional stability to the parachute 44.

Preferably it is envisaged that the sensors 52 in the extend- ed position, in which the rolls 40 are positioned to bear against the inner circumferential shell surface 42, are spaced from the inner circumferential shell surface 42. The distance of the sensors 52 from the inner circumferential shell surface 42 of the pipeline 26 in the extended position in this setup is ensured by the rolls 40, which provide for an at least essentially constant gap between the sensors 52 and the pipeline 26. This allows for inspecting the pipeline 26 from within under at least essentially constant operating conditions, in particular whilst the pig 24 moves within the pipeline 26 relative to same.

Instead of the parachute 44 as drive elements also at least essentially flexible surface formations can be employed that are arranged between the respective parallelogram rod assem- blies 30. Such a drive element is for instance a flexible or pliable foil, which for instance is arranged on the one side on one of the lever elements 32 and on the other side on another one of the lever elements 32 directly adjacent to the one of the lever elements 36.

Thereby the foil can move along with the corresponding lever elements 32 and is folded up in the retracted position. By moving the parallelogram rod assemblies 30 from the retracted into the extended position the foil is unfolded and stretched out between the lever elements 32 directly adjacent to each other, so that the foil can capture the fluid flowing through the pipeline 26 and as a consequence can drive the pig 24 in the described way. It is the main task of such drive element, i.e. for instance of the parachute 44 or the foil, to provide a sufficiently large tensile force as a consequence of the capturing of the fluid surrounding the pig 24, in order to thereby move the pig 24 along within the pipeline 26.

If a cross-sectional surface of the pig 24, which for instance is formed by the housing element 28 and/or the parallelogram rod assemblies 30 and which is hit by the fluid flowing through the pipeline 26, is large enough to effect together with the flow strength of the fluid flowing through the pipeline 26 a sufficiently large drive force for moving the pig 24 along the pipeline 26, possibly it can be done without an additional drive element such as the parachute 44 and/or the foil.

In FIGS 4 and 5 also a butterfly valve 10 for adjusting the flow of the fluid through the pipeline 26 can be discerned. A butterfly valve 10 is an obstacle, which diminishes the flow cross section of the pipeline 26 in comparison with flow cross sections arranged downstream and upstream of the obstacle.

If the pig 24 approaches such an obstacle, in the present case in the form of the butterfly valve 10, the pump is reac- tivated. However, the pump now is reversed in its conveying direction and accordingly is operated in a second conveying direction that is contrary to the first conveying direction, whereby the pump conveys the fluid present in the bellows 48 back out from the bellows 48 and via the channel back into the pipeline 26.

Due to the pressure prevailing in the pipeline 26 the bellows 48 are pressed together, from which a movement of the paral- lelogram rod assemblies 30 from the extended position into the retracted position results. Accordingly also the pig 24 is decreased in its outer diameter, in particular in its cross-sectional surface area, which in particular can be seen from FIG 5. Owing to the flexibility of the parachute 44 the parachute 44 can pass the butterfly valve 10 and move through it. As the pig 24 in the retracted position has an only very small outer circumference or an only very small cross- sectional surface area, also the pig 24 within the pipeline 26 can pass the butterfly valve 10 and move through it, so that the parachute 44 can draw the pig 24 within the pipeline 26 through the butterfly valve 10. This can be seen in particular from FIG 6a and 6b. After the pig 24 has passed the obstacle, in the present case in the form of the butterfly valve 10, the parallelogram rod assemblies 30 downstream of the butterfly valve 10 can be moved back from the retracted position into the extended position.

Once the pig 24 reaches for instance a removal station, the pig 24 can be removed from the pipeline 26.

The pig 24 explained by referring to FIGS 2 to 6b facilitates a top quality examination of predeterminable portions of the pipeline 26. Optionally the pig 24 may merely be activated in predetermined portions of the pipeline 26 and accordingly be brought into the extended position, so that energy as well as storage space for storing measuring data established by means of the sensors 52 can be saved and for instance can be saved for the predeterminable portion of the pipeline 26 actually to be examined.

Through the foldable parallelogram rod assemblies 30 the pig 24 can be used for different flow cross sections of pipelines as well as for pipelines, which have obstacles such as the butterfly valve 10. For instance the pig 24 facilitates a complete examination of the pipeline 26 from within. The pig 24 for instance can be equipped with corresponding tools allowing for an optical and/or acoustic examination of the pipeline 26 and/or by means of which otherwise methods for analysing the surroundings of the pig 24.

A further advantage of the pig 24 consists in that the transport, i.e. the flow of the fluid through the pipeline 26 need not be interrupted, even if the pig 24 should become stuck. Therefore, the determination of the position of the pig 24 within the pipeline 26 is less critical than is the case with commonly known pigs. Further, it is possible to adjust the velocity of the pig 24 relative to the pipeline 26 as required. It is possible that the velocity of the pig 24 is essentially smaller than the velocity of flow of the fluid flowing through the pipeline 26. Thereby a very precise and high resolution determination of measuring data by means of the sensors 52 is possible. Further, the pig 24 has only a very small weight as well as small outer dimensions, so that for instance the transport of tools is particularly simple and cost-efficient.

List of References

10 butterfly valve

12 pipe segment

14 flap

16 pivot axis

18 flow cross section

20 actuation wheel

22 pig segment

24 pig

26 pipeline

28 housing element

30 parallelogram rod assembly

32 lever element

34 lever element

36 further lever element

38 directional arrow

40 roll

42 inner circumferential shell surface 44 parachute

46 ropes

48 bellows

50 sensor plate

52 sensor

54 passage

Claims

1. A pig for cleaning and/or inspecting a pipeline, the pig comprising at least one housing element on which at least one support element is held, via which the pig that is movable through the pipeline in a direction of movement is supportable on an inner circumferential shell surface of the pipeline, characterized in that the support element is held on the housing in a way movable relative to the housing between at least one extended position and at least one retracted position, in which the support element in comparison with the extended position is arranged closer to the housing in a direction extending perpendicularly to the direction of movement .

2. The pig according to claim 1, characterized in that for moving the support element two first lever elements spaced apart from each other in the direction of movement are provided, the two first lever elements being held on the housing in a way pivotable about a respective pivot axis relative to the housing and forming a four joint assembly are connected with each other via a further lever element, which is connected with the first lever elements in a way pivotable about a respective pivot axis relative to the first lever elements.

3. The pig according to claim 2, characterized in that the support element is held on the further lever element.

4. The pig according to claim 3, characterized in that the support element comprises at least one roll, which is held on the further lever element in a way rotatable about a rotation axis relative to the further lever element.

5. The pig according to any one of the previous claims, characterized in that at least one pump is provided, by means of which a fluid is conveyable for moving the support element.

6. The pig according to claim 5, characterized in that the pump is fluidically connected with a surroundings via at least one channel, via which a fluid flowing through the pipeline is capable of being sucked in by means of the pump for moving the support element into the extended position.

7. The pig according to any one of claims 5 or 6, characterized in that at least one volume element is provided which for moving the support element by way of conveying the fluid by means of the pump into the volume element and out of the volume element is changeable in its volume.

8. The pig according to any one of the preceding claims, characterized in that at least one sensor is provided which can be moved along with the support element.

9. The pig according to any one of the preceding claims, characterized in that at least one capture element is provid ed for capturing a fluid flowing through the pipeline and fo driving the pig as a consequence of the capturing.

10. The pig according to claim 8, characterized in that the capture element is formed from a flexible material.

11. A method for operating a pig for cleaning and/or inspect ing a pipeline, in which the pig comprising at least one housing element and at least one support element held on the housing element for supporting the pig on an inner circumfer ential shell surface of the pipeline is moved in a direction of movement through the pipeline, characterized in that the support element held on the housing in a way movable rel ative to the housing between at least one extended position and at least one retracted position, in which the support el ement in comparison with the extended position is arranged closer to the housing in a direction extending perpendicular ly to the direction of movement, is moved between the retracted and the extended position.