EP0918574A1

EP0918574A1 - Pipe cleaning apparatus for oil or gas pipelines

Info

Publication number: EP0918574A1
Application number: EP97928390A
Authority: EP
Inventors: Christian Geppert
Original assignee: Transglobal Ltd
Current assignee: Transglobal Ltd
Priority date: 1996-07-18
Filing date: 1997-07-10
Publication date: 1999-06-02
Anticipated expiration: 2017-07-10
Also published as: AU3270497A; EP0819480A1; US6070285A; DE59704470D1; EP0918574B1; WO1998003274A1

Abstract

Pipe cleaning apparatuses for oil and gas pipelines are disclosed, in which a shield with a cleaning device is moved forward through a stream of liquid in the pipeline. The shield forms one or several passages for a passing stream of liquid within the pipeline in order to build up a desired pressure and is provided on its rear side with braking means which prevent the speed of advancement from rising to an undesirable extend in that at least one clamping element momentarily adheres to the pipe wall and moves relative to the braking means. This movement is kinematically transmitted to a hydraulic displacer which generates a secondary stream of liquid which is braked through at least one throttle and thus determines the speed between shield and pipe wall.

Description

Pipe cleaning device for oil or gas pipelines

The invention relates to a pipe cleaning device for petroleum and gas pipelines which have deposits, for example in the form of paraffins, which device is pushed through the pipeline with a liquid flow for cleaning purposes, the device having a shield which has one or more openings for a passing liquid flow forms in order to form an intended flow resistance in the pipeline, the shield being coupled to a braking device and having a cleaning device on its front side.

Depending on the production area, oil and gas pipelines tend to deposit solids and viscous products such as paraffins on the walls. Such pipes grow particularly quickly if they are laid in a cold environment, such as on the seabed for offshore production. In such a case, attempts are being made today to mechanically clean the pipes, as long as they have not yet been completely clogged, with a pipe cleaning device which is moved by the pipe flow. This type of pipe cleaning, the "pigging", is only partially solved, since it has to be used over long distances, ie several miles. The devices often get stuck in the deposits and the cleaning head fails its service. The only way out is to cut out sections of pipe and clean them with boring bars, which is an extremely expensive undertaking for pipelines that are laid on the seabed if you imagine that

Pipe pieces welded together again after cleaning. Need to become.

Oil companies and suppliers are therefore endeavoring to develop pipe cleaning devices that can be transported over long distances by a liquid flow without any cable or hose connections, whereby the liquid flow can be opposed by a pressure of 40 to 60 bar. A brochure from GIRARD INDUSTRIES INC., 6531 North Eldridge Pkwy, Houston, TX 77041-3507 shows in a brochure from 1994 so-called "cleaning pigs", which consist of two plate-like plastic disks between which cleaning brushes are pressed radially outwards on a connector . The whole structure is moved forward with a liquid flow in the pipe to be cleaned, although some designs can also be moved in both directions. The plate-like discs push and pull the brushes in between to scrape dirt off the pipe wall. The pressure difference before and after the "Cleaning Pig" depends on the flow resistance of plates and brushes and the friction of plates and brushes on the pipe wall. Similar arrangements are offered by GIRARD in a brochure with Copy right 1988 as "F.H. Maloney Spring loaded Pipeline Cleaning Pigs".

A similar facility is proposed in Shell Oil Company application US Serial No. 08/396807 of March 2, 1995. The device consists of a sealing body, which can be rotated in the direction of flow mounted cleaning head with nozzles to remove solids such as wax from the inner tube wall. A brake device is attached to the sealing body, which presses radially with brake shoes against the pipe wall so as to prevent the movement of the

Braking the sealing body in the pipe flow and building up a pressure difference. This pressure difference is used to provide the nozzles with a liquid jet via internal by-pass lines and to set the cleaning head in rotation.

Furthermore, the U.S. patent shows 4,920,600 a pipe cleaning device consisting of a cleaning head with scrapers widening radially against the direction of flow. The cleaning head is axially fixed to a support body designed as a tube plug, which has two sealing plates, each consisting of a plurality of mutually movable elements, in order to transmit pressure surges driven by the flow to the cleaning head.

A disadvantage of the devices listed here is that they are limited to small incrustations and deposits because they simply get stuck in thicker layers of deposits. Furthermore, the thickness of the deposits to be encountered cannot be predicted easily. For this reason, the

Use of such devices always involves a high risk of getting stuck and the effort involved in removing pipeline sections.

The object of the invention is to provide a safe pipe cleaning device for petroleum or gas pipelines. This object is achieved with the characteristics of independent claim 1, in that the braking device has at least one clamping element, that currently adheres to the pipe wall and moves relative to the braking device in order to displace a secondary liquid with this movement, which is braked via at least one throttle point and thus determines the speed between the shield and the pipe wall.

This arrangement ensures that the pipe cleaning device does not increase with it

Feed speeds at which the cleaning head can jam move forward in the axial direction and that the feed movement can inevitably and autonomously be carried out. Braking energy is released by throttling to a secondary liquid flow, which heats up the pipe cleaning device and transfers the heat to the passing liquid flow and the environment via the device.

Another advantage is that some of the braking forces are coupled to the feed rate in such a way that the braking force also increases with the speed of the pipe cleaning device in the pipeline. It is therefore sufficient to stop the flow of liquid

Regulate the entry of the pipeline with a regulator to a constant liquid flow in order to obtain the same conditions everywhere along the pipeline for braking to a predetermined feed rate and for actuating the cleaning device. Due to the fact that the breakthroughs for a passing liquid flow are defined in the shield and cleaning head, a predetermined pressure difference across the shield can be maintained at a certain braking force coupled with a feed rate. Since in the present case the braking force is dependent on the advancing speed of the plate with respect to the pipe wall in an increasing characteristic, it is approximately constant A predetermined pressure difference at a predetermined feed rate. With such an arrangement, it is therefore possible to select the pressure difference across the shield so high that it can be used to feed nozzles that remove the deposits as in the case of

Dismantle water jet cutting at a distance in front of the sign into portable lumps or chips. Because the feed rate is limited to small values despite the relatively high pressure drop across the shield, nozzle jets can cut away the deposits down to the bottom of the pipe wall due to the low speed fluctuations.

The braking force is made up of three possible components: possible machining forces on the cleaning head in front of the shield, the sum of the sliding friction forces between the pipe cleaning device and the pipeline against the feed direction, and at least one partial braking force coupled with a certain feed speed. While the

Machining forces and the sliding friction forces with their fluctuations represent disturbance variables, the partial braking force, which is dependent on the feed speed, compensates for fluctuations of the first two in accordance with their throttle characteristics, in terms of the pressure force and

Feed rate are coupled. The smaller the disturbance variables, the more constant the feed rate. Corresponding to a throttle characteristic in the secondary fluid flow that has been achieved at least at times, an approximate dependence on the square of the feed speed can be generated for the partial braking force. This disproportionate dependency means that with relatively small changes in the feed rate, large ones Differences in the partial braking force are generated to compensate for disturbances.

In the case of a pipe cleaning device without mechanically machining cleaning elements, there are also smaller disturbances in the braking force. Thus, with an arrangement of nozzles cutting with liquid jets, only the momentum forces generated by jet steering are constant, so that practically only the fluctuations in the sliding friction forces have to be compensated for by changing the partial braking force, which, as described above, only leads to small changes in the feed rate leads.

For the function of the braking device, the clamping element, which determines the feed rate based on the force to be compensated, is as safe as possible, i.e. be connected to the pipe wall without slippage. It is therefore necessary to generate a sufficiently large radial force between the clamping elements and the tube wall in order to achieve momentary adhesion of the contact surface of a clamping element. Since the pressure on the contact surfaces cannot be increased arbitrarily due to inadmissible deformations on the inner pipe wall and because there are limits to the generation of large constant radial forces with fluctuating inner pipe diameters, it is advantageous to connect several

To use braking devices. This allows large pressure differences to be generated on the shield, as are necessary, for example, for cutting deposits with liquid jets.

Further advantageous developments result from the dependent claims 2 to 23. A first possibility is to design clamping elements as rotating rollers pressed radially against the pipe wall, which in turn, with their rotation, displace a secondary liquid in predetermined volumes and to brake the resulting secondary liquid flow with throttles. So a role, for example, like a push crank on hydraulic brake cylinders with throttle points, respectively. Shock absorbers act, with the use of multiple rollers and multiple shock absorbers on one roller compensating for the fluctuating force / travel characteristics of the individual thrust cranks.

Another possibility is that the roller drives a volumetric pump such as a vane pump, the volume flow of which is braked via throttling points.

Another option is one

Displacement pump, which is designed as a multiple piston pump. The pistons are arranged in a star shape in a first part that rotates with the roller and are guided radially along a shaft line during their rotation in order to draw in secondary liquid with two check valves from a low-pressure line and to discharge it into a high-pressure line.

When using idling braking rollers in pipelines with a diameter of a few inches, you quickly reach design limits. A role has the advantage that it can overcome obstacles such as weld seams or fluctuations in the diameter of the pipeline, provided that it is appropriately flexible.

On the other hand, the roller should generate the greatest possible radial contact force and its rotation into displaced volume via a kinematic chain a secondary liquid. Both of these requirements require a relatively large amount of space in the pipeline. It has therefore proven to be advantageous to use a gas accumulator as a soft but strongly prestressed spring element, which can be arranged spatially displaced from the roller and which acts with its pressure on a high-pressure cylinder, which braces the roller radially. Because a liquid medium is used in the high-pressure cylinder, leakage losses on the cylinder can be kept small.

Another requirement for the points of application of braking forces would be that the radial forces do not generate any tilting moments that cause the supporting housing parts of the pipe cleaning device to tilt. It would be ideal if the radial forces were in one

Lift the transverse plane to the longitudinal axis. In theory, one would have to arrange at least two opposing roles in a cross-section. In practice, however, it has been shown that, for reasons of space, it makes more sense to provide a sliding shoe that grinds against the tube wall on the opposite side to a roller and is pressed on with an equal but opposite radial force as the roller. Tests have shown that with a cambered slide shoe made of wear-resistant material in the relatively low range considered

Feed speeds only slight fluctuations in the magnitude of the sliding friction force occur. This has the advantage that part of the necessary braking force can be generated via approximately constant sliding friction and the braking device in the secondary fluid area can be dimensioned correspondingly smaller. It goes without saying that the radial contact pressure may only be selected so high that the roller with its partial braking force determines the feed rate. For such an arrangement, it has proven to be advantageous if the radial contact pressure has a component that is proportional to the pressure difference across the pipe cleaning device. Such a requirement is solved constructively elegant that the radial

Contact pressure is generated via hydraulic pistons that are exposed to the high pressure of the secondary liquid upstream of the throttle and that there is a reservoir for secondary liquid on the low-pressure side of the secondary liquid, which, in addition to a pressure component generated by a spring, has a pressure component that corresponds to the pressure difference is generated via the pipe cleaning device. In this way, a radial pressing of the braking device is first achieved by the spring-generated pressure component, i.e. reached by roller and slide shoe. The positive displacement pump drives the positive displacement pump, which generates a high pressure limited by the throttle as the number of revolutions increases, which simultaneously acts on the radially pressing hydraulic pistons. With a sensible adjustment of the piston surfaces to the pressure generated by the pump and throttle, radial pressure forces are generated which are so great that the roller does not slip on the pipe wall and which, conversely, are not so large that the braking device is blocked by the sliding block.

A further embodiment of a braking device with a controlled feed rate consists in gradually using two axially offset clamping elements, the radial forces of which vary in each case

Cross-section cancel each other and limit the stroke of the momentarily clamping element in the axial direction with a piston that moves a secondary, throttled liquid flow, while the second, momentarily not clamping element in one Starting position is moved, which moves a secondary throttled liquid flow when changing the clamping of the second element. When changing the clamping, it makes sense to provide an overlap of the clamping times so that no uncontrolled sliding can occur. The sequence then looks like that at the end of the braked stroke for the first clamping element there is a standstill, in which the clamping of the second clamping element takes place in its starting position. When the second clamping element has been clamped, the clamping of the first clamping element is released, for example via a pressure switch, the pipe cleaning device only hangs on the second clamping element and makes an axial movement relative to the second clamping element

Feed movement with controlled, almost constant speed. The movement of the pipe cleaning device in the pipeline is then practically gradual and is like that of an artist who can be lowered on a rope without crossing or sliding his hands. This

At the same time, comparison also shows how difficult it would be to maintain a constant feed rate only by means of radial pressure and sliding friction.

Basically, any sign can be used on a sign with the braking devices described here

Attach cleaning heads and improve their effectiveness by limiting the feed rate.

Simultaneously with the almost constant feed, a preselectable pressure difference across the plate is also offered, which makes it possible to provide hydraulic motors for auxiliary drives in the plate; be it that pressure booster for the braking device or mechanical Drives for a cleaning device are driven.

With a high pressure difference across the shield, a new concept for one can be used for the brake systems described here as well as for other brake systems in general

Implement the cleaning facility directly on the sign. A baffle grille is pushed in front of the shield on a central mounting arm, which is arranged transversely to the pipe axis and whose dimensions are slightly smaller than the expected free core of the contaminated pipeline. In the shield itself there are nozzles with different jet directions, some of which are directed towards the pipe wall between the baffle and shield to remove the dirt in the form of lumps and chips, while another part is directed towards the baffle to remove the lumps and Swirl chips and beat them into smaller pieces on the baffle and remove these pieces with the passing liquid flow in the free core of the dirty pipeline in front of the baffle.

With their jet, the nozzles generally also have a directional component directed forward in order to keep the shield free from dirt. If the nozzles are distributed in concentric circles to the pipe axis, a uniform cross-section that is independent of the angle of rotation can be created in the deposits on the pipe wall. In particular, it is advantageous if the sign near the tube wall has a protruding ring with a plurality of nozzles for the removal of residual deposits in order to cut the web for the sign freely. The nozzle jets can also have an essential component in the circumferential direction in order to cut transversely to the feed direction and at an acute angle to the tube wall. When the momentum of the impulses from the nozzles on the shield and cleaning head is largely cancels, the coupling part between the shield and the braking device is subjected to less torsion.

Since petroleum and gas pipelines have curvatures, especially at their beginning and at their end, the radius of curvature of which corresponds to a few pipe diameters, pipe cleaning devices are also composed of a plurality of movable members which are connected to one another via couplings. When driving through a bend, such couplings must be able to accommodate the deflections due to their arrangement and design. As soon as the couplings are subjected to pressure in the axial direction when driving through pipe bends, there is an increased risk that the links wedge in the pipe. It is therefore an advantage if there is always a certain tensile stress between the members of a pipe cleaning device. For a pipe cleaning device that has a shield as the front link and an effective braking device as the rear link, this condition is fulfilled as long as the shield does not drive into an obstacle that is too large. In such a situation of a stuck pipe cleaning device, it is advantageous if with a reversal of the liquid flow i.e. Infeed from the other end of the pipeline the functions of the links are swapped. For this purpose, a reversing plate is attached to the last link, which forms a substantially greater flow resistance when the flow is reversed, and a type of backflow device, for example a non-return valve, is provided in the original plate, which additionally in the opposite direction of flow

Free passage area. Since no limitation of the speed is necessary for the backward movement in the already cleaned pipe and a still effective braking device would rather lead to wedging between the braking device and the shield it makes sense to reverse the effect of the braking device with the flow reversal, which can be triggered, for example, by the release movement of the kickback mechanism on the shield.

For example, flaps such as a "butterfly" valve can be provided as the reversing plate, the flap wings only being released in the open position when the flow reverses, for example, together with the release of the braking effect, in order to reliably preclude mechanical blocking during the forward movement.

The invention is described below on the basis of exemplary embodiments:

Fig. 1 Schematic of a shield with a cleaning head, which can be used for different braking devices, wherein a hydraulic motor is also provided in the shield as a drive for actuators in the cleaning device;

2a εche atisch a pipe cleaning device with a braking device that allows a gradually controlled feed from a cleaning head;

Fig. 2b schematically shows an internal piping for a secondary liquid flow used in Fig. 2a;

Fig. 2c schematically shows a hydraulic circuit for the interaction of clamping elements and brake pistons in Fig. 2a, b. 3a, b schematically an embodiment for clamping elements according to Fig. 2a;

Fig. 4 shows schematically parts of a braking device according to Fig. 2a;

5, 6 schematically a pipe cleaning device with a

Braking device, which is connected to the shield via a deflection roller and which allows a step-by-step controlled feed via a single, double-acting piston.

7 schematically shows a hydraulic circuit for clamping elements according to FIGS. 5 and 6;

Fig. 8 schematically shows a shield with a cleaning head, which can be used for different braking devices, with a pressure accumulator for hydraulic on the shield

Connects clamping devices and a hydraulic motor is installed in the shield to compensate for leakage losses on clamping devices;

9, 10 schematically, longitudinal sections offset by 90 ° through a braking device with idler rollers which determine the feed rate by driving a throttled volumetric pump;

11, 12 schematically offset by 90 °

Longitudinal sections, through a braking device with a rotating roller, which determines the feed rate by in the manner of a crank mechanism of two shock absorbers offset by 90 ° are braked;

FIG. 13 schematically shows a cross section through the roller in FIG. 11;

14 schematically shows a cross section through a clamping cylinder in FIG. 11;

Fig. 15 schematically shows a fold-out

Backward sign to pull back a cleaning device in reverse flow direction;

16, 17, 18 schematically show a longitudinal section through a pipe cleaning device with a braking device which has a sliding shoe and pressure rollers, with a center piece which has a reservoir for hydraulic fluid, and with a shield which has a rotatable ring with cleaning nozzles;

19 schematically shows an enlarged section of a radial piston pump from FIG. 16;

20 schematically shows an enlarged section for a friction shoe mounted on swivel arms, which inevitably folds in when reversing due to the wall friction;

21 schematically shows a variant of FIG. 18, in which the rotatable ring is guided in its rotational movement via elastically supported rollers;

22 schematically shows an enlarged detail from FIG. 21 with such a guide roller; and 23 schematically shows a top view of a guide roller from FIG. 22.

The figures show pipe cleaning devices for oil and gas pipelines, in which a shield with a cleaning device is moved forward by a liquid flow in the pipeline. The shield forms one or more breakthroughs in the pipeline for a passing liquid flow in order to build up an intended pressure and is provided on its rear side with a braking device that is unintentionally large

Feed speeds thereby prevents at least one clamping element from currently sticking to the pipe wall and moving relative to the braking device. This movement is kinematically transmitted to a hydraulic displacer, which is a secondary one

Liquid flow generated, which is braked via at least one throttle point and thus determines the speed between the shield and the pipe wall.

FIG. 1 shows a shield 3 with a cleaning device 5, which is coupled, for example, to braking devices 8 according to FIGS. 2 to 7, which limit its feed rate. In a pipeline 1, a liquid stream 2 drives the shield 3 in front of it, the outer housing 50 of which is sealed against the pipeline 1 via packs 42 and is guided at the same time. The packs 42 are secured by a retaining ring 51. Breakthroughs 45, 46, 47 exist over the shield; 44, 43, 49, 36, 37, 38, which allow a passing liquid flow 7 and build up a pressure of, for example, 30 bar against the liquid flow 2 at a predetermined feed rate of the shield 3. This pressure can be seen on the sign 3 regardless of the location of the sign in the Build the pipeline if the liquid flow 2 is regulated to a constant amount at the input end.

In the inner housing 48, a hydraulic motor 15 formed with gear wheels 56 with cam disks 88 acts as a pressure booster via a pump system 15 with pistons 58 and check valves 61, 62 on the suction and pressure lines 59, 60 of a hydraulic auxiliary system which, for example, maintains the clamping force radial clamping elements 9a, 9b can be used. The cross-section of an inlet 45 and an outlet 46 are coordinated with one another in such a way that the hydraulic motor 55 cannot rotate in the direction of rotation 57 beyond a specific speed at a predetermined pressure difference.

An actual cleaning device 5 is integrated in the shield 3 on its front side 4. A baffle grille 39, which has bores 52, is attached to an arm of the outer housing 50 concentrically with the pipe axis 14. The baffle 39 has an outer diameter that is smaller than that

Is the inside diameter of the expected deposits 6, and - since it projects at a distance from the shield 3 - a cavity 40 which is limited by the tube wall 1 and deposits 6 not removed. In the shield 3, nozzles 36, 37, 38 are provided, which are fed with flushing liquid under pressure via connecting channels 44, an annular channel 43 and pilot bores 49. Some of the nozzles spray against the tube wall 1 in order to cut away 3 lumps and chips from deposits 6 during the advancing movement of the shield. Another part of the nozzles injects directly or indirectly into the cavity 40 in order to break up the detached lumps and chips to a size that can pass through the baffle 39 and to advance the particles in front of the baffle 39 with the to transport passing and displaced liquid stream 7 away. The small particle size offers a good guarantee that no blockages will occur. In front of the packs 42, the shield 3 has a ring 41 near the tube wall with nozzles 36, which remove any residual deposits and cut the web for the packs. Between the inner housing 48 and the outer housing 50 there is an annular channel 53 which is connected to the space in front of the baffle 39 via a connecting bore 54 and which provides the reference pressure in front of the baffle 39 for pressure-actuated switching elements.

FIGS. 2a, 2b, 2c, 3a, 3b, 4 describe the principle and design details of a braking device that can be combined with a sign according to FIG. 1.

The basic arrangement of the elements can be seen in FIG. 2a, the internal piping 65, 66 with an adjustable throttle 21 for braking the secondary liquid 10 being drawn out in FIG. 2b, while FIG. 2c shows a hydraulic circuit for the

Clamping elements 9a, b shows. The first clamping element 9a is clamped in the tube 1 with clamping jaws 11a and brakes the shield 3 via the braking devices 8a, 8b in between. The force flow for the braking force goes from the clamping element 9a via a clutch 77a to the piston rod

27a and piston 13a of the first braking device 8a, secondary liquid 10 being displaced by the piston 13a via a dropping point 21 and the piston 13b of the second braking device 8b and an associated piston rod 27b and clutch 77c a second one

Clamping element 9b moved in idle in the feed direction. The actual braking movement is transmitted from the brake cylinder 12b and from there via tension elements 24, for example wire ropes, to the shield 3. Instead of pure tension elements 24 tie rods mounted on joints are also possible, which can also transmit compressive forces within the scope of their kink length. The jaws 11b of the second clamping element 9b are retracted. Guide fins 80 are attached to the housing parts and hold the housing parts approximately in the middle of the tube. Leakage losses of the secondary liquid 10 can be compensated for by a pressure accumulator 64 traveling with it. Due to the fact that pistons 13a, b and cylinders 12a, b have the same dimensions, the pistons reach their end positions practically simultaneously, in such a way that they are closest to each other at one time and the farthest apart the other time.

In FIG. 2c, the shield 3 with a pump system 15 and a pressure limiting valve 20 is shown in the hydraulic diagram. Pressure accumulators 63, 68 supplement any leakage quantities on the high-pressure and low-pressure sides. Pressure line 60 and suction line 59 go in the form of hydraulic hoses, which are guided parallel to the tension elements 24, from the shield 3 to the second braking device 8b and further as branches 60a, 59a via the coupling 77b to the first braking device 8a, the structure of which can be seen in FIG . Switching valves S11, S12 and S21, S22 are attached to the braking devices, which, depending on the piston end positions, reverse the clamping on the clamping elements 9a and 9b with an overlap of the clamping, so that no undesired slippage occurs with respect to the tube wall 1.

Starting with a position according to FIG. 2a, the following valve position results: - Control valve S12 protrudes through

Check valve because the second clamping element 9b is at low pressure.

Switch valve Sll passes on the high pressure from pressure line 60a.

=> Jaws 11a are extended under pressure.

Switching valve S22 stands for passage in both directions because the first clamping element 9a is at high pressure.

- Switching valve S21 passes on the low pressure from intake line 59a

-z-> jaws 11b are retracted.

When the end position is reached in which the pistons 13a, 13b are the farthest apart, the following switching steps are carried out:

Switching valve Sll is switched to low pressure, which however cannot be passed on because the pressure to switch S12 is missing. Clamping element 9a remains clamped.

- Switching valve S21 is switched to high pressure and can pass on the high pressure to the clamping element 9b regardless of the position of the switching element S22.

= Jaws 11b are extended and high pressure builds up when the jaws are fixed, which now builds the switching valve S12

Continuity switches in both directions. = Jaws 11a are retracted.

The second clamping element 9b is now rigidly connected to the piston 13b in the axial direction. The shield 3, which is suspended from the second brake cylinder 12b, presses the secondary liquid back in the opposite direction via the throttle line 65 and at the same time brings the first piston 13a back into its starting position. In this position, as described above, the pistons 13a, 13b change direction with a short "stop" during the overlapping clamping.

The shield moves in steps in this way, the speed being adjustable with the throttle 21.

The spatial arrangement of the components of the braking device 8a is shown in FIG. The brake cylinder 12a with base 22 and intermediate base 23 forms with a spacer 16a a supporting housing for the remaining elements. In the intermediate piece 16a there are windows 30 which facilitate access and control. A coupling 77b with a spherical body 33 and a socket connects the intermediate bodies 16a, 16b of the two braking devices 8a and 8b. The socket has longitudinal slots 31 which prevent the coupling from twisting via pins 32 embedded in the spherical body 33. The spherical body 33 is dimensioned so large that hydraulic lines 65, 66, 59a, 60a, 158a, 158b can be put through. The permissible axis deflection between the pan and the ball body 33 is limited in order not to expose hydraulic hoses to unnecessary loads. The switching valves S11, S12 are attached at the transition to the intermediate floor 23, the switching valve S11 storing an end position in each case until the next end position is reached. The connecting line 75a to the clamping element 9a is first led to the intermediate floor 23 and then continues as a hydraulic hose on the end face of the piston rod 27a and as a bore in the piston rod 27a up to the coupling 77a. In order to prevent inadmissible rotation of the piston rod 27a, it can be guided along the intermediate piece 16a via a guide cam 29 on the end face.

The structure of the second braking device 8b with its clamping element 9b is analog.

Clamping elements 9a, 9b are shown in FIGS. 3a, 3b. The piston rods of the associated clamping pistons 19 protrude into the central part 76 and act on a displacer 18 with inclined surfaces 81. Sliding blocks 17, which are designed as clamping jaws 11a, 11b, move movably to the inclined surfaces 81 and to counter surfaces 82 and project through slots 83 through them Contour of the middle parts 76 out. Bottoms 34 form the end of the clamping cylinders 78. A return spring 79 embedded in the cylinder head 39 causes the clamping to be released at low pressure and this

Retracting the jaws 11a, 11b. The clamping element 9b is passed here on its outside by the tension elements 24 and the supply lines 60, 59. However, it would also be possible to design the piston rods as hollow piston rods mounted on both sides and the pistons 19 with a larger central bore in order, for example, to accommodate a central pull and push rod, which at the same time also houses the lines 59, 60.

Another embodiment of a step by step

The braking device is shown in FIGS. 5, 6 and 7, in which the braking device 8 only has one brake piston 13 with a piston rod 28 that is continuous on both sides and the displaced secondary liquid 10 is expanded via a throttle 21 on the piston 13. The tension elements 24 (once dashed, once pulled out) are attached as flexible cables or straps to the braking device 8 and to the clamping element 9b and are guided in a loop 25 over a deflection roller 26 on the shield 3. As a result, the shield 3 only carries out half of the relative movement between the housing of the braking device 8 and the clamping element 9b. In FIG. 5, the clamping element 9a clamps with clamping jaws 11a and blocks, via a coupling 77a, an intermediate piece 16 from the housing of the braking device 8 and thus the one end of the tension elements 24, the other end of which generates a tensile load on the second clamping element via a deflection roller 87. This traction pulls over the second

Clamping element 9b and, via a coupling 77c, the piston 13 into a front end position, the displaced secondary liquid 10 reaching the rear cylinder space via a throttle point 21, which can be installed in the piston, for example. That secondary

Liquid flow can just as well be guided past an adjustable throttle on the outside of the cylinder.

In Figure 6, the jaws 11b of the second clamping element 9b are extended, while the first

Clamping element 9a the jaws 11a are retracted. This causes the piston 13 to stand still relative to the pipe wall and the shield 3 to move forward from the housing 16 at half the speed. The piston 13 thus reaches the intermediate floor 23 on the other side of the cylinder, while the secondary liquid 10 can be expanded in the opposite direction via the same throttle point 21. An advantage of this arrangement is that no piping is necessary for the secondary liquid. The Heat generated by throttling is dissipated to the environment via the outer cylinder jacket. A further advantage is that all switching valves S30, S12, S22 for reversing the clamping are accommodated on the second clamping element 9b. FIG. 7 shows a hydraulic diagram from which a circuit can be seen with which the clamping is reversed. The shield 3 houses a pump 15, a pressure relief valve 20 and a high-pressure and low-pressure accumulator 63, 68, which are connected to the second clamping element 9b via lines 59, 60. The connection is made using rollable hydraulic hoses. A switching valve S30 taps the end positions from the piston 13 indirectly on the tension element 24, a switchover taking place each time an end position is reached, ie an end position reached remains stored until the next one is reached. The supply line to the first clamping element 9a is routed via a check valve in the switching valve S12, which is switched over to passage in both directions as soon as on the second

Clamping element 9b the high pressure is reached by clamping. So there is again a small overlap in the clamping. The clamping elements 9a, 9b which are described in FIGS. 3a and 3b can be used. An advantage of these arrangements is that the pipe cleaning device only stops during this short overlap period for safety reasons and that the movement sequence is inevitably controlled by a sequence control that is dependent on the position of the brake cylinder.

Another shield 3 with pressure booster 135, gas storage 95 and cleaning device 5 is shown in FIG. The cleaning unit 5 is integrated in the shield 3 on the downstream side. It consists essentially of nozzles 36, 37, 38 and one the baffle 39 upstream of the nozzles, which creates a cavity 40 towards the tube wall 1, in which the nozzle jets for the targeted smashing of deposits 6 are better kept under control. Some nozzles 36, 37 are directed towards the deposits 6 on the tube wall. Other nozzles 38 are directed forwards towards the pipe axis 14 in order to suck detached particles into their liquid flow and to reduce these particles to a size on the housing or on the baffle grid, which allows them to wash away to the front with the liquid flow 7 that passes through them. The baffle 39 should also prevent premature detachment of the deposits and thus prevent pipe blockages. The lattice structure is reached through holes 52. A ring 41 near the tube wall with nozzles 36 prevents residual deposits from remaining in the area of sealing packs 42. An outer housing part 136 carries the packings 42 which seal to the tube wall 1 and which are fixed by means of retaining rings 142. An inner housing 146 is connected to the outer housing part 136 via a front and a rear cover. There are large passage areas 137, 138 between the outer and inner housings in order to supply the nozzles 36, 37, 38 with liquid without large pressure losses. As a pressure difference across the shield 3, pressures of 20 to 30 bar have proven to be sufficient to dissolve incrustations of paraffins with the nozzles. Higher pressures are possible, keeping in mind that the braking devices 8 must be designed to be correspondingly powerful.

A backflow device 141 is installed in the shield 3, which releases a large additional flow cross section when the flow direction is reversed. A piston 141 preloaded by a spring 143 is mounted in the inner housing 146 and gives the reverse Flow direction a passage surface 140 and mouths 47 free. With normal flow in the feed direction, the piston 141 is acted upon in addition to the spring 143 with the differential pressure on the shield, which the rear through holes in the inner housing

Piston area reached. This space 139 is bounded at the rear by a commercially available pressure booster 135, the connection 133 for the drive opens into this space, while a low-pressure connection 144 in the form of a connecting pipe 145 with play through the piston

141 protrudes into the mouth area 47 on the baffle grille 39 in order to deliver the rinsing liquid driving the pressure booster there. The pressure booster 135 is an Iversen HC2 product from Sherex Industries Ltd., 1400 Commerce Parkway, Lancaster, NY, USA. The pressure booster 135 has a high-pressure outlet 134, in which flushing liquid is present at a presettable increased pressure, for example to compensate for leakage losses in a high-pressure system during pipe cleaning. In the present example, the pressure acts via a hydraulic hose 148 and a connecting pipe 157, which is locked with a nut 156, on the liquid side 153 of a gas accumulator 95. The gas accumulator 95 is equipped with a separating piston 154 to form the liquid 153 and forms a soft, strongly pre-tensioned spring in order to pretension clamping cylinder 93 via an approximately constant pressure, ie independently of the piston path in the clamping cylinder, via a connection 155. The delivery pressure of the pressure booster 135 is somewhat lower than the specified gas pressure when the clamping cylinders are extended, in order to reload liquid only in the event of leaks in the liquid part. Clamping cylinders 93 with permanent clamping action are described later in FIGS. 9 and 11. An outer housing 152 of the gas accumulator 95 forms the pan with a cover 151 Ball joint 149, which is secured to the extension 147 of the inner housing 146 via a retaining ring 150. The pressure booster 135 is designed in such a way that a pilot valve connects the liquid area 153 with the

Connection tube 145 short-circuits. The pressure in the liquid region can thus be released to a substantially lower pressure than the gas cushion has when the separating piston 154 stops, and there is practically no more jamming, which is desirable for reversing. This reduction in pressure can also be used to trigger auxiliary movements which are advantageous for reversing.

FIGS. 9 and 10 show a braking device 8 in which two rollers 89 connected via a bridge 128 are pressed radially against the pipe wall with the bridge 128. The pressure is applied by a clamping cylinder 93, which is supported by a sliding shoe 96 on the opposite tube side, by a clamping piston 94 to a guide 121, 129

Transfer element 123 and further transferred to a pivot axis 122 of the bridge 128. The clamping cylinder 93 is connected via a high-pressure liquid 112 and a hydraulic line 114 to a traveling gas accumulator 95 (FIG. 8), the pressure of which is set in such a way that, when the sliding shoe 96 rubs against the pipe wall, the pressed and braked rollers 89 form the clamping elements 9, which stick to their contact points on the pipe wall and determine the feed rate. An outer housing 130 absorbs the forces

Direction of the pipe axis and transfers them to adjacent links via pins 119 and tabs 120. The sliding block 96 is fastened to the outer housing as a wearing part with screws 127. The hydraulic line 114 ends with a connection 113 for one Hydraulic hose. The clamping force is transmitted from the bridge 128 to the rollers 89 via axes 118. The rollers 89 are rotatably supported as axles 115 on the axles 118 and, together with a stator 117 anchored on the axles, which supports vanes 116, form a volumetric pump. The fact that secondary liquid 132 is constantly displaced in an area of pressure on an eccentric inner surface of the rollers 89 with the vanes 116 and pressed into a next chamber by means of throttle positions 131, creates a braking force on each roller due to the characteristics of the throttle locations 131 is determined. In the suction area there are recesses on the inner surface of the roller which make it easy for the liquid to flow back. Shaft seals 126 seal the bearings 125 of the rollers from the outside. The wings 116 are additionally guided with lugs in a circumferential groove 124. This type of braking device 8 has the advantage that it is short and can be assembled into a multi-link chain, which, when the links are offset by 90 ° from each other, can also pass through narrower pipe bends. The necessary number of coupled brake elements 8 also depends on the differential pressure across the shield 3 if a certain feed rate is not to be exceeded. The clamping force for the rollers 89 may only be selected so high that the sliding shoes 96 do not block the shield 3.

Another arrangement is shown in FIGS. 16, 17, 18. The brake device in FIG. 16 bears against the tube wall 1 with a slide shoe 96 and is secured in the axial direction against the housing 130 of the brake device via an axis 122. Clamping cylinders 93 connected to the housing 130 act with their clamping pistons 94 on the slide shoe 96 and at the same time press the pressure rollers mounted in the housing 130 89 on the opposite side to the pipe wall 1. The rollers 89 are arranged in pairs and each form radial piston pumps with the housing, which pumps into a high-pressure line 65. Branch lines go from the high-pressure line 65 to the clamping cylinders 93, so that the

Clamping piston 94 are exposed to the delivery pressure of the radial piston pumps 159. The liquid delivered by the radial piston pumps is expanded via a throttle 21a, which, with its non-linear characteristic, the delivery pressure of the pumps and to the clamping pistons 94

Contact force determined. Connection lines 66 return the liquid on the low pressure side behind the throttle 21a to the suction side of the pumps. The fluctuations in the liquid volume in the clamping cylinders 93 are compensated for by the pumps 159 and the throttle 21a and the corresponding deficit or the excess on the low-pressure side is compensated for by a connecting line 169 through a liquid reservoir (FIG. 17). The hydraulic lines are drawn out schematically in FIG. 16 in order to better recognize the inner piping.

17, the liquid reservoir 164 is arranged in an outer housing 170, which is supported on the brake device (FIG. 16) by a cover 167 and pins 119 and which is supported on the other side by a cover 172 and a ball joint on the shield ( Fig. 18) supports. The accumulator for the hydraulic fluid 153 consists of a piston, which is connected to the housing in both directions via a piston rod 160, 160a, and a cylinder 164, which is movable to it, and which is pressed in the direction of the piston 163 via a spring 161. The enclosed hydraulic fluid 153 therefore always experiences a pressure component that is determined by the momentary spring force. Since the outer housing has 170 openings to the outside, there is also a pressure inside as in pipeline 1, so that the pressure in pipeline 1 is added to the pressure in hydraulic fluid 153 as a second pressure component. The transition to the connecting line 169 takes place through the hollow piston rod 160. This arrangement ensures that the pressure at the clamping piston 94 when the device is at a standstill is always greater than on the outside. When starting from a standstill, the rollers 89 are already in engagement with the tube wall 1 and start pumping immediately. With increasing speed, the contact pressure in the clamping cylinders 93 and the braking force generated by the throttle 21a increase until compensation with a tensile force from the shield 3 occurs.

A further piston 165 rides on the piston rod 160a, which seals against the outer housing 170 and forms a pressure chamber 171. This pressure chamber 171 is connected via a connecting line 174 to the space in front of the shield 3 in the vicinity of the baffle 39. At the

Driving forward, the pressure in the inner housing is higher than at the baffle 39, so that the piston 165 bears against the cover 172. When reversing, the pressure conditions are reversed and the piston 165 mechanically opens against the cylinder 164, compensates the biasing force of the spring 161 and lowers the pressure on the low pressure side. The clamping pistons 94 give way under external forces and the excess liquid flows to the reservoir. At the same time, the rollers 89 lose their engagement and there is no longer any pumping. In this way, reversing the conveying direction in the pipeline enables reverse travel without a brake. A similar effect is achieved if the reverse pressure conditions are used to actuate a valve which lets the accumulator run out until the spring 161 has its Loses effect. O-rings 168 and piston seals 162, 163, 166 ensure tightness.

The shield 3 in FIG. 18 has two packs 42 which seal against the pipe wall 1. An outer housing 173, 175 is closed on the front by a cover 176, which forms a bearing 202 for a rotatable ring 41 with cleaning nozzles. If the moments from the impulses at the cleaning nozzles are not balanced, a rotation of ring 41 can be generated. The cover 176 is continued towards the front by a fastening arm 201 which carries an impact grille 39. The connecting line 174 leads through the entire shield to the baffle 39.

FIG. 19 shows a radial piston pump with a running body 177, which is connected to the roller 89 (FIG. 16) and which has a wavy inner contour. In a stationary inner part, which is connected to the outer housing 130 (FIG. 16), star-shaped radial pistons 179 are arranged, which follow the inner contour of the rotating barrel body 177. The pistons 179 with seal 178 each run in bores and are pressed outwards with springs 180. When the pistons 179 are raised, liquid is sucked out of an inlet line 183 via a check valve 182, which is expelled into a high-pressure line via a further check valve 181 when the piston is lowered. With the check valve 182 on the inlet side, a spherical closing body is supported by a spring 184 which rests on a holding disc 185.

In Figures 21, 22, 23, the inner housing 176 is on the front pack 42 through an extended cover

176 continued in order to accommodate a support body 195 which rotates with the ring 41 in the space obtained. The warehouse 202 is correspondingly longer Supporting bodies 195 project from elastically supported guide rollers, which have a slight inclination to the longitudinal axis of the tube 1 and thus run under pressure on a helix in the tube in order to give the ring 41 a predetermined rotation. The cleaning nozzles rotating with the ring cut into the deposits in the pipeline in a helical shape, whereby radial cuts can be produced with additional non-rotating nozzles, which cut free and detach the crude-shaped bodies in the deposits. A prerequisite for good cleaning is that the dwell time of the jet streams is as constant as possible, which is achieved with the braking device.

It can be seen from FIGS. 22 and 23 that the rollers 194 have a pin 196 in a cylinder

Carrier body 199 are stored. The carrier body 199 is displaceable in a bore with guide grooves 197 and secured against rotation. A prestressed pressure spring 200 presses the carrier body 199 and guide roller 194 outward against the tube wall 1. The disengagement of the roller 194 is limited by locking jaws 198. The inclination 203 of the running direction of the roller 194 to the longitudinal axis of the pipeline can be varied in that a plurality of guide grooves 197 are provided for a counter shoulder on the carrier body 199, or that carrier bodies 199 are available with counter shoulders which are oriented differently to the running direction of the roller 194.

20, a movable friction shoe 189 is shown, which rests on stops 187 of the carrier body 191 during forward movement 192. The friction shoe 189 is connected to the carrier body 191 via swivel arms 190 and bearings 188 and forms a parallelogram. The stops 187 are set back somewhat in the axial direction with respect to the highest radial deflections (break points), so that there is definitely no buckling under the radial pressing forces of clamping piston 94 when driving forward. During the forward movement, the friction shoe 189 exerts a frictional force which depends on the pressure in the clamping cylinders 93 and which is transmitted via an axis 122 from the support body 191 to the outer housing 186. During a backward movement 193, a frictional force occurs in the opposite direction on the friction shoe 189 in this position. The friction shoe stops and the liquid 112 in the clamping cylinders 93 is partially displaced into a pressure accumulator, not shown, so that the outer housing 186 on the swivel arms 190 is lifted over the stationary friction shoe 189 until a "kink point" is reached at which the clamping piston 94 support the complete kickback of the friction shoe 189. Since the stroke of the clamping pistons 94 is less than the radial immersion of the friction shoe into a retracted position 189a, the friction shoe 189 is simply loosely dragged along when reversing 193. When reversing this is apart from this

In the initial phase, only a small pressure difference across the entire pipe cleaning device is required. At the same time, the friction points of the braking device are protected. If there are pressure rollers with radial piston pumps on the opposite side of such a friction shoe 93, the pumps only have to turn backwards in the initial phase until the friction shoe 189 disengages and are protected on an actual return trip. A similar effect is also achieved with a friction shoe, which is guided in a wedge path that changes to the axis of the pipeline from a parallel path to an inclined path to the axis.

A further braking device 8 is described in FIGS. 11, 12, 13, 14. It prevents an uncontrolled advance of the cleaning device 5, in that a thrust crank drive is driven by the rotation of the rollers 89, which are pressed against the inner tube wall 1 by a clamping cylinder 93, and which consists of two hydraulic brake cylinders 91a, 91b offset at 90 °, the piston rods 97 of which are directly offset by 90 ° to the roller 89 are connected by means of attachment 109. Bearings 107 built into the roller 89 enable the thrust crank drive, which drives a secondary liquid 10 through throttling points 92 by means of the pistons 90, and in each case achieves the greatest volume flow and the greatest braking effect with the second cylinder 91b at the dead center of the first cylinder 91a.

The double roller 89 is mounted in a slide bearing 108, the bearing bush 111 of which is pressed into two supporting bodies. These two support bodies are pivotally attached on both sides via a common axis 102 to a support body 100 which has an elongated hole-shaped recess 99 in the area of the bush 111. A clamping cylinder 93 uses a liquid 112 to generate the necessary contact pressure, which is further transferred into a piston 94

Cone 105 and thus introduced into two pivotable support body 101 and which presses the double roller 89 screwed with screws 110 against the inner tube wall 1 via bushing 111 with bearing 108. The reaction force corresponding to the pressing force of the roller is introduced via a common axis 102 and the clamping cylinder 93 built into the support body 100 into a sliding shoe 96 with recess 98 lying opposite the roller, which is pressed against the inner tube wall with the corresponding normal force, which is caused by the axial

Expansion of the sliding block together with the pressed-on roller leads to a three-point support, which prevents the entire unit from tipping out of the tube axis and, due to the additional sliding friction, allows the thrust crank unit to be dimensioned smaller. To increase the nozzle pressure required for cleaning, this braking device 8 can be connected to other identical braking device elements 8 by means of articulated elements 104, which are fastened with axles 106, which results in a higher feed rate of the liquid flow used for cleaning at a same feed rate with increased cleaning pressure in the nozzles 36 , 37, 38 leads from sign 3.

A reversing sign 103 is described in FIG. 15, which can cooperate with a sign 3 as described in FIG. 8. When the flow is reversed, the flow resistance on the shield 3 is reduced by a backflow device 141. At the same time, it would be desirable to have a reversing sign 103 at the other end, which pulls back the relaxed braking devices 8 and the sign 3. Pulling prevents the elements from wedging, especially in pipe bends. The reversing plate 103 therefore consists of a carrier plate 69 which is arranged in the center with play in the tube 1 and is held in this center by lateral guide fins 80. A hinge pin 72 is connected to the support plate 69, on which two flap vanes 73a are mounted as in a butterfly valve, the elliptical flap vanes however only being able to reach an acute-angled extension position 71 to the pipe axis, in which the pipe cross-section is largely closed. The greatest play to the tube wall is in the area of the ends of the hinge pin 72, while the ends of the flap wing can slide over obstacles such as weld seams. The pressure on the flap vanes 73a, minus the friction of the flap vanes on the pipe wall, is available as a tensile force. Since the braking elements are out of operation when reversing because the necessary clamping is missing, the pulling force by the reversing plate 103 only has to be so great that the Friction on the elements behind, which also experience a train through a passing flow, is certainly compensated for.

During the forward movement of the pipe cleaning device, the flap vanes 73a on the carrier plate 69 are blocked by a pawl 86. A pressurized metal bellows 85a with piston rod 70, which is arranged in a housing 85b, presses the pawl 86 against its pressure against a return spring 74. Only when the pressure in the metal bellows 85a drops, which is coupled with the flow reversal, are the flap vanes 73a released, so that they can move into the flow, supported by an expansion spring which rests in grooves 73b. The metal bellows 85a is held under pressure via a pressure connection 84. Its use as an actuator is supported by the fact that only small strokes are necessary, that it can be made small due to the low power requirement and that there are no seals that generate friction or leakage as disturbance variables.

Claims

1. Pipe cleaning device for oil and gas pipelines (1), the deposits (6), for example in the form of paraffins, which device with a

Liquid flow (2) is pushed through the pipeline (1) for cleaning purposes, the device having a shield (3) which forms one or more openings for a passing liquid flow (7) in order to provide an intended flow resistance in the pipeline (1) form, the shield (3) being coupled to a braking device (8) and having a cleaning device (5) on its front side (4), characterized in that the braking device (8) has at least one clamping element (9, 9a, 9b) which currently adheres to the tube wall (1) and moves relative to the braking device (8) in order to displace a secondary liquid (10, 132) with this movement, which is braked by at least one throttle point (21, 92, 131) and so determines the speed between the shield (3) and pipe wall (1).

2. Pipe cleaning device according to claim 1, characterized in that the clamping element (9, 9a, 9b) has at least one roller (89) mounted in the braking device (8) and pressed radially against the tube wall, with the rotation of which the secondary liquid (10) is displaceable.

3. Pipe cleaning device according to claim 2, characterized in that with the rotation of the roller

(89) at least one hydraulic cylinder (91a, 91b) is movable like a thrust crank to secondary To displace liquid (10) between piston (90) and cylinder (91a) and to brake with droεεelstellen (92).

4. Pipe cleaning device according to claim 3, characterized in that on the roller (89) a second 90 ° offset hydraulic cylinder (91b) is moved as with a push crank and drives secondary liquid (10) through throttling points (92), in each case at dead center of the first cylinder (91a) to achieve the greatest volume flow and the greatest braking effect with the second cylinder (91b).

5. Pipe cleaning device according to claim 2, characterized in that with the movement of the roller (89) a volumetric pump (115, 116, 117, 118) can be driven, the flow of which is braked by one or more throttle points (131).

6. Pipe cleaning device according to one of claims 2 to 5, characterized in that opposite to a roller (89) with the braking device (8) connected to the slide shoe (96) is arranged to with one of the

Pressing force of the roller corresponding to normal force on the slide shoe to generate a sliding friction force to the pipe wall (1) and thus to be able to dimension the brake device on the roller (89) correspondingly smaller.

7. Rohrreinigungεgerät according to any one of claims 2 to 6, characterized in that the roller (90) is biased relative to the braking device (8) via a high pressure cylinder (93), the piston (94) of which is exposed to the pressure of a traveling pressure accumulator (95) .

8. Pipe cleaning device according to one of claims 2 to 6, characterized in that it is the pressure of the secondary liquid (112) upstream of the throttle point (21a), which acts on a high-pressure cylinder (93) with piston (94), which the roller ( 89) pre-tension against the wall (1) of the pipeline relative to the braking device.

9. Pipe cleaning device according to claim 8, characterized in that a traveling storage (164) for secondary liquid (153) on the

Low pressure side is connected behind the throttle (21a) in order to compensate for leakage of secondary liquid and to determine the low pressure (66) behind the throttle point.

10. Pipe cleaning device according to claim 9, characterized in that the memory (164) experiences a minimum pressure via a spring force and that a second force acts on the memory, which is proportional to the pressure difference across the pipe cleaning device in the pipeline.

11. Pipe cleaning device according to claim 10, characterized in that when driving backwards due to a pressure difference in the opposite direction, the pressure in the reservoir (164) of the secondary liquid (153) can be degraded to the extent that there is no more radial pressing force when driving backwards.

12. Pipe cleaning device according to claim 6, characterized in that the slide shoe (96) is forced to take a smaller radial distance from the braking device when driving backwards than when driving forward.

13. Pipe cleaning device according to claim 1, characterized in that the braking device (8, 8a, 8b) has at least two axially offset clamping elements (9a, 9b) which have radially extendable clamping jaws (Ha, 11b) and which have a brake cylinder and piston (12a, 12b, 13a, 13b) are connected to one another in an axially movable manner in order to allow the shield (3) to be gradually braked by throttling the displaced liquid.

14. Pipe cleaning device according to claim 1, characterized in that in the shield (3) a hydraulic motor (55, 135) is installed in the pasεierendem liquid stream (7) in order to drive a liquid pump (58) for auxiliary movements on the pipe cleaning device.

15. Pipe cleaning device with a braking device (8) according to one of claims 1 to 14, characterized in that the shield (3) has a plurality of nozzles (36, 37, 38) on ε its front side (4) which are offset with respect to one another

Liquid jets cut the deposits (6) into pieces.

16. Pipe cleaning device according to claim 15, characterized in that the shield (3) on the front in front of the nozzles (36, 37, 38)

Baffle grille (39), which only fills a fraction of the pipe cross-section so as not to get stuck in the deposits, but which is positioned in front of the nozzles (36, 37, 38) to such an extent that a cavity (40) for swirling cut-off pieces arises to the swirled pieces with the help of the baffle (39) to break up and mix with the passing liquid stream (7).

17. Pipe cleaning device according to claim 16, characterized in that nozzles (37, 38) are each distributed as groups on circles which are concentric with one another and have in their jet direction at least one directional component parallel to the pipe axis and pointing forward in order to prevent the contamination before the arrival of the shield dissipate.

18. Pipe cleaning device according to claim 17, characterized in that the pulses from the nozzles on the cleaning head on the shield (3) in

To a large extent cancel the circumferential direction as the sum of the moments.

19. Pipe cleaning device according to one of claims 15 to 18, characterized in that the shield (3) near the pipe wall (1) has a protruding ring (41) with a plurality of nozzles (36) for the removal of residual deposits around the web for the shield (3) to cut freely.

20. Pipe cleaning device according to claim 15, characterized in that the front (4, 41) of the shield (3) is rotatable relative to the sealing part (42).

21. Pipe cleaning device according to claim 20, characterized in that in the front (4) at least two resiliently supported support rollers (194) are installed, which roll helically in the pipeline and which give the front (41) a rotation by their rolling movement.

22. Pipe cleaning device according to one of claims 1 to 21, characterized in that the shield (3) has a type of backflow device (141) which, when the flow is reversed to the liquid flow (2), releases additional passage area (140), and in that the pipe cleaning device Rear has an additional reversing plate (103), which forms a much greater flow resistance when the flow is reversed in order to move the pipe cleaning device in the opposite direction.

23. Pipe cleaning device according to one of claims 1 to 21, characterized in that the shield (3) by the flow reversal releases a larger cross section in the pipe (1) and that through this

Release movement, the effect of the clamping elements (9, 9a, 9b) on the braking device (8) can be canceled.