The present invention relates to an apparatus for reducing embedded or inherent friction in a multiduct pipe comprising a bundle of ducts within an outer casing being shrunk around the bundle of ducts.

Prior art

The outer casing of a multiduct pipe is known to and preferable applied to a bundle of ducts through extruding or shrinkage of a wrapping material before the multiduct pipe, which is then quite rigid, is rolled onto a pipe drum.

A multiduct pipe comprising a bundle of ducts within an outer casing being shrunk around the bundle of ducts, which are subsequently unrolled from a drum, will be somewhat curly, like streamers.

Therefore, there will be some friction between the ducts in the casing, especially at the smallest diameter of the unrolled multiduct pipe. Furthermore, there will be some variation in length between the duct closest to the smallest diameter of the unrolled pipe and the duct closest to the largest diameter of the unrolled pipe.

Multiduct pipes are also known comprising a bundle of ducts within an outer casing where the outer casing is loose around the bundle of ducts and hence, there is no friction in the multiduct pipe. Instead the ducts in the outer casing are disorganized - somewhat like boiled spaghetti - twisted around each other in the lengthwise direction. This is not a solution which is desirable.

Before the development of the present invention, it was therefore known to be a hassle unrolling, handling and getting the multiduct pipes down into the trenches when burying a multiduct pipe. The disadvantages are therefore the curly, streamer-like multiduct pipe being unrolled due to the friction between the ducts in the casing.

Object of the invention

Thus, the object of this invention is to provide an apparatus for reducing embedded or inherent friction in a multiduct pipe of the type mentioned in the introduction which e.g. improves the handling of the multiduct pipes compared to the prior-art technology which does not use the method.

Description of the invention

An object of the invention is achieved by a multiduct pipe straightener apparatus configured for reducing friction in a multiduct pipe with a bundle of ducts within an outer casting. The apparatus comprising a first arrangement of at least two straightening rollers with a first row spacing between adjacent rollers and arranged for pressing the multiduct pipe on a side when pulled along rollers and a second arrangement of least two rollers with a second row spacing between adjacent rollers with at least one roller arranged opposite the least first row spacing and arranged for pressing the multiduct pipe on the opposite side.

The multiduct pipe will typically be stored on and unrolled from a drum, where each of the ducts of the multiduct pipe will have an inherit friction and a position, which depends at least partly on the relative position of the duct to the center of the drum. The forces exerted by the straightening rollers in the first arrangement and by straightening rollers in the second arrangement causes due to the relative positioning of the straightening rollers the ducts in the multiple duct pipe to move within the multiple duct pipe such that the ducts have about the same internal friction, thereby straightening the multiduct pipe straightener. In an aspect of the invention at least one roller in the corresponding least one opposite spacing may be configured with adjustment means for adjusting the position of at least one roller in the corresponding least one opposite spacing.

As previously mentioned, the multiduct pipe is stored on and unrolled from a drum and the friction on each of the ducts of the multiduct pipe depends at least partly on the position relative to the center of the drum. The distance to the center changes as the multiduct pipe and thus the necessary forces exerted on the multiduct pipe by the multiduct pipe straightener apparatus will change as the multiduct pipe is unrolled. Thus, the multiduct pipe straightener will by having adjustment means for adjusting the position of at least one roller be able to adjust the forces exerted on the multiduct pipe as the multiduct pipe is unrolled.

Furthermore, the friction forces will depend on other parameters, such as material, each ducts position lengthwise relative to the other ducts, temperature, and temperature changes experience by the multiduct pipe while being stored on the drum. The multiduct pipe straightener apparatus will by the adjustment means for adjusting the position of at least one roller be able to counteract these friction forces by adjusting the positioning.

In an aspect of the invention the rollers in the second arrangement may be supported by a second support in a second row.

The second support will stabilize the multiduct straightener apparatus along the length of the multiduct straightener apparatus.

The second support may comprise two parallel girders supporting the at least two rollers of the second arrangement and two or more U-shaped units positioned along the two girders, each U-shaped unit has two arms, where each arm is connected to a girder. Thereby, the stability of the multiduct straightener apparatus is increased further. In an aspect of the invention at least one roller in the first arrangement is supported by a first support extending away from the second support and configured with adjustment means for positioning of the at least one roller in the corresponding least one opposite spacing.

As previously mentioned, the adjustment means enable the multiduct pipe straightener to exert the correct force onto the multiduct pipe for the multiduct pipe to straighten.

The rollers in the first arrangement can be supported by a first support extending away from the second and this makes it easier to change the positioning of the rollers in the first arrangement.

In an aspect of the invention the adjustment means may be configured with a cylinder for a lateral positioning and an angular positioning.

The adjustment means may also be configured with a cylinder for a lateral positioning, only.

The adjustment means may also be configured with a cylinder for an angular positioning, only.

The cylinder for a lateral positioning may be controlled by a handle, where the rotation of the handle will cause the cylinder and thus the roller to change the lateral positioning. Thereby the lateral positioning and thus the force exerted on the multiduct pipe can be controlled as the multiduct pipe is unrolled which enables a more precise control as the user can during unrolling view the resulting multiduct pipe and thus adjust the lateral positioning of the roller and thus control the exerted force on the multiduct pipe in order to achieve a straightened multiduct pipe. In an embodiment, two, three or all rollers in the first arrangement is supported by respective first supports extending away from the second support and being configured with respective cylinders for lateral positioning and/or angular positioning of the two, three or all rollers. Thereby, the force exerted by the multiduct pipe straightener along the multiduct pipe straightener can be varied, which has in test proven to increase the straightening of the multiduct pipe.

The angular positioning of the cylinder and thus the roller enable the multiduct pipe straightener to exert a force on the multiduct pipe, which is not parallel with the lateral positioning. This will enable the multiduct pipe straightener to better counteract the friction forces which may depend on material, each duct’s position lengthwise relative to the other ducts, temperature, and temperature changes experience by the multiduct pipe while being stored on the drum.

Thus, the multiduct pipe straightener is able to adjust the multiduct pipe along two dimensions in a compact manner.

In an aspect of the invention, the first support comprises a slit for locking the at least one roller in a predetermined position by engaging with an arm holding said at least one roller.

Thereby, the person adjusting the multiduct pipe straightener can lock the multiduct pipe straightener into position when a suitable position of the rollers is found.

In an aspect of the invention the second arrangement of rollers may comprise three rollers forming two second row spacings and the first arrangement with two rollers arranged opposite to the two second row spacings. The above mentioned embodiment of a multiduct pipe straightener has shown excellent results in test. The straightening capability is especially good when each of the rollers in the first arrangement is supported by a first support extending away from the second support and configured with adjustment means for positioning of the two rollers in the corresponding opposite spacing, where the adjustment means are configured with a cylinder for a lateral positioning and an angular positioning.

This enables the lateral positioning and the angular positioning of each of the rollers in the first arrangement to be controlled independently of each other. Surprisingly, this increases the straightening effect of the multiduct pipe straightener significantly and thus the multiduct pipe straightener can be made more compact and with fewer parts while achieving the same straightening effects of larger and more complex straighteners.

The multiduct pipe straightener can be made with more rollers in the respective first and second arrangements, however there will be a diminishing return by adding more components while the complexity of the multiduct pipe straightener increases.

In an aspect of the invention, each roller in the first arrangement is supported by a first support extending away from the second support and configured with adjustment means for positioning of each roller in the corresponding opposite spacing, wherein each adjustment means is configured with a cylinder for a lateral positioning and an angular positioning.

Thereby excellent straightening capabilities and a compact multiduct pipe straightener is achieved as previously mentioned.

According to a first aspect of the invention, the above object is achieved with a method of reducing embedded or inherent friction in a multiduct pipe of the type mentioned in the introduction, the method comprising the steps of:

guiding said multiduct pipe in between two rows of straightening rollers having at least two straightening rollers in the first row for being pressed against one side of the multiduct pipe, and at least two straightening rollers in the second row for being pressed against the diametrically opposite side of the multiduct pipe.

In this context the meaning of pipe is an integrated unit comprising a number of (multi) long, hollow channels (duct) in which e.g. optical fibres at some stage might be blown through.

When the bundle of ducts within an outer casing of the multiduct pipe are exposed for the claimed method they are being massaged into a more linear form, hence the friction at the smallest diameter of the unrolled pipe are somewhat evened out, at least minimized and so are the variation in length between the ducts.

In another aspect, the present invention also relates to a method, where the guiding step comprises alternating pressing against the opposite sides of the multiduct pipe as one of the straightening rollers in the first row is arranged just opposite a spacing between the straightening rollers in the second row.

This ensures that the multiduct pipe is passing the straightening rollers in a waveform, hence massaging the multiduct pipe in an optimal way.

In another aspect, the present invention also relates to a method, where the guiding step is effected with a constant pressing as said straightening rollers in one row are locked in their position for the formation of a curved path for the multiduct pipe passage between the closest straightening rollers in the other row of straightening rollers.

This makes it further possible massaging the multiduct pipe in an optimal way with constant pressure impact. In another aspect, the present invention also relates to a method, where before initiating the pressing step an adjusting step is performed in which the mutual distance in a plane containing said opposing sides of the multiduct pipe between the two rows of straightening rollers is established with a common displacement of the first row.

The initiating step makes it possible to establish the size and the direction of the said displacement of the one straightening rollers for the multiduct pipe in question. This may have been empirically established in advance.

This has proven to be a construction which reduces the friction significant within the multiduct pipe in a very efficient way and which also fulfills the requirements on site, in terms of handling the multiduct pipe.

In another aspect, the present invention also relates to a method, where during said adjusting step an adjusting of the mutual distance in a plane containing said opposing sides of the multiduct pipe between the two rows of straightening rollers is established based on a visually feedback from the straightened multiduct pipe.

This makes it further possible to operate the adjustment means on site either manually e.g. by means of a manual operated winch or crank handle, a hand wheel or other adjustment means, screws, devices etc. or alternatively it is possible to operate the adjustment means by use of automation, electrical tools etc.

With the straightening rollers in the same plane it takes up less room during transportation which is also worth remembering since the apparatus is mobile.

In another aspect, the present invention also relates to a method, where the guiding step comprises guidance for the multiduct pipe at the first straightening roller in the second row, where the guidance is controlling the feed of the multiduct pipe in between two rows of straightening rollers.

When the multiduct pipe is unrolled from a drum the multiduct pipe will be somewhat curly, like streamers. It is therefore - if not necessary - then at least preferred to have a bracket or other kind of guidance arranged in front of the first straightening rollers, to ensure that the multiduct pipe enters the apparatus in the most appropriate way and remains in the best position the whole time between the two rows of straightening rollers.

In another aspect, the present invention also relates to a method, where the guiding step comprises guidance for the multiduct pipe at the last straightening roller in the second row, where the guidance is controlling the multiduct pipe when it leaves the two rows of straightening rollers.

This further ensures that the multiduct pipe remains in the best position the whole time within the apparatus and ensures where it actually leaves the two rows of straightening rollers as well. The guidance is preferably a bracket or other kind of controlled guidance.

In another aspect, the present invention also relates to a method, where the guiding step comprises guiding the said multiduct pipe in recesses or grooves in circumference of the straightening rollers, where the recesses preferably are formed substantially as a V or a U.

In another aspect, the present invention also relates to a method, where the guiding step comprises guiding the said multiduct pipe in depressions formed in an elastic annular ring provided on the straightening rollers.

Recesses, grooves or depressions formed in an elastic annular ring provided on the straightening rollers are all guiding means which not only guide and affect the multiduct pipe in between the two rows of straightening rollers but does indeed also stabilize and fixate the multiduct pipe in a position in which the multiduct pipe is not in a risk of sliding off the straightening rollers as the recesses, grooves or depressions formed in an elastic annular ring embrace the multiduct pipe at a much wider circumferential angle than straightening rollers without the recesses, grooves or depressions formed in an elastic annular ring.

In another aspect, the present invention also relates to a method, where guiding said multiduct pipe in between two rows of straightening rollers having at least two straightening rollers in the first row for being pressed against one side of the multiduct pipe, and at least two straightening rollers in the second row for being pressed against the diametrically opposite side of the multiduct pipe where the two rows of straightening rollers are arranged in a first plane, are succeeded by guiding said multiduct pipe in between two rows of straightening rollers having at least two straightening rollers in the first row for being pressed against one side of the multiduct pipe, and at least two straightening rollers in the second row for being pressed against the diametrically opposite side of the multiduct pipe where the two rows of straightening rollers are arranged in a second plane arranged under an angle relative to said first plane.

This makes it possible to repeat the method and further reduce the embedded or inherent friction in a multiduct pipe affecting the multiduct pipe from a different angle than the previous passage.

In another aspect, the present invention also relates to an apparatus of the type mentioned in the introduction, where the apparatus comprises two rows of straightening rollers having at least two straightening rollers in the first row for being pressed against one side of the multiduct pipe, and at least two straightening rollers in the second row for being pressed against the diametrically opposite side of the multiduct pipe, where one of the straightening rollers in one row is arranged just opposite a spacing between the straightening rollers in the other row, where said straightening rollers are locked in their position for the formation of a curved path for the multiduct pipe passage between the closest straightening rollers in the opposite row of straightening rollers, where the mutual distance in a plane containing said opposing sides of the multiduct pipe between the two rows of straightening rollers is established with a common displacement of the first row.

This makes it possible to massage the bundle of ducts within an outer casing of the multiduct pipe into a more linear form, where the friction at the smallest diameter of the unrolled pipe are somewhat evened out, at least minimized as well as the variation in length between the ducts, where the multiduct pipe is passing the straightening rollers in a waveform, with constant pressure impact which reduces the friction significant within the multiduct pipe, in a very efficient way.

This makes it also possible to operate the adjustment means manually e.g. by means of a manual operated winch or crank handle, a hand wheel or other adjustment means, screws, devices etc., alternatively it is possible to operate the adjustment means by use of automation, electrical tools etc. and with the straightening rollers in the same plane it takes up less room during transportation which is also worth remembering since the apparatus is mobile.

In another aspect, the present invention also relates to an apparatus, where the apparatus comprises at least one of: guidance for the multiduct pipe arranged at the first straightening roller in the second row, a guidance for the multiduct pipe arranged at the last straightening roller in the second row.

This makes it possible to ensure that the multiduct pipe enters the apparatus in the most appropriate way and remains in the best position the whole time between the two rows of straightening rollers and/or to ensure that the multiduct pipe remains in the best position the whole time within the apparatus and ensures where it actually leaves the two rows of straightening rollers.

In another aspect, the present invention also relates to an apparatus, where at least one of the straightening rollers comprises recesses or grooves in circumference of the straightening rollers where the recesses preferably are formed substantially as a V or a U. In yet another aspect, the present invention also relates to an apparatus, where at least one of the straightening rollers comprises depressions formed in an elastic annular ring provided on the straightening rollers.

This makes it possible not only to guide and affect the multiduct pipe in between the two rows of straightening rollers but also to stabilize and fixate the multiduct pipe in a position in which the multiduct pipe is not in a risk of sliding off the straightening rollers as the recesses, grooves or depressions formed in an elastic annular ring embrace the multiduct pipe at a much wider circumferential angle than straightening rollers without the recesses, grooves or depressions formed in an elastic annular ring.

In another aspect, the present invention also relates to an apparatus, where stabilizing means for stabilizing the apparatus are positioned across the plane of the straightening rollers.

This makes the apparatus mobile, easy to transport, easy to set up and to operate on location, hence the stabilizing means are necessary to keep the apparatus in the normally operating position which is vertical during operation. Therefore the stabilizing means are preferably positioned perpendicular to the plane of the straightening rollers. When the apparatus is no longer needed and in use the stabilizing means is advantageously able to be folded into the same plane as the straightening rollers or it might be dismantled. Drawing

The invention will be described in further detail below by means of non-limiting embodiments with reference to the drawing, in which:

Fig. 1 a-1 e show a multiduct pipe and the multiduct pipe before and after reducing embedded or inherent friction,

Fig. 2 shows a perspective view of the apparatus as claimed with a multiduct pipe shown,

Fig. 3 shows a perspective view of the apparatus as claimed without a multiduct pipe,

Fig. 4 shows a side view of the apparatus as claimed,

Fig. 5 shows a view from above of the apparatus as claimed,

Fig. 6 shows multiduct pipes without reduced embedded or inherent friction in a situation where the pipes are to be arranged into a trench for burying the multiduct pipes,

Fig. 7 shows two multiduct pipes, one without and one with reduced embedded or inherent friction.

In the drawing, the following reference numerals have been used for the designations used in the detailed part of the description:

1 Multiduct pipe

2 Duct

3 Outer casing

4 Drum

5 Centerline

6 Apparatus

7 Straightening roller

8 First row

8A First row spacing 9 Second row

9A Second row spacing

10 One side, multiduct pipe

11 Diametrically opposite side, multiduct pipe

12 Guidance

13 First straightening roller

14 Last straightening roller

15 Recesses or grooves

16 Stabilizing means

17 Plane, of the straightening rollers

18 Trench

19 Winch or Crank handle

20 Adjustment means

101 First arrangement

102 Second arrangement

110 Support

111 First Support

112 Second Support

120 Lateral positioning

122 Angular positioning

124 Lateral position adjustment

Detailed description of the invention

Figure 1 a shows a multiduct pipe 1 comprising a bundle of ducts 2 within an outer casing 3 being shrunk around the bundle of ducts 2.

Figure 1 b shows a multiduct pipe 1 which is unrolled from a drum 4 - where the drum 4 is positioned with its centerline 5 in a substantially horizontal position - and it shows that the multiduct pipe 1 will behave in a somewhat curly manner, like streamers. Figure 1 c shows a multiduct pipe 1 which is unrolled from a drum 4 - where the drum 4 is positioned with its centerline in a substantially vertical position - and it also shows that the multiduct pipe 1 will behave in a somewhat curly manner, like streamers.

Figure 1 d shows a multiduct pipe 1 which is bent and in which friction - indicated by arrows - exists between the ducts 2 and the outer casing 3 as well as between the ducts 2 within the outer casing 3.

Figure 1e shows the principle of the invention in which a multiduct pipe 1 passes an apparatus 6 for use in the method of reducing embedded or inherent friction in a multiduct pipe 1. The figure shows a multiduct pipe 1 before its embedded or inherent friction is reduced at the left side of the apparatus 6, and following the arrows in the operational direction through the apparatus 6 to the right side of the apparatus 6 after the reduction of the embedded or inherent friction in the multiduct pipe 1.

Figure 2 shows a perspective view of the apparatus 6 as claimed, where the apparatus 6 comprises two straightening rollers 7 in a first row 8 for being pressed against one side 10 of the multiduct pipe 1 , and three straightening rollers 7 in a second row 9 for being pressed against the diametrically opposite side 11 of the multiduct pipe 1 , where one of the straightening rollers 7 in one row 8,9 is arranged just opposite a spacing between the straightening rollers 7 in the other row 8,9, and where the straightening rollers 7 are locked in their position for the formation of a curved path (see also figure 1e) for the multiduct pipe 1 passage between the closest straightening rollers 7 in the opposite row 8,9 of straightening rollers 7, where the mutual distance in a plane 17 containing said opposing sides of the multiduct pipe 1 between the two rows 8,9 of straightening rollers 7 is established with a common displacement of the first row 8. In the shown embodiment it is possible to operate adjustment means manually for each straightening roller 7 in the first row 8 by means of a manual operated winch or crank handle 19.

The figure also shows guidance 12 for the multiduct pipe 12 arranged at the first straightening roller 13 in the second row 9 and guidance 12 for the multiduct pipe 1 arranged at the last straightening roller 14 in the second row 9.

The figure further shows that the straightening rollers 7 comprises recesses or grooves 15 in circumference of the straightening rollers 7 where the recesses or grooves 15 are formed substantially as a V or a U.

The figure also further shows that stabilizing means 16 for stabilizing the apparatus 6 are positioned across the plane 17 of the straightening rollers 7.

Figures 3, 4 and 5 show a multiduct pipe straightener apparatus 6 comprising a first arrangement 101 of at least two straightening rollers 7 with a first row spacing 8A between adjacent rollers 7 and arranged for pressing a multiduct pipe 1 (not shown) on a side when pulled along rollers 7. There is a second arrangement 102 of least two rollers 7 with a second row spacing 9A between adjacent rollers 7 with at least one roller 7 arranged opposite the least first row spacing 8A and arranged for pressing the multiduct pipe 1 on the opposite side.

At least one roller 7 in the corresponding least one opposite spacing 8A, 9A is configured with adjustment means 20 for adjusting the position of at least one roller 7 in the corresponding least one opposite spacing 8A,9A.

The rollers 7 in the second arrangement 102 are supported by a second support 112 in a second row 9.

The rollers 7 are supported in a support 110. A roller 7 is supported by a first support 111 extending away from the second support 112 and configured with adjustment means 20 for positioning of at least one roller 7 in the corresponding least one opposite spacing 9A.

The roller 7 the adjustment means 20 is configured with a cylinder for a lateral positioning 120 and an angular positioning 122.

The second arrangement of rollers 7 comprises three rollers 7 forming two second row spacings 9AI, 9AII and the first arrangement 101 with two rollers 7 arranged opposite to the two second row spacings 9AI, 9AII.

It is noted that figure 3 shows yet another perspective view of the apparatus 6, but without a multiduct pipe 1 and figure 4 shows a side view of the apparatus 6.

Figure 5 shows a view from above of the apparatus 6 from where it is shown that the straightening rollers 7 comprises recesses or grooves 15 in circumference of the straightening rollers 7 where the recesses or grooves 15 are formed substantially as a V or a U.

The figure also shows that stabilizing means 16 for stabilizing the apparatus 6 are positioned substantially perpendicular across the plane 17 of the straightening rollers 7.

Figure 6 shows multiduct pipes 1 without reduced embedded or inherent friction in a situation where the multiduct pipes 1 are to be arranged into a trench 18 for burying the multiduct pipes 1.

Figure 7 shows two multiduct pipes 1 , one without reduced embedded or inherent friction (the one to the right) and one with reduced embedded or inherent friction (the one to the left) which have passed the apparatus 6 which is also shown at the figure. Items

Item 1 - Method of reducing embedded or inherent friction in a multiduct pipe (1 ) comprising a bundle of ducts (2) within an outer casing (3) being shrunk around the bundle of ducts (2), characterized in the steps of:

guiding said multiduct pipe (1 ) in between two rows of straightening rollers (7) having at least two straightening rollers (7) in the first row (8) for being pressed against one side (10) of the multiduct pipe (1 ), and at least two straightening rollers (7) in the second row (9) for being pressed against the diametrically opposite side (11 ) of the multiduct pipe (1 ).

Item 2 - Method according to item 1 , characterized in that:

the guiding step comprises alternating pressing against the opposite sides of the multiduct pipe (1 ) as one of the straightening rollers (7) in the first row (8) is arranged just opposite a spacing between the straightening rollers (7) in the second row (9).

Item 3 - Method according to any one of items 1 to 2, characterized in that:

the guiding step is effected with a constant pressing as said straightening rollers (7) in one row are locked in their position for the formation of a curved path for the multiduct pipe (1 ) passage between the closest straightening rollers (7) in the other row of straightening rollers (7).

Item 4 - Method according to any one of items 1 to 3, characterized in that:

before initiating the pressing step an adjusting step is performed in which the mutual distance in a plane (17) containing said opposing sides of the multiduct pipe (1 ) between the two rows of straightening rollers (7) is established with a common displacement of the first row (8).

Item 5 - Method according to item 4, characterized in that: during said adjusting step an adjusting of the mutual distance in a plane (17) containing said opposing sides of the multiduct pipe (1 ) between the two rows of straightening rollers (7) is established based on a visually feedback from the straightened multiduct pipe (1 ).

Item 6 - Method according to any one of items 1 to 5, characterized in that:

the guiding step comprises guidance (12) for the multiduct pipe (1 ) at the first straightening roller (13) in the second row (9), where the guidance (12) is controlling the feed of the multiduct pipe (1 ) in between two rows of straightening rollers (7).

Item 7 - Method according to any one of items 1 to 6, characterized in that:

the guiding step comprises guidance (12) for the multiduct pipe (1 ) at the last straightening roller (14) in the second row (9), where the guidance (12) is controlling the multiduct pipe (1 ) when it leaves the two rows of straightening rollers (7).

Item 8 - Method according to any one of Items 1 to 7, characterized in that:

the guiding step comprises guiding the said multiduct pipe (1 ) in recesses or grooves (15) in circumference of the straightening rollers (7), where the recesses (15) preferably are formed substantially as a V or a U.

Item 9 - Method according to any one of items 1 to 7, characterized in that:

the guiding step comprises guiding the said multiduct pipe (1 ) in depressions formed in an elastic annular ring provided on the straightening rollers (7).

Item 10 - Method according to any one of items 1 to 9, characterized in that guiding said multiduct pipe (1 ) in between two rows of straightening rollers (7) having at least two straightening rollers (7) in the first row (8) for being pressed against one side (10) of the multiduct pipe (1 ), and at least two straightening rollers (7) in the second row (9) for being pressed against the diametrically opposite side (11 ) of the multiduct pipe (1 ) where the two rows of straightening rollers (7) are arranged in a first plane, are succeeded by guiding said multiduct pipe (1 ) in between two rows of straightening rollers (7) having at least two straightening rollers (7) in the first row (8) for being pressed against one side (10) of the multiduct pipe (1 ), and at least two straightening roller (7) in the second row (9) for being pressed against the diametrically opposite side (11 ) of the multiduct pipe (1 ) where the two rows of straightening rollers (7) are arranged in a second plane arranged under an angle relative to said first plane.

Items 11 - Apparatus (6) for use in the method of reducing embedded or inherent friction in a multiduct pipe (1 ) comprising a bundle of ducts (2) within an outer casing (3) being shrunk around the bundle of ducts (2) according to claims 1 to 10, characterized in that the apparatus (6) comprises two rows of straightening rollers (7) having at least two straightening rollers (7) in the first row (8) for being pressed against one side (10) of the multiduct pipe (1 ), and at least two straightening rollers (7) in the second row (9) for being pressed against the diametrically opposite side (11 ) of the multiduct pipe (1 ), where one of the straightening rollers (7) in one row is arranged just opposite a spacing between the straightening rollers (7) in the other row, where said straightening rollers (7) are locked in their position for the formation of a curved path for the multiduct pipe (1 ) passage between the closest straightening rollers (7) in the opposite row of straightening rollers (7), where the mutual distance in a plane (17) containing said opposing sides of the multiduct pipe (1 ) between the two rows of straightening rollers (7) is established with a common displacement of the first row (8).

Item 12 - Apparatus (6) according to item 11 , characterized in that the apparatus (6) comprises at least one of: guidance (12) for the multiduct pipe (1 ) arranged at the first straightening roller (13) in the second row (9), a guidance (12) for the multiduct pipe arranged at the last straightening roller (14) in the second row (9). Item 13 - Apparatus (6) according to any one of items 11 to 12, characterized in that at least one of the straightening rollers (7) comprises recesses or grooves (15) in circumference of the straightening rollers (7) where the recesses (15) preferably are formed substantially as a V or a U.

Item 14 Apparatus (6) according to any one of items 11 to 13, characterized in that at least one of the straightening rollers (7) comprises depressions formed in an elastic annular ring provided on the straightening rollers (7). Item 15 - Apparatus (6) according to any one of items 11 to 14, characterized in that stabilizing means (16) for stabilizing the apparatus (6) are positioned across the plane (17) of the straightening rollers (7).