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Title:
BI-DIRECTIONAL PIG FOR INSTALLING A CABLE IN A CONDUIT
Document Type and Number:
WIPO Patent Application WO/2020/212472
Kind Code:
A1
Abstract:
A pig (5) for installing an elongated element in a conduit (3), the pig (5) being arranged to be driven in the conduit (3) by a driving fluid (16) introduced under pressure in said conduit (3), the pig (5) comprising: - a body (28), - a seal (30) arranged on the body (28) and comprising an external side arranged to contact an internal surface of the conduit (3), characterized in that: - the seal (30) further comprises an internal side opposed to the external side and defining a closed volume (42) between the seal (30) and the body (28), and in that the pig (5) further comprises: - at least one valve (32), arranged to be in communication with the driving fluid (16), so as to adapt a pressure of the closed volume (42) with the driving fluid (16).

Inventors:
GRIFFIOEN WILLEM (NL)
UHL ALEXANDRE (CH)
WACINSKI ANDRZEJ (CH)
Application Number:
EP2020/060675
Publication Date:
October 22, 2020
Filing Date:
April 16, 2020
Export Citation:
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Assignee:
PLUMETTAZ HOLDING S A (CH)
International Classes:
F16L55/38; F16K3/26; F16L55/44; H02G1/08
Domestic Patent References:
WO2011054551A22011-05-12
Foreign References:
GB2474964A2011-05-04
CN104075073B2016-01-13
GB1273726A1972-05-10
GB1452232A1976-10-13
US3908682A1975-09-30
EP1518307B12006-07-12
US8770550B22014-07-08
US9287689B22016-03-15
Attorney, Agent or Firm:
NOVAGRAAF INTERNATIONAL SA et al. (CH)
Download PDF:
Claims:
CLAI MS

1. A pig (5, 92) for installing an elongated element (80, 100) in a conduit (3), the pig (5, 92) being arranged to be driven in the conduit (3, 84) by a driving fluid (16) introduced under pressure in said conduit (3, 84), the pig (5, 92) comprising:

- a body (28),

- a seal (30) arranged on the body (28) and comprising an external side arranged to contact an internal surface of the conduit (3, 84),

characterized in that:

- the seal (30) further comprises an internal side opposed to the external side and defining a closed volume (42) between the seal (30) and the body (28), and

in that the pig (5, 92) further comprises:

- at least one valve (32), arranged to be in communication with the driving fluid (16), so as to adapt a pressure of the closed volume (42) with the driving fluid (16).

2. The pig (5, 92) according to the preceding claim, wherein the pig (5, 92) is arranged to travel in the conduit (3, 84) along an axial direction, the pig (5, 92) presenting a first axial side and a second axial side, and wherein the at least one valve (32) is arranged to selectively allow communication with the driving fluid (16) towards the closed volume (42):

- from the first axial side, or

- from the second axial side.

3. The pig (5, 92) according to the preceding claim, wherein the communication with the driving fluid (16) towards the closed volume (42) is arranged from the first or second axial side directed to the upstream side of the driving fluid (16). 4. The pig (5, 92) according to claim 2, comprising two valves being check valves:

- the first of the two check valves being arranged on the first axial side and arranged to allow communication with the driving fluid (16) towards the closed volume (42) when the driving fluid (16) is coming from the first axial side and to avoid the driving fluid (16) to flow out of the body (28) on first axial side when the driving fluid (16) is coming from the second axial side, and

- the second of the two check valves being arranged on the second axial side and arranged to allow communication with the driving fluid (16) towards the closed volume (42) when the driving fluid (16) is coming from the second axial side and to avoid the driving fluid (16) to flow out of the body (28) on second axial side when the driving fluid (16) is coming from the first axial side. 5. The pig (5, 92) according to claim 2, comprising a single valve, placed between the first axial side and second axial side, preferably at half distance.

6. The pig (5, 92) according to any one of the preceding claims, wherein the pig (5, 92) is arranged to travel in the conduit (3, 84) along an axial direction, the pig (5, 92) presenting a first axial side and a second axial side, and wherein

the seal (30) presents an annular shape and comprises:

- a first portion extending from the first axial side to an external diameter of the seal (30),

- a second portion extending from the second axial side to the external diameter of the seal (30), and

wherein the first portion and the second portion are continuous or tight sealed, so as to form the closed volume (42) between the seal (30) and the body (28). 7. The pig (5, 92) according to the preceding claim, wherein the body (28) comprises at least one stepped portion,

the seal (30) further comprises at least one stepped portion arranged to abut on the stepped portion of the body (28).

8. The pig (5, 92) according to any one of the preceding claims, wherein the pig (5, 92) further comprises a sliding ring (46) arranged between the seal (30) and the body (28). 9. The pig (5, 92) according to any one of the preceding claims, wherein the seal (30) is arranged to:

- seal the conduit (3, 84) when a pressure of the driving fluid (16) under pressure is between an operating threshold and a maximum threshold,

- provide a leak when the pressure of the driving fluid (16) under pressure is above the maximum threshold.

10. The pig (5, 92) according to the preceding claim, wherein the maximum threshold is below a maximum allowable pressure of the conduit (3, 84).

1 1. The pig (5, 92) according to any one of the preceding claim, the pig (5, 92) is arranged to travel in the conduit (3, 84) along an axial direction, the pig (5, 92) presenting a first axial side and a second axial side, and wherein

the body (28) comprises at least one axial body through hole on the first axial side and/or on the second axial side and arranged to allow communication between the driving fluid (16) and the at least one valve (32),

and wherein the at least one axial body through hole presents a predetermined diameter to limit the flow of driving fluid (16). 12. The pig (5, 92) according to any one of the preceding claim, wherein the pig (5, 92) is arranged to travel in the conduit (3, 84) along an axial direction, the pig (5, 92) presenting a first axial side and a second axial side, and wherein

the body (28) comprises on each first axial side and second axial side at least one leakage through hole to allow a leak communication of the driving fluid (16):

- from the first axial side to the second axial side or

- from the second axial side to the first axial side.

13. The pig (5, 92) according to any one of the preceding claims, wherein the pig (5, 92) further comprises a safety valve arranged to release the driving fluid. 14. The pig (5, 92) according to any one of the preceding claims, wherein the body is a hollow body arranged to receive the elongated element (80, 100).

15. The pig (5, 92) according to the preceding claim, further comprising inner sealing means (94, 94a) arranged between the body (28) and the elongated element (80, 100), so as to define an inner closed volume arranged between the closed volume (42) and the elongated element (80, 100), when the pig (5, 92) is coupled to the elongated element (80, 100). 16. The pig (5, 92) according to any one of the claims 14 to 15, wherein the pig (5, 92) is arranged to be clamped on the conduit (3, 84) by a lock pin (98).

17. The pig (5, 92) according to any one of the claims 14 to 16, wherein the pig (5, 92) further comprises a releasable dividable clamp ring (100A) arranged to present two positions, wherein when the releasable dividable clamp ring (100A) is in the first position, the pig (5, 92) is clamped onto the elongated element (80, 100), wherein when the releasable dividable clamp ring (100A) is in the second position, the pig (5, 92) is unclamped from the elongated element (80, 100).

Description:
DESC RI PTION

BI-D I RECTIONAL P IG FO R I NSTALLI NG A CABLE I N A

CON DU IT

[0001 ] The present invention relates to the laying of cables into conduits or ducts, and in particular the invention relates to cases where a pig for installing cables need to travel in both directions inside the conduits.

[0002] It is known form the prior art a pig for installing cables in a duct, the pig having a lip-seal. However, the pig with such lip-seal is not able to travel in both directions along the duct. Indeed, when travelling back on obstacles on the duct surface, the lip-seal of the pig according to the prior art leaks and/or flips over. The flip over also appears with such lip-seal in case of light over-pressure.

[0003] Further, the document US3908682 discloses a pig for plugging off sections of a pipe line with a ring connected to an inert gas bottle. The expansion of the ring is performed with a remote control. The pig according to this document has the drawback to require additional on-board equipment such as pressurized bottle therein, which render the system complex. In addition, this requires the remote control of the expansion of the ring, which also render the system more complex. Indeed, as the pig is located inside the pipe without easy access therein for maintenance, it is very uncomfortable in case of troubleshooting for the remote control, for the expansion of the ring or for the pressurized bottle.

[0004] The present invention aims to address the above mentioned drawbacks of the prior art, and to propose a pig for installing an elongated element in a conduit, with the ability to travel in both directions with the same behavior in both directions (i.e. no leaks, no damages on seal), and the ability to pass through obstacles on the duct surface, with a robust structure to ease maintenance, and to limit on-pipe troubleshooting of components. In particular, the travelling in both directions may be required when the pig got stuck. Further, it allows to have a control of the pig from the ground (i.e. outside of the conduit, in order to have more comfortable condition for man work) and a pig well suited to lay elongated elements such as cables, ropes, tubes into conduits or ducts. Still further, it allows to take in account the ovality of the conduit and also some necking down of the total free cross-sectional area in the duct.

[0005] In this aim, a first aspect of the invention relates to a pig for installing an elongated element in a conduit, the pig being arranged to be driven in the conduit by a driving fluid introduced under pressure in said conduit,

the pig comprising:

- a body,

- a seal arranged on the body and comprising an external side arranged to contact an internal surface of the conduit,

characterized in that:

- the seal further comprises an internal side opposed to the external side and defining a closed volume between the seal and the body, and

in that the pig further comprises:

- at least one valve, arranged to be in communication with the driving fluid, so as to adapt a pressure of the closed volume with the driving fluid.

[0006] This allows to provide a pig with the ability to travel in both directions without damages to the seal and without leaks in said both directions in normal conditions of use, and to pass through obstacles on conduit surface. Further, the pig has a robust design in order to limit maintenance, as there is no electronic control to control a pressurized bottle inside the pig (as in the prior art). Indeed, the valve may be driven directly by the driving fluid. Thereby, the maintenance of components inside the pig when installed in the conduit is limited. Still further, as there is no electronic control of the pressurized bottle as in the prior art, the control of the pig can be performed from the ground, by controlling the driving fluid. The pig according to the present invention is well suited to lay elongated elements in conduits or ducts. In addition, the design of the pig is more simple, reducing the cost of manufacturing.

[0007] Furthermore, it allows to make the remote tuning of the position of the cable less critical, because of the ability to move back too. This is extremely useful in case of difficult to access places, like in tunnels and in offshore environment. It can keep uphill water columns in place, easing the laying of the elongated element.

[0008] In other words, the valve is arranged to be in communication with the driving fluid and to allow the driving fluid to contact the internal side of the seal so as to pressurize the closed volume. The driving fluid under pressure communicates with the internal side of the seal, so as to pressurize the volume and to seal the conduit.

[0009] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and

wherein the at least one valve is arranged to selectively allow communication with the driving fluid towards the closed volume:

- from the first axial side, or

- from the second axial side.

[0010] Advantageously, the communication with the driving fluid towards the closed volume is arranged from the first or second axial side directed to the upstream side of the driving fluid.

[001 1 ] Advantageously, the pig comprises two valves being check valves:

- the first of the two check valves being arranged on the first axial side and arranged to allow communication with the driving fluid towards the closed volume when the driving fluid is coming from the first axial side and to avoid the driving fluid to flow out of the body on first axial side when the driving fluid is coming from the second axial side, and

- the second of the two check valves being arranged on the second axial side and arranged to allow communication with the driving fluid towards the closed volume when the driving fluid is coming from the second axial side and to avoid the driving fluid to flow out of the body on second axial side when the driving fluid is coming from the first axial side.

[0012] Advantageously, the pig comprises a single valve, placed between the first axial side and second axial side, preferably at half distance.

[0013] This allows to provide a pig able to travel in both directions with the driving fluid coming (alternatively) from the first axial side or from the second axial side, or coming from both sides, preferably with a pressure difference between the first side and the second side, and to propose a design which eases the manufacturing of the pig.

[0014] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and wherein

the seal presents an annular shape and comprises:

- a first portion extending from the first axial side to an external diameter of the seal,

- a second portion extending from the second axial side to the external diameter of the seal, and

wherein the first portion and the second portion are continuous or tight sealed, so as to form the closed volume between the seal and the body.

[0015] Advantageously, the body comprises at least one stepped portion, the seal further comprises at least one stepped portion arranged to abut on the stepped portion of the body.

[0016] Advantageously, the seal further comprises at least one heel portion arranged on the body. [0017] This allows to propose a pig having a seal which is easy to manufacture, and efficient to travel in both directions without leaks under normal conditions of use.

[0018] Advantageously, the pig comprises means for attaching the elongated element in order to install the elongated element in the conduit. The means for attaching can be clamp, clamp ring, eye such as lifting eye, or the like.

[0019] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and wherein the body comprises at least one inner portion through hole facing the closed volume and at least one axial body through hole on the first axial side and/or on the second axial side and arranged to allow communication between the driving fluid and the at least one valve, the at least one valve comprises a spool arranged to uncover or cover the at least one inner portion through hole facing the closed volume.

[0020] Advantageously, the body comprises one first inner portion through hole facing the closed volume on the side of the first axial side and one second inner portion through hole facing the closed volume on the side of the second axial side, and

wherein the spool is arranged to selectively :

- cover the first inner portion through hole facing the closed volume on the side of the first axial side and uncover the second inner portion through hole facing the closed volume on the side of the second axial side, when the driving fluid is coming from the second axial side,

- cover the second inner portion through hole facing the closed volume on the side of the second axial side and uncover the first inner portion through hole facing the closed volume on the side of the first axial side, when the driving fluid is coming from the first axial side.

[0021 ] In other words, the spool of the valve is a bobbin shaped body or a sliding drawer. The spool is opening or closing a communication between the driving fluid under pressure and the closed volume. In a general manner, a spool valve comprises a spool and a valve body arranged to guide the spool. The valve body may be part of the valve itself or part of the body of the pig, that is to say the body of the pig comprises a guiding portion to guide the spool.

[0022] This allows to provide a pig having a simple design being very robust when driven by the driving fluid.

[0023] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and wherein

the pig is symmetrical on a symmetrical axis which is arranged to be perpendicular to the axial axis of the conduit.

[0024] That is to say the pig is symmetrical on a symmetrical axis which is arranged to be perpendicular to the axis of the conduit and at an equal distance from the first axial side and the second axial side.

[0025] This allows to provide a pig able to travel in both directions with a very convenient design, allowing to install the pig without checking the side putted first in the conduit, thereby easing the installation of the pig in the conduit.

[0026] Advantageously, the pig further comprises a sliding ring arranged between the seal and the body.

[0027] This allow to better adjust the seal on the body to have a better behaviour of the seal regarding the leak and mechanical stress and movement.

[0028] Advantageously, the seal is arranged to:

- seal the conduit when a pressure of the driving fluid under pressure is between an operating threshold and a maximum threshold,

- provide a leak when the pressure of the driving fluid under pressure is above the maximum threshold. [0029] The sealing of the conduit is understood as the fact there is no leak during normal use. This is the contact and/or sliding over of external side of the seal with the internal side of the conduit.

[0030] Advantageously, the maximum threshold is below a maximum allowable pressure of the conduit.

[0031 ] This allows to provide a protection of the conduit wherein the pig in travelling, so that there is no fatigue or damages on the conduit and on the pig. In particular, this render the pig more simple without using special safety valve, or if using safety valve, this render the pig safer.

[0032] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and wherein

the body comprises at least one axial body through hole on the first axial side and/or on the second axial side and arranged to allow communication between the driving fluid and the at least one valve,

and wherein the at least one axial body through hole presents a predetermined diameter to limit the flow of driving fluid, such that not too much flow of driving fluid is lost.

[0033] Advantageously, the pig is arranged to travel in the conduit along an axial direction, the pig presenting a first axial side and a second axial side, and wherein

the body comprises on each first axial side and second axial side at least one leakage through hole to allow a leak communication of the driving fluid:

- from the first axial side to the second axial side or

- from the second axial side to the first axial side.

[0034] This allows to share fluid pressure between two pigs placed in the conduit, and ease the installation of the elongated element in the conduit. [0035] Advantageously, the pig comprises means for obtaining a pressure drop of the driving fluid between a rear of the pig and a front of the pig. The means are communication holes in an embodiment.

[0036] In case of use of a plurality of pigs linked by a connecting cable along the conduit, the pressure drop between the rear end of the connecting cable and the front end of the connecting cable is divided over the plurality of pigs.

[0037] Advantageously, said pressure drop between the rear end of the connecting cable and the front end of the connecting cable is equally divided over the plurality of pigs. In other words, each pig of the plurality of pigs causes an equal pressure drop.

[0038] Further, the at least one leakage through hole allows leak communication to pass through the pig, and allows to have pressure sharing between pigs installed along the conduit. The at least one leakage through hole is preferably small, and more preferably smaller than the hole (or housing) in the body receiving the valve or the holes in the valve. Indeed, the at least one leakage through hole needs to be small compared to the valve dimension to allow built-up of the pressure in the closed volume, while allowing pressure sharing between pigs, when the plurality of pigs is installed in the conduit. In an embodiment wherein the pig has a safety valve, the hole/housing in the body receiving the safety valve is of larger dimension compared to the leakage through hole, and preferably of the same size than the hole/housing (inner portion of body) receiving the valve, so as to allow the release of the total water flow when the pig stops within the limited max pressure, in particular during a water hammer occurring in the conduit (e.g. due to pump reason, gate closing, cable retention or sudden stop of the pig).

[0039] Advantageously, the pig further comprises a safety valve arranged to release the driving fluid.

[0040] This allows to protect the pig and the conduit in case of overpressure. [0041 ] Advantageously, the body is a hollow body arranged to receive the elongated element.

[0042] In other words, the hollow body is arranged to be coupled over the elongated element.

[0043] This allows to lay the elongated element such as the cable or the plurality of cables, in a conduit in an efficient manner, in particular in the case of large elongated element.

[0044] Advantageously, the at least one valve is a check valve.

[0045] Advantageously, the pig further comprises inner sealing means arranged between the body and the elongated element, so as to define an inner closed volume arranged between the closed volume and the elongated element, when the pig is coupled to the elongated element.

[0046] Advantageously, the at least one valve is arranged to be in communication with the driving fluid, so as to adapt a pressure of the closed volume and the inner closed volume.

[0047] Advantageously, the pig is arranged to be clamped on the conduit by a lock pin.

[0048] Advantageously, the pig further comprises a releasable dividable clamp ring arranged to present two positions,

wherein when the releasable dividable clamp ring is in the first position, the pig is clamped onto the elongated element,

wherein when the releasable dividable clamp ring is in the second position, the pig is unclamped from the elongated element.

[0049] This allows to connect and disconnect the pig to the conduit and to the elongated element in order to lay the elongated element in the conduit, and also to built up the conduit by sections of conduit. [0050] Advantageously, the driving fluid is water, or sea water, or high salinity water, or water with additives (alcohol, lubricant, oil...) to improve the driving of the pig and the laying of the elongated element.

[0051 ] Other features and advantages of the present invention will appear more clearly from the following detailed description of particular non-limitative examples of the invention, illustrated by the appended drawings where:

- figure 1 represents a pig having a seal according to the prior art installed in a conduit,

- figure 2 represents the pig according to the prior art passing an obstacle of the conduit,

- figure 3 represents the pig according to the prior art equipped with a large seal, installed in the conduit,

- figure 4 represents the pig according to the prior art equipped with the large seal, passing the obstacle in the conduit,

- figure 5 represents the pig according to the prior art equipped with the large seal in the conduit, wherein overpressure is introduced in the conduit,

- figure 6 represents the pig according to the prior art equipped with the seal mounted on a skirt, in the conduit,

- figure 7 represents the pig according to the prior art equipped with the seal mounted on the skirt, passing the obstacle in the conduit,

- figure 8 represents a pig in a first embodiment according to the present invention installed in a conduit, wherein a driving fluid is coming from a first axial side,

- figure 9 represents the pig of the present invention installed in the conduit, wherein the driving fluid is coming from a second axial side, opposite to the first axial side, - figure 10 represents the pig of the present invention installed in the conduit, wherein overpressure is introduced in the conduit,

- figure 1 1 represents the pig of the present invention installed in the conduit, wherein a desired maximum pressure is introduced in the conduit,

- figure 12 represents a second embodiment of the pig according to the present invention installed in the conduit, wherein sliding rings are installed on the pig,

- figure 13 represents a third embodiment of the pig according to the present invention installed in the conduit, the pig having a small leaking spool,

- figure 14 represents a fourth embodiment of the pig according to the present invention installed in the conduit, the pig having a safety valve and a small leaking hole,

- figure 15 represents a fifth embodiment of the pig according to the present invention installed in the conduit, the pig having check valves and safety valves,

- figure 16 represents a sixth embodiment of the pig according to the present invention installed in the conduit, the pig having guiding fingers and hybrid valves,

- figure 17 represents a seventh embodiment of the pig according to the present invention installed in the conduit, the pig having a hollow body to receive an elongated element, wherein the pig is clamped on the conduit and unclamped from the elongated element,

- figure 18 represents the seventh embodiment of the pig according to the present invention installed in the conduit, the pig having the hollow body to receive the elongated element, wherein the pig is unclamped from the conduit and clamped on the elongated element,

- figure 19 represents a detailed view of a part of the hybrid valve, seen from a first side, - figure 20 represents a detailed view of the part of the hybrid valve, seen from a second side.

[0052] Figure 1 represents a pig according to the prior art installed in a conduit.

[0053] In the prior art, the pig 2 pulls a cable 100 (or elongated element) into a duct or conduit 3. The pig 2 is driven by a driving fluid 16 introduced under pressure in the duct 3. In figure 1 , the driving fluid is on the bottom part of the figure 1 , which means that the pig 2 is moving from bottom to top of figure 1 in such configuration. The pig 2 is equipped with a seal 6 mounted of the body 4 of the pig 2. The pig 2 is also equipped with a bar 8, 12 attached to a pulling eye 10 and a pushing eye 14, and extending from both sides of the body 4.

[0054] In all figures, the reference numbers are kept unchanged, as far as possible, for the common parts.

[0055] Figure 2 represents the pig according to the prior art passing an obstacle of the conduit.

[0056] Besides the fact that the pig 2 of the prior art cannot be pulled back due to the shape of the seal 6, there is not much play for passing an obstacle like 18 in Figure 2.

[0057] Figure 3 represents the pig according to the prior art equipped with a large seal, installed in the conduit.

[0058] In figure 3, the pig 2 of the prior art is equipped with a large lip seal 26 mounted on the body 24, which is larger than the seal 6 of the pig 2 of the prior art represented in figures 1 to 2.

[0059] Figure 4 represents the pig according to the prior art equipped with the large seal, passing the obstacle in the conduit.

[0060] The pig 2 of the prior art has more margin to pass such obstacle 18 in one way (from bottom to top on figure 4). In the other way (from top to bottom on figure 4), the large lip seal 26 will abut on the obstacle and will be damaged and then leaking.

[0061 ] Figure 5 represents the pig according to the prior art equipped with the large seal in the conduit, wherein overpressure is introduced in the conduit.

[0062] Lip seals such as the large seal 26 do also easier collapse (flip over) when the pressure becomes a bit too high as shown in Figure 5, which is a drawback of the prior art pig 2.

[0063] Figure 6 represents the pig according to the prior art equipped with the seal mounted on a skirt, in the conduit.

[0064] In Figure 6 an embodiment of the prior art pig 2 is shown where the skirt 20 is used, installed on the body 24 having a flange body 22. Said skirt 20 allows elliptical deformation of an hem of the lip seal 6, as disclosed in the prior art document EP1518307B1.

[0065] Figure 7 represents the pig according to the prior art equipped with the seal mounted on the skirt, passing the obstacle in the conduit.

[0066] The prior art pig 2 equipped with the skirt 20 having the lip seal 6 therein is able to pass obstacle 18 (in particular with asperities 18a) in the conduit 3, in one way only. Flowever, in case of an entirely narrowed opening in the duct, the skirt cannot pass, because it cannot decrease its circumference. In the other way, the shape of the lip seal will abut on the obstacle 18 and will damaged.

[0067] The drawback of the prior art pig 2 is that it cannot reverse back, and in particular it cannot reverse back when passing obstacles 18 in the conduit 3. Further, the prior art pig 2 has no protection in case of a water hammer in the conduit 3, due to for example suddenly closure of a general valve in the conduit 3. [0068] Figure 8 represents a pig in a first embodiment, installed in a conduit, wherein a driving fluid is coming from a first axial side.

[0069] References numbers are kept in figures, as far as possible, for the common parts.

[0070] A pig 5 comprises a body 28 equipped with eyes 10, 14 in order to install an elongated element, such as a cable 100 or a plurality of cables. The pig 5 is installed in a conduit 3, which is similar to the conduit 3 of the prior art. The pig 5 further comprises a balloon-shaped seal 30 mounted on the body 28, that is to say, the balloon-shaped seal 30 is arranged between the body 28 and the conduit 3, when the pig 5 is installed in the conduit 3.

[0071 ] In a preferred embodiment, said balloon-shaped seal 30 is formed with two larges lip seals 26 shown in Figure 3 glued one by one to each other, as mirrored counterparts. In other words, the balloon-shaped seal 30 is formed with two large lip seal which are glued or tight sealed together in the reverse position.

[0072] The balloon-shaped seal 30 presents an annular shape, an external side 30b facing the internal side 3a of the conduit 3 and an internal side 30a on the side of the body 28, opposite to the external side of the balloon-shaped seal 30. As the balloon-shaped seal 30 is mounted on the body 28 and is annular shaped, a closed volume 42 is formed between the balloon-shaped seal 30 and the body 28.

[0073] Driving fluid 16 is introduced under pressure in the conduit 3. In the example of figure 8, the driving fluid 16 is introduced by the bottom, so that the pig 5 is driven from the bottom to the top of figure 8 along an axial direction X of the conduit 3.

[0074] The pig 5 presents a first axial side X1 and a second axial side X2, which are in opposition to each other along the axial direction X of pig’s movement. The pig 5 further comprises axial body through holes 40, 40a on the body 28, on the first axial side X1 and on the second axial side X2, in order to allow communication between the driving fluid 16 and the inside volume of the body 28.

[0075] Inside the body 28, at the level of a cylindrical inner portion 50 of the body 28, a spool 32 of a valve is installed that moves into the direction where the driving fluid 16 under pressure pushes it to. In other words, when the driving fluid 16 is coming from the first axial side X1 of the body 28 (ie. from the bottom side of figure 8), the spool 32 moves towards the second axial side X2 due to the pressure applied on it; and when the driving fluid 16 is coming from the second axial side X2 (i.e. from the top of figure 8), the spool 32 is moving to the first axial side X1.

[0076] The spool 32 is a part of a spool valve arranged to move along the longitudinal direction. In other words, the spool 32 is a bobbin shaped body. The valve body can either be a sleeve surrounding the spool 32 or the cylindrical inner portion 50 directly facing the spool 32.

[0077] In the example of figure 8, the spool 32 comprises two annular voids 34 and 34a and openings (or valve through holes) 38 and 38a are present in spool 32. The annular void 34 and the opening 38 are arranged on the spool 32 on the side of the first axial side X1 and the annular void 34a and the opening 38a are arranged on the spool 32 on the side of the second axial side X2. The spool 32 further comprises a full cylinder portion 34c between the two annular voids 34 and 34a. The openings 38 and 38a are placed at opposite end of the spool 32.

[0078] Furthermore, openings or inner portion through holes 36, 36a are present in body 28 (at the level of the cylindrical inner portion 50) and face the closed volume 42, so as to allow communication of the driving fluid 16 with the internal side of the balloon-shaped seal 30 and the closed volume 42. [0079] The opening 36 is arranged on the body 28 on the side of the first axial side X1 and the opening 36a is arranged on the body on the side of the second axial side X2.

[0080] The opening 36 is arranged to face the annular void 34 or the full cylinder portion 34c, while the opening 36a is arranged to face the annular void 34a or the full cylinder portion 34c, depending on the position of the spool 32 in the cylindrical inner portion 50 according to the side from where comes the driving fluid 16.

[0081 ] That is to say, when the driving fluid 16 under pressure comes from the first axial side X1 , as represented in Figure 8, the spool 32 is pushed towards the second axial side X2 (up of the figure 8) such that the driving fluid 16 communicates with the closed volume 42 between pig body 28 and balloon-shaped seal 30, through holes 40 and 38, via annular void 34 and through hole 36. The balloon-shaped seal 30 is now pressurized and the pressure adapted. The pig 5 is driven by the driving fluid 16 under pressure and moves (to the upper side of the figure 8). The closed volume 42 can be deformed by the pressure from the driving fluid 16, depending on the rigidity of the balloon-shaped seal 30 and the pressure of the driving fluid 16 under pressure. In other words, the closed volume 42 may be a deformable closed volume. In particular, the balloon-shaped seal 30 can be reinforced with metallic parts to enhance its rigidity.

[0082] The spool 32 comprises step portions to abut on the body 28, when driven by the driving fluid 16, so that the position of the spool 32 in the cylindrical inner portion 50 is limited and secured.

[0083] The balloon-shaped seal 30 comprises two annular step portions 31 , 31 a arranged on abutment against corresponding annular step portion 49, 49a of the body 28, so as to realize a mechanical engagement between the two annular step portions 31 , 31 a of the balloon-shaped seal 30 and the two annular step portions 49, 49a of the body 28. [0084] Figure 9 represents the pig of the first embodiment installed in the conduit, wherein the driving fluid is coming from the second axial side.

[0085] The pig 5 of figure 9 is the same than the pig 5 of figure 8. Figure 9 differs from figure 8 in that the driving fluid 16 is coming from the second axial side X2.

[0086] When the driving fluid 16 comes from the second axial side X2 (upper side of figure 9), spool 32 is pushed towards the first axial side X1 (bottom side of figure 9), such that the driving fluid 16 communicates with the closed volume 42 through holes 40a and 38a, via annular void 34a and through hole 36a. The balloon-shaped seal 30 is now pressurized and the pressure adapted.

[0087] The closed volume 42 can be deformed by the pressure from the driving fluid 16, depending on the rigidity of the balloon-shaped seal 30 and the pressure of the driving fluid 16 under pressure.

[0088] The pig 5 is driven by the driving fluid 16 under pressure and moves (to the bottom side of the figure 9).

[0089] Figure 10 represents the pig of the first embodiment installed in the conduit, wherein overpressure is introduced in the conduit.

[0090] In Figure 10 the pressure of the driving fluid 16 under pressure is increased. In this case, the balloon-shaped seal 30 is deformed due to the overpressure.

[0091 ] The contact between the balloon-shaped seal 30 and the conduit 3 may depend on the internal stress and constraint inside the balloon- shaped seal 30, the stiffness and shape of the front part and rear part of the balloon-shaped seal 30 and the pressure of the driving fluid 16.

[0092] With the Finite Element Method (FEM) analysis or any other method of calculation, a seal such as the balloon-shaped seal 30 can be designed to operate until the desired maximum pressure. This desired maximum pressure can be much higher than the pressure where the large lip seal 26 of the prior art would collapse (flip over), because it is held in position by “pulling” of its mirrored counter-part. The balloon-shaped seal 30 is deformed by the pressure of the driving fluid which is higher than the pressure of the driving fluid 16 in figure 9.

[0093] Figure 1 1 represents the pig of the first embodiment installed in the conduit, wherein a desired maximum pressure is introduced in the conduit.

[0094] With the Finite Element Method (FEM) analysis or any other calculation method, a desired maximum pressure can be set or determined so that the balloon-shaped seal 30 also opens as represented in figure 1 1. This“opening pressure”, where the balloon-shaped seal 30 leaks or presents a slight leak, can be designed such that it matches or is below the maximum allowable conduit pressure. In this way, the conduit 3 is protected, also in case when a water hammer occurs, due to for example a suddenly closure of a general closing valve installed on the conduit 3.

[0095] When the pressure of the driving fluid 16 is greater than the maximum allowable pressure of the balloon-shaped seal 30, the balloon shaped seal 30 leaks (as indicated by dot curved lines in figure 1 1 ). Preferably, the maximum allowable pressure of the balloon-shaped seal 30 is lower than the maximum allowable pressure of the conduit 3, so that the conduit 3 is protected.

[0096] Figure 12 represents a second embodiment of the pig installed in the conduit, wherein sliding rings are installed on the pig.

[0097] In Figure 12, the pig 5 comprises a sliding ring 46 arranged between the body 28 and the balloon-shaped seal 30. The pig 5 is represented in a case where the driving fluid 16 is under high pressure deforming the balloon-shaped seal 30 and pushing the sliding ring 46 (arrows in figure 12). [0098] The sliding ring 46 is in particular very interesting in the case it is not possible to design a balloon-shaped seal 30 that is able to withstand enough pressure, because the“pulling back” of the rear part of the balloon-shaped seal 30 starts too soon. In this case, an higher“opening pressure” (where the balloon-shaped seal 30 presents a slight leak) can be realized with heel portions 44 and 44a of the balloon-shaped seal 30 sliding over a certain length along the body 28.

[0099] In order to minimize the sliding friction of the balloon shaped seal 30 (e.g. made of rubber, nitrile or plastic), sliding rings or metal low friction cylinders 46 and 46a (e.g. brass cylinders, or surface treated steel) can be used to slide over the body 28 (e.g. made of steel). It is understood that also other combinations of metal or plastic can be used. The sliding rings 46 may also be monobloc and have at least one sliding ring through hole to allow communication between the closed volume 42 and the inside of the body 28, so that the driving fluid 16 can communicate to the closed volume 42 thanks to the spool 32.

[0100] Figure 13 represents a third embodiment of the pig installed in the conduit, the pig having a small leaking spool.

[0101 ] In the third embodiment represented in figure 13, the pig 5 differs from the second embodiment in that the spool 32 has a leakage longitudinal through hole 48.

[0102] The leakage longitudinal through hole 48 will in use cause a small or desired leak through the pig 5. This leak of driving fluid 16 is flowing through the upstream side (here the bottom side of figure 13, or X1 ) to the downstream side (here the upper side of figure 13, or X2).

[0103] When a plurality of pigs 5 are installed in the conduit 3 and used in tandem, with similar longitudinal through holes 48 on each pig 5, the pigs 5 share the water pressure equally, which is useful in applications with so-called MultiPig (which is described in details in the document US8770550B2) and/or with so-called FreeFloating (which is described in details in the document US9287689B2).

[0104] Of course, the pig 5 can still be used with other accessories, e.g. general safety valves for water hammer prevention.

[0105] Figure 14 represents a fourth embodiment of the pig installed in the conduit, the pig having a directional safety valve and a small leaking hole.

[0106] The pig 5 of the fourth embodiment comprises a pig safety valve 70. The cylindrical inner portion 50 of the body 28 differs from the other embodiment in that it is larger to allow a directional safety valve 52 (or directional valve 52), which is larger in diameter compared to the spool 32. Inside the directional valve 52 are installed two safety valves, one safety valve on the side of the first axial side 56 and one safety valve on the side of the second axial side 58, forming the pig safety valve 70. Each safety valve 56, 58 are kept in position by spring 60 and mounted with lid 62, attached with screws 64. The directional valve 52 is perforated with multiple openings 66 and with annular voids 68.

[0107] In the fourth embodiment, the openings 36, 36a, 38, 38a, 40 and 40a presented above are each made of multiple openings or larger openings. This is done in order to allow larger flows through them, which may be needed when handling a water hammer. Cylindrical arrays 54 are provided in the directional valve 52 to allow larger flows. In other words, cylindrical arrays 54 are long through openings provided in the directional valve 52. Cylindrical arrays 54 can be oblong shaped opening, square or rectangular shaped openings, or any other suitable shapes. Cylindrical arrays 54 are placed on the directional valve 52, the directional valve 52 having a cylindrical shape in the embodiment of figure 14, to allow large flow to flow from the internal side of the directional valve 52 to the external side of the directional valve 52. The cylindrical arrays 54 allow the flow to travel in radial direction (and not in axial direction). The cylindrical arrays 54 extend in axial length/direction to be able to match the covered or uncovered position of the inner portion through holes 36, 36a. In Figure 14, the check valve 52 is represented in upward position, that is to say on the side of the second axial side X2. Annular voids 68 of the directional valve 52 in the side of the first axial side X1 are then communicating with the inner portion through holes 36 on the side of the first axial side X1 , thereby filling the closed volume 42 thanks to hole 38. The inner portion through holes 36a on the side of the second axial side X2 are not in connection with the annular voids 68 on the side of second axial side X2. Instead the closed volume 42 is communicating with the hollow cylindrical space 52a inside the check valve 52, through the cylindrical arrays 54 (which are positioned « open » with the holes 36a, but « closed » with the holes 36). When the pressure of the driving fluid 16 exceeds a pre-set maximum, the upper (or second side X2) safety valve 58 opens thanks to upward movement of lid 62 on spring 60 (similar functioning apply in figure 16 explained below). It is also possible to have the cylindrical arrays 54 as tangentially extending slits, where at least two of those slits shall exist, one on the side of the first axial side X1 and one on the side of the second axial side.

[0108] Thank to axial body through holes 40, 40a, communication can be made between the driving fluid 16 and the closed volume 42 (inside the balloon-shaped seal 30) and inside the directional valve 52, with large flows (due to the large number of openings). The small channel or small longitudinal through holes 48a are similar to longitudinal through holes 48 in the third embodiment of figure 13. The springs 60 are limiting the pressure inside the directional valve 52 and act as safety valve to evacuate the driving fluid 16 from the first axial side X1 to the second axial side X2 with larger flows than the small channel 48a. Of course, the springs 60 are acting also to evacuate overpressure of the driving fluid 16 from the second axial side X2 to the first axial side X1 (when the driving fluid is coming from the first axial side X1 ). [0109] Figure 15 represents a fifth embodiment of the pig installed in the conduit, the pig having check valves and safety valves.

[01 10] The pig 5 of the fifth embodiment has two check valves 41 , 41 a to cover two axial body through holes 40, 40a on the body 28, on the first axial side X1 and on the second axial side X2 respectively, in order to allow communication between the driving fluid 16 and the inside volume of the body 28. In the example shown in figure 15, the driving fluid 16 comes from the first axial side X1 , opens the check valve 41 on the first axial side X1 and closes the check valves 41 a on the second axial side X2.

[01 1 1 ] The pig 5 further comprises small leak through holes 78,

78a arranged on the body 28 (on the first axial side X1 and on the second axial side X2 respectively), so as to create a small leak from the first axial side X1 to the second axial side X2 or from the second axial side X2 to the first axial side X1. This small leak is in particular useful when a plurality of pigs 5 are installed in the conduit 3. The pig 5 further comprises two safety valves 77, 77a, arranged respectively on the first axial side X1 and on the second axial side X2, and covering safety valves holes 76, 76a on the body 28. Each safety valve 77, 77a comprises a safety valve body 77b, 77ab attached to the body 28 of the pig 5, a plunger 77p, 77ap arranged to face the safety valves hole 76, 76a on the body 28 and a spring 77s, 77as arranged to force the plunger 77p, 77ap against the safety valve holes 76, 76a when the pressure of driving fluid 16 is bellow a predetermined value. Each safety valve 77, 77a further comprises holes 77h, 77ah on the safety valve body 77b, 77ab to allow the release of pressure when the pressure is above the predetermined value. The predetermined value can be the max allowable pressure of the duct 3. The safety valve holes 76, 76a have preferably the same diameter than the axial body through holes 40, 40a, and at least a larger diameter than the small leak through holes 78, 78a, to allow a quick release of over pressure. The holes 77h, 77ah on the safety valve body 77b, 77ab are also large enough for quick release, that is to say preferably similar (equivalent) diameter than the axial body through holes 40, 40a. Each of the safety valves 77, 77a comprises a plunger contacting plate having plunger contact plate holes 77q, 77aq respectively. The plunger contacting plate cooperates with the spring 77s, 77as to bias the plunger 77p, 77ap. When the plunger 77p, 77ap contacts the safety valves hole 76, 76a on the body 28 due to driving fluid 16 (or spring effort), there is no flow passing through the safety valve 77, 77a. When the pressure of driving fluid 16 is above the predetermined value, the safety valve 77, 77a opens and the driving fluid 16 flows through the safety valve 77, 77a, via safety valve holes 76, 76a, plunger contact plate holes 77q, 77aq and safety valve body holes 77h, 77ah. The plunger contact plate holes 77q, 77aq have similar (equivalent) diameter than holes 77h, 77ah on the safety valve body 77b, 77ab.

[01 12] In the example shown in figure 15, the driving fluid 16 comes from the first axial side X1 through the pig 5, going inside the body 28 of the pig 5 by the check valve 41 uncovering the axial body through hole 40 and built the pressure in the closed volume 42 on the internal side of the seal 30 via the openings or inner portion through holes 36b present in body 28; while leaking a little bit in the small leak though hole 78a. The leak at the level of the small leak through hole 78a is small enough to allow the pressure to be built in the closed volume 42, that is to say that the small leak through holes 78, 78a have smaller diameter than the inner portion through holes 36b, the axial body through holes 40, 40a and the safety valve holes 76, 76a receiving safety valves 77, 77a.

[01 13] The axial body through holes 40, 40a are arranged on the body 28 on the first axial side X1 and the second axial side X2 respectively. They can also be placed on the body 28 on the lateral side of the body 28: the axial body through hole 40 of the first axial side X1 being arranged between the seal 30 and the first axial side X1 so as to allow communication from the first axial side X1 to the inside of the pig 5 and the internal face of the seal 30; while the axial body through hole 40a of the second axial side X2 being arranged between the seal 30 and the second axial side X2 so as to allow communication from the second axial side X2 to the inside of the pig 5 and the internal face of the seal 30.

[01 14] Figure 16 represents a sixth embodiment of the pig installed in the conduit, the pig having guiding fingers.

[01 15] The pig 5 is installed in the conduit 3 and is equipped with eyes 10, 14 in order to install the elongated element, such as a cable 100 or a plurality of cables.

[01 16] The pig 5 also comprises the balloon-shaped seal 30 to seal the conduit 3 and to allow the pig 5 to travel in both direction, in the direction from the first axial side X1 to the second axil side X2 or in the direction from the second axial side X2 to the first axial side X1.

[01 17] The pig 5 further comprises guiding fingers 21 to allow guidance of the pig 5 in the conduit 3. The guiding fingers 21 are made of a plurality of guiding fingers 21 at each of the first axial side X1 and the second axial side X2 of the body 28.

[01 18] The pig 5 further comprises two hybrid valves 79s, one arranged on the side of the first axial side X1 of the pig 5, and one arranged on the side of the second axial side X2 of the pig 5.

[01 19] The body 28 comprises the axial body through holes 40,

40a, to allow communication from the first axial side X1 or from the second axial side X2 respectively, to the hybrid valves 79s.

[0120] Each of the hybrid valves 79s comprises a spring 79sp, and a hollow cylinder having a hollow cylinder hole 40b therein, so that the hollow cylinder acts as a check valve allowing the flow to pass only in one direction (from the first axial side X1 to the inside of the body 28 for the hybrid valve 79s installed on the side of first axial side X1 of the pig 5 and from the second axial side X2 to the inside of the body 28 for the hybrid valve 79s installed on the side of the second axial side X2). [0121 ] Each hybrid valve 79s further comprises a small leak hole 48 to allow a small leak to flow from the first the axial side X1 to the second axial side X2, and vice-versa.

[0122] Each hybrid valve 79s further comprises array holes 66 having a total cross section of holes large enough to release the flow during a water hammer occurring in the conduit 3. The total cross section is at least equal to the cross section of axial body through holes 40, 40a.

[0123] In a case where the pressure comes from the first axial side X1 , the driving fluid 16 goes to the inside of the valve 79s installed on the first axial side X1 , and goes through the hollow cylinder hole 40b (the hollow cylinder acting as a check valve). Then, the driving fluid 16 goes to the inside of the body 28 and goes to the closed volume 42 (internal side of the seal 30) via inner portion through holes 36 and frame body hole 51. The seal 30 is pressurized and the conduit 3 is sealed. The driving fluid 16 flow out on the second axial side X2 via the small leak through hole 48, but not with large flow as the hollow cylinder of the hybrid valve 79 on the second axial side X2 acts as a check valve (that is to say, the hollow cylinder hole 40b of the valve 79s on the second axial side X2 is covered), when the pressure of the driving fluid 16 is below an overruling value. In case of overruling of the safety valves 79s (as shown on the second axial side X2), wherein the pressure of driving fluid 16 is higher than the overruling value, the driving fluid 16 is released from the inside of the body 28 by the valve 79s on the second axial side X2, as the spring 79sp is compressed up to a position wherein the array holes 66 are uncovered (a large flow is thereby released to the second axial side X2). The total cross-section of array holes 66 is similar to the size of hollow cylinder hole 40b, similar to the size of hollow cylinder arrays 40c of hollow cylinder 79h, and amply larger than the small leak through hole 48. Instead of array holes 66, array slits can be provided. In case of water hammer occurring in the conduit 3, wherein the pressure is (much) higher than the overruling value, the spring of the safety valve 79s is fully compressed and the flow is even higher. There is three working positions of the safety valve 79s: a first position (as shown on the first side X1 ) wherein the safety valve is biased by the spring 79sp against a shoulder of the body 28, a second position wherein the safety valve is still biased by the spring, but the hollow cylinder hole 40b is in“closed check valve position” (not shown, would occur on the second side X2 at lower pressure), and a third position wherein the spring 79s is compressed and the safety valve is“open” in case of too high pressure, e.g. in case of a water hammer (as shown on the second side X2).

[0124] Similar functioning may also appear when the driving fluid 16 comes from the second axial side X2. The pig 5 is thereby able to travel in both directions.

[0125] The spring 79sp of hybrid valves 79s may also be adjusted so that the valves 79s have an adjustable max pressure which is set to the allowable maximum pressure of the conduit 3.

[0126] Each hybrid valve 79s further comprises a hybrid valve large opening 48z to allow large flow to pass through, in opposite position of the small leak hole 48.

[0127] Figure 17 represents a seventh embodiment of the pig installed in the conduit, the pig having a hollow body to receive an elongated element, wherein the pig is clamped on the conduit and unclamped with the elongated element.

[0128] The body 28 of the pig 92 in the seventh embodiment is a hollow body arranged to receive the elongated element 80, which is for example a cable. The cable 80 may differ from the cable 100 in figure 1 in that the cable 80 may be bigger. The elongated element 80 and the pig 92 are installed in the conduit 84.

[0129] The pig 92 comprises a check valve 1 10 arranged to allow communication between the first side and the closed volume 42. The check valve is mounted on the hollow body 28 in front of a hollow body through hole 104a, connecting the first side and the closed volume 42, thanks to body support through hole 108.

[0130] The balloon-shaped seal 30 is formed with a first 96 and a second portion 96a which are placed and tight joined together to form the closed volume 42. The balloon-shaped seal 30 also comprises a heel portion 1 10 arranged between the first 96 and second portions 96a on one side and the hollow body 28 on the other side.

[0131 ] The pig 92 further comprises a set of internal seals 94, 94a mounted on the hollow body 28 to contact and seal the elongated cable 80. In other words, the internal seals 94, 94a are placed between the hollow body 28 and the elongated element 80 in order to seal the elongated element 80.

[0132] The pig 92 further comprises a releasable dividable clamp ring 100A arranged to cooperate with the corresponding clamp 100B of the gate portion 102 installed in the conduit 84. In figure 17, the pig 92 is in a released position, wherein the releasable dividable clamp ring 100A is released and not in contact with the corresponding clamp 100B. In this released position compared to the elongated element 80, the pig 92 is clamped on the conduit 84 via the normal clamp 98, which is perpendicular to the conduit 84.

[0133] In this case, there is the possibility to build up further parts of the conduit 84, which are additional conduit 82, 82a, sealed to the conduit 84 thanks to lip-seals 86, 86a and mounting rings 88, 88a.

[0134] Figure 18 represents the seventh embodiment of the pig installed in the conduit, the pig having the hollow body to receive the elongated element, wherein the pig is unclamped from the conduit.

[0135] In figure 18, the pig 92 is unclamped from the conduit 84, that is to say that the normal clamp 98 is not contacting anymore the pig 92. [0136] The pig 92 is pushed to the corresponding clamp 100B by the driving fluid (coming from valve 90) and thereby clamped onto the elongated element 80. The gate portion 102 is rotated and removed from the corresponding clamp 100B to allow the movement of the pig 92 thanks to the driving fluid. The elongated element 80 is now able to be driven by the pig 92. The check valve 106 is open to allow communication between the driving fluid and the closed volume 42 and seal the conduit 84.

[0137] Note that in the position of Figure 17 it is possible to have fluid pressure at the right side of the pig 92 and zero or no pressure at the left side (the duct or conduit 84 might be open there), while in Figure 18 there might be pressure at the left side of the pig 92 and not at the right side. For this valve 90 is closed, not anymore connected to the pump, the latter now active to supply water from the left side, fed through additional conduit 82a.

[0138] Figure 19 represents a detailed view of a part of the hybrid valve, seen from a first side.

[0139] The hybrid valves 79s may be arranged in all embodiments of the pig 5, 92, and in particular in the embodiment of figure 16 (sixth embodiment).

[0140] As explained above, each of the hybrid valves 79s comprises a spring 79sp, and a hollow cylinder 79h having a hollow cylinder hole 40b therein, so that the hollow cylinder 79h acts as a check valve, if the pressure is below the overruling value or safety opening value, thereby allowing the flow to pass only in one direction (from the first axial side X1 to the inside of the body 28 for the hybrid valve 79s installed on the side of first axial side X1 of the pig 5 and from the second axial side X2 to the inside of the body 28 for the hybrid valve 79s installed on the side of the second axial side X2). The hollow cylinder hole 40b can be formed as hollow cylinder arrays 40b as shown in figure 19.

[0141 ] Each hybrid valve 79s further comprises a small leak hole 48 to allow a small leak to flow from the first the axial side X1 to the second axial side X2, and vice-versa, when the hybrid valve 79s is installed in the pig 5, 92.

[0142] A similar construction could be used for the safety valves 56 and 58 in Figure 14.

[0143] Similar slits are present in the center part of valve 52 of

Figure 14 (the cylindrical arrays 54 or slit), which are extending over a length so that they are connected to either holes 36 or 36a, but not both at the same time. The slits can also extend tangentially instead of axially, but then there must be two of such“ring openings”, not in axial contact. They must position for either holes 36 or holes 36a, but not both at the same time. Advantage of the ring shape is that there is freedom to rotate the center part of valve 52, without the risk that the holes are“missing each other” or not matching each other.

[0144] Figure 20 represents a detailed view of the part of the hybrid valve, seen from a second side.

[0145] Each hybrid valve 79s further comprises a hybrid valve large opening 48z to allow large flow to pass through, in opposite position of the small leak hole 48.

[0146] It is of course understood that obvious improvements and/or modifications for one skilled in the art may be implemented, still being under the scope of the invention as it is defined by the appended claims.

[0001 ] In particular, it is referred to the possibility to have several balloon-shaped seal 30.