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Patent Searching and Data


Title:
PIPE SEAL, PIPE ASSEMBLY, AND A METHOD OF FORMING A SEAL
Document Type and Number:
WIPO Patent Application WO/2019/076453
Kind Code:
A1
Abstract:
The invention refers to a pipe assembly, comprising a seal (16) having an annular carrier member (26) and an annular sealing member (28) attached to the carrier member(26), and a pipe (12) having an annular groove (18) to the receive the seal (16), the carrier member (26) being resiliently deformable such that the seal (16) can be inserted into the groove (18) preformed in the pipe (12), and the seal (16) having an axial length (AL) shorter than an axial length (AL) of the groove (18) in a non-compressed state of the seal (16).

Inventors:
BICHLER, Andreas (Oberndorf 14, 6341 Ebbs / Tirol, 6341, AT)
LOPEZ-CHAVES, Bernal (Landfort 45, 8219 AJ Lelystad, 8219 AJ, NL)
Application Number:
EP2017/076643
Publication Date:
April 25, 2019
Filing Date:
October 18, 2017
Export Citation:
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Assignee:
TRELLEBORG PIPE SEALS LELYSTAD B.V. (Pascallaan 80, 8218 NJ Lelystad, 8218 NJ, NL)
International Classes:
F16L21/03; F16J15/02; F16J15/08; F16L47/08
Foreign References:
EP0560104A11993-09-15
DE102007048119A12009-04-16
Other References:
None
Attorney, Agent or Firm:
FLÜGEL PREISSNER SCHOBER SEIDEL PATENTANWÄLTE PARTG MBB (Nymphenburger Strasse 20, München, 80335, DE)
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Claims:
Claims

1 . A pipe seal for fitting in a groove (18) of a first pipe (12) to engage with a second pipe (14) inserted in the first pipe (12), the seal (16) comprising

an annular carrier member (26) and

an annular sealing member (28) attached to the carrier member (26), the carrier member (26) being resiliently deformable such that the seal

(16) can be inserted into the groove (18) preformed in the first pipe (12),

the seal (16) having an axial length (AL) shorter than an axial length (AL) of the groove (18) in a free state of the seal (16).

2. The pipe of claim 1 , wherein the carrier member (26) comprises at least two carrier projections (30) contacting an adjacent side wall (22) of the groove (18), the projections being spaced apart in a radial direction (RD).

3. The pipe of claim 2, wherein the carrier projections (30) are constituted by a circumferentially extending carrier recess (28) in the carrier member (26).

4. The pipe of claims 2 or 3, wherein tip ends of the carrier projections (30) lie within a plane that extends parallel to the adjacent side wall (22) of the groove (18).

5. The pipe of one of the preceding claims, wherein the sealing member (28) comprises a first arm portion (38) extending in an axial direction (AD) of the seal (16) and a second arm portion (40) being inclined to the first arm portion (38), a distance between an inner exterior surface (48) of the first arm portion (38) adjacent to the second arm portion (40) and an outer exterior surface (50) of the second arm portion (40) adjacent to the first arm portion (38) linearly increasing along the axial direction (AD) in a non-compressed state of the seal (16).

6. The pipe of claim 5, wherein the carrier member (26) is constituted by a first leg (34) and a second leg (36), the first arm portion (38) being mainly connected to the first leg (34) and the second arm portion (40) being mainly connected to the second leg (36).

7. The pipe of claims 5 or 6, wherein the second arm portion (40) further comprises an inner exterior surface (52), the inner exterior surface (52) and outer exterior surface (50) of the second arm portion (40) being substantially parallel to each other in a non-compressed state of the seal (16).

8. The pipe of one of the claims 5 to 7, wherein, in a non-compressed state of the seal (16), the first arm portion (38) and the second arm portion (40) each have a radial thickness (RT), the sum of radial thicknesses (RT) of the first and second arm portion (40) being higher than a radial depth (GD) of the groove (18).

9. The pipe of one of the claims 5 to 8, wherein, in a non-compressed state of the seal (16), the first arm portion (38) juts out above the second arm portion (40) in the axial direction (AD).

10. The pipe of one of the claims 5 to 9, wherein the first arm portion (38) comprises at least two sealing protrusions (42) extending in the axial direction (AD) for contacting an adjacent side wall (24) of the groove (18).

1 1 . The pipe of one of the claims 5 to 10, wherein the first arm portion (38) further comprises a bulge (44) on an outer exterior surface (46), the bulge (44) projecting from the carrier member (26) in the radial direction (RD).

12. A pipe assembly, comprising

a seal (16) having an annular carrier member (26) and an annular sealing member (28) attached to the carrier member (26), and

a pipe (12) having an annular groove (18) to the receive the seal (16), the carrier member (26) being resiliently deformable such that the seal (16) can be inserted into the groove (18) preformed in the pipe (12), and

the seal (16) having an axial length (AL) shorter than an axial length (AL) of the groove (18) in a non-compressed state of the seal (16).

13. A method of forming a seal (16) between a first pipe (12) having a groove (18) and a second pipe (14) for being inserted into the first pipe (12), comprising the steps

inserting the seal (16) into the groove (18), wherein the seal (16) has an axial length (AL) shorter than an axial length (AL) of the groove (18) in a non- compressed state of the seal (16),

inserting the second pipe (14) into the first pipe (12) such that the seal (16) is compressed in a radial direction (RD) thereby expanding the seal (16) in an axial direction (AD) such that the seal (16) contacts opposing side walls (22, 24) of the groove (18).

Description:
Pipe Seal, Pipe Assembly, and a Method of Forming a Seal

The invention refers to a pipe seal for fitting in a groove of a first pipe to engage with a second pipe inserted in the first pipe. The seal has an annual carrier member and an annual sealing member attached to the carrier member, wherein the carrier member is resiliently deformable such that the seal can be inserted into the groove preformed in the first pipe. The pipe has an annular groove to receive the seal. The invention further refers to a pipe assembly comprising the seal and a pipe. The invention also refers to a method of forming a seal between a first pipe having a groove and a second pipe for being inserted into the first pipe.

Pipe assemblies are known for comprising a ring-shaped elastomer seal that is located in a groove in a first pipe or pipe fitting that is to be connected with a second pipe or pipe fitting, with the seal located circumferentially between the two pipes. Generally, a pipe seal must be made within specific tolerances to fit a particular size of a pipe and a groove.

For achieving a good sealing performance, it is necessary that the seal is correctly positioned within the groove. In this case, the sealing portions of the seal properly contact both the groove of the first pipe and the outer surface of the second pipe. However, during the insertion of the second pipe into the first pipe, there is the risk that the seal is dislocated within the groove such that the sealing performance is deteriorated or completely destroyed.

Hence, it is an object of the invention to provide a pipe seal and a pipe assembly having an improved sealing performance.

The above objective is solved by a pipe assembly according to claim 1 , a pipe seal according to claim 12, and a method according to claim 13. The dependent claims describe preferred embodiments of the invention. A pipe seal is provided for fitting in a groove of a first pipe to engage with a second pipe inserted in the first pipe. The seal comprises an annular carrier member and an annular sealing member attached to the carrier member. The carrier member is resiliently deformable such that the seal can be inserted into the groove preformed in the first pipe. The seal has an axial length shorter than an axial length of the groove in a non-compressed state of the seal.

A pipe assembly comprises a seal and a pipe. The seal has an annular carrier member and an annular sealing member attached to the carrier member. The pipe has an annular groove to receive the seal. The carrier member is resiliently deformable such that the seal can be inserted into the groove preformed in the pipe. The seal has an axial length shorter than an axial length of the groove in a non-compressed state of the seal.

A method of forming a seal between a first pipe having a groove and a second pipe for being inserted into the first pipe comprises the following steps: a first step is inserting a seal into the groove, wherein the seal has an axial length shorter than an axial length of the groove in a non-compressed state of the seal. A second step is inserting the second pipe into the first pipe such that the seal is radially compressed, thereby expanding the seal in an axial direction such that the seal contacts opposing side walls of the groove.

An advantage is that the seal can be easily inserted into the groove of the first pipe. In particular, it is not necessary to pre-position the seal in the groove.

Seals of the prior art may have an axial length that is longer than the axial length of the groove such that the seal is axially compressed when inserting the seal into the groove. This axial compression helps to pre-position the seal in the groove. Such a pre-positioning is not necessary with the seal of the current invention. In fact, the seal can move in the axial direction within the groove since the axial length of the seal is shorter than the axial length of the groove. This possible movement increases the flexibility of the seal within the groove which, in turn, facilitates the correct positioning of the seal within the groove when the second pipe is inserted into the first pipe. Generally speaking, the seal is automatically moved to the correct positon when the second pipe is inserted into the first pipe.

Another advantage is that, when the seal is radially compressed by the insertion of the second pipe into the first pipe, the seal may be axially expanded which preferably is constituted by the axial expansion of the sealing member due to the radial compression of the sealing member and the incompressible nature of the material of the sealing member. This expansion in the axial direction is preferably constituted by the rubber-like nature of the sealing member. Since the seal axially expands when it is radially compressed, for example when the second pipe is inserted into the first pipe, the seal can better adapt to the walls of the groove. Hence, a better sealing performance can be achieved.

The first pipe and the second pipe may be concentric to each other. The first pipe may be regarded as a female pipe, a pipe fitting, or a pipe having a bell end. The second pipe may be constituted by a male pipe, a pipe fitting, or spigot end. The two concentric pipes may be plastic pipes, such as PVC pipes.

However, other materials, for example ductile iron pipes can be contemplated.

The groove in the first pipe is preformed. The groove is arranged in the pipe wall of the first pipe; in particular the groove is formed by a contour of the pipe wall. For example, the pipe wall has an outer exterior surface having a shape similar to the groove, i.e. an inner surface of the pipe follows the contour of the outer surface providing a constant thickness of the pipe even at the location of the groove.

The groove may have a rectangular or triangular shape in a cross-sectional view of the groove. For example, the groove has a base wall preferably extending in the axial direction, a first side wall, and a second side wall which may extend parallel to the radial direction or inclined to the radial direction. The groove is open to an inside of the first pipe such that the seal can contact the second pipe if the second pipe is inserted into the first pipe. The seal seals an inner surface of the first pipe to an outer surface of the second pipe. The seal is an annular or ring-shaped seal; preferably the seal is uninterrupted. The seal may be called a gasket. The seal is resiliently deformable for inserting the seal into the groove. To this end, the seal is resiliently deformed, for example, by pressing diametrically opposing portions of the seal together and this deformed seal is placed below the groove. By releasing the seal, the seal returns to its original shape and is placed within the groove. The seal is held in the groove by its resilient nature; i.e. the seal needs not be otherwise fixed to the groove. In fact, the seal can freely move in the axial direction within the groove.

The seal may have a diameter which is adapted to the diameter of the pipe and the groove, respectively. Hence, various seals having different diameter can be employed for different pipes.

The carrier member is intended for providing the rigidity of the seal. The carrier member is, for example, made of a non-elastomeric, substantially non-flexible, or rigid material, such as plastic. In particular, the elastic modulus, the IHRD hardness, or the shore A hardness of the carrier member is greater than the corresponding hardness of the sealing member. For example, the shore A hardness of the carrier member is at least 90 or at least 100, whereas the shore A hardness of the sealing member is between 40 and 80, more preferably between 50 and 70 and most preferably about 55. The carrier member may be made of thermoplastic materials which include polyolefins, such as polyethylene or polypropylene (polyvinylchloride PVC) and like materials. Furthermore, the reinforcing member may be made from polyamide.

The sealing member is intended to provide the sealing capability of the sealing. To this end, the sealing member has a lower hardness than the carrier member, such that the sealing member can better adapt its contour to the shape of the groove. The sealing member is preferably made of an incompressible material. The sealing member may include elastomers, natural and synthetic rubbers, including, for example, SPR, EPDM, NBR, nitrile rubber, fluoroelastomers, such as perfluoroelastomers, tetrafluoroethylene-propylene rubbers (FEPM) or an elastomer sold under the name of Viton ® . Furthermore, the sealing member may be made from thermoplastic elastomers (TPE) or thermoplastic

vulcanizates (TPV or TPE-V).

The sealing member is attached to the carrier member by various means, for example, by vulcanization, by adhesion, or by lock-fitting. The sealing member and the carrier member may be made using a 2-component moulding process. Generally, the carrier member and the sealing member can be manufactured by co-extrusion. The sealing member may be made from the same material as the carrier member, however, the rigidity differs.

A radial direction of the seal extends in a direction of the diameter the seal. A circumferential direction is perpendicular to the radial direction and extends along the circumference of the seal. An axial direction is perpendicular to both the radial direction and the circumferential direction.

The axial length of both the groove and the seal refer to the dimension of the groove and the seal, respectively, measured in the axial direction. For example, the axial length of the groove is measured between two opposing side walls of the groove. If the opposing side walls are parallel to each other, the axial length can be measured at any radial position between the two opposing side walls. If the side walls are inclined to each other, the axial length preferably is measured between the two opposing radial positions of the side walls which are closest to each other. For example, the axial length is measured at the base wall of the groove, when the side walls are inclined from the pipe wall to the base wall of the groove, i.e. the side wall and the base wall form an angle greater than 90°. Basically, the axial length of the groove may correspond to the length of the base wall in the axial direction. The axial length of the seal is preferably measured between two planes extending in the radial direction and touching those parts of the seal that are spaced part the furthest in the axial direction. The non-compressed state of the seal preferably is the state in which the seal has not been placed into the groove of the first pipe which can also be considered as a free state of the seal. Another possibility of the non- compressed state of the seal is when the seal is mounted into the groove of the first pipe, however, the second pipe has not been inserted into the first pipe. This state can also be considered the mounted state of the seal. In both cases, the seal is not compressed in a radial direction, which leads to the axial expansion of the sealing member increasing the axial length of the seal, such that the seal may contact the side walls of the groove.

In an unmounted state of the seal, i.e. when the second pipe has not been inserted into the first pipe, the seal may either contact only one side wall of the groove or does not contact neither side wall of the groove due to the shorter axial length of the seal compared to the axial length of the groove. Hence, the seal can be freely moved either in one axial direction or both axial directions during the insertion of the second pipe into the first pipe.

In a preferred embodiment, the carrier member comprises two carrier

projections contacting an adjacent side wall of the groove, wherein preferably the carrier projections are spaced apart in a radial direction.

Preferably, both carrier projections contact the side wall of the groove. The provision of at least two carrier projections facilitates a proper alignment of the seal within the groove while the second pipe is inserted in to the first pipe. In particular, the at least two carrier projections help that the seal is not rotated around an axis parallel to the circumferential direction; such a rotation could be possible if only one carrier projection was present. Due to the radial separation of the carrier projections, such unwanted rotations of the seal can be prevented.

Furthermore, the two carrier projections provide a good seat for axially supporting the seal in the groove. In particular, the seal is properly supported at one side wall such that, on the other side wall, where the sealing member is arranged, the sealing member may be properly pressed against the other side wall due to the axial expansion of the seal when the second pipe is inserted into the first pipe. Hence, this ensures a proper contact between the axial side wall and the sealing member which increases the sealing performance of the seal.

The carrier projections may be constituted by ribs that at least partially extend in the circumferential direction. In particular, the seals are ribs that completely extend in the circumferential direction, or the ribs are non-continuous, for example, interrupted by recesses in the ribs. The carrier projection may protrude from the carrier member in the axial direction. The carrier projections are preferably a unitary piece with the carrier member, i.e. the carrier member and the carrier projections are made from the same material and are preferably formed in the same moulding process.

In a preferred embodiment, the carrier projections are constituted by a circumferentially extending carrier recess in the carrier member. For example, the carrier projections are arranged at the most radially spaced apart ends of the carrier member. The carrier recess is arranged between these ends of the carrier member in the radial direction. Preferably, the carrier recess completely extends along the circumferential direction.

In a preferred embodiment, tip ends of the carrier projections lie within a plane, wherein preferably the plane is parallel to the adjacent side wall of the groove. For example, the plane extends in the radial direction. Such an embodiment is preferred, if the axial side walls of the groove also extend in a radial direction, such that the tip ends of the carrier projections both contact the side wall ensuring a proper position of the seal within the groove. It is also possible that the projections lie within a plane that is inclined to the radial direction if the side walls are also inclined to the radial direction. The tip ends refer to those parts of the carrier projections that contact the side wall.

In a preferred embodiment, the sealing member comprises a first arm portion preferably extending in an axial direction of the seal and a second arm portion preferably being inclined to the first arm portion, wherein, further preferably, a distance between an inner exterior surface of the first arm portion adjacent to the second arm portion and an outer exterior surface of the second arm portion adjacent to the first arm portion linearly increases along the axial direction in an unmounted state of the seal.

Preferably, the sealing member mainly consists of the first arm portion and the second arm portion. The first arm portion generally extends in the axial direction, while the second arm portion is inclined to the first arm portion and/or the axial direction. In particular, the second arm portion projects radially inwards.

The inner exterior surface of the first arm portion as well as the outer exterior surface of the second arm portion may extend along the complete

circumferential direction. The inner exterior surface of the first arm portion and the outer exterior surface of the second arm portion may be separated by a gap whose cross-section as seen along the circumferential direction has a triangular shape. In particular, the value of the distance measured at a first axial position between the inner exterior surface of the first arm portion and the outer exterior surface of the second arm portion divided by the value of the distance measured at a second axial direction equals a constant value irrespective of the exact position of the first and second distance.

This can be constituted by that the inner exterior surface of the first arm portion as well as the outer exterior surface of the second arm portion are not bent along the axial direction, but solely in the circumferential direction for providing the annual shape of the sealing member. For example, the inner exterior surface of the first arm portion as well as the outer exterior surface of the second arm portion may both be straight along their extension in the axial direction.

The configuration of the inner exterior surface of the first arm portion and the outer exterior surface of the second arm portion as described above has the effect that, when the second arm portion is pressed against the first arm portion due to the insertion of the second pipe into the first pipe, both the first arm portion and the second arm portion are compressed not only at certain axial position of the sealing member, but roughly all along the axial direction.

Furthermore, the compression in the radial direction is approximately constant along the axial direction. Such a constant compression along the axial direction cannot be achieved with sealing lips known from the prior art, in which the first and/or the second arm portion taper towards their free end, respectively. The provision of a roughly constant compression along the axial direction thus provides a better overall compression of the sealing member which, in turn, presses the sealing member better against the groove increasing the sealing performance.

In a preferred embodiment, the carrier member is constituted by a first leg and a second leg, preferably the first arm portion being mainly connected to the first leg and/or the second arm portion being mainly connected to the second leg.

Preferably, the carrier recess has a V-shape, wherein the first leg and the second leg preferably have an approximately constant thickness, such that the carrier member also has a V-shape. The respective side of the first leg and the second leg that is adjacent to the sealing member is connected to the sealing member. The respective other side of the first and second leg forms the carrier recess. The V-shape refers to a cross-sectional view when seen in the circumferential direction. Due to the connection of the first arm portion to the first leg and the second arm portion to the second leg, the gap between the first arm portion and the second arm portion is formed close to the portion where the first leg is connected to the second leg. Preferably, the first leg and the first arm portion are arranged roughly at the same radial distance, i.e. the first leg and the first arm portion are arranged in a line extending in the axial direction.

In a preferred embodiment, the second arm portion further comprises an inner exterior surface, wherein preferably the inner and outer exterior surfaces of the second arm portion are substantially parallel to each other. Hence, in this embodiment, the seal as described therein differs from sealing lips of the prior art in which the seal tapers towards its free end. Here, the thickness of the second arm portion is approximately constant, which

contributes to the approximately constant compression of the sealing member, in particular the first arm portion, along the axial direction. The thickness of the second arm portion is preferably constant both along the circumferential direction and the direction of its extension.

Optionally, the first arm portion further comprises an outer exterior surface, wherein preferably the inner and outer exterior surfaces of the first arm portion are substantially parallel to each other.

In a preferred embodiment, the first arm portion and the second arm portion, in a non-compressed state of the seal, each have a radial thickness, wherein preferably the sum of the radial thickness of the first and the second arm portion is higher than the radial thickness of the carrier member. In particular, the sum of the radial thicknesses of the first and second arm portion is higher than a radial depth of the groove. This facilitates that both the first arm portion and the second arm portion are compressed in a radial direction if the second pipe is inserted into the first pipe. This compression in a radial direction may increase - due to the incompressible nature of the sealing member - the compression of the sealing member along the axial direction such that a better adaption of the sealing member against the contour of the groove can be achieved increasing the sealing performance.

In a preferred embodiment, in a non-compressed state of the seal, the first arm portion juts out above the second arm portion in the axial direction.

In other words, the first arm portion is longer than the second arm portion when viewed along the radial direction. When the second arm portion is pressed against the first arm portion, the second arm portion may still be longer than the second arm portion, however, it is also possible that in this state, the first arm portion and the second arm portion have the same axial length. In the former case, only the first arm portion contacts a sidewall of the groove in a compressed state of the sealing member, i.e. in mounted state of the seal. In the latter, both the first arm portion and the second arm portion contact the sidewall of the groove in a mounted state of the seal.

It is preferred that the second arm portion is shorter than the first arm portion such that a compensation gap between the second arm portion and the side wall of the groove is present in the compressed state of the seal. In this case, the axial and radial compression of the second arm is unlikely to press parts of the second arm portion in the gap between the first pipe and the second pipe such that the insertion of second pipe into the first pipe is not blocked by the second arm portion. Furthermore, the compensation gap provides space for the first arm portion if the first arm portion is severely compressed. In this case, due to the incompressible nature of the first arm portion, there is space for the first arm portion to evade which reduces the risk that severe compressions of the first arm portion lead to deformations of the sealing member and/or the pipes causing leakages.

In a preferred embodiment, the first arm portion comprises at least two sealing protrusions extending in the axial direction for contacting an adjacent side wall of the groove.

The two sealing protrusions preferably extend along the circumferential direction and may be spaced apart in the radial direction. The two sealing protrusions may be constituted by a circumferentially extending sealing recess on an axial side of the first arm portion. In a state, in which the seal is located in the groove, but the second pipe has not been inserted into the first pipe, only the sealing protrusions of the first arm portion may contact the sidewall of the groove. After the insertion of the second pipe into the first pipe, the area over which the sealing protrusions contact the sidewall of the groove may be increased. In particular, there may be no longer a free space between the two protrusions and the sidewall of the groove, i.e. the sealing recess between the sealing protrusions is no longer present. Furthermore, the at least two sealing protrusions provide a seat of the seal against the sidewall of the groove; in particular, when the sealing member axially expands due to a radial compression thereof. In addition, a rotation of the seal can be suppressed during the insertion of the second pipe into the first pipe due to the sealing protrusions.

In a preferred embodiment, the first arm portion further comprises a bulge on an outer exterior surface, wherein preferably the bulge projects from the carrier member in the radial direction.

The bulge ensures that a good sealing performance is achieved between a radially outer exterior surface of the seal and a base wall of the groove. Since the bulge of the sealing member projects from the carrier member in the radial direction, it is ensured that the sealing member contacts the groove in the radial direction, in particular, it is avoided that the carrier member is the main contact between the seal and a base wall of the grove. In this unwanted situation, the radial compression would be at least partly absorbed by the carrier member. This is avoided by the provision of the bulge, such that the compression of the seal in the radial direction is mainly absorbed by the sealing member increasing pressure in the sealing members and, thus, the sealing performance.

Fig. 1 shows a partial cross-sectional view of a pipe assembly in an

unmounted state;

Fig. 2 shows the partial cross-sectional view of the pipe assembly of Fig. 1 , however, in the mounted state;

Fig. 3a shows a perspective view of a seal of the pipe assembly of Figs. 1 and

2;

Fig. 3b shows a cross-sectional view of the seal of Fig. 3a along the line A-A;

and

Fig. 3c shows a cross-sectional view of the highlighted end of Fig. 3b. A pipe assembly 10 in an unmounted state as shown in Fig. 1 comprises a first pipe 12, a second pipe 14 and a seal 16. The unmounted state is a state in which the second pipe 14 has not been fully inserted into the first pipe 12. This mounted state is shown in Fig. 2. In the unmounted state, the seal 16 is not radially compressed such that the unmounted state is an example for the non- compressed state of the seal 16.

The first pipe 12 and the second pipe 14 may be plastic pipes, for example, made from PVC. The first pipe 12 may be a bell end of a female pipe. The first pipe 12 comprises a groove 18 which has an approximately rectangular cross- section as viewed along a circumferential direction CD, i.e. a direction along the seal 16 and the groove 18, respectively. However, the groove 18 may have a triangular shape in a cross-sectional view. The groove 18 is constituted by a pipe wall of the first pipe 12 and is preformed in the first pipe 12.

The circumferential direction CD is perpendicular to a radial direction RD and an axial direction AD, both with reference to the first pipe 12, the second pipe 14 and the seal 16, respectively.

The groove 18 has a base wall 20, a first sidewall 22 and a second sidewall 24. The groove 18 has a groove depth GD along the radial direction RD. The groove depth GD is smaller than a radial thickness RT of the seal 16 in a non- compressed state of the seal 16, i.e. a state in which the second pipe 14 has not been inserted into the first pipe 12, as shown in Fig. 1 . The compressed state of the seal 16 is shown in Fig. 2.

The second pipe 14 may be a male pipe or spigot that can be inserted into the first pipe 12. This means the second pipe 14 has an outer diameter that is smaller than an inner diameter of the first pipe 12.

An axial length AL of the seal 16 in a non-compressed or unmounted state as shown in Fig. 1 as well as Figs. 3a to Fig. 3c is shorter than an axial length AL of the groove 18. In particular, there is a gap between the first side wall 22 and the seal 16 in the axial direction AD. Furthermore, there is a gap between the second side wall 24 and the seal 16 in the axial direction AD.

As also seen in Figs. 3a to 3c, the seal 16 has a carrier member 26 and a sealing member 28. The carrier member 26 is made of a polyolefin, in particular PVC. The carrier member 26 has a radial thickness RT that is smaller than the groove depth GD. The carrier member 26 comprises two radially spaced-apart carrier projections 30 which are spaced apart by a carrier recess 32. Both the carrier projections 30 as well as the carrier recess 32 fully extend in the circumferential direction CD. Tip ends of the carrier projections 30 contact the first side wall 22 of the groove 18 in a mounted state of the seal 16 as shown in Fig. 2. This means, the tip ends of the carrier projections 30 define a plane which is parallel to the first side wall 22 of the groove 18. In the embodiment shown in the drawings, the plane defined by the tip ends of the carrier projections 30 extends in the radial direction RD.

The carrier member 26 comprises a first leg 34 and a second leg 36. In the cross-sectional view as shown in Figs. 1 , 2 and 3c, the carrier recess 32 as well as carrier member 26 have a V-shape in a cross-sectional view. The first leg 34 is mainly connected to a first arm portion 38 of the sealing member 28, while the second leg 36 is mainly connected to a second arm portion 40 of the sealing member 28. The first leg 34 and the first arm portion 38 are arranged roughly at the same radial distance, i.e. the first leg 34 and the first arm portion 38 are arranged in a line extending in the axial direction AD.

The sealing member 28 is made of an incompressible material, such as rubber, comprises the first arm portion 38 that extends along the axial direction AD and the second arm portion 40 that is inclined to the first arm portion 38. The first arm portion 38 comprises two sealing protrusions 42 that contact the second sidewall 24 of the groove 18. The sealing protrusions 42 completely extend along the circumferential direction CD. The sealing protrusions 42 are formed by a circumferentially extending recess in a sidewall of the first arm portion 38. The first arm portion 38 may further comprises a bulge 44 which projects from the carrier member 26 in the radial direction RD outwards such that the bulge 44 contacts the base wall 20 of the groove 18.

The first arm portion 38 has an outer exterior surface 46 and an inner exterior surface 48. The outer exterior surface 46 and the inner exterior surface 48 of the first arm portion 38 are at least partially parallel to each other. This means that the thickness of the first arm portion 38 is approximately constant except for the bulge 44.

The second arm portion 40 also has an outer exterior surface 50 and an inner exterior surface 52. The outer exterior surface 50 and the inner exterior surface 52 of the second arm portion 40 are also approximately parallel to each other.

The distance between the inner exterior surface 48 of the first arm portion 38 and the outer exterior surface 50 of the second arm portion 40 linearly increases along the axial direction AD in a non-compressed state of the seal 16 (see Fig. 1 ). The sum of the radial thicknesses RT of the first arm portion 38 and the second arm portion 40 is higher than a radial thickness RT of the carrier member 26 and in particular higher than the groove depth GD of the groove 18.

As seen from Figs. 1 and 2, the first arm portion 38 is longer in the axial direction AD than the second arm portion 40 providing a compensation gap 41 between the second arm portion 40 and the second side wall 24 of the groove 18 in the compressed state of the seal 16. In this case, the axial and radial compression of the second arm 40 is unlikely to press parts of the second arm portion 40 in the gap between the first pipe 12 and the second pipe 14 such that the insertion of second pipe 14 into the first pipe 12 is not jammed.

Furthermore, the compensation gap 41 provides space for the first arm portion 38 if the first arm portion 38 is severely compressed. In this case, due to the incompressible nature of the first arm portion 38, there is space for the first arm portion 38 to evade which reduces the risk that severe compressions of the first arm portion 38 leading to deformations of the sealing member 28 and/ or of the pipe 12, 14 causing leakages. A method for forming the seal 16 between the first pipe 12 and the second pipe 14 and the functioning of the seal 16 is described in the following. The seal 16 is positioned within the groove 18. The seal 16 is swimmingly arranged within the groove 18, i.e. the seal 16 can move in the axial direction AD within the groove 18. Since the axial length AL of the seal 16 is shorter than the axial length AL of the groove 18, the positioning of the seal 16 within the groove 18 is easy. In particular, a pre-positioning of the seal 16 within the groove 18 is not necessary.

After the arrangement of the seal 16 within the groove 18, the second pipe 14 is inserted into the first pipe 12. Since the radial thickness RT of the seal 16 is greater than the groove depth GD, in particular, the sum of the radial

thicknesses RT of the first arm portion 38 and the second arm portion 40 is higher than the groove depth GD of the groove 18, the seal 16 is radially compressed. Due to the rubber-like nature of the sealing member 28, i.e. the incompressible nature of the sealing member 28, the radial compression of the sealing member 28 results in an axial expansion of the sealing member 28. Due to the axial expansion, both the carrier member 26 as well as the sealing member 28 contact the first side wall 22 and the second side wall 24,

respectively. In particular, the carrier projections 30 contact the first side wall 22, while the sealing protrusions 42 contact the second side wall 24. The sealing protrusions 42 are compressed in the axial direction AD resulting in an enlarged area of contact between the sealing member 28 and the second side wall 24. Furthermore, due to the radial compression of the seal 16, there is no free space between the base wall 20 of the groove 18 and the second pipe 14 in a radial direction RD such that liquid cannot flow in the axial direction AD between the first pipe 12 and the second pipe 14. List of reference signs

10 pipe assembly

12 first pipe

14 second pipe

16 seal

18 groove

20 base wall

22 first side wall

24 second side wall

26 carrier member

28 sealing member

30 carrier projection

32 carrier recess

34 first leg

36 second leg

38 first arm portion

40 second arm portion

41 compensation gap

42 sealing protrusion

44 bulge

46 outer exterior surface (of the first arm portion)

48 inner exterior surface (of the first arm portion)

50 outer exterior surface (of the second arm portion)

52 inner exterior surface (of the second arm portion)

AD axial direction

AL axial length

CD circumferential direction

GD groove depth

RD radial direction

RT radial thickness