Swivel with sealing device

Abstract

A swivel comprising inner and outer mutually rotatable swivel members having respective internal fluid paths communicating with each other through an annular space at an interface between the swivel members, wherein a sealing device is provided on a side of the annular space at the interface, the sealing device comprising a peripheral groove provided in the inner and / or outer swivel member and a sealing element received therein and arranged for static sealing against a first one of the swivel members inside the peripheral groove and dynamic sealing against a second one of the swivel members, wherein an inner surface of the peripheral groove in a first one of the swivel members that abuts the sealing element is a textured surface extending along at least a portion of one or more inner surfaces of the peripheral groove and has a three-dimensional texture element for frictional contact with the sealing element.

Description

[Technical Field]

[0001] The present invention relates to a swivel comprising an inner swivel member and an outer swivel member rotatably arranged around the inner swivel member, the swivel members having respective fluid paths communicating with each other through an annular space at an interface between the swivel members, the swivel being provided with a sealing device on a side of the annular space at the interface, the sealing device comprising a peripheral groove provided in the inner swivel member and / or the outer swivel member, and a sealing element received within the peripheral groove and arranged for static sealing against a first one of the swivel members and dynamic sealing against a second one of the swivel members inside the peripheral groove.

[0002] The invention further relates to a shim for a method of mounting a sealing element in a peripheral groove of a swivel. [Background technology]

[0003] A swivel with a sealing device is known from U.S. Patent No. 8,814,220. The swivel sealing device is an essential part of the swivel stack, the seals restricting the fluids to their respective fluid paths and ensuring the integrity of the fluid paths under the most severe conditions.

[0004] During weathervaning of an offshore production unit equipped with such a swivel, the seal typically remains stationary in the seal groove while the rotating portion of the swivel moves over the seal running surface.

[0005] However, under operating conditions, the coefficient of friction at the seal running face and / or seal groove surface can change, causing one portion of the seal to move with the swivel while another portion of the seal remains stationary inside the seal groove, ultimately resulting in radial rupture of the seal or backup ring. Common causes of seal failure are seen in seal compression / extension, which causes increased friction on the sides of the running face, and / or accumulation of fluid between the seal and seal groove, such as "oil pockets," which causes localized reductions in friction on the sides of the seal groove.

[0006] The present invention seeks to provide a swivel with a sealing arrangement that has improved resistance to such seal failure. Summary of the Invention

[0007] According to a first aspect herein, the present invention provides a swivel, the swivel comprising an inner swivel member and an outer swivel member rotatably arranged around the inner swivel member, the swivel members having respective fluid paths communicating with each other through an annular space at an interface between the swivel members, the swivel being provided with sealing devices on the sides of the annular space at the interface, the sealing devices comprising: a peripheral groove provided in the inner swivel member and / or the outer swivel member; a sealing device received within the peripheral groove and configured to seal one of the swivel members inside the peripheral groove; a sealing element arranged to statically seal against the first swivel member and dynamically seal against the second one of the swivel members, wherein an inner surface of the peripheral groove in the first one of the swivel members that abuts the sealing element is a textured surface extending along at least a portion of the two inner surfaces of the peripheral groove, the textured surface having three-dimensional texture elements for frictional contact with the sealing element, and wherein a cross-sectional shape of the textured surface viewed perpendicular to the radial plane of the peripheral groove is substantially L-shaped.

[0008] The increased frictional contact provided by the textured surface allows the position of the sealing element relative to the textured surface to remain substantially constant, thus reducing the risk of seal failure.

[0009] Furthermore, the textured elements press into the surface of the sealing element, creating a localized pressure differential on this surface, providing a path for any liquid that leaks between the sealing element surface and the textured surface to flow. This can substantially prevent initial pooling of liquids, i.e., the formation of "oil pockets," which would otherwise cause a localized reduction in friction on the static sealing side of the sealing element.

[0010] The L-shaped textured surface corresponds to the adjacent inner surface of the peripheral groove that abuts the static sealing side of the sealing element, and by providing texture along a substantial radial length of both surfaces, stiction between the textured surface and the sealing element is improved.

[0011] The L-shaped textured surface can be used in a sealing device, such as a piston seal or face seal, in which a static sealing side of a sealing element abuts two adjacent inner surfaces of a peripheral groove. The texture element extending from the first end to the second end of the L-shaped cross section allows at least some liquid that may have leaked between the static sealing side of the sealing element and the peripheral groove to be evacuated, for example, through a narrow passage provided between the inner and outer swivel members on the downstream side of the sealing element relative to the annular space. Typically, the pressure of the liquid or fluid in such a narrow passage is monitored to detect swivel seal failure.

[0012] While seals generally comprise or are made from synthetic elastomers or (thermo)plastic low-friction materials such as rubber, PTFE, PEEK, and HDPE compounds, swivel members typically have smooth, precisely machined metal surfaces with a surface roughness, at least in the groove, in the range of 0.2 to 0.8 μm Ra according to ISO 4287:1997. When the textured surface is a groove surface formed, for example, by machining a texture into the groove, it provides additional friction between the sealing element and the inner surface of the peripheral groove, which may also be referred to as improved stiction when the sealing element and the inner surface rest against each other. Textured surfaces with three-dimensional texture elements can be formed as grooves, ridges, depressions, and / or protrusions, which can be formed by one or more techniques, such as machining, etching, ablation, punching, and / or application of rough paint or other surface texturing layers such as mesh, sandpaper, or textiles. The increased static coefficient of friction provided by the textured surface requires a greater change in the coefficient of friction and / or shear force to reach the threshold friction and / or shear force above which a portion of the sealing device begins to rotate within the peripheral groove. This increases the difference between the stiction of the static sealing side of the sealing element and the coefficient of friction of the dynamic sealing side of the sealing element, providing improved circumferential stability of the sealing element as the inner swivel member rotates relative to the outer swivel member.

[0013] In an embodiment, the three-dimensional texture elements comprise ridges, each of which has a longitudinal direction extending substantially in the radial plane of the peripheral groove. The radial plane is a plane parallel to both the radial direction of the groove and the central axis of the groove. In this manner, increased circumferential stability in the rotational position of the sealing element can be achieved without significantly increasing the axial and / or radial stiction of the sealing element. Axial and radial movement of the sealing element ensures optimal function of the sealing element, and therefore, it is highly preferred that such movement is substantially unhindered.

[0014] The sealing element preferably comprises two outer surfaces, each abutting a different leg of the L-shaped textured surface.

[0015] Preferably, a first leg of the L-shaped textured surface extends along the inner surface of the peripheral groove, and a second leg of the L-shaped textured surface extends along a first portion of another surface of the peripheral groove facing the sealing element, such that a second portion of the another surface is not textured. Herein, the sealing element abuts both the first and second portions of the another surface. The non-textured portion is a smooth surface that is in full contact with the sealing element surface section that abuts along the circumference of the peripheral groove to substantially prevent liquid from passing between the sealing element and the inner surface of the peripheral groove. The radial length of the textured surface along one of the adjacent inner surfaces closest to the annular space can be selected to achieve a predetermined optimum between substantially preventing liquid from passing between the sealing element and the inner surface of the peripheral groove and the minimum stiction required to provide circumferential stability of the sealing element inside the peripheral groove.

[0016] In one embodiment, the outer swivel member is arranged to rotate around the inner swivel member about a rotation axis, and the L-shaped shim has a first leg and a second leg, where the first vertical leg extends substantially parallel to the rotation axis and the second horizontal leg extends in a radial direction substantially perpendicular to the rotation axis. In this manner, the shim abuts two sides of the sealing element. Preferably, the second leg has a length along the rotation axis that is shorter, e.g., at least twice as long, as the length of the first leg in the radial direction. In this manner, rotational movement of the sealing element within the groove is substantially prevented, while some axial movement of the sealing element within the groove remains possible.

[0017] In embodiments, the textured surface is disposed in the groove so as to surround the sealing element substantially over 350°, preferably substantially over 360°, i.e., in a circle, such that the sealing element is substantially prevented from rotating in the groove around the entire circumference of the groove.

[0018] In embodiments, the textured surface is an inner surface of the peripheral groove in a first of the swivel members that extends across the inner surface of the peripheral groove and at least a portion of the bottom surface. The textured surface may thus be formed as an integral part of the groove, and the sealing element may be disposed in the groove so as to directly contact the textured surface of the groove.

[0019] In an embodiment, the sealing device includes a shim positioned between the sealing element and the inner surface of the peripheral groove in the first of the swivel members, the shim forming a textured surface. Such a shim can be provided separately, which has the added advantage of enabling the implementation of the present invention in an existing sealing device of a swivel. The shim can be inserted into the groove, and the sealing element can then be installed in the groove so that it abuts against the shim. When an L-shaped shim is used, the L-shape helps to keep the shim in the corner of the peripheral groove blocked by the sealing element. This reduces the risk of jamming of the swivel, which could occur if the shim moves and gets stuck between the inner and outer swivel members through the seal protrusion gaps present on two sides of the peripheral groove. Preferably, the shim is made of or includes a metal, for example, a metal or alloy plate provided with a plurality of through openings and / or cutout sections that form the textured elements.

[0020] Typically, the shim spans substantially the entire inner surface of the groove, and preferably there are at least 100 such through openings and / or cut-out segments provided around the circumference of the shim.

[0021] In embodiments, the shim has a wave-like and / or zigzag shape extending along the circumferential direction of the peripheral groove, or the shim has protruding fingers extending perpendicular to the circumferential direction of the peripheral groove, preferably toward the lower end of the shim. Such repeating geometric patterns are easily manufactured. The shim can be manufactured, for example, by first machining a strip of sheet material, such as sheet metal or sheet alloy, to provide a textured surface pattern in the strip. Manufacturing can include, for example, one or more steps of punching, engraving, laser cutting, waterjet cutting, or milling methods to cut the strip and / or provide texture elements in the strip. The strip of material is cut or machined to a predetermined length that preferably substantially corresponds circumferentially to the length of the groove in which the strip is disposed. The resulting shim is a longitudinal strip of sheet material provided with a series of parallel elongated openings and / or grooves having their longitudinal directions perpendicular to the longitudinal direction of the strip, forming the texture elements. Several series of parallel longitudinal openings and / or grooves in the shim may extend into the peripheral side of the longitudinal strip so that the series of parallel longitudinal openings and / or grooves are not separated on the peripheral side of the strip.

[0022] A subsequent manufacturing step may be performed in which the length of the patterned strip of textured surface is folded to have an L-shaped cross section when viewed longitudinally of the strip. The L-shape preferably has fold lines that intersect at least some of several parallel longitudinal openings extending through the sides of the strip, which allows the legs of the L-shape to be positioned in the groove to abut a surface of the peripheral groove perpendicular to the axis of rotation of the swivel member that conforms to its in-plane curvature without in-plane compression in the legs.

[0023] For installation in the swivel, first the shim is placed in the peripheral groove, followed by the sealing element.

[0024] Preferably, the shim comprises or is made of a metallic material and / or metal alloy having a tensile strength of at least 100 MP according to ASTM E8 / E8M-16a and a hardness of at least 60 Rockwell B according to ISO 6508.1-2015. Materials from the group comprising stainless steel, copper alloys, aluminum alloys, and austenitic nickel-chromium-based alloys may be used. A preferred material for the shim is stainless steel, as listed in ISO standard 15510:2010, in particular AISI 316L stainless steel, which is known to be resistant to corrosion and have sufficient strength.

[0025] The textured surface may be provided in segments, but according to a preferred embodiment, the textured surface is a uniformly textured, uninterrupted surface that extends along the entire circumference of the peripheral groove, causing the friction force to be substantially uniform along the circumference of the peripheral groove.

[0026] When a shim is used to provide the textured surface, the textured surface being a uniformly textured, uninterrupted surface extending along the entire circumference of the peripheral groove means that the shim is ring-shaped. Such a ring-shaped shim is provided as a strip of material having a length substantially equal to the circumference of the peripheral groove, so that the strip forms a ring when inserted, allowing the shim to be inserted as a single element. This has the advantage of being easier and quicker to position and replace during manufacturing and maintenance / repair. After insertion, the abutting ends of the shim can be joined to form a permanent ring element, for example by welding.

[0027] According to an embodiment, the sealing element comprises a lip seal having two flexible legs arranged in a general C, U, or V-shaped orientation, both legs extending between the respective surfaces of the inner and outer swivel members.

[0028] The legs allow the seal to adapt to pressure changes and changes in the smoothness of the swivel member surface on the running side of the seal where the second of the swivel members slides along the seal surface. This allows a C-, U-, or V-shaped seal to provide a reliable seal of the gap between the inner and outer swivel members while still allowing the swivel members to rotate relative to one another.

[0029] In an embodiment, the sealing element further comprises a backup ring element that abuts against the textured surface, i.e., the textured surface provided by the shim or the textured surface of the internal groove. The backup ring is made of a harder material than the dynamic sealing side of the sealing element to prevent the dynamic portion of the sealing element from deforming relative to the annular passage into the narrow passage downstream thereof. Such a backup ring makes the sealing device suitable for use in high-pressure swivels. The backup ring is preferably disposed around the dynamic sealing side of the sealing element around a portion of the sealing element where the two flexible legs are connected.

[0030] According to a second aspect, the present invention provides a shim for a sealing device, the shim being adapted to form a textured surface extending along at least a portion of one or more inner surfaces of a peripheral groove in which the sealing device is to be disposed, the shim being a longitudinal strip of sheet material provided with a series of parallel longitudinal openings and / or grooves perpendicular to the longitudinal direction of the strip forming the texture elements.

[0031] In an embodiment, several series of parallel longitudinal openings and / or grooves in the shim extend into the sides of the longitudinal strip, so that the series of parallel longitudinal openings and / or grooves are not separated on the sides of the longitudinal strip.

[0032] In an embodiment, the shim is L-shaped when viewed longitudinally, with the L-shape having fold lines that intersect at least some of a series of parallel longitudinal openings that extend through the sides of the longitudinal strip.

[0033] According to a third aspect, the present invention provides an assembly of a shim according to the second aspect and a sealing element arranged concentrically within and abutting the shim.

[0034] According to a fourth aspect, the present invention provides a method for mounting a sealing element in a peripheral groove of a swivel, the method comprising: providing the peripheral groove with at least one textured surface extending along at least a portion of two adjacent inner surfaces of the peripheral groove, the textured surfaces having texture elements each having a longitudinal direction substantially extending in a radial plane of the peripheral groove; and inserting the sealing element into the peripheral groove such that at least a portion of one surface abuts one of the two adjacent textured surfaces and one adjacent surface of the sealing element abuts the other of the adjacent textured surfaces. The swivel preferably comprises an inner swivel member and an outer swivel member rotatably arranged around the inner swivel member, the swivel members having respective fluid paths communicating with each other through an annular space at the interface between the swivel members. After the sealing element has been placed in the groove, a swivel according to the first aspect of the present invention may be obtained.

[0035] An embodiment of a swivel according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0036] [Figure 1] 1 shows a portion of a swivel having an annular space between an inner swivel member and an outer swivel member, with a sealing device to prevent leakage in the annular space. [Figure 2A] 2 shows the piston sealing device in an enlarged view of section II of FIG. 1; [Figure 2B] 2 shows a face sealing device in an enlarged view of section II of FIG. 1; [Figure 3A] 1 shows a radial cross-section of a sealing device according to an embodiment of the invention, in which a textured surface formed as part of a groove abuts a seal. [Figure 3B] 1 shows a schematic isometric view of the textured surface. [Figure 4A] 1 shows a radial cross-section of a sealing device according to an embodiment of the present invention, in which a shim forming a textured surface is inserted into a groove. [Figure 4B] 1 shows a radial cross section of a sealing device according to an embodiment of the invention, comprising such a shim abutting a backup ring element. [Figure 5A] 10 illustrates an example of a textured surface on a section of a shim according to an embodiment of the present invention. [Figure 5B] 10 illustrates an example of a textured surface on a section of a shim according to an embodiment of the present invention. [Figure 5C] 10 illustrates an example of a textured surface on a section of a shim according to an embodiment of the present invention. [Figure 5D] 10 illustrates an example of a textured surface on a section of a shim according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] 1 shows a portion of a swivel 10 having an annular space 5 between an inner swivel member 2 and an outer swivel member 1 for transferring a fluid, e.g., a liquid such as LNG or a liquid hydrocarbon mixture, from a fluid path defined by an inlet pipe 3 connected to a riser or the like to a fluid path defined by a pipe 4 connected to a storage facility on a ship weathervaning around the riser. The swivel 10 is provided with sealing devices 20 for preventing leakage of the annular space 5, the sealing devices 20 being positioned on both sides of and parallel to the annular space 5 in the gap between the inner swivel member 2 and the outer swivel member 1. The inner swivel member 2 and the outer swivel member 1 are tubular members arranged coaxially about a longitudinal axis of rotation V, and both the annular space 5 and the sealing devices 20 extend along the entire circumference of the outer wall of the inner swivel member 2 and the inner wall of the outer swivel member 1. The sealing devices 20 above and below the annular space 5 are positioned in such a way that they perform a sealing function in the operating position of the swivel.

[0038] 2A and 2B show a piston seal and a face seal, respectively, such as may be used in section II of FIG. 1, although both types of seals are commonly used.

[0039] 2A, the inner wall of the outer swivel member 1 and the outer wall of the inner swivel member 2 above and below the annular space 5 are vertical walls. The sealing device 20 is provided in the inner wall of the outer swivel member 1 at some distance above and below the annular space 5. The sealing device 20 comprises a peripheral groove 7 within which a sealing element is located, has a stationary position relative to the inner wall of the outer swivel member 1, and has a running surface abutting the outer wall of the inner swivel member 2 to provide dynamic sealing during rotation of the inner swivel member 2 relative to the outer swivel member 1. The concave side of a lip seal, which may form or be part of the sealing element, is positioned parallel to the space extending from the annular space 5 between the outer wall of the inner swivel member 2 and the inner wall of the outer swivel member 1. Thus, when the fluid pressure in chamber 5 is greater than the pressure on the downstream side 8 of the gap between the inner swivel member 2 and the outer swivel member 1, the legs of the lip seal are forced apart to provide a seal between the inner and outer swivel members.

[0040] In FIG. 2B , the outer wall of the inner swivel member 2′ and the inner wall of the outer swivel member 1′ are stepped walls with an interference fit such that a longer channel extending from the annular space is formed between the respective walls while the swivel members maintain their rotatability relative to one another. A peripheral groove 7′ is provided in the outer wall of the inner swivel member 2′ at a predetermined location along the channel, spaced some distance above and below the annular space 5. A sealing device 20 is provided in the peripheral groove 7′ and has a stationary position relative to the outer wall of the inner swivel member 2′ and a running surface that abuts the inner wall of the outer swivel member 1′ to provide dynamic sealing during rotation of the inner swivel member 2′ relative to the outer swivel member 1′. A lip seal opening that is part of the sealing device 20 is positioned perpendicular to the space extending from the annular space 5 between the outer wall of the inner swivel member 2′ and the inner wall of the outer swivel member 1′.

[0041] Alternative shapes of the inner wall of the outer swivel member 1 and the outer wall of the inner swivel member 2 and the positioning of the peripheral groove with the sealing device 20 located therein are possible.

[0042] The sealing elements are described in more detail in connection with Figures 3A, 4A and 4B as disposed in the piston sealing device 20 shown in Figure 2A. It will be apparent to those skilled in the art that these sealing elements may be used mutatis mutandis in the face sealing device 20' shown in Figure 2B.

[0043] Figure 3A shows schematically a radial cross section of a sealing device 20 according to an embodiment of the invention, in which a peripheral groove 7 is provided in the inner wall of the outer swivel member 1, with a textured surface 23 machined into the inner surface of the groove abutting the sealing element 25. Although not visible in Figure 3A, three-dimensional structural elements 39a, 39b of the textured surface 23 are shown schematically in Figure 3B.

[0044] The sealing element 25 is a U-shaped lip seal, well known for use in offshore swivels. The lip seal is positioned inside the peripheral groove 7 and has a first outer leg surface 27 abutting the bottom surface 11 of the groove and a second outer leg surface 26 abutting the outer wall of the inner swivel member 2. The side of the seal connecting the first and second legs abuts the inner surface 12 of the peripheral groove 7, which is adjacent to the bottom surface 11 of the groove. The legs of the sealing element 25 press outward to achieve a sealing effect between the inner and outer swivel members. The bottom surface 11 and the adjacent inner surface 12 of the peripheral groove 7 include a textured surface 23 extending over a portion of the inner surface 12 and the bottom surface 11. The textured surface 23 provides increased stiction of the sealing element 25 inside the peripheral groove 7, thus improving the circumferential stability of the seal therein. A portion of the bottom surface 11 not adjacent to the inner surface 12 of the peripheral groove is substantially smooth and has an untextured section that provides a sealing zone for sealingly abutting the sealing element. The sealing zone extends radially along the section of the bottom surface 11 that abuts at least the tip 28 of the lip seal. The sealing zone generally prevents liquid flowing through the annular space 5 from passing through the seal. However, in known sealing systems, a relatively small amount of liquid is known to become trapped between the seal and one or more of the inner surfaces of the peripheral groove, for example, due to imperfections in the seal or said inner surfaces. The textured surface 23 allows such trapped liquid to pass through the textured element and drain to the downstream side 8 of the gap. The textured element may extend from a lower end 23a of the textured surface to an upper end 23b of the textured surface, the upper end being at or near the downstream side 8 of the gap between the inner swivel member 2 and the outer swivel member 1.

[0045] FIG. 3B schematically illustrates an isometric view of a portion of groove 7, in which surfaces 11 and 12 are textured surfaces provided with three-dimensional texture elements in the form of ridges 39a and 39b. Ridges 39a and 39b extend longitudinally in the radial plane of the groove. It will be appreciated that other types of three-dimensional texture elements adapted to provide greater friction with the sealing element in the rotational direction than along the radial plane of the groove can be used instead of the continuous ridges 39a and 39b shown in FIG. 3B. For example, texture elements such as grooves, depressions, and / or protrusions can be used in addition to or instead of ridges. Such texture elements are pressed into the abutment surface of sealing element 25, effectively increasing the contact area between the sealing element and the inner surface of the peripheral groove and improving the grip between the groove surface(s) and the sealing element.

[0046] FIG. 4A schematically illustrates a radial cross-section of a sealing device 20′ according to another embodiment of the present invention, in which the inner surface of the groove is substantially smooth. That is, the inner surface of the peripheral groove 7 may have a smoothness and surface finish similar to that of the inner surface of a known peripheral groove in a swivel. To provide sufficient friction between the sealing element 25 and the inner surface of the groove, a shim 30 is provided, forming a textured surface 23′. The shim 30 is L-shaped, with a vertical leg extending along the height of the inner surface 12 of the peripheral groove and a horizontal leg extending along a section of the bottom surface 11 of the peripheral groove 7. The vertical leg has a free end 23′b and an end 23′c that merges with the horizontal leg, which has a free end 23′a. The shape of the shim 30 provides a textured surface 23′ that abuts the sealing element 25, examples of which are shown in FIGS. 4A-4C. An advantage of the configuration illustrated in FIG. 4A is that the shim 30 can be added to an existing sealing device in a swivel.

[0047] FIG. 4B schematically illustrates a radial cross-sectional view of a sealing device 20″ according to an embodiment of the present invention, in which the sealing element is additionally provided with a backup ring element 21. The backup ring element 21 is positioned between the dynamic side of the sealing element 25 and the shim 30, such that the side of the lip seal connecting the first and second legs of the lip seal abuts the inner circumferential surface of the backup ring 21, and the outer circumferential surface of the backup ring 21 abuts the inner circumferential surface of the shim 30. The backup ring 21 is fabricated from a harder material than the dynamic side of the sealing element 25 and is adapted to substantially prevent the dynamic side from deforming into the downstream gap 8 between the inner swivel member 2 and the outer swivel member 1. The addition of the backup ring element 21 thus enables the sealing device 20″ to be used in a high-pressure swivel. It will be understood that such a backup ring may also be used in combination with a textured inner surface of a peripheral groove, as shown in FIG. 4A.

[0048] 5A and 5B show planar and isometric views, respectively, of a section of shim 30' provided with a textured surface. Figures 5C and 5D show planar views of sections of alternative shims 30" and 30'" provided with textured surfaces. While only sections of the shims are shown, it will be appreciated that each shim may have a length that substantially corresponds to the length of the groove in which the shim is placed.

[0049] Shim segment 30' shown in Figures 5A and 5B has a zigzag shape extending in the circumferential direction L of the peripheral groove, with the zigzag shape having interior corners C1 and C2 near the lower and upper ends 23'a and 23'b of the shim, respectively. In Figure 5A, shim segment 30' is shown as an unfolded strip. Prior to being placed in the groove, the lower end 23'a of the strip is preferably folded relative to the upper end 23'b of the strip about fold line F so that the two ends are at a substantially perpendicular angle to each other.

[0050] The inner corner C1 faces an elongated opening 31 that opens at the upper end 23'b, and the inner corner C2 faces an elongated opening 32 that opens at the lower end 23'a. The shim thus provides a three-dimensional textured surface, and the openings 31, 32, and particularly their edges, form textured elements for frictional contact with the sealing element. When the shim is placed in the groove, the longitudinal direction of the opening 31 will be located in the radial plane of the groove.

[0051] As shown in FIG. 5B, when shim 30' is folded to have an L-shaped cross section, openings 31 extend from a first side of fold line F to a second side thereof, such that liquid can flow through each of openings 31 in shim 30' from the lower end 23'a of the textured surface to the upper end 23'b of the textured surface. This provides the zigzag shape with excellent flushing capabilities, making it a preferred shape for the removal of trapped liquid. Shim section 30' is shown in a folded state in the peripheral view of FIG. 4B. The lower ends 23'c of the vertical legs are formed at fold line F.

[0052] The shim section 30'' shown in FIG. 5C is a strip of material extending in the circumferential direction L of the peripheral groove and having a series of fingers 33 of substantially equal width and length, spaced apart at substantially equal distances from one another, extending perpendicular to the circumferential direction L of the peripheral groove from a position above the fold position along fold line F of the strip to the lower end forming the lower end 23'a of the textured surface. A series of longitudinal openings 35 of substantially equal lengths, spaced apart at equal distances from one another, extending perpendicular to the circumferential direction L of the peripheral groove are provided in the strip above the fingers 33, each opening 35 being closed near its upper end forming the upper end 23'b of the textured surface. The discontinuous openings formed between the upper end 23'b and the lower end 23'a of the textured surface provide a less direct, and therefore slower, flow path for trapped liquid, but provide the textured surface with improved strength and stability in the circumferential direction L.

[0053] The shim segment 30''' shown in Figure 5D has a zigzag shape similar to that shown in Figure 5A, except that each zigzag vertical segment 36 has a width W greater than the height h of its horizontal segment 37 and is provided with longitudinal openings 38 extending perpendicular to the circumferential direction L of the peripheral groove, each opening being closed near its upper and lower ends that form the lower and upper ends 23'a and 23'b of the textured surface provided by the shim segment. When the shim 30''' is folded along fold line F to have an L-shaped cross section, liquid can flow from each of the openings 31, 38 in the shim toward the downstream side of the gap between the inner and outer swivel members.

[0054] Shim segments 30′, 30″, 30′″ may be formed from commonly available strips of material commonly used to form springs for spring-loaded seals, or from specially machined shim strips. These shim strips may be machined using techniques such as punching, engraving, laser cutting, waterjet cutting, or milling. After obtaining the shim strip, the strip is bent along fold line F to form a shim having an L-shaped cross-section. The shim may have a relatively short length compared to the circumference of the peripheral groove, such that multiple shims are used in a single peripheral groove to provide a textured surface section along the entire circumference. Preferably, the shim strip is long enough so that the resulting shim is long enough to cover the entire circumference of the peripheral groove, such that a continuously patterned inner surface section is present along the entire circumference. In the latter case, the two ends of the shim may be joined, for example, using welding, to form a circular shim. When the shim is inserted into the peripheral groove, the shim curves so that the vertical leg of the shim conforms to the curvature of the adjacent inner surface 12 of the peripheral groove 7, automatically determining the radius of the adjacent end of the horizontal leg of the shim and forcing the opposite free end of the horizontal leg to assume a smaller radius. In the shim section shown in Figures 5A-5C, the bottom end below fold line F comprises multiple equidistant segments, allowing the bottom end to undergo in-plane bending without experiencing excessive compressive forces.

[0055] The present invention has been described above with reference to several exemplary embodiments as shown in the drawings. Modifications and alternative implementations of several parts or elements are possible and fall within the scope of protection defined in the appended claims. The inventions described in the original claims of this application are set forth below. [1] A swivel, comprising: an inner swivel member (2) and an outer swivel member (1) rotatably disposed about the inner swivel member (2), wherein the two swivel members have respective fluid paths (3, 4) communicating with each other through an annular space (5) at the interface between the two swivel members; a sealing device (20) on the side of the annular space at the interface; The sealing device comprises: - peripheral grooves (7, 7') provided in the inner swivel member (2) and / or the outer swivel member (1); a sealing element (25) received in said peripheral groove (7) and arranged to statically seal against a first one of said swivel members (1,2) inside said peripheral groove and to dynamically seal against a second one of said swivel members (2,1); an inner surface of the peripheral groove in the first of the swivel members that abuts the sealing element (25) is a textured surface (11, 12) extending along at least a portion of two inner surfaces of the peripheral groove, the textured surfaces (11, 12) having three-dimensional texture elements for frictional contact with the sealing element, and a cross-sectional shape of the textured surface taken perpendicular to a radial plane of the peripheral groove is substantially L-shaped. [2] The swivel of [1], wherein the texture elements comprise ridges, each of which has a longitudinal direction extending substantially in a radial plane of the peripheral groove. [3] The swivel according to [1] or [2], wherein a first leg of the L-shaped textured surface extends along the inner surface (12) of the peripheral groove (7, 7') and a second leg of the L-shaped textured surface extends along a first portion of the bottom surface (11) of the peripheral groove (7, 7'), such that a second portion of the bottom surface (11) is not textured, and the sealing element (25) abuts both the first and second portions of the bottom surface (11). [4] A swivel as described in any one of [1] to [3], wherein the textured surface is the inner surface of the peripheral groove in the first swivel member of the swivel members, extending over the inner surface (12) of the peripheral groove and at least a portion of the bottom surface (11). [5] The swivel of any one of [1] to [3], wherein the sealing device comprises a shim (30, 30', 30'', 30'') positioned between the sealing element (25) and an inner surface of the peripheral groove in the first of the swivel members, the shim forming the textured surface. [6] The swivel according to [5], wherein the shim (30') has a wave-like and / or zigzag shape extending along the circumferential direction of the peripheral groove, or the shim (30'') has protruding fingers extending perpendicular to the circumferential direction of the peripheral groove, preferably towards the lower end of the shim. [7] The swivel of [5] or [6], wherein the shim is formed from a longitudinal strip of sheet material, in which a series of parallel longitudinal openings and / or grooves perpendicular to the longitudinal direction of the longitudinal strip form the three-dimensional texture elements. [8] The swivel of [7], wherein the wavy, zigzag, and / or protruding fingers of the shim are formed by a series of several parallel longitudinal openings and / or grooves in the shim that extend into the sides of the longitudinal strip, such that the series of parallel longitudinal openings and / or grooves are not separated on the sides of the longitudinal strip. [9] The swivel of [8], wherein the shim is L-shaped when viewed in the longitudinal direction, the L-shape having fold lines that intersect some of the series of parallel longitudinal openings that extend through the sides of the longitudinal strip.

[10] The swivel according to any one of [5] to [9], wherein the shim comprises or is made from a metallic material and / or a metallic alloy and has a tensile strength of at least 100 MP according to ASTM E8 / E8M and a hardness of at least 60 Rockwell B according to ISO 6508.1-2015.

[11] A swivel as described in any one of [1] to

[10] , wherein the textured surface is a uniformly textured, uninterrupted surface extending along the entire circumference of the peripheral groove.

[12] A swivel as described in any one of [1] to

[11] , wherein the sealing element comprises a lip seal having two flexible legs arranged in a general C, U, or V-shape, both legs extending between the respective surfaces of the inner and outer swivel members.

[13] The swivel according to any one of [1] to

[12] , wherein the sealing element further comprises a backup ring element (21) that abuts the textured surface.

[14] A method for mounting a sealing element in a peripheral groove of a swivel, said method comprising: providing at least one textured surface (11, 12) in the peripheral groove extending along at least a portion of two adjacent inner surfaces of the peripheral groove, the textured surfaces having texture elements each having a longitudinal direction extending substantially in a radial plane of the peripheral groove; inserting a sealing element (25) into the peripheral groove (7) such that at least a portion of one surface of the sealing element abuts one of two adjacent textured surfaces and one adjacent surface of the sealing element abuts the other of the adjacent textured surfaces; A method comprising:

Claims

1. A swivel, the swivel comprising: an inner swivel member (2) and an outer swivel member (1) rotatably disposed around the inner swivel member (2), wherein the two swivel members have respective fluid paths (3, 4) communicating with each other through an annular space (5) at the interface between the two swivel members; a sealing device (20) on the side of the annular space at the interface; The sealing device comprises: - peripheral grooves (7, 7') provided in the inner swivel member (2) and / or the outer swivel member (1); a sealing element (25) received in said peripheral groove (7) and arranged to statically seal against a first one of said swivel members (1, 2) inside said peripheral groove and to dynamically seal against a second one of said swivel members (2, 1), wherein the inner surface of said peripheral groove in said first one of said swivel members abutting said sealing element (25) is a textured surface (11, 12) extending along at least a part of two inner surfaces of said peripheral groove, said textured surfaces (11, 12) having three-dimensional texture elements for frictional contact with said sealing element, and wherein the cross-sectional shape of said textured surface taken perpendicular to the radial plane of said peripheral groove is substantially L-shaped; the sealing device comprises a shim (30, 30', 30'', 30''') located between the sealing element (25) and an inner peripheral surface of the peripheral groove in the first swivel member; the shim forms the L-shaped textured surface; and a first leg of the L-shaped textured surface extends along the inner surface (12) of the peripheral groove (7, 7') and a second leg of the L-shaped textured surface extends along a first portion of the bottom surface (11) of the peripheral groove (7, 7'), such that a second portion of the bottom surface (11) is not textured and the sealing element (25) abuts both the first and second portions of the bottom surface (11); Swivel.

2. The swivel of claim 1 , wherein the texture elements comprise ridges, each of which has a longitudinal direction extending substantially in a radial plane of the peripheral groove.

3. 3. A swivel as claimed in claim 1 or 2, wherein the textured surface is an inner surface of the peripheral groove in the first one of the swivel members that extends over the inner side (12) of the peripheral groove and over at least a portion of the bottom surface (11).

4. Swivel according to any one of claims 1 to 3, wherein the shim (30') has a wave-like and / or zigzag shape extending along the circumferential direction of the peripheral groove, or the shim (30'') comprises protruding fingers extending perpendicular to the circumferential direction of the peripheral groove.

5. A swivel as described in any one of claims 1 to 3, wherein the shim (30') has a wavy and / or zigzag shape extending along the circumferential direction of the peripheral groove, or the shim (30'') has protruding fingers extending perpendicular to the circumferential direction of the peripheral groove towards the lower end of the shim.

6. 6. A swivel as claimed in claim 4 or 5, wherein the shim is formed from a longitudinal strip of sheet material, in which a series of parallel longitudinal openings and / or grooves perpendicular to the longitudinal direction of the longitudinal strip form the three-dimensional texture elements.

7. 7. The swivel of claim 6, wherein the wavy, zigzag, and / or protruding fingers of the shim are formed by a series of several parallel longitudinal openings and / or grooves in the shim that extend into the sides of the longitudinal strip, such that the series of parallel longitudinal openings and / or grooves are not separated on the sides of the longitudinal strip.

8. 8. The swivel of claim 7, wherein the shim is L-shaped when viewed in the longitudinal direction, the L-shape having fold lines that intersect some of the series of parallel longitudinal openings that extend through a side of the longitudinal strip.

9. 9. A swivel according to any one of claims 1 to 8, wherein the shim comprises or is made from a metallic material and / or a metallic alloy and has a tensile strength of at least 100 MP according to ASTM E8 / E8M and a hardness of at least 60 Rockwell B according to ISO 6508.1-2015.

10. A swivel according to any preceding claim, wherein the textured surface is a uniformly textured, uninterrupted surface extending around the entire circumference of the peripheral groove.

11. 11. A swivel as claimed in any one of claims 1 to 10, wherein the sealing element comprises a lip seal having two flexible legs arranged in a general C, U or V-shaped orientation, both legs extending between respective surfaces of the inner and outer swivel members.

12. Swivel according to any one of the preceding claims, wherein the sealing element further comprises a back-up ring element (21) abutting the textured surface.

13. 1. A method for mounting a sealing element in a peripheral groove of a swivel, said method comprising: providing at least one textured surface (11, 12) in the peripheral groove extending along at least a portion of two adjacent inner surfaces of the peripheral groove, the textured surfaces having texture elements each having a longitudinal direction extending substantially in a radial plane of the peripheral groove; inserting a sealing element (25) into the peripheral groove (7) such that at least a portion of one surface of the sealing element abuts one of two adjacent textured surfaces and one adjacent surface of the sealing element abuts the other of the adjacent textured surfaces; positioning a shim (30, 30', 30'', 30''') between the sealing element (25) and an inner peripheral surface of the peripheral groove in the first swivel member, the shim forming an L-shaped textured surface, a first leg of the L-shaped textured surface extending along the inner surface (12) of the peripheral groove (7, 7') and a second leg of the L-shaped textured surface extending along a first portion of a bottom surface (11) of the peripheral groove (7, 7'), such that a second portion of the bottom surface (11) is not textured, and the sealing element (25) abuts both the first and second portions of the bottom surface (11); A method comprising:

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