Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L27/00—Adjustable joints; Joints allowing movement
  • F16L27/08—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe
  • F16L27/0804—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another
  • F16L27/0808—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation
  • F16L27/0812—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with slide bearings
  • F16L27/082—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with slide bearings having axial sealing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L27/00—Adjustable joints; Joints allowing movement
  • F16L27/08—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe
  • F16L27/0804—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another
  • F16L27/0808—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation
  • F16L27/0824—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with ball or roller bearings
  • F16L27/0828—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with ball or roller bearings having radial bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L27/00—Adjustable joints; Joints allowing movement
  • F16L27/08—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe
  • F16L27/0804—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another
  • F16L27/0808—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation
  • F16L27/0824—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with ball or roller bearings
  • F16L27/0832—Adjustable joints; Joints allowing movement allowing adjustment or movement only about the axis of one pipe the fluid passing axially from one joint element to another the joint elements extending coaxially for some distance from their point of separation with ball or roller bearings having axial bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2361/00—Apparatus or articles in engineering in general

Definitions

• Swivel a decoupled central ring member
• the invention relates to a swivel comprising an inner and an outer ring, the rings being coaxial and rotatable relative to one another around a central axis, the rings defining a toroidal chamber and an axial seal annulus gap between the rings, the inner and outer rings being rotatably interconnected via a bearing structure.
• a swivel of the above-mentioned type is described in WO 90/02289.
• a swivel for offshore hydrocarbon production wherein dynamic face seals are mounted in complementary stepped annular regions.
• the pressurisation effects on the swivel cause the outer ring to decrease in axial length and the inner ring to increase in axial length, hence reducing the axial space of the sealing area.
• the outer seal ring that contains the face seals deflects outwardly due to pressurisation hence increasing the axial sealing space.
• the effects could cancel out and the axial sealing space remains substantially at the designed dimension.
• the seal annulus gap variation is governed by several complex parameters, some of which are highly non-linear.
• the extension of the axial dimension of the inner swivel ring and the decrease in axial dimension of the outer swivel ring, or so-called "Poisson's effect” requires advanced Finite Element Analysis (FEA) methods.
• FEA Finite Element Analysis
• the radial deformations of each swivel part are not uniform along the vertical axis due to the pressurized area acting only over a limited height, as top and bottom ends of the seal annulus gap are not pressurised for zones beyond the topmost and lowermost dynamic seals.
• the non- uniform thickness of the swivel rings also affects the radial deformations of each swivel part.
• the "bowing" of each swivel part requires again advanced FEA analysis methods to arrive at matching vertical deflections of the deformed parts.
• varying bolt preloads and varying friction coefficients at the various bolted interfaces affect the stiffness of the different swivel parts.
• bolt pretension and friction coefficient influence the sliding at the different bolted interfaces which in turn affects the bending (bowing) of the swivel parts.
• all the above effects mostly impact on the bottom dynamic seals that are situated furthest away from the swivel bearing.
• Face seal swivel fabrication also requires very high machining accuracies. Due to the large number of stacked machined rings, the cumulated fabrication tolerances can be too large, leading to unsuitable seal extrusion gaps, i.e. too large or too narrow. Current swivel designs are at the limit of best manufacturing capabilities base on the current design criteria.
• a swivel according to the invention is characterised by an upper bearing structure and a lower bearing structure each side of the toroidal chamber, each bearing structure interconnecting the inner and outer rings, an upper and a lower sealing member being situated in the seal annulus gap near a respective upper and lower bearing structure, wherein at least one of the inner and outer rings is comprised of an upper member, a lower member and a central member, the upper and lower members being fixedly attached to the respective upper and lower bearing structures and the central member being independently displaceable relative to the upper and lower ring members.
• each seal By placing each seal in the vicinity of an upper and a lower bearing, these seals are hardly affected by any thermal, pressure or mechanical loading of the swivel and the non-linear behaviour of the swivel rings is eliminated. Moreover, the cumulated fabrication tolerances are also significantly better for the corresponding seal grooves and seal extrusion gaps due to fewer stacked pieces.
• By physically decoupling the upper and lower members of either inner ring or outer ring, or of both inner and outer rings small axial movements of the central ring member relative to the upper and lower ring members are possible.
• sufficient flexibility in the axial direction is obtained in view of minimizing internal axial loads resulting from the differential deformations of the different swivel rings, while providing increased stiffness of the sealing area in the vicinity of the upper and lower bearings.
• the upper and lower ring members are of L-shaped cross-section having axially extending legs, the central ring member contacting the axially extending legs with an axial surface along an interface gap that is situated at a radial distance from the seal annulus gap.
• the central ring section defines a static extrusion gap that is situated at a radial distance from the seal annulus gap.
• the axially oriented surfaces of the L-shaped upper and lower ring members abut against the axial surface of the central ring member while allowing small movements of the central member relative to the upper and lower ring members and decoupling the upper and lower ring members in the axial direction.
• At least one axial sealing element is comprised in the interface gap on each side of the toroidal chamber.
• These sealing elements can be static sealing elements providing a reliable fluid containment in the toroidal chamber.
• the central ring member In order for the central ring member to rotate together with the upper and lower ring members, the central ring member is rotatable by a drive element about the central axis.
• the drive member comprises mechanical connections between the upper and lower ring members and the central ring member.
• At least one of the upper and the lower sealing members comprises a first face seal along a radial face at the upper part of the seal annulus gap and two coaxial seal containment members attached to the inner and outer ring respectively each comprising stepped section, the stepped section being placed in an overlapping relationship to form a radial seal cavity in which a second face seal is comprised, the bearing structure being attached to the seal containment members.
• the face seal areas near the upper and lower bearings can be effectively designed to be subject to a minimum of deformation and in a way that upon pressurisation the
• the central ring part comprises a part of the toroidal cavity and may comprise a recessed channel forming half of the toroidal cavity.
• the cross-sectional shape of this channel may for instance be U-shaped or semicircular, while the static seals may for instance be incorporated in the "legs" of the U-shaped or semi-circular channel.
• the central ring member has a higher stiffness than the upper and lower ring members.
• the radial cross-section of the central ring part is larger than that of the upper and lower ring parts, providing additional rigidity to the central member.
• the he central ring member In order to axially position the he central ring member, it comprises an upper and a lower interface plane, the central ring part being along the lower interface plane provided with an axially projecting support part for contacting the lower ring member.
• the support part maintains a gap between the central ring member and the lower ring member downstream from the static seals.
• a gap is also present at the upper interface plane between the central and the upper ring members, so that the ring parts are sufficiently decoupled and relative small movements in an axial direction between the upper and lower ring parts are possible.
• the bearings of the upper and/or lower ring members may comprises a slide bearing using low friction materials such as brass or low friction thermoplastics.
• at least one of the upper and lower bearings comprises a three-raceway roller bearing.
• Fig. 1 schematically shows an axial cross-section of a swivel known in the prior art
• Fig. 2 shows an axial cross-section of a swivel according to the invention comprising upper and lower three-raceway bearings
• Fig. 3 shows an axial cross-section of an embodiment of a swivel according to the invention comprising an upper slide bearing and a lower three-raceway bearing.
• Fig. 1 shows a known swivel 1 with inner ring 2 and outer ring 3.
• the inner ring 2 is stationary relative to the central axis 4, while the outer ring 2 can rotate around the central axis 4.
• the inner and outer rings 2, 3 are placed in a coaxial contacting relationship along a seal annulus gap 5 and enclose a toroidal chamber 7.
• the inner and outer rings 2,3 are interconnected via an upper slewing bearing structure 8, which in this embodiment is a three-raceway roller bearing.
• the seal annulus gap 5 is sealed by upper and lower primary face seals 10, 12 and by upper and lower secondary face seals 11, 13.
• the face seals 10-13 are placed in sealing grooves that are covered by upper sealing rings 14,15 and lower sealing rings 16,17.
• the sealing rings 14-17 are connected to the inner and outer rings 2, 3 via connecting members such as bolts 18, 19, 18', 19'. Replacement or inspection of the seals 10-13 can be carried out by releasing the bolts 18-19' and removing the rings 14-17.
• the number of dynamic seals 10-13 on either sides of the toroidal chamber must at least be one but can also be more than 2 where the standard is 3, and up to 4 seals on very high pressure system featuring a cascade system invented by the applicant.
• the inner ring 2 is connected to a stationary hydrocarbon transfer pipe, while the outer swivel ring 3 is connected to rotating hydrocarbon transfer pipe, which pipes are not shown in the figure.
• the swivel 1 can be used in a swivel stack on a floating offshore structure, such as for instance an FPSO, for offshore hydrocarbon exploration and/or processing.
• a floating offshore structure such as for instance an FPSO
• Such a swivel stack is placed on a turret that is connected to subsea hydrocarbon risers, the offshore structure being able to weathervane around the turret in order to align itself with the prevailing wind and current directions.
• the risers will be attached to the inner swivel rings 2 of the swivel stack, whereas piping on the vessel is connected to outer rings 3 of swivels in the stack.
• Fig. 2 shows a swivel 1 according to the invention, comprising an upper bearing structure 8 and a lower bearing structure 9.
• the outer ring 3 is made of an upper ring member 20, central ring member 21 and lower ring member 22.
• the ring members 20- 22 are formed of separate parts, and are mechanically interconnected via a
• link or drive element 24 The main purpose of the drive element is to connect simultaneously in rotation the ring members 20-22 while permitting free relative axial movements.
• the central ring member 21 can move over small distances, typically up to a couple of millimeters, relative to the upper and lower ring members 20, 22 in the axial direction.
• the upper and lower bearing structures 8,9 are sufficiently uncoupled to rotate freely without being unnecessarily loaded by the internal loads developed by the differential deformations of the different swivel parts under pressure.
• the upper and lower ring members 20, 22 each have an L- shaped cross-section with axially extending legs 28,29.
• the central ring member 21 is generally U-shaped and forms a part of the toroidal chamber 7.
• the upstanding sides of the U-shaped ring member 21 each comprise two static seals 30, 31, 32, 33 that seal the axial interface gap 35 between the ring members 20, 22 and the central ring member 21.
• a support part 36' is provided, contacting the lower ring member 22 for positioning the central member 21 such that at the upper interface plane 37 and the lower interface plane 36, a few millimeters gap in width remains.
• the small movements of the central ring member 21 along the vertical axis include sliding at the piston seals interface - reference numerals 30 and 31. Sliding at the lower interface near reference numerals 32 and 33 would be significantly less due to their close proximity to the axial contact 36' permitting, for instance, the ring 20 to slide (almost freely) up and down with respect to ring 21.
• the corresponding axial displacements can be as large a couple of millimeters.
• FIG. 3 shows an embodiment in which the top bearing structure 40 is formed by thrust low friction bushes 41, 42, that are comprised in recesses enclosed by stepped surfaces of the upper sealing rings 14, 15.
• the lower bearing 9 is formed by a three- raceway bearing. It is also possible to replace bearing 9 by a slide bearing of a type similar to the top bearing structure 40.
• the outer, rotating ring 3 is formed of three individual members 20,21,22, but alternatively, it is also possible to form the inner ring 2 of three individual members.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Sealing Of Bearings (AREA)
• Sealing Devices (AREA)
• Rolling Contact Bearings (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=49880432

Family Applications (1)

Country Status (6)

Citations (3)

Family Cites Families (7)

• 2014
  • 2014-12-12 NO NO14811901A patent/NO3084279T3/no unknown
  • 2014-12-12 SG SG11201604872WA patent/SG11201604872WA/en unknown
  • 2014-12-12 EP EP14811901.9A patent/EP3084279B1/en active Active
  • 2014-12-12 MY MYPI2016001121A patent/MY186732A/en unknown
  • 2014-12-12 WO PCT/EP2014/077571 patent/WO2015091266A1/en active Application Filing
  • 2014-12-12 US US15/105,150 patent/US10648600B2/en active Active

Patent Citations (3)

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