GB2454455A - Lubricated under water flexible coupling - Google Patents
Lubricated under water flexible coupling Download PDFInfo
- Publication number
- GB2454455A GB2454455A GB0719411A GB0719411A GB2454455A GB 2454455 A GB2454455 A GB 2454455A GB 0719411 A GB0719411 A GB 0719411A GB 0719411 A GB0719411 A GB 0719411A GB 2454455 A GB2454455 A GB 2454455A
- Authority
- GB
- United Kingdom
- Prior art keywords
- connector
- bodies
- links
- chain
- bellows
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000008878 coupling Effects 0.000 title description 5
- 238000010168 coupling process Methods 0.000 title description 5
- 238000005859 coupling reaction Methods 0.000 title description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title description 3
- 239000000314 lubricant Substances 0.000 claims abstract description 13
- 238000009434 installation Methods 0.000 claims 2
- 238000013461 design Methods 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000005452 bending Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 210000002445 nipple Anatomy 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 239000004519 grease Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 208000031872 Body Remains Diseases 0.000 description 1
- 229920000459 Nitrile rubber Polymers 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003032 molecular docking Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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
- F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
- F16G15/00—Chain couplings, Shackles; Chain joints; Chain links; Chain bushes
- F16G15/02—Chain couplings, Shackles; Chain joints; Chain links; Chain bushes for fastening more or less permanently
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/02—Surface sealing or packing
- E21B33/03—Well heads; Setting-up thereof
- E21B33/035—Well heads; Setting-up thereof specially adapted for underwater installations
- E21B33/038—Connectors used on well heads, e.g. for connecting blow-out preventer and riser
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- Earth Drilling (AREA)
Abstract
A connector 18 for connecting two bodies 20 22 is designed to allow some freedom of movement. The connector 18 has two interlinked chain links 24, 26, which are held fast to the bodies 20 22 and allow relative angular movement. The space around the chain links is enclosed by a bellows 28, allowing the space to be completely filled with a lubricant. The connector can be used to connect the bottom end of an offshore riser 12 to a fixed seabed structure 10.
Description
CONNECTOR
Field of the Invention
This invention relates to a connector for structurally connecting bodies whilst allowing articulation between such bodies. Such a connector could be used to connect a deep water riser used in oil and gas extraction to a seabed foundation or in another application a mooring line to a floating production unit.
The invention is particularly (but not exclusively) intended for use underwater.
Background to the Invention
Risers are long tubular structures assembled from steel pipe. In service they are constantly moving due to a number of environmental and operational loads applied along their.Iength. Since service lives in excess of 20 years are typical the fatigue and wear of riser components is an important design issue.
Currently risers are connected to seabed foundations via flex element connectors. These are connectors that combine composite alternate steel and r.. 20 rubber elements that allow the connector to accommodate riser rotational deflections about the foundation structure. The main feature of the rubber flex S. element is that articulation is achieved without components physically sliding over each otherthus eliminating wear at the interface.
* S p.,, * . : 25 Practical flex element design limitations are such that the degree of rotation is r* :* limited to less than approximately 20 degrees and flex elements have an inherent rotational stiffness that produces detrimental bending loads in the connected bodies. Furthermore the manufacturing process for the flex element connector is complex and time consuming resulting in a component with a high cost and long procurement lead time.
According to the present invention, there is provided a connector for connecting two bodies which are to have some relative freedom of movement, the connector having two parts, one for connection to each of the bodies, each part incorporating a chain link, and the chain links of the two parts being linked to one another in the manner of a chain, each link being held substantially rigid within its respective body, the connector also including a bellows fitted between the bodies and enclosing the chain links, the space within the bellows being filled with a lubricant.
When the two bodies are held in tension, the engagement of the links with one another will allow the bodies to move relative to one another.
The respective bodies can have an outer casing and the chain links can then be secured in the respective bodies by shear pins passing through the links and through the outer casing.
Transducers can be mounted in the connector to monitor the relative movement between the links and in particular to monitor wear between the links so that the connector can be replaced or maintained before failure occurs. Strain gauges can be mounted in the shear pins to monitor the strain the pins are experiencing.
I *1**
The internal cavities of the bodies can be sealed to one another by a flexible bellows which surrounds the chain links. The space within the bellows and the I.....
:.: internal cavities of the bodies is preferably filled with a lubricant, preferably an Incompressible lubricant.
The connector has particular application in connecting an offshore riser to a fixed subsea structure. Either one or both of the bodies can take the form of a male stab fitting adapted to be connected into a female stab fitting on the subsea structure and/or the riser.
The connector can accommodate large articulation angles with small or zero rotational stiffness. The design is based on sliding metal components but Importantly the wear produced Is managed through appropriate design and monitoring. The design has a simple construction with minimum forgings and machining allowing cost effective manufacture within short time schedules.
At the centre of the design are the two Interlocked chain links that provide the axial load transfer and ability for the connector to articulate. Such chain links are widely used in offshore mooring applications and are readily available from a number of suppliers in high quality steel and in a wide range of sizes.
It is well known that such mooring links corrode and wear particularly when highly loaded and subjected to large and frequent angular movements.
However, such links are normally operated in open seawater where dirt and corrosion greatly accelerate wear. They are also typically used at higher loads and with greater angle fluctuations. In order to prevent corrosion and minimise wear in the current design the chain links can be encapsulated within a lubricant filled chamber.
The invention seeks to provide the following characteristics which overcome difficulties with existing designs: * Ability to accommodate rotational deflection with low rotational stiffness.
* Ability to accommodate rotational deflection in more than one plane with * low rotational stiffness.
* Uses low cost components and fabrication methods.
* Offers potential for manufacture with short lead time.
The invention wfll now be further described, by way of example, with reference to the accompanying drawings, In which: Figure 1 is a perspective view, partly cut away, of a connector in accordance with the invention; Figure 2 is a sectional view through the connector of Figure 1; and Figure 3 is a perspective view, similar to Figure 1, but showing a second embodiment of the Invention.
Figure 1 shows a sea bed structure 10, permanently fixed on the sea bed and a riser bottom end structure at 12. At the bottom of the riser a male part 14 of a stab coupling is fitted. The female part of the stab coupling is shown at 16.
The connector is shown generally at 18. It comprises two bodies 20, 22 each of generally cylindrical form. In Figure 1, parts of the bodies are cut away to show the Internal components. (Figure 3 shows the bodies without any cut away portion). A flexible bellows extends between the two bodies to form an :. 20 enclosed camber within the connector. * .e* * . ***
Two standard inteiiinked chain links 24, 26 are mounted within the tubular bodies 20, 22 to form the male part of the coupling shown in Figure 1. One end of the male body is connected to the riser structure via a flange and the other end connects Into a female receptacle and is locked through a series of latches *. ***.
that interface with a profile on the lower male body forming a structural connection.
The male body is manufactured in two tubular sections 20, 22 connected by a bellows unit 28. The upper and lower tubular bodies are mounted onto the chain links 24, 26 such that the two bodies articulate with the chain. The bellows connects and seals between the two body halves and the internal volume 27 inside the bellows and around the chain links is filled with grease or another incompressible lubricant. This ensures that wear occurring at the chain link interface and corrosion is managed and the unit can offer a long service life.
Instrumentation to monitor angular rotations, applied load and resulting wear rate is also provided allowing continuous integrity management of the connection and of the riser system generally.
Figure 1 shows the male body 20 above the female receptacle 16 prior to connecting the riser 12 to the structure 10. The bellows unit 28 and parts of the bodies 20, 22 are shown partly cut away so that the Internals of the connector can be seen. The female receptacle 16 is shown welded to the subsea structure which In this case is a fabrication suction pile 10.
The tubular bodies 20, 22 are mounted to the chain links 24, 26 via lateral load shear pins 30, 32 that pass through both the chain link and tubular bodies.
Additionally, structural cheek plates 34 inside the tubular bodies located either side of the links ensure that the links are fixed laterally relative to their respective bodies. Further shims are provided to ensure that there is no * S..
movement between the chain link and its respective tubular body. This ensures * S. that when the connection articulates, all rotation is concentrated between the * chain links and not between the chain links and their respective tubular bodies.
The shear pins pass through the full diameter of the cylindrical bodies and * :* hence present an exposed end on the surface. To prevent water ingress or lubricant loss in these areas, 0-ring seals are included at the shear pin 30, 32 to housing interfaces.
The structural cheek plates 34 are fabricated from thick walled plate to ensure that the load transfer from the links into the tubular bodies 20, 22 is efficient and that the tubular body remains rigid. The structural cheek plates also provide additional lateral support to the chain links 24, 26 and reduce stresses resulting from loading perpendicular to the plane of the link (often referred to as out of plane bending). At large angles this can result in significant loads and can be a key fatigue issue when such loads are cyclic. Therefore the structural cheek plates are highly desirable to control this mode of failure.
The chain link dimensions need to be carefully selected with respect to the anticipated loading regime and in respect to both the axial load and the angles of deflection. The chain links must be significantly oversized to ensure that the contact stresses are maintained below threshold limits that minimise wear. Test results show that the relationship between applied load and wear rate is highly non linear.
The bellows 28 is fitted over the chain link and sealed onto each end of the tubular bodies 20, 22. It is designed from a high strength reinforced nitrile rubber that will allow free articulation of the joint but also protection from the subsea environment and organisms. It must be resistant to cracking and embrlttlement and provide a watertight seal throughout the intended design life. *e.. * .
The invention incJudes provision for serviceability in the form of lubricant top-up U..
facility by ROV (Remote Operated Vehicle). The chain wear rate is reliant on the presence of lubrication in the joint therefore it is essential that the level of lubricant is maintained. The design includes a top up grease nipple at the base : * of the connector and an overflow nipple at the top. The nipples are not shown in * the drawings.
Monitoring devices included in the design will detect wear and stress of critical components. Displacement DVRTs (Digital Variable Reluctance Transducer) 40 mounted in the chain link apertures (see Figure 2) monitor wear of the links by measuring the increase in aperture dimension. Strain gauges in the shear pins 30,32 Will allow the loading conditions to be monitored and provide early warning if critical changes occur.
The female receptacle 10 is a fabricated plate structure with a large upward facing funnel. The funnel Is designed to capture and align the male tubular assembly thus enabling easy docking. Once in position, the stab-in' process is assisted by ballast weight in the lower section of the male tubular body. The latch assembly is then automatically locked in position by hydraulicafly actuated plates that interface with the locking profile on the lower male tubular section.
The hydraulic pressure is provided by a pre-charged oil-nitrogen accumulator.
To enable release, the plates are designed to be operable by ROV.
A second embodiment is shown in Figure 3. In this embodiment, a separate connector 118 is designed to be stabbed into both the subsea structure 10 and the bottom end of the riser 12. This design allows the connector to be disconnected from between the two female receptacles and removed and replaced. This operation could be conducted subsea. * *
The design presents an innovative method of applying existing instrumentation to monitor chain loads and wear characteristics In service. The displacement DVRTs mounted within the chain aperture will provide real-time information on *:** intertink wear, whilst the shear pin strain gauges (inserted within a drilled central hole In the shear pins 30, 32) wIll provide the associated load data.
*.*... * . ** **
* Central to the design are the chain links that allow articulation between the upper and lower tubular housings. Each chain link is tightly contained within its housing therefore as the assembly articulates, movement is confined to the interface between the two exposed sections of chain. Free movement between the chain links and the housing structure is eliminated therefore fretting does not occur. The chain acts as a structural extension to each section of the housing and provides a simple coupling between the two.
Each chain link is supported on either side by a cheek plate. The cheek plate limits out of plane bending by providing lateral support for two thirds of the total link length. The maximum bending stresses in the link are reduced and the fatigue life of the link is extended.
In order to minimise costs and fabrication lead time the construction is specifically designed to use only steel plate, simple machined parts and off the shelf components. There are no forgings within the design and the design can be easily fabricated without the need for specialist equipment or techniques thus increasing the pool of potential contractors capable of manufacturing the product. S. * . * S*. S... * * *.* *5** * S ** * * . us... * S *S * . . *
Claims (10)
- Claims 1. A connector for connecting Iwo bodies which are to have some relative freedom of movement, the connector having two parts, one for connection to each of the bodies, each part incorporating a chain link, and the chain links of the two parts being linked to one another in the manner of a chain, each link being held substantially rigid within its respective body, the connector also including a bellows fitted between the bodies and enclosing the chain links, the space within the bellows being filled with a lubricant.
- 2. A connector as daimed in Claim 1, wherein the respective bodies each have an outer casing and the chain links are secured in the respective bodies by shear pins passing through the links and through the outer casing.
- 3. A connector as cJaimed in Claim 2, wherein the bodies have internal cavities and the cavities are sealed to one another by a flexible bellows which surrounds the chain links.
- 4. A connector as claimed in Claim 3, wherein the space within the bellows and the internal cavities of the bodies is filled with a lubricant.
- 5. A connector as claimed in Claim 4, wherein the lubricant is an incompressible lubricant.S 55S*. * S
- 6. A connector as claimed in any preceding claim, wherein transducers are *..* * mounted in the connector to monitor the relative movement between the links. ** S. * * S * S
- 7. A connector as claimed in any one of Claims 2 to 6, wherein strain gauges are mounted in the hsear pins.
- 8. An offshore riser pipe installation wherein the riser is connected to a subsea structure by a connector as claimed in any preceding claim.
- 9. A riser pipe installation as claimed in Claim 8, wherein a male stab fitting is provided on the lower end of the riser and a female stab fitting is provided on the subsea structure.
- 10. A connector substantially as herein described with reference to the accompanying drawings. * * * **. * * **.* ***. * *S * S *S.....S S * .e* . .*S S
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0719411A GB2454455A (en) | 2007-10-03 | 2007-10-03 | Lubricated under water flexible coupling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0719411A GB2454455A (en) | 2007-10-03 | 2007-10-03 | Lubricated under water flexible coupling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0719411D0 GB0719411D0 (en) | 2007-11-14 |
| GB2454455A true GB2454455A (en) | 2009-05-13 |
Family
ID=38739139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0719411A Withdrawn GB2454455A (en) | 2007-10-03 | 2007-10-03 | Lubricated under water flexible coupling |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2454455A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017079627A1 (en) * | 2015-11-06 | 2017-05-11 | Vetco Gray Inc. | Installation assembly for a subsea wellhead |
| NO20200733A1 (en) * | 2019-09-19 | 2021-03-22 | Vetco Gray Scandinavia As | Male-male hot stab assembly |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1000617A (en) * | 1963-06-19 | 1965-08-11 | Alford & Alder Engineers Ltd | Improvements in or relating to ball and like joints |
| JPS579318A (en) * | 1980-06-19 | 1982-01-18 | Hideo Hiki | Flexible shaft |
| WO2003087527A1 (en) * | 2002-04-15 | 2003-10-23 | Stolt Offshore Sa | Marine riser installation |
-
2007
- 2007-10-03 GB GB0719411A patent/GB2454455A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1000617A (en) * | 1963-06-19 | 1965-08-11 | Alford & Alder Engineers Ltd | Improvements in or relating to ball and like joints |
| JPS579318A (en) * | 1980-06-19 | 1982-01-18 | Hideo Hiki | Flexible shaft |
| WO2003087527A1 (en) * | 2002-04-15 | 2003-10-23 | Stolt Offshore Sa | Marine riser installation |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017079627A1 (en) * | 2015-11-06 | 2017-05-11 | Vetco Gray Inc. | Installation assembly for a subsea wellhead |
| NO20200733A1 (en) * | 2019-09-19 | 2021-03-22 | Vetco Gray Scandinavia As | Male-male hot stab assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0719411D0 (en) | 2007-11-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) |
Free format text: REGISTERED BETWEEN 20111208 AND 20111214 |
|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |