Information
-
Patent Grant
-
6695539
-
Patent Number
6,695,539
-
Date Filed
Friday, October 19, 200122 years ago
-
Date Issued
Tuesday, February 24, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Vidovich; Gregory
- Omgba; Essama
Agents
- Gilbreth & Associates, P.C.
- Gilbreth; J. M. (Mark)
- Gilbreth; Mary A.
-
CPC
-
US Classifications
Field of Search
US
- 405 190
- 405 191
- 405 188
- 405 1842
- 405 1841
- 405 1844
- 405 158
- 166 335
- 166 338
- 166 356
- 029 728
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International Classifications
-
Abstract
Apparatus and methods for remotely installing vortex-induced vibration (VIV) reduction and drag reduction devices on elongated structures in flowing fluid environments. The apparatus is a tool for transporting and installing the devices. The devices installed can include clamshell-shaped strakes, shrouds, fairings, sleeves and flotation modules.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to apparatus and methods for remotely installing vortex-induced vibration (VIV) and drag reduction devices on structures in flowing fluid environments. In another aspect, the present invention relates to apparatus and methods for installing VIV and drag reduction devices on underwater structures using equipment that can be remotely operated from above the surface of the water. In even another aspect, the present invention relates to apparatus and methods for remotely installing VIV and drag reduction devices on structures in an atmospheric environment using equipment that can be operated from the surface of the ground.
2. Description of the Related Art
Whenever a bluff body, such as a cylinder, experiences a current in a flowing fluid environment, it is possible for the body to experience vortex-induced vibrations (VIV). These vibrations are caused by oscillating dynamic forces on the surface which can cause substantial vibrations of the structure, especially if the forcing frequency is at or near a structural natural frequency. The vibrations are largest in the transverse (to flow) direction; however, in-line vibrations can also cause stresses which are sometimes larger than those in the transverse direction.
Drilling for and/or producing hydrocarbons or the like from subterranean deposits which exist under a body of water exposes underwater drilling and production equipment to water currents and the possibility of VIV. Equipment exposed to VIV includes structures ranging from the smaller tubes of a riser system, anchoring tendons, or lateral pipelines to the larger underwater cylinders of the hull of a minispar or spar floating production system (hereinafter “spar”).
Risers are discussed here as a non-exclusive example of an aquatic element subject to VIV. A riser system is used for establishing fluid communication between the surface and the bottom of a water body. The principal purpose of the riser is to provide a fluid flow path between a drilling vessel and a well bore and to guide a drill string to the well bore.
A typical riser system normally consists of one or more fluid-conducting conduits which extend from the surface to a structure (e.g., wellhead) on the bottom of a water body. For example, in the drilling of a submerged well, a drilling riser usually consists of a main conduit through which the drill string is lowered and through which the drilling mud is circulated from the lower end of the drill string back to the surface. In addition to the main conduit, it is conventional to provide auxiliary conduits, e.g., choke and kill lines, etc., which extend parallel to and are carried by the main conduit.
This drilling for and/or producing of hydrocarbons from aquatic, and especially offshore, fields has created many unique engineering challenges. For example, in order to limit the angular deflections of the upper and lower ends of the riser pipe or anchor tendons and to provide required resistance to lateral forces, it is common practice to use apparatus for adding axial tension to the riser pipe string. Further complexities are added when the drilling structure is a floating vessel, as the tensioning apparatus must accommodate considerable heave due to wave action. Still further, the lateral forces due to current drag require some means for resisting them whether the drilling structure is a floating vessel or a platform fixed to the subsurface level.
The magnitude of the stresses on the riser pipe, tendons or spars is generally a function of and increases with the velocity of the water current passing these structures and the length of the structure.
It is noted that even moderate velocity currents in flowing fluid environments acting on linear structures can cause stresses. Such moderate or higher currents are readily encountered when drilling for offshore oil and gas at greater depths in the ocean or in an ocean inlet or near a river mouth.
Drilling in ever deeper water depths requires longer riser pipe strings which because of their increased length and subsequent greater surface area are subject to greater drag forces which must be resisted by more tension. This is believed to occur as the resistance to lateral forces due to the bending stresses in the riser decreases as the depth of the body of water increases.
Accordingly, the adverse effects of drag forces against a riser or other structure caused by strong and shifting currents in these deeper waters increase and set up stresses in the structure which can lead to severe fatigue and/or failure of the structure if left unchecked.
There are generally two kinds of current-induced stresses in flowing fluid environments. The first kind of stress is caused by vortex-induced alternating forces that vibrate the structure (“vortex-induced vibrations”) in a direction perpendicular to the direction of the current. When fluid flows past the structure, vortices are alternately shed from each side of the structure. This produces a fluctuating force on the structure transverse to the current. If the frequency of this harmonic load is near the resonant frequency of the structure, large vibrations transverse to the current can occur. These vibrations can, depending on the stiffness and the strength of the structure and any welds, lead to unacceptably short fatigue lives. In fact, stresses caused by high current conditions in marine environments have been known to cause structures such as risers to break apart and fall to the ocean floor.
The second type of stress is caused by drag forces which push the structure in the direction of the current due to the structure's resistance to fluid flow. The drag forces are amplified by vortex induced vibrations of the structure. For instance, a riser pipe that is vibrating due to vortex shedding will disrupt the flow of water around it more than a stationary riser. This results in more energy transfer from the current to the riser, and hence more drag.
Many types of devices have been developed to reduce vibrations of subsea structures. Some of these devices used to reduce vibrations caused by vortex shedding from subsea structures operate by stabilization of the wake. These methods include use of streamlined fairings, wake splitters and flags.
Streamlined or teardrop shaped, fairings that swivel around a structure have been developed that almost eliminate the shedding of vortices. The major drawbacks to teardrop shaped fairings is the cost of the fairing and the time required to install such fairings. Additionally, the critically required rotation of the fairing around the structure is challenged by long-term operation in the undersea environment. Over time in the harsh marine environment, fairing rotation may either be hindered or stopped altogether. A non-rotating fairing subjected to a cross-current may result in vortex shedding that induces greater vibration than the bare structure would incur.
Other devices used to reduce vibrations caused by vortex shedding from sub-sea structures operate by modifying the boundary layer of the flow around the structure to prevent the correlation of vortex shedding along the length of the structure. Examples of such devices include sleeve-like devices such as helical strakes, shrouds, fairings and substantially cylindrical sleeves.
Some VIV and drag reduction devices can be installed on risers and similar structures before those structures are deployed underwater. Alternatively, VIV and drag reduction devices can be installed by divers on structures after those structures are deployed underwater.
Use of human divers to install VIV and drag reduction equipment at shallower depths can be cost effective. However, strong currents can also occur at great depths causing VIV and drag of risers and other underwater structures at those greater depths. However, using divers to install VIV and drag reduction equipment at greater depths subjects divers to greater risks and the divers cannot work as long as they can at shallower depths. The fees charged, therefore, by diving contractors are much greater for work at greater depths than for shallower depths. Also, the time required by divers to complete work at greater depths is greater than at shallower depths, both because of the shorter work periods for divers working at great depths and the greater travel time for divers working at greater depths. This greater travel time is caused not only by greater distances between an underwater work site and the water surface, but also by the requirement that divers returning from greater depths ascend slowly to the surface. Slow ascent allows gases, such as nitrogen, dissolved in the diver's blood caused by breathing air at greater depths, to slowly return to a gaseous state without forming bubbles in the diver's blood circulation system. Bubbles formed in the blood of a diver who ascends too rapidly cause the diver to experience the debilitating symptoms of the bends.
Elongated structures in wind in the atmosphere can also encounter VIV and drag, comparable to that encountered in aquatic environments. Likewise, elongated structures with excessive VIV and drag forces that extend far above the ground can be difficult, expensive and dangerous to reach by human workers to install VIV and drag reduction devices.
However, in spite of the above advancements, there still exists a need in the art for apparatus and methods for installing VIV and drag reduction devices on structures in flowing fluid environments.
There is another need in the art for apparatus and methods for installing VIV and drag reduction devices on structures in flowing fluid environments, which do not suffer from the disadvantages of the prior art apparatus and methods.
There is even another need in the art for apparatus and methods for installing VIV and drag reduction equipment on underwater structures without using human divers.
There is still another need in the art for apparatus and methods for installing VIV and drag reduction devices on underwater structures using equipment that can be remotely operated from the surface of the water.
There is yet another need in the art for apparatus and methods for installing VIV and drag reduction devices on above-ground devices using equipment that can be operated from the surface of the ground.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for apparatus and methods for installing VIV and drag reduction devices on structures in flowing fluid environments.
It is another object of the present invention to provide for apparatus and methods for installing VIV and drag reduction devices on structures in flowing fluid environments, which do not suffer from the disadvantages of the prior art apparatus and methods.
It is even another object of the present invention for apparatus and methods for installing VIV and drag reduction devices on underwater structures without using human divers.
It is still an object of the present invention to provide for apparatus and methods for installing VIV and drag reduction devices on underwater structures using equipment that can be remotely operated from the surface of the water.
It is yet another object for the present invention to provide for apparatus and methods for installing VIV and drag reduction devices on above-ground structures using equipment that can be operated from the surface of the ground.
These and other objects of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
According to one embodiment of the present invention, there is provided a tool for remotely installing a device around an element. The tool generally includes a frame and a hydraulic system supported by the frame. The tool further includes at least one set of two clamps supported by the frame, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices. The set of clamps is connected to the hydraulic system.
According to another embodiment of the present invention, there is provided a method of remotely installing a device around an element having a diameter. The method generally includes positioning a tool adjacent to the element, wherein the tool carries the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices. The method next includes moving the tool to position the clamshell device around the element. The method further includes operating the tool to close the clamshell device around the element, wherein the device covers from about 50% to about 100% of the diameter of the element. The method finally includes securing the device in position around the diameter of the element.
These and other embodiments of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top view of Diverless Suppression Deployment Tool (DSDT)
100
, showing carousel clamps
110
.
FIG. 2
is a side elevational view of DSDT
100
showing tubular framework supports
150
and
155
.
FIG. 3
is a side elevational view of DSDT
100
in a shortened or retracted position.
FIG. 4
is a side elevational view of DSDT
100
in an extended position.
FIG. 5
is an illustration of a helical strake with nipples.
FIG. 6
is an illustration of carousel clamp
600
in its closed position and designed for holding a fairing.
FIG. 7
is an illustration of carousel clamp
110
in its open position and designed to hold such devices as a helical strake.
FIG. 8A
is a top view of DSDT
100
with clamp
110
A open and
110
B closed.
FIG. 8B
is a detailed illustration of nipple
820
attached to strake
500
.
FIG. 9
is an illustration of remotely operated vehicle (ROV)
900
manipulating Diverless Suppression Deployment Tool (DSDT)
100
.
FIG. 10
is an illustration of a top view of ROV
900
manipulating DSDT
100
to encircle fairing
950
.
FIG. 11
is an illustration of a top view of ROV
900
manipulating fairing
950
to close around riser
810
.
FIG. 12
is an alternative embodiment showing nipple
710
positioned on arm
740
, and received into passage
713
in the strake.
FIG. 13
is a top view of alternative clamp
600
with a fairing installed.
FIG. 14
shows an equivalent view to
FIG. 1
showing a DSDT
100
, except that alternative clamp
600
of
FIG. 13
has replaced collar
110
.
FIGS. 15-24
shown a sequence of installing a collar onto a riser, focusing on a top view of one alternative clamp
600
(as shown in
FIG. 13
) of a DSDT
100
, specifically,
FIG. 15
shows a collar
22
being inserted thereto;
FIG. 16
shows a collar half rotated into fixed insert;
FIG. 17
shows an opposite half of the collar rotated into moving insert;
FIG. 18
shows the DSDT being moved onto the pipe
23
;
FIG. 19
shows a further advance of the DSDT being moved onto the pipe;
FIG. 20
shows an even further advance of the DSDT being moved onto the pipe;
FIG. 21
shows the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 22
shows a further advance of the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 23
shows an even further advance of the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 24
shows the DSDT moving away from the riser pipe with collar and fairing installed.
FIGS. 25 and 27
show a fairing
35
having a locking mechanism
33
.
FIG. 26
is a sequence showing the locking of locking mechanism
33
.
DETAILED DESCRIPTION OF THE INVENTION
Referring first to
FIG. 1
, there is illustrated a top view of Diverless Suppression Deployment Tool (DSDT)
100
, which is designed to be remotely operated without the use of human divers in the installation of clamshell-shaped strakes, shrouds, fairings, regular and ultra-smooth sleeves and other VIV and drag reduction equipment underwater to such structures, including but not limited to, oil and gas drilling or production risers, steel catenary risers, and anchor tendons. Slight modifications in DSDT
100
might be required for each particular type of VIV and drag reduction equipment to be installed. These modifications generally will involve modification to clamps
110
so that they can physically accommodate the various types of VIV and drag reduction equipment to be installed.
For example, the embodiment as shown in
FIGS. 1 and 2
is more conducive for the installation of helical strakes.
Ultra-smooth sleeves are described in U.S. patent application Ser. No. 09/625,893 filed Jul. 26, 2000 by Allen et al., which is incorporated herein by reference.
Shown in this embodiment of
FIG. 1
are six carousel clamps
110
connected to top plate
125
of DSDT
100
. Clamps
110
are designed to hold such VIV and drag reduction structures such as a strake, sleeve or other substantially cylindrical device. Also shown is top plate
125
attached to brace
130
, which in this embodiment comprises six lateral braces, but may comprise an unlimited number of lateral braces. Top plate
125
defines hydraulics port opening
135
, which provides access for a valve and hydraulic control system lines through DSDT
100
from water surface
910
, illustrated in FIG.
9
.
Referring now to
FIG. 2
, there is illustrated a lateral view of DSDT
100
of
FIG. 1
, showing six carousel clamps
110
connected to top plate
125
. Carousel clamps
110
are designed to hold structures similar to a strake, sleeve or other substantially cylindrical device. It should be noted that an unlimited number of clamps may be connected to the top plate
125
of DSDT
100
, so long as that number is suitable for completing a task in a flowing fluid environment. The number of clamps may be about two, preferably about four, more preferably about six, even more preferably about eight, still more preferably about ten, yet more preferably about twelve. A similar range of numbers of clamps may also be connected to bottom plate
165
of DSDT
100
.
FIG. 2
also illustrates brace
130
with connector
120
designed to attach to a line for lowering and raising DSDT
100
. Also shown are six ball valves
115
each used for hydraulically controlling one pair of clamps
110
oriented in a vertical line, between one clamp
110
connected to top plate
125
and another clamp
110
connected to bottom plate
165
. Shown also is rod assembly
140
connected to top plate
125
, wherein assembly
140
serves as a handle for manipulation of DSDT
100
by a remotely operated vehicle.
Also shown in
FIG. 2
is first tubular brace
150
, comprised of vertical and cross pieces which are interconnected with second tubular brace
155
, which is in turn connected to bottom plate
165
. In addition, first central tube
170
is connected to top plate
125
and to second central tube
175
, which in turn is connected to bottom plate
165
. Braces
150
and
155
, central tubes
170
and
175
, and plates
125
and comprise a framework.
Shown in
FIG. 2
also are hydraulic cylinders
160
, each of which connects one clamp
110
with either top plate
125
or bottom plate
165
. A tubular hydraulic system (not shown), containing a hydraulic fluid, extends from hydraulics port
135
at least partially through tubular braces
150
and
155
and central tubes
170
and
175
to hydraulic cylinders
160
. Hydraulic cylinders
160
are supplied with hydraulic fluid and hydraulic fluid pressure modulations to open and close clamps
110
which can hold clamshell devices such as strakes, shrouds, fairings or sleeves and close them around a structure.
Referring now to
FIG. 3
, there is illustrated a side view of DSDT
100
in a retracted position that minimizes the size of DSDT
100
for storage and handling. Shown are first tubular brace
150
, first central tube
170
, rod assembly
140
, hydraulic cylinder
160
, and bottom brace
310
.
Referring next to
FIG. 4
, there is illustrated an extended position for DSDT
100
, showing first brace
150
, first central tube
170
, second brace
155
, and second central tube
175
. Second brace
155
and second central tube
175
are capable of moving into and partially out of first brace
150
and first cental tube
175
, respectively. An extended position for DSDT
100
allows it to carry and install longer strakes, shrouds, fairings or other sleeve-like structures than would be possible with the retracted position of DSDT
100
, shown in FIG.
3
.
Referring next to
FIG. 5
, there is illustrated a side view of clamshell helical strake
500
, with tubular body
510
and fins
520
projecting from tubular body
510
. Any number of apparatus and methods could be utilized to anchor strake
500
to carousel clamp
110
while strake
500
is being carried and installed by DSDT
100
. As a non-limiting example, nipples
540
are shown projecting out of each end of the exterior of strake
500
and will mate with a matching recess in clamp
110
, while Hinge/clamps
530
are shown in their closed position on both sides of strake
500
. Hinge/clamps
530
are normally closed on both sides of strake
500
only during shipping or after strake
500
has been fastened around a structure such as a riser, or horizontal or catenary pipe. At other times, hinge/clamps
530
are closed on one side of strake
500
and open on the other side. With closed hinge/clamps
530
on just one side of strake
500
, hinge/clamps
530
serve as hinges allowing clamshell strake
500
to open like a clamshell on the side of strake
500
opposite the closed hinge/clamps
530
.
Of course, the nipples and recesses could be reversed, that is, the nipples could be on clamp
110
, and the mating recesses on strake
500
as is shown in an alternative embodiment in
FIG. 7
, and as shown connected in
FIG. 12
(with
FIGS. 7 and 12
discussed in more detail below).
Referring now to
FIG. 6
, there is illustrated one embodiment of a clamp designed to hold a tear-drop shaped fairing both in an open and a closed position (another embodiment is discussed below).
Carousel clamp
600
, shown in its closed position, is comprised primarily of two arms, first arm
630
and second arm
640
. Shown are nipples
610
in arms
630
and
640
. These nipples
610
are designed to pass through an opening on a fairing and temporarily anchor a fairing to an interior face of the clamp
600
. Attachment
620
is designed to attach to hydraulic cylinder
160
, which cylinder
160
, when activated, can open and close clamp
600
.
In some instances, depending upon the circumference of the fairing, and flexibility of the materials, the essentially circular shape of the back of closed clamp
600
as shown in
FIG. 6
is likely to cause problems handling a fairing, as the fairing will bow back and strike clamp
600
, and will either be unstable or prone to coming loose.
A preferred alternative embodiment of clamp
600
is shown in
FIG. 13
, showing a top view of alternative clamp
600
with a fairing installed. For alternative clamp
600
, its arms
630
and
640
are provided different rotation axis, which operate to provide space for a closed fairing to bow backward. In more detail, alternative clamp
600
further includes fairing retainer mechanism
631
and
641
on their respective arms
630
and
640
. Also shown are fixed collar grip
632
, collar index
633
, closer cylinder
644
, stiffener
643
, and collar closer grip
642
. Referring additionally to
FIG. 14
, there is shown an equivalent view to
FIG. 1
showing a DSDT
100
, except that alternative clamp
600
of
FIG. 13
has replaced collar
110
.
Referring next to
FIG. 7
, there is illustrated carousel clamp
110
with first arm
730
and second arm
740
. Clamp
110
is designed to hold strake
500
. Shown inserted into arms
730
and
740
are nipples
710
which are designed to penetrate an opening on strake
500
and temporarily anchor strake
500
to clamp
110
. Attachment
720
in arm
740
is designed to attach to hydraulic cylinder
160
. Hydraulic cylinder
160
, when activated, can open and close clamp
110
.
Referring now to
FIG. 8A
, there is illustrated a top view of DSDT
100
with carousel clamps
110
A and
110
B at two of six possible positions. Clamp
110
A is open and has attached to it strake
500
in an open position. Fin
520
of strake
500
is shown in cross-section. Also shown is a top or cross-sectional view of riser
810
. Manipulation of DSDT
100
positions strake
500
around an underwater structure such as riser
810
. After strake
500
is positioned around a structure such as riser
810
, clamp
110
is closed, thereby closing strake
500
closely around riser
810
. With strake
500
closed, hinge/clamp halves
532
and
534
are positioned adjacent to and overlapping each other. Closed strake
500
is shown attached to clamp
110
B. Closed hinge/clamps
530
, comprised of hinge/clamp halves
532
and
534
are positioned on two sides of strake
500
. One hinge/clamp
530
acted as a hinge until strake
500
was closed. The remaining hinge/clamp
530
can be locked closed by inserting a captive pin into it after it is closed.
Referring next to
FIG. 8B
, which is a detail of clamp
110
A in
FIG. 8A
, there is illustrated nipple
820
attached to strake
500
inserted inside of rubber padding
830
held by coupling
850
(again, any suitable type of connection can be used in place of the nipple/recess, and the nipple/recess can be reversed). Coupling
850
is encircled by space
860
, which allows limited movement of coupling
850
inside of clamp
110
A. Coupling can rotate to a limited extent about pivot point
840
.
Referring now to
FIG. 9
, there is illustrated remotely operated vehicle (ROV)
900
manipulating, via arm
920
, DSDT
100
. DSDT
100
is suspended by line
930
from the vicinity of water's surface
910
. Line
930
carries hydraulic lines
935
(not shown) that extend from a vessel or production platform (not shown) into DSDT
100
for the purpose of operating hydraulic cylinders
160
to open and close clamps such as clamps
110
, which can carry sleeve-like devices. DSDT
100
is shown carrying fairing
950
to be placed around riser
810
. Fairing
950
is to be placed above previously positioned fairing
955
.
FIG. 9
can further be used to illustrate an overview of DSDT
100
deployment where the steps involve DSDT
100
being positioned adjacent to the riser on which the strakes, shrouds, fairings or other sleeve-like devices, including flotation modules, will be installed. The most effective way to control the uppermost position of sleeves around riser
810
is to attach one collar
940
above the area where the DSDT
100
is to be lowered.
Strakes, shrouds, fairings, or other sleeve-like devices, will stack up on each other if they have low buoyancy and sink to another collar
940
placed around riser
810
at a desired lower stop point. DSDT
100
can be lowered to the bottom position and work can commence from the bottom-most position upward. When the DSDT
100
is at the proper position, the first strake or fairing section can be opened by retracting hydraulic cylinder
160
. ROV
900
can then assist by gently tugging the DSDT
100
over to engage the strake or fairing around the riser. DSDT
100
should be about a foot above the lower collar
940
. Once the clamshell device, such as strake, shroud, fairing, or sleeve has engaged the riser, the hydraulic cylinder is extended. This closes the clamshell around the riser. At this time ROV
900
can visually check to see if the alignment looks good. If so, ROV
900
strokes a captive pin
956
downward, locking the strake, fairing or clamshell sleeve around the riser. Carousel arms, such as
630
and
640
are then disengaged by retracting the hydraulic cylinders. DSDT
100
will then move away from the riser, and the first strake, fairing or clamshell sleeve section will drop down, coming to rest on the lower collar
940
. DSDT
100
is then moved up until it is about a foot above the first of the sleeve-like devices.
The installation continues until all six sleeve-like devices are installed. DSDT
100
is then retrieved and six more sections are installed. The installation is not extremely fast. It should keep in mind, however, that only platform resources are being used, so the job can be done in times of inactivity and calm sea states.
Referring now to
FIG. 10
, there is illustrated a top view of ROV
900
manipulating with arm
920
DSDT
100
to encircle riser
810
with fairing
950
. Only one of 6 positions around DSDT
100
is shown as occupied with a carousel clamp, such as here clamp
640
for installation of fairings. However, all six position may be occupied by carousel clamps. Note that hydraulic cylinder
160
is in a retracted position. Shown are connecting ends
952
and
954
of fairing
950
.
Referring to
FIG. 11
, there is illustrated a fastening step occurring after the encircling step shown in FIG.
10
.
FIG. 11
illustrates a top view of ROV
900
closing together ends
952
and
954
with arm
920
so that the ends can be connected to each other. Note that hydraulic cylinder
160
is extended forcing clamp
600
to close, thereby closing fairing
950
. Captive pin
956
can be stroked down by ROV
900
to lock the fairing in place.
Referring now to
FIGS. 15-24
, there is shown a sequence of installing a collar onto a riser. This sequence focuses on a top view of one alternative clamp
600
(as shown in
FIG. 13
, with the reference numbers of
FIG. 13
applying to these
FIGS. 15-24
) of a DSDT. Specifically,
FIG. 15
shows a collar
22
being inserted thereto;
FIG. 16
shows a collar half rotated into fixed insert;
FIG. 17
shows an opposite half of the collar rotated into moving insert;
FIG. 18
shows the DSDT being moved onto the pipe
23
;
FIG. 19
shows a further advance of the DSDT being moved onto the pipe;
FIG. 20
shows an even further advance of the DSDT being moved onto the pipe;
FIG. 21
shows the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 22
shows a further advance of the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 23
shows an even further advance of the cylinder closing the fairing clamp as the collar grip drives the collar closed;
FIG. 24
shows the DSDT moving away from the riser pipe with collar and fairing installed.
Although any fairing is believed to be suitable for use in the present invention, preferably a fairing utilized in the present invention will comprise a locking mechanism that will allow the DSDT to lock the fairing around a riser pipe upon installation. Generally, the ends of the fairing will be outfitted with a mating locking mechanism that locks upon contact. A non-limiting example of such a locking mechanism
33
is shown in
FIGS. 25 and 27
as part of fairing
35
. A sequence showing the locking of locking mechanism
33
is shown in FIG.
26
.
While the Diverless Suppression Deployment Tool
100
has been described as being used in aquatic environments, that embodiment or another embodiment of the present invention may also be used for installing VIV and drag reduction devices on elongated structures in atmospheric environments with the use of an apparatus such as a crane.
While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which this invention pertains.
Claims
- 1. A tool for remotely installing a clamshell device around an element, the tool comprising:(a) a frame; (b) a hydraulic system supported by the frame; and (c) at least one set of two clamps supported by the frame, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices, wherein the set of clamps is connected to the hydraulic system wherein the frame has a top and a bottom, wherein the set of clamps is comprised of a first clamp and a second clamp, wherein the first clamp is supported by the top of the frame and the second clamp is supported by the bottom of the frame, and wherein the first clamp and the second clamp each comprise at least one nipple for anchoring the clamshell device to the set of clamps.
- 2. The tool of claim 1, wherein there are at least two sets of clamps.
- 3. The tool of claim 1, wherein the set of clamps holds the clamshell device.
- 4. The tool of claim 1, wherein the frame has a taller first height and is collapsible to a shorter second height for holding shorter devices or for storage of the tool.
- 5. A tool for remotely installing a clamshell device around an element, the tool comprising:(a) a frame; (b) a hydraulic system supported by the frame; and (c) at least one set of two clamps supported by the frame, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices, wherein the set of clamps is connected to the hydraulic system wherein there are at least two sets of clamps wherein there are at least two clamshell devices, and wherein each of the at least two sets of clamps holds one clamshell device.
- 6. The tool of claim 5, wherein the frame has a top and a bottom,wherein the set of clamps is comprised of a first clamp and a second clamp, and wherein the first clamp is supported by the top of the frame and the second clamp is supported by the bottom of the frame.
- 7. The tool of claim 5, wherein the frame has a tallor first height and is collapsible to a shorter second height for holding shorter devices or for storage of the tool.
US Referenced Citations (35)