Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13249~7
1. CASO 2800
"REVERSIBLE, ARTICULATED MECHANICAL COUPLING AND RELEVANT
SEAT, FOR ANCHORAGES UNDER TENSION"
The present ;nvention relates to a reversible,
articulated mechanical coupling and to the seat for such
a coupl;ng, for the structural connect;on to the
foundation bases, positioned at the sea bottom, of the
anchorages of offshore platforms with anchorages under
tension, known as "TLP", i.e., "Tension Leg Platforms".
It is known that such types of offshore platforms
are anchored to the sea bottom by means of a set of
anchorages under tension, which are structurally
connected to the foundation bases, positioned at the sea
bottom, by means of reversible mechanical couplings which
get engaged inside suitable seats purposely provided in
said foundation bases~
Now then, the various types of reversible mechanical
couplings for connecting to the sea bottom offshore
platforms of TLP type, known from the prior art~ require
that the members constituting the same coupling be
mechanically or hydraulically actuated in order to
realize the engagement and the disengagement of the
coupling in/from the relevant seat provided on the
foundation bases.
The need for such actuation procedures, to be
performed at the sea bottom, involves the use of
auxiliary equipment, or of hydraulic l;nes ~hich connect
the coupling with the platform, with consequent increases
in costs and duration of the operat10ns, as well as with
;~ increasing risks of failure of the same operations due to
a malfunctioning of said coupling-actuation equipment or
members.
qP
132~7
2.
The purpose of the present invention is obviating
the above sa;d drawbacks and therefore supplying a novel
coupling, which can be engaged and disengaged in/from the
relevant seat in an automatic way, by simply sinking and
lifting, and, possibly, rotating the anchorage.
eesides that, the coupling of the present invention
is constituted by a s~all number of components, and is
endowed with a high mechanical simpleness, with
consequent advantages in terms of cost, operating
reliab;lity, and sureness that the operations of
engagement and disengagement can be carried out.
The above purpose is substantially achieved by means
of the fact that the coupling is constituted by a hollow
body open at its top, on whose outer surface a set of
teeth protrude, which are positioned in a sunburst
pattern, and to the bottom end of which a cylindrical
appendix is fastened, which makes it easier to insert and
correctly position the coupling inside the seat.
Inside the body of the coupling a flexible element
of ring shape is fastened, inside ~hich a ring is
fastened in its turn, which is mounted on the top
surface, of cone frustum shape, or of spherical shape, of
the enLarged portion provided at the bottom end of a rod.
Said rod comes out from the top opening of the body
of the coupling, and in correspondence of its top end it
is ~elded to~ or anyway made integral ~ith, the bottom
end of the anchorage.
Said ring, and the members connected to it, i.e.,
the flexible element, the body of the coupl~ng and the
relevant appendix, can rotate relatively to the rod
around the vertical axis~
1324917
The seat of the coupling, fastened to the founda-
tion basis, comprises a cylindrical shell on whose inner
surface grooves are provided, between which at least a set
of entry grooves are provided in a number equal to the
number of the teeth, between which a set of grooves blind at
their top end are provided in order to engage the same
teeth.
More particularly, there is provided a reversible
mechanical coupling and relevant seat of the type provided
in a foundation basis in order to anchor an anchorage of an
offshore platform of tension leg platform type to said basis
and to allow the anchorage to be engaged in the seat or to
be disengaged from it, ch~racterized in that said coupling
comprising a hollow body having a top opening, an inner
surface, an outer surface and a bottom end, a set of teeth
being positioned in a sunburst pattern on said outer
sllrface, a downwardly-tapered appendix being fastened to the
bottom end by a rod having an upper end rigidly attached to
the bottom end of the anchorage, the rod passing through the
top opening of the body and having an enlarged end portion
inside the body, a flexible ring-shaped element being
positioned between an upper surface of the enlarged portion
:~ and the inner surface of the body, the element being
directly or indirectly fastened to the upper and inner
surfaces, the coupling having a seat comprising a
~: cylindrical shell, the shell having an inner surface on
which one set of entry grooves are provided in a number
equal to the number of the teeth, the entry grooves being
separated by downwardly set blind grooves provided in a
number equal to the number of the teeth, each entry groove
having two side walls initially inclined, with reference to
a vertical axis, and downwardly convergent towards a minimum
entry groove cross-section area, each blind groove having
an inclined upwardly convergent side wall and a vertical
side wall.
1~249~
3a
The coupling is engaged in the relevant seat by
completeLy inserting the coupling inside the same seat~
and then lift1ng it.
When the coupling is inserted, the teeth slide
inside the entry grooves of the cylindrical shell, which
grooves, by being inclined, involve the rotation around
the vertical axis of the body of the coupl;ng; when the
coupling is lifted, owing to the effect caused by the
rotation occurred during the insertion, the teeth sl;de
inside the blind-top grooves, at whose top end they
remain engaged.
The coupling is disengaged from the seat by
completely sinking the coupling inside the seat and then
extracting said coupl1ng from said seat.
When the coupling is sunk, the teeth are guided by
the grooves, which, by being inclined, cause a further
rotation around the vertical axis of the body of the
coupLing; when the coupling is lifted at a later time,
owing to the effect of the rotation occurred during the
sinking, the teeth enter the entry grooves, thus making
it poss1ble the coupling to be extracted from the seat.
When the coupllng 1s engaged in the seat, it is
capable of transferring to said seat, through the teeth,
the body of the coupling, the flexible element, the r~ng
~2~:91~`7
4.
and the rod, the forces transm;tted by the anchorage,
which anchorange cam ~wing by tilt;ng relatively to the
vert;cal by virtue of the deformabil;ty of the flexible
element.
Further characteristics and preferred forms of
practical embodiment of the present invention wiLl become
known from the follo~ing, ~herein the invention is better
explained with reference to the herPto attached drawings,
which dep;ct a preferred form of practical embodiment
given for merely exemplifying and non-Limitative
purposes, in that techn;cal or structuraL changes can be
supplied without departing from the scope of the present
invention.
- Figure 1 represents a partially sectional front view of
the coupling according to the invention, inserted and
engaged inside the relevant seat;
- Figure 2 represents a vertical sectional view of the
seat of the coupling, according to the present
invention; and
- Figure 3 represents a partialLy sectional front view of
the coupling~ according to the invention, fully
inserted in the relevant seat and with the rod and the
anchorage inclined relatively to the vertical
direction.
Referring to the figures, the coupling is
constituted by a hollo~ body 1, open at its top, on whose
outer surface a set of teeth 2 protrude, ~hich are
positioned in a sunburst pattern, and at ~hose bottom end
an appendix 3 is fastened.
Said appendix 3 has an upper cross-section equal to
the bottom cross-section of the hollow body 1 of the
~2~9~`7
5.
coupLing and the cross-section progressively decreases
towards the bottom, down to a diameter beyond which said
cross-section remains constant, and the appendix takes
its cylindr;cal shape, possibly ending at its bottom with
S a cone or a half-sphere.
From the ;nter;or of the hollow body 1 of the
coupl;ng, through its upper opening, the rod 4 comes out,
whose upper end is welded toO or is anyway ~ade integral
~ith, the lower end of the anchoraye 5.
The bottom end of said rod 4 ends inside said hollow
body 1 of the coupl;ng ~ith an enlarged portion 6 which,
is its upper port;on, preferably has, at least partially,
a from cone-frustu~ to spherical shape.
In correspondence of its bottom end, said rod 4
rests on the spherical seat 7 fastened inside the
appendix 3.
On the upper surface, ~hifh preferably has a cone-
frustum or spher;cal shape, of the enlarged port;on 6,
the ring 8 is mounted, ~hich can rotate relat;vely to the
rod 4 around the vert;cal axis.
9etween the outer surface of the ring 8 and the
inner surface of the hollo~ body 1, the flexible element
of ring shape is fastened, which is composed by
elastomer and metaL, or by other suitable materials; said
flexible element 9, by elastically deform;ng, enables the
rod 4, and there~ore the lower end o~ the anchorage 5, to
tilt relati~ely to ~he vertical d;rect;on, as shown in
Figure 3~
rhe seat of the coupling, wh;ch is fastened to the
foundation bases installed at the sea bottom, comprises a
cylindr;cal shell 11 ~ith an entry cone 10 at the top.
~324917
Inside said cylindrical shell 11, the grooves 12, 13, 14
and 15 are provided; inside such grooves 12, 13, 14 and
15, the teeth 2 of the coupling body slide when this
latter is inserted into, or extracted from, the seat.
Inside the cyl;ndrical sheLL 11, under the reg;on
concerned by said grooves, the centering cone 17 is
fastened, which is provided with a top opening having a
diameter equal to the inner diameter of the shell 11, and
with a bottom opening having a diameter slightly larger
than the diameter of the cyLindrical portion of the
appendix 3; at the bottom end of the centering cone 17,
the centering ring 18 is fastened.
The entry grooves 12, whose number is equal to the
number of the teeth 2, are provided near the upper end of
the cylindrical shell 11. In the upper portion, the side
~alls of each of said entry grooves 12 are inclined
relatively ~o the vertical dirertion, and ar~ convergent
downwards, and in the bottom portion the wall 12a
diverges downwards and the wall 12b becomes vertical.
The bLind-top grooves 13 are provided near the upper
end of the cylindr;cal shelL 11 in the areas between the
entry grooves 12. The side walL 13a of each one of the
blind-top grooves 13 adjacent to the waLl 12b of the
entry groove 12 is inclined and convergent up~ards,
whilst the side wall 13b of each one of the blind grooves
13 is vertical; said bLind grooves 13 are closed at their
top end by the surface against which the teeth16 are
designed to come to rest~
The lo~er entry grooves 14 are provided inside the
cylindrical sheLL 11 under the entry grooves 12 and the
bLind grooves 13.
132~917
The lower entry grooves 14 are in a number equal to
the number of the teeth, and each one thereof has a side
wall 14a which begins on the vertical of the narrowest
cross-section of an upper entry groove 12 and continues
5downwards in;t;ally inclined and convergent towards the
second side wall 14b, with this latter being vertical and
under the inclined side wall of a blind groove 13.
The lower exit grooves 15 are provided inside the
cylindrical shell 11 under the entry grooves 12 and the
10blind grooves 13, in the areas between the lower entry
grooves 14.
Each one of the lower ex;t grooves 15 has a s;de
wall 15a wh;ch begins on the verticaL of a blind groove
13 and continues downwards initially inclined and
15convergent to~ards the second side wall 15b, with this
latter being vertical and under the inclined, do~nwards-
divergent side wall of an upper entry groove 12.
The engasement of the coupling inside the relevant
seat takes place by inserting the coupling ins;de the
: 20cylindrical shell 11, in this way the teeth 2 of the body
1 of the coupling entering ~he entry grooves 12; the
insertion of the coupling continues until the teeth slide
into the lower entry grooves 14.
: During the sinking of the coupling, due to the
25effect of the slope of the side walls of the entry
grooves 12 and of the lo~er entry grooves 14a, the body
of the coupling 1, and, consequently, the flexible
element 9 and the ring 8 rotate around the vertical axis.
During the sink;ng of the coupling, the cylindrical
30appendix 3 guided by the centering cone 17 enters the
centering ring 18; when the coupling is completely
~L~32~91~
8.
inserted ;n the seat, the body 1 of the coupling rests
aga;nst the centering cone 17 (see specificaLly Figure
3).
When after being completely inserted in the seat,
the coupling is lifted, the teeth 2 of the body 1 of the
coupling enter the blind grooves 13, at whose top end the
teeth 2 stop against the tooth resting surfaces 16
provided in the cylindrical shell 11.
Said tooth resting surfaces 16 prevent any further
vertical and horizontal movements, asc well as any
rotations of the body 1 of the coupLing.
When the coupling is lifted, due to the effect of
the slope of the side ~3lls of the blind grooves 13a, the
body of the coupling 1, the flexible element 9 and the
ring 8 rotate around the vertical axis.
In order to disengage the couplin~ from the seat, it
is enough to make it sink again inside the cylindrical
shelL 11; - the teeth 2 of the body of the coupling 1,
leaving the blind grooves 13, enter the lower exit
grooves 15. When, after being completely sunk inside the
seat, the coupling is subsequently lifted, the teeth 2
sLide into the entry grooves 12, enabling the coupling to
be extracted from the seat.
Also during the sinking and the lifting of the
coupl1ng in order to engage it in, or disengage it from,
the seat, due to the effect of the slope of the side
walls of the lo~er exit grooves 15a and of the entry
grooves 12a, the body of the coupling 1, the flexible
element 9 and the ring 8 rotate around the vertical axis.
3û The coupling can also be oade ~ithout the ring 8 and
with the flexible element 9 being directly fastened to
~32~17
9.
the enlarged portion 6 of the rod 4; in such event, the
engagement and diseng~gement of the coupling ;n/from the
seat will stiLl take place according to the above
dislosed procedure, but, in th;s case, when the coupling
is lifted and sunk ;nside the seat, also the rod 4 and
the anchorage 5 will rotate~
The shape of the grooves as shown in Figure 2 makes
it possible the coupling to be engaged in, or disegnaged
from, the seat, by simply sinking and lifting the same
c 10 coupling, without any need for controlling the amplitude
of the rotations of the body of the coupling, ;n that
these are determined by the geometry of the grooves;
however, ;t is aLso possible to realize grooves with a
different geometry, on condition that entry grooves and
exit grooves for the teeth of the coupling, and blind-top
grooves in order to prevent further vertical and
horizontal movements of the teeth, and therefore of the
same coupling body, once that said teeth have entered
them, are provided.
