Note: Descriptions are shown in the official language in which they were submitted.
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4-220(B) CVE-371
COLLET TYPE CONNECTOR
DESCRIPTION
BACKGROUND
This invention relates to the connection of tubular
members. The invention has particular application to the
connections of subsea tubular members such as wellheads and
pipelines. It is a requirement of such connections that they
cannot be released by pressure to which they are exposed.
Furthermore, it is a requirement that the connection be
releasable when there is a requirement to disconnect the tubular
members.
Many prior art arrangements have used connectors which rely
upon the angle of taper between locking dogs or a ring and an
actuator mechanism in such a way there is a self-locking taper.
This creates problems in that it relies upon the coefficient of
friction between the engaged members remaining the same and the
application of a lubricant may so change this coefficient that
the taper does not remain self-locking.
U. S. Patent No. 3,321,217 describes a subsea connector
which i8 remotely actuated and relies upon a wedge ring to force
locking dogs into engagement with grooves to complete the
connection and also relies on a self-locking taper between the
two to maintain the locked position.
U. S. Patent No. 4,057,267 discloses a pipe connector which
is said to be particularly useful for connecting underwater
riser 6ections and includes remotely actuated hydraulic means
for moving a locking dog radially inwardly into a locked
position and a remotely actuated hydraulic means for moving a
locking dog radially inwardly into a locked position and a
remotely actuated hydraulic means for movina a cam into position
to lock the dogs and their actuator in a locked position.
center position of the toggle mechanism resists unlatching of
the dogs from their grooves.
Examples of collet type connectors for the connection of
tubular members are described in, for example, U. S. Patent Nos.
4,165,470, 4,049,297 and 4,074,912.
U. S. Patent No. 4,265,891 describes a tubular connector
in which first and second tubular members have ~xternal engaging
means. The members can be latched by a latching means which can
be releasably retained by a locking means.
U. S. Patent No. 4,557,508 describes a tubular connector
in which a collet type segmented engaging element has
projections which can engage grooves in the adjacent ends of two
tubular members to be connected. The engaging means is urged
into engagement with the grooves by means of an actuator ring
which wedges the engaging means into tight latching engagement
with the grooves on the tubular members. The actuating ring is
held in position by a split ring.
SIJMMARY
According to the present invention there is provided a
tubular connector of the type in which a segmented latching
means is disposed around adjacent ends of first and second
tubular member and is movable to a latching position in which
grooves on either of the tubular members or the latching means
i8 engaged by correspondingly shaped projection on the other,
the connector including a pair of axially spaced cam rings which
can engage the latching means and means for drawing the cam
rings axially together to force the latching means into latching
engagement with the tubular members. Each end of the first and
second tubular members may be formed with a plurality of annular
grooves engageable by correspondingly shaped projections formed
on the segmented latching means.
The cam rings may be provided with a double profile inner
surface which engages a radially outer profiled surface on the
latching means. The means for drawing the cam rings together
may comprise at least one threaded stud extending through said
cam rings and having, at each end thereof, a nut engaging said
threads.
A snap ring may contact the inner annular surface of the
latching means to bias said latching means towards its unlatched
position.
An object of the present invention is to provide an
improved tubular connector which is relatively simple to handle
and can be latched and unlatched quickly.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described now by way of example only,
with particular reference to the accompanying drawings wherein:
FIGURE 1 is a plan view of a connector in accordance with
the present invention.
FIGURE 2 is a sectional view taken along line 2 -- 2 in
FIGURE 1.
FIGURE 3 is a partial sectional view taken along line 3 -
3 in FIGURE 1.
FIGURE 4 i8 another partial sectional, view taken along
line 4 - 4 in FIGURE 1.
FIGURE 5 i8 a partial sectional view on a larger scale
illustrating a connector in accordance with the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, the present connector is
arranged to provide a connection between two coaxial tubular
members shown as 10 and 11 in FIGURE 5. The connector includes
latching means in the form of a plurality of circumferentially
spaced collet type segments 14 which extend around adjacent ends
of the tubular members 10 and 11. The collet type segments 14
have inwardly directed projections 16 which can engage
corre~pondingly shaped grooves 18 formed in the outer periphery
of each tubular member 10 and 11. A snap ring 20 engages an
inner central portion of the collet segments 14 and biases these
radially outwardly. As shown in, for example, FIGUR~ 5 the
radially outer surface of the segments 14 is profiled to define
surface portions 24, 26, and 28.
21.~.~
-- 4 --
Upper and lower cam rings 30, 32 are disposed around the
collet segments 14. The cam rings have a plurality of through
bores which accommodate threaded studs 36 the opposite ends of
which are engaged by nuts 38. A~ will be apparent, tightening
of the nuts 38 has the effect of drawing the cam rings axially
towards each other. Each cam ring also has four aligned closed
bores (see for example FIGURE 3) which accommodate compression
springs 40. These compression springs act to bias the cam rings
away from each other. Additionally the upper cam ring has two
further through bores 44 which accommodate a threaded pin 46
which engages a threaded bore in the lower cam ring. A slave
screw 50 engages the upper portion of the threaded pin 46.
As can be seen in FIGURE 5 the radially inner surface of
each cam ring is profiled to define a surface 58 which engages
the surface 26 on the collet segments and a surface 56 which can
engage the surface 24 or the surface 28 on the collet segments.
In the unlatched position of the connector the cam rings are
biased apart by the compression springs 40. In this position
the ~egments 14 are biased apart by the snap rings 20 that they
can be located around the tubular members 10 and 11.
In order to latch the connector the slave screws 50 are
initially operated to draw the cam rings partially towards each
other. This brings the surfaces 56 and 58 and the cam rings
into contact with the surfaces 24, 26 and 28 on the segments 14.
Then the nuts 38 are tightened to complete latching of the
segments. Such that the projections on the segments engage the
grooves formed in the adjacent ends of the tubular members 10
and 11. These studs can be tightened using a hydraulic wrench
and this tightening gives the required connector preload.
The stud, nut and cam ring arrangement shown in the
drawings, gives the connector a mechanical advantage of
approximately six to one and this enables the connector to be
constructed with a relatively small overall diameter. The
result is a mechanically operated connector of compact overall
size which has a high clamping preload and high bending moment
capacity. The connector has the advantage that it is easy to
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handle and operate. The slave screws 50 enable the connector
elements to be moved quickly from the unlocked to the locked
position.
The overall size is small compared with a conventional API
flange or traditional hub clamp. In the present connector, the
collets take mainly direct stress and the cam rings mainly hoop
stress. ~hen the connector is latched the clamping loads do not
go through the studs and the interface between the cam rings and
collets is a locking taper.
When it is desired to unlatch the connector this can be
achieved by using jack screws in tappings in the top of the cam
ring to break the locking taper.
In the arrange described above, twelve collet segments 14
are used. It will be appreciated that connectors in accordance
with the invention can be constructed which have different
numbers of such segments.
