Note: Descriptions are shown in the official language in which they were submitted.
- 1 - .. -i
"Improvements in and Relating to Pipe Conn~ctors"
The present invention relates to improvements
in pipe connectors particularly but not exclusively
designed and adapted for use in connectin~ pipes and other
tubular structures for use in the drilling and/or
" 5 completion of off-shore oil and/or gas wells.
In oopending C ~ dian Application No, 294,837 filed Jan. 12,
1978, by ~ s~ applieant, ~re is descr~x~ a pipe oonnector ~ris-
ing a tubular pin m~ and a tubu~ bo~ m~ which are telescopicall~
engageable, the pin and box menlbers having corresponding
10 frusto-conical outer and inner peripheral surfaces which
overlie each other when the members are engaged. To
axially lock the pin and box members togethe~, the frusto-
conical surfaces have interengageable annular projections
and ~rooves. To engage the members together, the box
15 ~lember is ~orced over the pin member, the box member
expanding and/or the pin member contracting to enable the
projections to ride,into the groo~es. The pin and box
membcrs are, irA the preferred embodiment, made of metal
¦ and ensagement is facilitated by supplying liquid under
20 pressure between the frusto-conical surfaces to expand
the box member and/or contract the pin member. For the
liquid to be effective, seals have to be provided betwe~n
the overlapped parts of the f'rusto-conical
surfaces of the members and this is simply obtained by
25 arranging the frusto-conical surfaces so that metal-to-
metal contact is obtained sufficient to seal or at least
restrict the flow of the l,iquid between the over-
lapping parts of the surfaces.
In tne above referred to application, the
30 pl~ojections and srooves of the frusto-conical surfaces are
substantially equally axially spaced apart alons the a~ial
length of the frusto conical surfaces and of equal a~ial
extent. The members are dimensioned so that when the
n~ember~ are pllshed together each pro~jection comes into
35 n~etal-to-metal conk.-ct wit,ll tl~c part of the frll~to-conical
I
. . . . . .
,, ,
.: ; .
,., . .. ,,
-~
,. ~h~
_ _ _ _ _ __ _ __ _ ___ _ _ _ I
surface upstream of i.ts groove so th~t a seal i~ .initially
I provided by each projection and the projeetiorlllas merely
i ~ to slide over the upstream pa.r-t of the frus~o-conical
surface :into i.ts groove.
It has now been appreciated that it is
: unnecessary to provide this metal-to-metal contact betwe~n
all projec-t~.~ns and grooves, metal-to-metal se~ling
contact being Inerely required at eachi end of the surfaces~
As will become apparent, th;.s enables a substanti.al
lO reduetion in the axial length of the frus-to-conical
: surfaces and therefore of the pin and box members ~Yith a
. consequent substantial saving in material.
Aeeording to one aspeet o~ the present inventi.on
there is provided a pipe connector comprising a tubul.ar
15 pin member and a tubular box member teleseopieally en~rage-
~ able -with the pin member, the pin me1nber ha~ing a fr~lsto-
., eonieal outer peripheral surfaee and 1he box member having
t ¦ a eorresponding frusto-eonieal inner peripheral surface
. ~hich overlies the frusto~eonieal surface of the pin
20 n1ember when the members are engaged, the frusto-eonical
surfaces having a plurality of axially spaeed interengage-
able projections and grooves extend.ing eircumferentially
i thereof and interengageable to axially lock the pi.n and
box members together, wherein the projections and grooves
25 are dimr-~nsioned so that i.nitial metal-to-metal contaet
is made be-tween the crest surfaces of the end projections
` at each end of the one frusto-conical surfaee provided
i with the projeetions and the surfaees of the other
t frusto-eonical surface adjacent the end grooves, the
30 projeetions and grooves intermediate the end projeetions
f and groovos bein~ of lrsser axial dimensions and spacing
i ¦ than the end projections and grooves, and -the radial
dimensions of the projoetions and crrooves aro such th.~t
the expan.si.on of the box member ~Ind/or contrae-ti.on Or
135 the pin mcnlber rosultin$ frc)m fOl~citlg tho prO jOCtiOllS .~.~ltO
~`` I .
:
:- : "
: '
~, ,. . ,,, i -: , :, . ., , ~ ~;
; I the corrosponding grooves during engagement of the membcrs
, does not exceed the elastic limit of the material of
., tlle members.
¦ Advantageously thc root and crest surfaces of
¦ 5 the projections and grooves lie on f~usto-conical surfaces
¦ parallel to the frusto-conical surfaces of the pin and
~ox members. The projection may be provided on the pin
or the box member, with *he corresponding grooves being
provided on the other member. Preferably the projections
10 and grooves and surfaces therebetween are arranged so
~ that, considering one of the frusto-conical surfaces it
i can be said to ha~-e either projections or grooves~
The radially e~tending end surfaces ~t one end
of the projections and grooves can be arranged to transmit
15 forces of compression through the connector and are, for
this reason, arranged to extend radially or at a small
! ar.gle to the radial plane. The members may be arranged
so that these end surfaces of the projections and grooves
, are in positive abutment when the members are engaged.
i 20 For the input of liquid under pressure between
the surfaces of the members during enga$ement, a radial
inlet duct may be provided in the box member intermediate
the ends of the frusto-conical surface th~reof.
Further features and advantages of the present
¦ invention will become apparcnt from the following
30 description of embodiments thereof, given by way o~ example
only, with reference to the accompanying drawings, ln
which: ¦
Figure 1 is a diagrammatie sectionnl view
showirlg part of an emborlinlcnt of a conncctor according
35 to the invelltion;
i !
, ~ , 1
$~
~.
"
Fisure 2 is a par-t sectional, part side view of
¦ the box member o the connector of Flgure 1;
Figure 3 is an enlarsed view of part of one end
of the connector of l'igure 1 during enga~ement of the pin
5 and box membe~s; aI~d
Figure ~ is a view corresponding to that of
Figure 3 showing the pi~ and box members when engagedO
As shown in *he drawings, the pipe connector
comprises a tubular pin member l, for connection, e.g. by
10 ~elding, to the end of a pipe 2, and a tubular box member 3
for connection, e~g. by welding, to the end of a pipe 4
to be conn~cted to pipe 2. The pin and box members are
teloscopically engageable and have correspondins frusto-
conical outer and inner peripheral surfaces 5, 6
15 respectively which overlie one another when the pin member
1 is fully telescoped into the bo~ member 2.
To a~ially loc~ the pin member to the box member,
the bo~ member is provided with a plurality of
circumferentially e~tending annular grooves 7a, 7b .... 7J,
20 each groove extending in a radial plane and having radially
extending end surfaces o, 9 separated by root surface 10.
l The grooves are axially spaced apart by surfaces lla, llb
! ... lli forming the frusto~conical surface 6. The pin
, member has a plurality of axially spaced circurnferentially
1 25 extending annular projections 12a~ 12b ~.... 12j correspon-
ding to the grooves 7a .~.. 7~, each projection having
radiall~ extendin~ surfaces 13, 14 separated by crest
surface 15, the grooves being spaced by surfaces 16a, 16
... 16i formins the frusto conical surface 5.
~, 30 As shown, the root and crest sur-faces 10, 15 lie
on frusto-conical surfaces parallel to the surfaces 11, 16 1 -
so that all the ~rojections and the groGves are of equal
depth. The ~rojections and grooves rnay, .IA~ showrl, e~t~nd
over subst~ntially the entire extl?rlt of tlle s~lrfaces 5, 6
35 but m~y extend over a lesser part o:f tlle ~urfnce.
`` !
.~ . . , , ~ .
. .
.. ~ .
: The `box member i.s provided with a rad.ial
passage 17 communicating with an etx.ially extending recess
1.8 intersecti.ns some of the grooves centrally of the
grooved region. The passage is adapted for connection to
5 a source of liquid, e.g. oil, und~r pressure, eOg. at
about 175.7 to Zl~.9 Kg/m2 where the pin and bo~ members are
made of high tensile steel.
As shown, the connector is intended to transmit
compressive forces, eOg. pi.le driving forces, between the
10 pipes to which it is connected an.d to this end the surfaces
~, 13 at one end of each projection and groove are radially
extending, or ext~nd at a small angle to the radial plane.
Additionally the connector is arransed so that, when the
members are enga~ed, these surfaces 8, 13 are in abutment.
15 As shown this is obtairled by arranging the projections and
grooves so that a radial end surface 20 on the box member
coutes into abutment wi.th a corresponding radial surface 19
on the pin member to create a force fit between these
surface 19, 20 and the surfaces 8, 13. As shown, the
20 projections and grooves are dimonsioned so that there is
a slight radial clearance between the othor o~erlying
surfaces 15, 16, 10, 11 and radial and axial clearance
between surfaces 9, 14. In modifications, the radial
clearances between the surfaces I5, 16 and 10, 11 may be
25 omitted so that the pin mcmber is a force fit in the box
member.
The frusto conical surfaces 5, 6 and end srooves
. 7a, 7i and projections l~a, 12i are arranged and
dimensioned so that, when the pin and box members are
. 30 pushed together, initial mot.ll-to-metal contact i.s
obtained, as shown in Figure 3, between the crest surfaces
15 of the end projections 12a, 12~ of the pin me~nber and
the surfaces lla~ of the box mcmber ~djac~nt tho ond
grooves 7a, 7j Tho projoction.s and ~s~roo~os intermodi.ate
35 tltese end projoctions and ~roov~s necd n-Jt prov~de mctal-
, . ,
. . d
~__ __.. ... ___ _. __ __ __ _,.. _~.. _ __ .,_,, _, ".__ .. _ __ ~_ ~ ,_,, ,,,__,,_, , _ _,,__,_ ,_,_,_ .__,,_.. _,, .,___,_.~ ,. ~_,, .. _ _~.
_____, ._., _ . .. I
~ 6^
., ' I .
to-meta] conte~ct.
¦ The connector is assembled by tolescoping the
~ members tosether until metal-to-metal contact is obtained
; as shol~n in ~igure 3. At this point liquid under pressure
5 is supplied to the duct 17 and flows along recess 18
between the melllbers up to the regions of mctal to metal
l contact. The pressure oP the liquid is set at a level
I; sufficient to produce expansion o the box member and/or
contraction of the pin member sufficient to permit the
lO mombers to be pushed tosether on application of further
axial orce. It is found that in effect the liquid no~
only expands the box member and/or contracts the pin member
but also lubrioates the contacting surfaces of the members
which then form a hydrostatic bearing so that contact is
15 lost. While there is a consequent slight leakage o~ the
liquid at the ellds of overlap of the members, the leakage
is not sufficient to render the application of the liquid
ineffective. It will be appreciated that the frusto-conical
surfaces with their projections and grooves are arrcnged
20 so that, in expanding the box member andJor contracting
the pin member, the elastic limit of the material of
¦ the pin and box members is not exceeded~
When the members are assembled, it is essential
to ensure that no liquid is trapped in any of the groovesO
25 Should liquid be trapped, the corresponding projection
I will be unable to ensase fully in thc groove and there will
; therefore be a risk of the connector coming apart. To
avoid this possibility, the rocess 18 connected to the
liquid inlet duct 17 is extonded axially 50 that liquid
30 in the intermediate srooves can be drained through the
recess and duct 17. Any liquid in the end grooves can
¦ cscape round the end o the pin membor and box momber
¦ respectively.
¦ Seals 2l, 22 may be provided irl t~c ~urfacc of
¦35 the pin adjacetlt the ends tllc~oof, son;L Z2 is provLdcd
j
.: , ..
.. ..
-, . : : :: ; . : .:
. - :
-. .....
;:
- 7 -
primarily to render the interior of the eonneetor fluid
¦ tight. Seal 21 is provided in eonjunetion with seal 22
I to trap oil, not under pressure, between the surfaces to
reduce corrosion of the surfaces 5, 6. Under these eircum-
5 stanees the duet 17 is also closed.
As has been mentioned above, it has now been
appreciated that the intermediate projections and grooves
do not have to be arranged to provide initial metal-to metal
eontact between a crest o~ a projection and the surfaee up- ¦
10 stream of the corresponding groove. They ean therefore have
a lesser axial extent and spacing than the end projections
and grooves. In the embodiment described above, the mini-
mum a~ial extent and spacing of the projection~ and grooves
must merely be such that there is sufficient metal behind
15 each of the force transmitting surfaces 8, 13 that the sur-
faees ean withstand the force to be applied thereto. It is
found that this requirement produces intermediate protection
and grooves which have substantially smaller a~ial extent
of spacing so that the overall length of the frusto-conical ¦
¦20 surfaces can be substantially reduced with a substantial
¦ reduciion in the material in the pin and box member~ and
therefore a substantial cost saving. As shown, the inter-
mediate projections and grooves have approximately half the ~
axial extent and spacing o~ the end prsjections and srooves ¦
~5 whieh produees a conneetor which is less than half the
length of connectors in accordance with ~dianappliea~on No.
294,837, when eonsidering eonnectors for transmitting the
same axial force and therefore requiring the same nwnber of
foree transmitting surfaces 8, 13 of the same radial extent
As a consequence o~ this reduetion in axial extentl
of the intermediate projections and grooves, during assembly,
of the members and after initial metal-to-metal eontact
has been made, an intormedia-te projection may, ag shown, have~
to be moved past one or more groove~ upstream of it.q
; 35 eorresponding groove. rO assi~t movemerlt of a projeetion
! _.~,
. ~
,, . - 8 -
'.`'
out of the groove and onto the downstream surface
separating the grooves, the end surfaces 14 of the grooves
l, and the correspondin~ end surfaces 9 of the projections are
.~ inclined At a relatively small angle to the axis.
- l.`. 5 In a pre~erred embodiment, the pin and box members are
~¦ made of high tensile steel and have external and internal
diameters of approximately 71cm. The conicity of the
, 9` W ~ ',e~
.
.
`
.. . .
, ,.` .. . ,`.. . .
,~ .
. . ~ ,.. ~ .............. . .. .
. . .,~.
~:
:
roots and cr~sts of the groo~es and projections is 2.
¦ Each projection has a height of 0.122cm and each groove
has a depth of 0.112cm. The end grooves have a length
at the surface of 2.133 cm and the end projections have a
5 length at theïr base of 2.032cm. The surfaces upstream
of the end projections and grooves are correspondingly
dimensioned. The intermediate grooves and projections
may have, for example, half the dimensions of the end
grooves and pro~jection so that the overall length of the
10 frusto conical surfaces of the members is 12.70cm with an
overall connector length of 24.13cm. This compares with
a corresponding connector as described in C~dian Appln. No. I
294,837 which ~ould have a frusto conical surface length
of about 42cm and an overall length of-about 53cm.
The rorce transmitting surfaces 8, 13 of the
projections and groo~es preferably are inclined at 12
to the radial plane and the other end faces 9, l4 may be
inclined at an angle of 75 to the ra~ial plane.
It will ~e appreciated that by using a different
20 angle for the conicity of the frusto conical surfaces of
f~ the members and different materials for the members, the
foregoing dimensions and numbers of the projections and
grooves may be varied.
It will also be appreciated tha-t, while *he
25 above described connector has been described in terms o~
projections pro~ided on the pin member and grooves provided
in the box member, this is exactly equivalent to the
provision of grooves in the pin member and projections in
the bo~ member. Indeed, while the surfaces 131 14 and 15
30 have been described as defining a projection on the pin
member, the surfaces 13, 14 and 16 could equally be
described as providing a groo~e on the pin member with the
corresponding surfaces on the box member providins a
projection~ I
There is thu~ providod a pipo connoctor which
.
~ .
'` ~ ~ ' ' i ' "
:
6~
has a simple construction, is easy to assemble and does
¦ not rcly on moving par-ts to ensure intereng~gcment between
I the pin and box members.
It will be appreciated that many different
5 devices may be provided to apply the axial force to the
members to bring them into metal-to met~l contact and
during application of liquid under pressure between -the
frusto-conical surfaces. One such device is described
in the said C~an Appln. No. 294,837 and comprises two
10 plates which are split diametrically and arranged to be
engaged around a respective one of the members, for
example in abutment with surfaces 23, 24. A plurality
of hydraulic jacks are arranged to act between the plates,
the jacks being angularly spaced apart around the~ axis
15 of the members.
Should the above described connector be required
to transmit torque, as well as compressive forces, an
inwardly projecting pin may be provided at the inner end
of the frusto conical surface of the bGx member for
20 engagement in a recess provided in the leading edge of
,/ tne pin member.
- ~ :
