FIELD OF THE INVENTION
The present invention relates to a device which
5 makes it possible to close a pipework, a tank or a set
of tank(s) and pipe(s) in order to be able to isolate
them, especially with a view to maintenance, test or
hydraulic pressure testing operations.
10 PRIOR ART
Numerous industrial installations comprise
enclosures (reservoirs, tanks, exchangers, etc.)
coupled to pipes (pipework) for the passage of fluids,
liquid or gaseous, often under pressure. In order to
15 guarantee a reliable and secure operation of these
installations, the maintenance of such systems requires
regularly carrying out leak tightness tests and the
regulations for pressurised devices moreover impose
carrying out hydraulic pressure testing periodically.
20 For carrying out leak tightness tests or hydraulic
pressure testing of reservoirs, tanks, or any other
type of enclosure, it is at present necessary to modify
the configuration of the installation to create a test
or testing “bubble”, that is to say the creation of a
25 confined space enabling the pressurisation of the
enclosure with a view to its technical evaluation,
especially in terms of leak tightness.
For the creation of this confined space, it is
thus necessary to be able to seal each of the
30 inlets/outlets of the tank, especially when they are
2
coupled to a pipe, in order to isolate the internal
volume of the tank.
To do so, it is possible to use the plumbing
fixtures associated with the tank at the level of
5 inlets/outlets. Nevertheless, plumbing fixtures at the
level of each pipe do not in general exist. Moreover,
it is in general necessary to check and assure the
correct operation of each plumbing fixture before any
test or hydraulic pressure testing, and to guarantee
10 its leak tightness. Finally, the plumbing technologies
generally employed on tanks are often not suited to
obtain the perfect leak tightness required for a test
or for hydraulic pressure testing, and the plumbing
fixtures are not systematically dimensioned to
15 withstand pressurisation during tests or hydraulic
pressure testing.
When one of the pipes is not provided with such a
plumbing fixture, or when said fixture is not suited
for the stresses of tests or hydraulic testings, a
20 solution consists in using a plug suited for the
isolation of the tank. Nevertheless, in industries
using so-called hazardous fluids (toxic, inflammable,
explosive, etc.) or hot fluids (for example steam), the
enclosures and pipeworks are not equipped with clamps
25 which would have made it possible, after dismantling,
to install bolted shutters (blind holes, blind clamps),
enabling sealing. Thus, it is generally necessary to
cut the pipe and to weld a closing means at the level
of the cut section of the pipe.
30 Unfortunately, such a technique of sealing pipes
has a large number of drawbacks. Firstly, such a
3
solution implies a complex implementation, generating
an intervention of long duration, requiring specific
rare human resources (welders, controllers, etc.) and
considerable needs in material logistics (gantries,
5 scaffolding, airlock, de-lagging, etc.). The
intervention also comprises risks of important
implementation variables (defects, faults, etc.).
Finally, the implementation of this solution on certain
installations (especially those subjected to particular
10 regulations), requires establishing specific regulatory
files and carrying out specific controls, such as for
example radiographic controls. These controls have, for
their part, not insignificant risks from a radiation
protection viewpoint and prohibit any concurrent
15 activities.
A solution for avoiding these drawbacks linked to
the use of welded plugs consists in using existing
closing devices and in positioning them in the pipe to
seal it. The international application published on the
20 20 January 2000 under the reference WO 00/03172
describes a certain number of embodiments of clamp
plugs intended to be positioned at the end of the pipe.
Such plugs are robust and make it possible to withstand
high pressures but their handling remains very complex,
25 especially when the pipes to seal and isolate have
large diameters. In the case where the diameter of the
pipework to seal is greater than the diameter of the
manhole of the enclosure where the pipework is
connected, it is necessary to cut the pipework to
30 introduce the plug. Moreover, the intrinsic leak
tightness of such plugs cannot be checked or controlled
4
during leak tightness tests of the duct, which can
falsify the results of the test as the case may be. The
important risk of damaging the pipework due to the
system of prongs should also be noted.
5 A plug solution has also been proposed in the US
patent application published on the 27 April 2006 under
the reference US 2006/0086400. Such a closing device
makes it possible to seal and isolate a pipe to carry
out leak tightness tests and the specific configuration
10 of the plug further makes it possible to control the
intrinsic leak tightness of the plug. Nevertheless, the
solution proposed is not suitable for large pipe
diameters, and cannot withstand the high pressures of
leak tightness tests or hydraulic pressure testing. The
15 structure of such a plug is moreover complex and
massive, making its putting in place and implementation
more difficult.
Moreover, all existing sealing solutions have the
drawback of requiring cutting the pipe which has to be
20 sealed to isolate the tank and thereby form the
confined space necessary for the test.
An aim of the present invention is thus to propose
a pipe closing device which makes it possible to
resolve at least one of the aforementioned drawbacks.
25 In particular, an aim of the present invention is
to propose a closing device which may be put in place
in a pipe of an enclosure, such as a tank, without
having to cut said pipe. The closing device has a final
diameter after mounting greater than the diameter of
30 the orifice of the tank through which it will have been
introduced.
5
Another aim of the present invention is to propose
a closing device which is simple to put in place, not
requiring specific human skills and different to normal
maintenance operations.
5 A further aim of the present invention is to
propose a closing device being able to be arranged in
pipes having a large diameter (typically greater than
1000 mm) and to be able to position the plug in any
straight section of the pipework, and which is moreover
10 suited to withstand the stresses imposed by tests or
hydraulic pressure testing, especially in terms of
pressure.
Yet another aim of the invention is to propose a
closing device which is simple to put in place in the
15 pipes, and for which the holding in the pipe is simple,
efficient, and which can be carried out in any portion
of the pipe. The closing device is sufficiently robust
and maintained in position to enable pipe tests at high
pressure.
20
DESCRIPTION OF THE INVENTION
To this end, a closing device is proposed for
sealing and isolating a pipe having an inner wall
forming a substantially cylindrical cavity with a so25
called first diameter, the closing device comprising:
- a main body having substantially the shape of a
cylinder with a so-called second diameter, the
second diameter being smaller than the first
diameter to allow the closing device to be
30 inserted into the cavity; and
6
- sealing joint elements that project around the
side wall of the cylinder defining the shape of
the main body, so as to close a free space formed
between the main body and the inner wall of the
5 pipe,
characterised in that the main body comprises several
assembly elements capable of being assembled together
to form the cylinder defining the shape of the main
body, each assembly element having a shape inscribed
10 within a parallelepiped volume defined by three
orthogonal dimensions, in which at least two of the
three dimensions have a length smaller than the second
diameter.
The fact of having assembly elements having at
15 least two dimensions of a length smaller than the
diameter of the main cylindrical body enables the
handling of these assembly parts through orifices which
have smaller dimensions than the diameter of the main
body, and thus smaller than the diameter of the pipe.
20 According to a preferred aspect, the device
further comprises a position holding system comprising
a plurality of non-slip pads translationally mounted in
certain of the assembly elements to be deployed against
the inner wall of the pipe in order to assure a holding
25 of the closing device by compression, the set of nonslip
pads forming an overall contact surface extending
over at least half of the periphery of the section of
the cylinder defining the shape of the main body.
The layout and the configuration of the non-slip
30 pads guarantee a holding of the plug without requiring
a complementary holding contrivance, which is
7
particularly advantageous since this makes it possible
to position the plug in any portion of pipe and not
uniquely at its end.
5 Preferred but non-limiting aspects of this closing
device, taken alone or in combination, are the
following:
- the position holding system comprises force
measurement elements provided to measure the force
10 applied by the non-slip pads on the inner wall of
the pipe.
- each non-slip pad is mounted on a compression
system, such as a system of jacks or a screwsjacks
system, comprising a blocking system
15 preventing a translation of the non-slip pad after
deployment of the non-slip pad on the inner wall
of the pipe.
- the device further comprises an anti-extrusion
system provided to prevent a translation of the
20 closing device in the pipe in the event of failure
of the position holding system, said antiextrusion
system comprising blocking elements
arranged to be activated during a translation
movement of the closing device in the pipe.
25 - each blocking element of the anti-extrusion system
is a roller mounted eccentrically with respect to
a non-slip pad of the holding system, and having a
contact surface intended to be in contact with the
inner wall of the pipe.
30 - the set of non-slip pads forms an overall contact
surface extending over the totality of the
8
periphery of the section of the cylinder defining
the shape of the main body.
- the at least two dimensions among the three have a
length smaller than or equal to half of the second
5 diameter, preferably smaller than or equal to one
third of the second diameter.
- the main body is segmented along chords of the
circular section of the cylinder, several of the
assembly elements forming circular segments of the
10 cylinder.
- which main body is segmented along radiuses of the
circular section of the cylinder, several of the
assembly elements forming circular sectors of the
cylinder.
15 - the main body is moreover segmented along the
section of the cylinder so as to form several
elementary cylinders the assembly of which forms
the cylinder of the main body.
- the main body comprises intrinsic sealing joints,
20 each intrinsic sealing joint being arranged
between two adjacent elementary cylinders.
- the main body is segmented into at least three
elementary cylinders, each elementary cylinder
being segmented into at least three assembly
25 elements.
- the different non-slip pads of the holding system
are mounted in assembly elements forming one of
the elementary cylinders.
- the sealing joint elements comprise at least two
30 inflatable sealing joints intended to be
9
positioned around the cylinder forming the main
body.
- the device further comprises an instrumentation
system provided to command and control the
5 pressure in the inflatable sealing joints and in
each inter-joint space formed between two adjacent
inflatable sealing joints and the walls of the
main body and the duct.
- each assembly element has a honeycomb structure.
10
According to a particular aspect, this closing
device is used in a tank having a manhole for handling
assembly elements, the manhole having a diameter
comprised between 400 mm and 600 mm, with a view to
15 sealing a pipe having a diameter comprised between 1000
mm and 2000 mm.
DESCRIPTION OF THE FIGURES
Other characteristics and advantages of the
20 invention will become clearer from the description that
follows, which is purely illustrative and non-limiting
and should be read with regard to the appended
drawings, in which:
- figure 1 is a schematic view of a tank comprising
25 several pipes provided with different types of
plugs;
- figure 2 is a schematic representation of the
structure of the main body of the plug according
to an embodiment of the invention;
10
- figure 3 is a sectional view of the plug according
to a first embodiment of the invention placed
inside a pipe to be sealed;
- figure 4 is a schematic view of a tank comprising
5 the plug according to the invention with an
instrumentation system;
- figure 5 is a sectional view of the plug according
to a second embodiment of the invention placed
inside a pipe to be sealed;
10 - figure 6 is a view of the plug of figure 5 along
the plane A-A, representing the position holding
device;
- figure 7 is a perspective view of the plug of
figure 5;
15 - figure 8 is a schematic representation, side view,
of the anti-extrusion system of the plug according
to the invention;
- figure 9 is a schematic representation, frontal
view, of the anti-extrusion system of figure 8.
20
DETAILED DESCRIPTION OF THE INVENTION
In figure 1 is illustrated an enclosure such as a
tank 1 which could be used in any type of industrial
installation, such as for example inside a nuclear
25 power plant, in order to channel and store a fluid, in
liquid or gaseous form. This tank 1 comprises several
inlets/outlets, generally connected to pipes enabling
the circulation of the fluid to or from said tank 1.
The tanks may have highly varied dimensions and
30 associated volume, but they have in general an internal
volume comprised between 2 and 800 m3, being able in
11
this latter case to have a length of the order of 30 m
for a diameter of 6 m.
Figure 1 further illustrates different solutions
for closing said inlets/outlets, and especially
5 highlights the existing solutions of the prior art
described above.
Thus, the tank 1 comprises a pipe 2 having a
mounting clamp on which it is possible to fix a blind
hole 3 making it possible to seal said pipe 2.
10 Also represented are two pipes 4 provided with
valves 5, permanently present, especially for the
regulation of the flow of fluid, and which may thus be
used to close these pipes 4 and isolate the internal
volume of the tank 1.
15 The pipe 6 is in one piece with the tank 1 and
thus cannot be isolated by a valve or by a blind hole
without having to section this pipe 6. It is thus
necessary to position a specific plug inside the pipe 6
to be able to seal and thus isolate the inner volume of
20 the tank 1. A pipe is in particular qualified as “in
one piece” when it has been welded to an inlet/outlet
of the tank 1 with the appropriate controls.
The tank 1 furthermore comprises a manhole 7, that
is to say an opening, generally circular, the
25 dimensions of which enable someone to enter inside the
tank 1. Such a manhole 7 may have a nominal diameter
comprised between 400 mm and 600 mm, preferably of the
order of 500 mm.
If the pipe 6 has an internal diameter smaller
30 than the diameter of the manhole 7, it is possible to
make a plug 8 suited to the diameter of the pipe 6
12
penetrate into the cavity inside the tank 1 through the
manhole 7 which is sufficiently large. It is advisable
nevertheless that this plug 8 is suited to the physical
stresses, especially in terms of pressure, imposed by
5 the tests or hydraulic pressure testing to be carried
out on the tank 1. It is clearly obvious that this
sealing route is not possible with known plugs when the
diameter of the pipe 9 is greater than the diameter of
the manhole 7. The pipes can in fact have a diameter
10 greater than 700 mm, for example comprised between
1000 mm and 2000 mm, for example of the order of
1400 mm to 1500 mm.
A multi-element closing device 10, which can be
dismantled, is proposed here, each assembly element
15 making it up having dimensions enabling it to be
introduced inside the tank 1 through the manhole 7, and
the closing device 10 having – when all the assembly
elements are mounted together – dimensions
substantially equal to the internal dimensions of the
20 pipe 9.
Thus, the multi-element closing device 10 is a
plug designed to be firstly introduced into the tank 1
or any other type of enclosure, and then to be
assembled in or around the pipework 9 to seal.
25 To do so, the plug 10 comprises a plurality of
assembly elements which, once assembled together, form
a main body 110 having substantially the shape of a
cylinder with a diameter smaller than the diameter of
the pipe 9 to allow the closing device to be inserted
30 into the cavity of the pipe 9. Moreover, sealing joint
elements 120 project around the side wall of the main
13
body 110, so as to seal the free space formed between
the main body 110 and the inner wall of the pipe 9.
In order to be able to introduce the plug 10 into
the tank 1, it is necessary that the assembly elements
5 have at least two dimensions of which the length is
smaller than the diameter of the manhole 7. Since the
pipe diameters of the tank 1 are able to be up to two
to three times greater than that of the manhole 7, the
two dimensions of the assembly elements may have a
10 length smaller than or equal to half of the diameter of
the pipe 9, preferably smaller than or equal to one
third of this diameter.
The segmentation of the main body 110 of the plug
10 is optimised to form easy to handle assembly
15 elements, and enabling a simple mounting of the plug
from the inside of the tank 1.
Preferably, the main body 110 is segmented along
chords of the circular section of the cylinder,
parallel to one of the diameters of the circle or going
20 through the centre (the chord in question then
corresponds to a diameter).
When the main body 110 is segmented along chords
parallel to one of the diameters of the circle, several
of the assembly elements form circular segments of the
25 cylinder.
When the main body 110 is segmented along
diameters or radiuses of the circle, several of the
assembly elements form circular sectors of the
cylinder.
30 When the cylinder forming the main body 110 is
long, especially when its length is greater than the
14
diameter of the manhole 7, the main body 110 may also
be segmented along the section of the cylinder so as to
form several elementary cylinders the assembly of which
forms the cylinder of the main body.
5 Figure 2 illustrates a preferred segmentation for
the main body 110 of the plug 10. According to this
embodiment, the plug 10 is segmented into three
elementary cylinders (111;112;113), each elementary
cylinder (111;112;113) being segmented into three
10 assembly elements (1111,1112,1113; 1121,1122,1123;
1131,1132,1133).
According to the embodiment illustrated in figure
2, it may be noted that each elementary cylinder
(111;112;113) is segmented along two chords, breaking
15 down the assembly elements into two circular segments
(1111,1113; 1121,1123; 1131,1133) and a central segment
(1112;1122;1132) along a diameter of the cylinder.
Another possible segmentation is illustrated in
figure 7, where the plug 10 is segmented into several
20 elementary cylinders, each elementary cylinder being
segmented along radiuses, into assembly elements being
circular sectors. In the particular example illustrated
in this figure, the plug 10 comprises two elementary
cylinders (311;313), each elementary cylinder being
25 formed of ten assembly elements in the form of circular
sectors (3110;3130).
Each assembly element making up the structure of
the main body is designed so as to obtain the best
mass/resistance compromise. It is possible for example
30 to opt for a honeycomb structure. The material used is
also chosen in order to optimise this compromise, and
15
for example the assembly elements could be manufactured
from metal (stainless steel or titanium for example) or
made of composite materials. Preferably, the weight of
each part forming the plug is limited to 25 kg to
5 facilitate its manual handling.
Moreover, the plug 10 may comprise intrinsic
sealing joints 130, each intrinsic sealing joint 130
being arranged between two adjacent elementary
cylinders to assure the overall leak tightness of the
10 main body 110. Such intrinsic sealing joints 130 may
for example be disc and/or torus shaped, made of a leak
tight material such as for example neoprene.
Moreover, the sealing joint elements 120 of the
plug 10 comprise preferably at least two inflatable
15 sealing joints 120, for example O-rings or lip seals,
intended to be positioned around the cylinder forming
the main body 110.
These inflatable sealing joints 120 make it
possible not only to assure the total leak tightness of
20 the plug 10, but also to compensate geometric or
surface defects of the inner wall of the pipe.
Such inflatable sealing joints 120 may be
positioned for example in annular grooves formed by the
assembly of the assembly elements. An annular groove on
25 one or more elementary cylinders may in this respect be
provided. It may also be provided that the annular
groove is formed by the assembly of two adjacent
elementary cylinders. In this latter case, the
inflatable sealing joint 120 moreover has the advantage
30 of contributing to the intrinsic leak tightness of the
16
plug 10 since it reinforces the leak tightness between
two adjacent elementary cylinders.
Moreover, the layout with at least two inflatable
sealing joints 120 makes it possible to create a space
5 – called inter-joint space – formed by two adjacent
inflatable sealing joints and the walls of the main
body and the duct. By pressurising this inter-joint
space, it is possible to check the intrinsic leak
tightness of the plug 10 and to guarantee the
10 successful conduct of the test of the tank 1. In this
respect, it is possible for example to provide a
pressure sensor arranged to measure the pressure within
this inter-joint space.
This layout thus makes it possible to check the
15 intrinsic leak tightness of the plug 10 when it has
been positioned in the pipe 9. Moreover, with a
specific monitoring system, it is possible to check the
leak tightness of the plug also during the test, once
the confined space is under pressure. Thus, in the
20 event of a leak during the filling or the testing of
the tank 1, it is possible to check whether it stems in
all or part from the plug, and feeding back the
measured leak by monitoring the pressure at the level
of the inter-joint space in the results of the tank
25 test.
Generally speaking, there exists a connection
point between the inlet/outlet of the tank 1 and the
associated pipe 9, such as for example a weld 11 as
illustrated in figure 3. Preferably, the plug 10 is
30 placed upstream of the weld 11, to avoid having to test
it with a view to testing of the tank 1. In the case
17
where the length of the inlet/outlet pipe of the tank 1
is not long enough to receive the plug, it may be
advantageous to position the inter-joint space of the
plug 10 opposite the connection point 11, so as to be
5 able to pressurise the weld via the inter-joint control
line.
For the initial and/or continuous control of the
leak tightness of the plug 10, a console 20 may be
provided installed outside of the confined test or
10 testing space, as illustrated in figure 4. This control
console comprises instrumentation lines (201;202;203)
connected to the inflatable sealing joints 120 and to
the inter-joint space to command and control the
corresponding pressure. These instrumentation lines
15 (201;202;203) may for example pass through the
honeycombs formed in the assembly elements, and come
out of the tank 1 at the level of the manhole 7 to be
connected to the control console 20. The passage at the
level of the manhole may be achieved thanks to a test
20 cover 204 making it possible to seal the manhole while
enabling the passage of instrumentation lines.
The multi-element closing device 10 further
comprises non-slip pads which make it possible to block
the plug in the pipe 9, thus enabling its installation
25 in any straight part of a section of pipework connected
to the volume to test. In fact, each non-slip pad is
mounted on the main body 110 so as to be able to be
forced against one of the inner walls of the pipe 9.
The pads are preferably designed with a material of a
30 hardness smaller than that of the material of the
pipework in order not to mark the latter. For example
18
it may be possible to choose non-slip pads made of
neoprene, or even made of metal of lower hardness.
Each non-slip pad may further be coupled to a
force measuring system, for example of force sensor or
5 load pin type, so as to control with precision the
stress applied by the non-slip pad on the inner wall of
the pipe 9. This control makes it possible both to
guarantee that the force is sufficient to maintain the
plug in place in the pipe, but also to ensure that the
10 stress applied by the non-slip pad on the pipe 9 is not
going to deteriorate it.
The contact surface between the non-slip pad and
the inner wall of the pipe is preferably quite
significant, in order to maximise the holding of the
15 plug 10 in the pipe 9. Preferably, the set of non-slip
pads forms an overall contact surface extending over at
least half of the periphery of the section of the
cylinder 110 defining the shape of the main body, and
which corresponds substantially to the periphery of the
20 cylinder section of the inner wall of the pipe 9.
Also in a preferred manner, the overall contact
surface of the non-slip pads extends over at least 70%,
or at least 80%, or at least 90% of the periphery of
the section of the cylinder 110 defining the shape of
25 the main body.
According to yet another preferred embodiment, the
overall contact surface of the non-slip pads extends
over the totality of the periphery of the section of
the cylinder 110 defining the shape of the main body.
30 The pads are preferably interchangeable.
19
Preferably, the forces on the pads 140 are applied
by compression means, such as a system of jacks or a
screws-jacks system 141, which make it possible to
force the pads 140 against the inner walls of the pipe
5 9, or to move them away when the plug 10 has to be
removed.
Also preferably, these pads 140 are integral with
the jacks or screws-jacks 141 by means of a “ball and
socket” type connection in order to be able to exert
10 either a compressive stress, or a tensile stress.
In the embodiment illustrated in figure 3, the
non-slip pads 140 are each mounted on a screws-jack
system 141. They enable an overall holding of the plug
in the pipe.
15 Tie-rods 150 may complete the retaining of the
plug 10 if this proves to be necessary. These tie-rods
150 are themselves connected to a system of support
flange(s) 151 provided with adjustable support pads
152, preferably non-slip. The plug is nevertheless
20 designed to counter the forces due to pressure without
the use of tie-rods. The adherence of the non-slip pads
and the forces that are applied thereto are sufficient.
A centring rod 142 also provided with non-slip
pads 143 at its ends may also be provided, this
25 centring rod 142 facilitating the installation of the
first assembly elements in the pipe.
In the embodiment illustrated in figures 5 and 6,
the non-slip pads 340 are each mounted on a jack system
341.
30 Each non-slip pad 340 is moreover coupled to a
force sensor 342 which makes it possible to control
20
with precision the deployment and the stressing of the
non-slip pad 340 in the pipe 9.
The compression means and the force measurement
means, being respectively a jack 340 and a force sensor
5 342 in the example of figures 5 and 6, may moreover be
coupled to the control console by dedicated
instrumentation lines (211;212).
The jack 341 used may further integrate a blocking
system preventing, once the pad 340 has been deployed
10 against the inner wall of the pipe 9, a translation of
said non-slip pad 340 towards a retraction (that is to
say in the opposite sense of the deployment). Such a
blocking system is especially provided to avoid any
release of the stress in the event of pressure loss in
15 the jack 341.
In the embodiment illustrated in figures 5 and 6,
the position holding system comprises several non-slip
pads 340 which are arranged so that their contact
surface extends substantially over the totality of the
20 periphery of the section of the cylinder defining the
plug.
In the example illustrated in figure 6, there are
eight non-slip pads 340, of which the surface of each
pad extends over around 45°.
25 Each non-slip pad 340 with its deployment system
integrating especially a jack 341 and a force sensor
342, form an assembly element 3130 of circular sector
type. Once assembled through the intermediary of a
central axis 150, these assembly elements 3130
30 integrating the non-slip pads 340 form an elementary
cylinder 313 of the closing device.
21
The closing device furthermore comprises at least
one other elementary cylinder 311 integrating the
sealing joints 120. As illustrated in figure 7, the
elementary cylinder 311 may be formed of a plurality of
5 circular sectors 3110, which may for example be
honeycomb structures.
The example of figure 5 highlights a structure
with three elementary cylinders (311;312;313), the
sealing joints 120 being arranged between the different
10 elementary cylinders.
As indicated above, the specific layout of the
non-slip pads 340 makes it possible to assure a holding
of the plug in the pipe 9, without the aid of a
complementary holding. This is particularly
15 advantageous since it makes it possible to position the
plug at any position inside a straight portion of pipe,
and not uniquely at the end of the pipe as is generally
the case in plugs of the prior art where a flange
positioned outside of the pipe is necessary to assure
20 the holding in position.
According to a preferred embodiment, the plug may
further comprise an anti-extrusion system provided to
prevent a translation of the closing device in the pipe
in the event of failure of the position holding system,
25 in particular if the one or more of the non-slip pads
340 are no longer forced against the inner wall of the
pipe 9.
More precisely, the anti-extrusion system
comprises blocking elements which are provided to be
30 activated as soon as the plug has a slight translation
22
movement in the pipe 9, which could happen if the
holding system with the non-slip pads 340 is faulty.
For example, as illustrated in figures 8 and 9,
each blocking element of the anti-extrusion system may
5 comprise a roller 400 mounted eccentrically 410 with
respect to a non-slip pad 340 of the holding system.
This roller 400 is arranged to have a contact surface
intended to be in contact with the inner wall of the
pipe 9.
10 Thus, if the plug were to be translationally moved
in the pipe, for example in the event of failure of the
system of holding by non-slip pads and in the event of
excess pressure, the mounting of the roller 400
eccentrically 410 implies that the roller is going to
15 turn until it applies a stress against the inner wall
of the pipe 9 stopping the translation of the plug.
Such an anti-extrusion system may be used with a
multi-element plug as presented above, but also with
any other type of plug comprising a similar position
20 holding system, based for example on the use of nonslip
pads forced against the inner wall of the pipe.
In this respect, a closing device could thus be
provided intended to seal and isolate a pipe 9 having
an inner wall forming a substantially cylindrical
25 cavity with a so-called first diameter, the closing
device comprising:
- a main body 110 having substantially the shape of
a cylinder with a so-called second diameter, the
second diameter being smaller than the first
30 diameter to allow the closing device to be
inserted into the cavity; and
23
- sealing joint elements 120 that project around the
side wall of the cylinder 110 defining the shape
of the main body, so as to close a free space
formed between the main body 110 and the inner
5 wall of the pipe 9,
- a position holding system, which may for example
comprise a plurality of non-slip pads (140; 340)
translationally mounted in the main body to be
deployed against the inner wall of the pipe 9 in
10 order to assure a holding of the closing device
by compression, the set of non-slip pads forming
preferably an overall contact surface extending
over at least half of the periphery of the section
of the cylinder 110 defining the shape of the main
15 body, and
- an anti-extrusion system as presented above,
provided to prevent a translation of the closing
device in the pipe 9 in the event of failure of
the position holding system, said anti-extrusion
20 system comprising preferably blocking elements 400
arranged to be activated during a translation
movement of the closing device in the pipe 9.
The mounting of the plug 10 in the tank 1 takes
25 place according to the following general steps:
1. Opening of the tank 1;
2. Introduction in the tank 1 of the different
parts which make up the multi-element plug 10;
through the manhole 7;
30 3. Assembly of the multi-element plug 10;
24
4. Putting in place the instrumentation
system between the plug 10 and the manhole 7;
5. Pressurising the multi-element plug 10;
6. Filling the tank 1, pressurising the confined
5 space, testing the tank 1, emptying the tank 1;
7. Depressurisation of the multi-element plug
10;
8. Removal of the instrumentation system;
9. Dismantling of the multi-element plug 10;
10 10. Evacuation of the different parts that make
up the multi-element plug 10, through the manhole
7;
11. Closing the tank 1.
15 Step n°3 of assembling the multi-element plug 10
is detailed below for the case where the multi-element
plug 10 is assembled directly in the pipe, which
greatly facilitates its implementation, especially when
the parts are heavy and when the diameter of the pipe
20 is large.
The assembly steps for a plug as illustrated in
figures 2 and 3 may be the following:
3-1. Assembling the centring rod 142 on the
assembly element 1112;
25 3-2. Positioning the assembly element
1112 perpendicularly to the axis of the pipework
9, in the vertical sense and taking care to centre
it correctly by spreading out the clearances
between the pipework and the structure of the two
30 parts. The spreading out of the clearances and the
25
blocking takes place preferably by means of
screws-jack;
3-3. Assembling the assembly element 1111 on the
assembly element 1112 (for example with a screw in
5 the honeycomb structure);
3-4. Assembling the assembly element 1113 on the
assembly element 1112 (for example with a screw in
the honeycomb structure);
3-5. Applying the necessary effort on the non-slip
10 pads 140 while ensuring the clearances are
uniformly spread out between the parts and the
pipework 9 and checking the force measurements;
3-6. Positioning a first inter-disc sealing joint
130;
15 3-7. Positioning a first inflatable sealing joint
120;
3-8. Assembling the assembly element 1121 on the
elementary cylinder 111 formed by the assembly
elements (1111,1112,1113) (for example with a
20 screw in the honeycomb structure);
3-9. Assembling the assembly element 1122 on the
assembly elements 1121, 1111, 1112, 1113 (for
example with a screw in the honeycomb structure);
3-10. Assembling the assembly element 1123 on the
25 assembly elements 1121, 1122, 1111, 1112, 1113
(for example with a screw in the honeycomb
structure);
3-11. Pressurising the non-slip pads 140
against the walls while ensuring the clearances
30 between the parts and the pipework 9 are uniformly
spread out;
26
3-12. Positioning the second inter-disc sealing
joint 130;
3-13. Positioning the second inflatable sealing
joint 120;
5 3-14. Assembling the assembly element 1131 on the
elementary cylinder 112 formed by the assembly
elements (1121,1122,1123) (for example with a
screw in the honeycomb structure);
3-15. Assembling the assembly element 1132 on the
10 assembly elements 1131, 1121, 1122, 1123 (for
example with a screw in the honeycomb structure);
3-16. Assembling the assembly element 1133 on the
assembly elements 1131, 1132, 1121, 1122, 1123
(for example with a screw in the honeycomb
15 structure);
3-17. Applying the necessary force on the non-slip
pads 140 while ensuring the clearances between the
parts and the pipework 9 are uniformly spread out
and checking the force measurements;
20 3-18. Inserting the tie-rods 150 carefully through
the assembly elements forming the elementary
cylinders 112 and 113, and screwing them into the
assembly elements forming the elementary cylinder
111;
25 3-19. Assembling if necessary the supporting
flange system 151 and positioning the support
flange 151 by means of contact pads 152 on the
inlet of the tapping of the tank 1;
3-20. Screwing down the nuts onto the tie-rods 150
30 in order to block the support flange 151.
27
The assembly steps for a plug as illustrated in
figures 5, 6 and 7 may be the following:
3-1. Positioning the first non-slip pads 340
provided with force measurement sensors 342 and
5 anti-expulsion elements 400;
3-2. Positioning the first jacks / screws-jacks
341;
3-3. Positioning the central axis 150;
3-4. Positioning the final pads 340 provided with
10 force measurement sensors 342 and jacks / screwsjacks
341;
3-5. Pressurising the jacks 341 while controlling
the forces by means of sensors 342;
3-6. Positioning the first sectorial honeycomb
15 elements of one of the elementary cylinders 313;
3-7. Positioning a first inflatable sealing joint
120;
3-8. Positioning the second sectorial honeycomb
elements of another of the elementary cylinders
20 312;
3-9. Positioning the second inflatable sealing
joint 120;
3-10. Positioning the last sectorial honeycomb
elements of the last of the elementary cylinders
25 311.
Step n°5 of pressurising the multi-element plug
10 may be broken down as follows:
5-1. Pressurising the first inflatable sealing
30 joint 120;
28
5-2. Pressurising the second inflatable sealing
joint 120;
5-3. Pressurising the inter-joint space;
5-4. Checking the stability of the three
5 pressures, in order to check the intrinsic leak
tightness of the plug 10.
As can be seen from the above, the multi-element
plug 10 proposed is particularly advantageous, in the
10 first instance since it enables the sealing of any type
of pipe, whatever its diameter, without having to
section such a pipe and may, for a wide pressure range,
be positioned in a full pipework section without a
holding device.
15 It may in fact be introduced into any tank thanks
to its multi-element structure, and be used with any
diameter of pipework. The closing device has in fact a
final diameter after assembly greater than the diameter
of the orifice of the manhole through which it will
20 have been introduced.
The plug has been described with reference to the
isolation of a tank, or of a set of tank(s) and
pipe(s), where the manhole is cut in the tank. It is
also possible to envisage using the plug for the
25 isolation of pipes alone, of large diameter, which are
provided with a manhole through which the multi-element
plug 10 could be introduced.
If the plug proposed is particularly advantageous
for the sealing of pipes having diameters greater than
30 the diameter of the manhole, it may obviously also be
used in pipes with diameters smaller than the diameter
29
of the manhole. The multi-element structure enables in
fact a much easier handling of the parts with a view to
assembly.
With such a plug, the installation and removal
5 times are markedly shorter than the installation and
removal time of a welded plug. Moreover, no regulatory
file is necessary, nor any non-destructive testing.
Moreover, the logistics requirement is very
limited, and human resources qualified as “standard”
10 are sufficient for putting in place the plug. Such a
plug also makes it possible to dispense with hot work
(grinding, welding, etc.) which eliminates the risks of
fire.
Such a plug is further designed to withstand high
15 pressure (for example resistance to 35 bars for a pipe
of 1400 mm nominal diameter, and higher resistance for
smaller nominal diameters) and without holding device
to arrange outside of the pipe.
Moreover, this plug may be implemented in any type
20 of industrial installation, including in installations
at risk, such as for example nuclear power plants. Such
a plug may thus be used in response to any problem “of
isolation” of a reservoir, of a tank, of an exchanger
or of a pipe of pipework with a view to carrying out a
25 leak tightness test, hydraulic pressure testing or any
other operation requiring leak tightness, especially
for pipework having a large nominal diameter.
The reader will have understood that numerous
modifications may be made without materially going
30 beyond the novel teachings and advantages described
herein. Consequently, all modifications of this type
30
are intended to be incorporated within the scope of the
closing device described.
BIBLIOGRAPHIC REFERENCES

I/We Claim:
1. Closing device for closing and isolating a
5 pipe (9) having an inner wall forming a substantially
cylindrical cavity with a so-called first diameter, the
closing device comprising:
- a main body (110) having substantially a shape of
a cylinder with a so-called second diameter, the
10 second diameter being smaller than the first
diameter to allow the closing device to be
inserted into the cavity; and
- sealing joint elements (120) that project around
the side wall of the cylinder (110) defining the
15 shape of the main body, so as to close a free
space formed between the main body (110) and the
inner wall of the pipe (9),
characterised in that the main body (110) comprises
several assembly elements (1111,1112,1113;
20 1121,1122,1123; 1131,1132,1133; 3110; 3130) capable of
being assembled together to form the cylinder (110)
defining the shape of the main body, each assembly
element (1111,1112,1113; 1121,1122,1123;
1131,1132,1133; 3110; 3130) having a shape inscribed
25 within a parallelepiped volume defined by three
orthogonal dimensions, in which at least two of the
three dimensions have a length smaller than the second
diameter,
and in that the device further comprises a position
30 holding system comprising a plurality of non-slip pads
(140; 340) mounted in translation in some of the
assembly elements to be deployed against the inner wall
32
of the pipe (9) in order to assure a holding of the
closing device by compression, the set of non-slip pads
forming an overall contact surface extending over at
least half of the periphery of the section of the
5 cylinder (110) defining the shape of the main body, the
position holding system further comprising force
measurement elements (342) provided to measure the
force applied by the non-slip pads (340) on the inner
wall of the pipe (9).
10 2. Device according to claim 1, in which each
non-slip pad (140; 340) is mounted on a compression
system (141; 341), such as a system of jacks or a
screws-jacks system, comprising a blocking system
preventing a translation of the non-slip pad after
15 deployment of the non-slip pad on the inner wall of the
pipe (9).
3. Device according to any one of claims 1 or 2,
further comprising an anti-extrusion system provided to
prevent a translation of the closing device in the pipe
20 (9) in the event of failure of the position holding
system, said anti-extrusion system comprising blocking
elements (400) arranged to be activated during a
translation movement of the closing device in the pipe
(9).
25 4. Device according to claim 3, in which each
blocking element of the anti-extrusion system is a
roller (400) mounted eccentrically (410) with respect
to a non-slip pad (340) of the holding system, and
having a contact surface intended to be in contact with
30 the inner wall of the pipe (9).
33
5. Device according to any one of claims 1 to 4,
in which the set of non-slip pads forms an overall
contact surface extending over the totality of the
periphery of the section of the cylinder (110) defining
5 the shape of the main body.
6. Device according to any one of claims 1 to 5,
in which the at least two dimensions among the three
have a length smaller than or equal to half of the
second diameter, preferably smaller than or equal to
10 one third of the second diameter.
7. Device according to any one of claims 1 to 6,
in which the main body (110) is segmented along chords
of the circular section of the cylinder, several of the
assembly elements (1111,1113; 1121,1123; 1131,1133)
15 forming circular segments of the cylinder.
8. Device according to any one of claims 1 to 7,
in which the main body (110) is segmented along
radiuses of the circular section of the cylinder,
several of the assembly elements (3110;3130) forming
20 circular sectors of the cylinder.
9. Device according to any one of claims 1 to 8,
in which the main body is segmented along the section
of the cylinder so as to form several elementary
cylinders (111;112;113;311;312;313) the assembly of
25 which forms the cylinder of the main body (110).
10. Device according to claim 9, in which the
main body (110) comprises intrinsic sealing joints
(130), each intrinsic sealing joint (130) being
arranged between two adjacent elementary cylinders
30 (111;112;113; 311; 312; 313).
34
11. Device according to any one of claims 9 or
10, in which the main body (110) is segmented into at
least three elementary cylinders
(111;112;113;311;312;313), each elementary cylinder
5 being segmented into at least three assembly elements
(1111,1112,1113; 1121,1122,1123; 1131,1132,1133; 3110;
3130).
12. Device according to any one of claims 9 to
11, in which the different non-slip pads of the holding
10 system are mounted in assembly elements forming one of
the elementary cylinders (111;112;113;311;312;313).
13. Device according to any one of claims 1 to
12, in which the sealing joint elements (120) comprise
at least two inflatable sealing joints (120) intended
15 to be positioned around the cylinder forming the main
body (110).
14. Device according to claim 13, further
comprising an instrumentation system (200) provided to
command and control the pressure in the inflatable
20 sealing joints (120) and in each inter-joint space
formed between two adjacent inflatable sealing joints
and the walls of the main body and the duct.
15. Device according to any one of claims 1 to
14, in which each assembly element (1111,1112,1113;
25 1121,1122,1123; 1131,1132,1133; 3110; 3130) has a
honeycomb structure.
16. Device according to any one of claims 1 to 15
for use in a tank (1) having a manhole (7) for handling
assembly elements, the manhole (7) having a diameter
30 comprised between 400 mm and 600 mm, with a view to the
35
sealing of a pipe having a diameter comprised between
1000 mm and 2000 mm.