Note: Descriptions are shown in the official language in which they were submitted.
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SEALING OF PIPES
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to the sealing
of pipes, at e.g. joints, fractures and fissures. It
is particularly, but not exclusively, concerned with
sealing joints in a gas main.
SUMMARY OF THE PRIOR ART
One known method of sealing a leaking joint in a
gas main involves boring a hole in the main and
inserting a sealant spraying means. The spraying
means is mounted on a semi-flexible rod and inserted
through the hole in the main and moved along the main
by pushing the rod deeper into the main The rod is
inserted until the spraying means has reached the
joint, which is detected by a suitable joint location
of the spraying means, and the joint can then be
sprayed to seal it. ln order to detect the joint a
magnetic locator may be mounted on the spraying means.
This method is discussed in G~-A-2223553.
SUMMARY OF THE INVENTION
The known method described above has proved
satisfactory for small gas pipes. However, the
applicants have applied this method to pipes with a
larger diameter (e.g. up to 48 inches), and have
discovered -that there is then a problem. It has been
found that the flexible rod buckles and twists within
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a large pipe, and this buckling and twisting may be
sufficiently great that it proves impossible to move
the spraying means more than a relatively short
distance into the pipe. The pipe forms a series of
"S" bends which cause spring-back when it is attempted
-to push the rod further into the pipe. In thi.s
situation, a considerable length of extra rod can be
inserted into the pipe without any progress of the
spraying means. Furthermore, the spraying means
becomes angled relative to the line of the joint,
which could result in spraying across the line of the
joint, instead of on it. In smaller pipes, as can be
appreciated, the pipe itself limits the buckling of
the rod, and this is the reason why the problem has
not been discovered before.
The problem is made worse by the fact that it is
not desirable to make many holes in -the main, and
therefore there is the need to seal joints which are
relatively far from the point of insertion of the
spraying means and rod. Thus, the problem of buckling
becomes serious.
In order to solve this problem, the present
invention proposes, in a first aspect, that a
relatively rigid delivery tube lor carrier) be
positioned in the pipe, and the spraying means
inserted through that delivery tube using a flexible
rod, which may be the standard flexible rod used in
the known systems. The first aspect of the delivery
tube has a much smaller diameter than the pipe, and so
will restrict buckling and twisting of the rod. The
present invention then relates to a method involving
such an arrangement, and to an assembly of parts for
use in such an arrangement.
As in the existing systems, it will usually be
necessary to bore a hole in -the wall of the pipe to
insert the delivery tube, sprayiny means and flexible
rod. When the pipe is a gas main, it will normally be
necessary for a valve and sealing gland arrangement to
be provided at the point of insertion of the delivery
tube, spraying means and rod, to prevent gas escape.
Where it is desired to seal several joints,
spaced along the pipe, it is preferable -that the
delivery tube, spraying means and rod be inserted to
a distance corresponding to the furthest joint, and
the delivery tube, spraying means and rod can then be
withdrawn to seal successive joints.
The delivery tube may be of a light weight,
relatively rigid material which may be coiled but
which does not retain its curvature when uncoiled.
However, because rigidity is important to achie~e
maximum distance of insertion, the delivery tube may
be made up in straight lengths with e.g. spigoted
joints. It is preferable that the material is capable
of slight bending, so that it can be inserted through
a side wall of the pipe and accommodate itself to the
pipe after insertion. When the delivery tube is
inserted, it may have an end cap on the free end
thereof, which end cap prevents entry of material into
the delivery tube, but which end cap can be pushed off
by the spraying means when the spraying means is
pushed through the delivery tube by the flexible rod.
Rigid PVC or polypropylene may be suitable for the
delivery tube, al-though there could be problems with
it being too brittle.
The sealing material, and other features of the
spraying arrangement may be similar to those shown in
GB-A-2223553.
The rod may be solid, and carry the wiring for a
joint location of the spraying means. ALternatively,
the rod itself may be hollow, and carry within it a
solid member for such wiring and also carry a hollow
tube for the sealant. The use of a hollow rod permits
its diameter to be large without significant weight
increase, thereby giving increased rigidity to the rod
as compared with a solid rod of equivalent weight.
Furthermore, such a hollow rod may be made of straight
lengths connected by spigoted joints.
One problem with such a spraying means, however,
is that it is designed to provide a uniform spray
pattern. Therefore, particularly when the diameter of
the pipe is large, and the spraying means is located
at the bottom of the inside surface of the pipe, the
spray will not be uniform around the circumference of
the interior of -the pipe.
The part of the interior of the pipe close to the
spraying means will receive much more sealant than the
opposed part of the circumference of the pipe.
Therefore, a further development of the present
invention proposes that the spraying means be provided
with spraying outlets arranged to spray sealant in a
preferred direction, and also has means for detecting
the orientation of the spraying means, so that the
orientation of the spraying means can be adjusted to
cause the sealant to be sprayed in a selected
direction.
Thus, when the spraying means at the end of the
rod projects from the delivery tube, its weight will
inevitably cause it to be located at the bottom of the
pipe. The orientation means will identify the
orientation of the head, and by rotating the rod it is
possible to adjust the orientation of the head until
the spraying outlets spray upwardly towards the upper
inner surface of the pipe. Spraying then occurs in
that selected direction, and the sprayed sealant will
then flow around the interior surface of the pipe, so
that the whole of the pipe is sealed. This
arrangement is particularly advantageous for large
pipes where the problem of non-uniform spraying from
a standard head will be more extreme.
The use of a hollow rod with such a spra~ing head
is particularly advantageous as it permits all the
wiring for the spraying head to be contained within
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the rod.
Such a spraying means may be used in conjunction
with the delivery tube and rod of the first aspect of
the present invention. However, the use of such a
spraying means to the end of a rod represents a
second, independent, aspect of the present invention.
It is possible, for example, for the spraying means to
be at the end of a semi-rigid hollow conduit or solid
rod which is inserted directly into the pipe, and is
not passed through a more rigid delivery tube. The
conduit may then be made of relatively rigid straight
sections connected by spigots.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be
described in detail, by way of example, with reference
to the accompanying drawing in which:
Fig. 1 shows a sectional view through a pipe in
which a delivery tube has been inserted, at the point
at which the spraying means in inserted into the
delivery tube;
Fig. 2 shows a part of the embodiment to Fig. 1,
but with the spraying means inserted through the
delivery tube into the pipe;
Fig. 3 shows the spraying of a relatively small
pipe, using the embodiment of Fig. 1;
Fig. 4 shows the spraying of a relatively large
pipe, using the embodiment of Fig. 1;
Fig. 5 shows a spraying means which may be used
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in the present invention;
Fig. 6 shows the spraying of a relatively large
pipe, using the spraying means of Fig. 5;
Fig. 7 shows a second embodiment of the present
invention, incorporating the spraying means of Fig. 5;
and
Fig. 8 shows a third embodiment of the present
invention, incorporating the spraying means of Fig. 5.
DETAILED DESCRIPTION
Referring to Fig. 1 which shows a first
embodiment of the present invention a live gas main 1
has a faulty joint therein which is to be sealed. An
excavation 2 is dug at a portion of the gas main 1
which is spaced from any joints which are to be
sealed. A hole 3 is bored through the wall of the
main 1, following established techniques. A valve and
gland arrangement 4 is fitted to the main 2 at the
site of the hole 3.
A hollow delivery tube 5, which has a push-off
end cap 6, is inserted through the valve 4 and is
moved a suitable distance along the main 1, so that
its end is proximate the joint to be sealed.
A sealant spraying means 7 has a nozzle 8 through
which a sealant is sprayable and is mounted on a
flexible rod 9. The nozzle 8 is mounted on the end of
the rod 9 in flow communication therewith so that the
rod acts as a delivery hose for sealant. The sealant
spraying means 7 is inserted into the delivery tube 5,
and is moved along the tube 5 by pushing the rod 9
until the sealant spraying means 7 pushes off the end
cap 6 of the delivery tube 5 so that the nozzle 8 and
the part of -the rod 9 proximate the nozzle 8 extend
from the end of the delivery tube 5. The nozzle 8 is
moved ad;acent a site on the wall of the -tube which is
to be sealed.
A sealant which may be settable anserobic
sealant, is -then pumped through the rod 9 and sprays
through the nozzle 8 to contact and adhere to -the wall
of the main 1. The sealant spraying means 7 may then
be moved adjacent another site which is to be seled or
may be removed, together with the delivery tube 5,
from the gas main 1 through the bored hole 3. The
hole 3 may then be resealed using established
techniques.
As shown in Figure 2, the sealant spraying means
7 may have magnetic joint locator 10. The joint
locator 10 may have electrical connections leading
along the rod 9, or may be in the formed of signal
generation and transmission means to cooperate with
receiving means which receiving means may be distal
from the transmission means.
Known spraying means 7 may be used in the
arrangements described with reference to Figs. 1 and
2, such as those disclosed in GB-A-2223553. Such
spraying means have a plurality of spraying outlets
arranged substantially uniformly around the periphery
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of the spraying means 7 (which is normally
cylindrical). Thus, as shown in Fig. 3, sealant is
sprayed in all directions within the pipe 1, as shown
by arrows 15. The weight of the spraying means 7, and
the manner of insertion shown in Figs. 1 and 2 means
that the spraying means 7 is located at the bo-ttom of
the interior of the pipe, so it can be seen from Fig.
3 that parts of the pipe 1 adjacent the spraying means
will receive more sealant than those parts of the pipe
l remote from the spraying means. In a small pipe,
such as shown in Fig. 3, this is not a problem.
However, Fig. 4 shows the situation in a larger pipe,
and it can then be seen that those parts of the pipe
1 remote from the spraying means 7 will receive much
less sealant, per unit leng-th of circumference, than
will the parts of the pipe close to the spraying means
7. Thus, the amount of sealant sprayed on the part of
the pipe 1 remote from the spraying means 7 may be
insufficient to seal the leak of joint.
Fig. 5 shows, both inside and section view a
spreading means which may enable this problem to be
overcome. The spraying means 16 has a plurality of
spraying outlets 17 arranged to extend around only
part of its circumference (spraying means 16 is again
generally cylindrical), so that directional spraying
can be achieved. Furthermore, the spraying means
includes means 18 for dPtecting the orientation of the
spraying means 16. The orientation detection means 18
may be e.y. an electronic angular displacement
inclicator (e.g. that designed and manufactured by D.
G. Electronics). The orientation detection means 18
enables the spraying means 16 to be positioned within
the pipe so that the spraying outlet 17 are directed
to the opposed surface of the pipe. This is shown in
Fig. 6, in which the spraying means 16 is located at
the bottom of the pipe, but the spraying outlets 17
direct sealant upwardly towards-the opposed surface of
the pipe 1. By suitable arrangement of these spraying
outlets, i-t ran be arranged that the sealant is spread
substantially uniformly around the interior of the
pipe, at least to that part remote from the spraying
means 16. This is shown by arrows 19. Of course,
such a directional spraying arrangement will not then
spray the interior of the pipe 1 close to the spraying
means, but it has been found that the sealant is
normally sufficiently fluid that it will flow around
the interior of the pipe, as shown by arrows 20, so
that the whole of the interior of the pipe, will, in
due course, receive an appropriate amount of sealant.
This arrangement also has the advantage that it is
efficient in terms of the amount of sealant used,
which is advantageous for large pipes to avoid
excessive use of sealant. As can be appreciated from
Fig. 6, it is important that the spraying means 16 has
the appropriate orientation, to direct the sealant
towards the opposed surface of the pipe 1,
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corresponding to the upper segment of the pipe 1, but,
as mentioned above, this orientation may be detected
by the orientation detection means 18. Therefore, if
after insertion of the rod 9, wi-th the spraying means
16 thereon, it is found that the spraying means does
not have the correct orientation, the rod may be
rotated until the orientation is correct.
Thus, Fig. 7 shows an embodiment of the present
invention similar to that of Figs. l and 2 but
incorporating spraying means 16 described with
reference to Figs. 5 and 6. In Fig. 7, parts which
correspond to those in Figs. l and 2 are indicated by
the same reference numerals. There is thus again a
hollow delivery tube 5 which receives a flexible rod
9 on the end of which is the spraying means 16. Since
the spraying means 16 is somewhat larger than a
standard spraying means, the rod 9 may have to be more
rigid, and thereor thicker than for the embodiments
of Figs. 1 and 2, but the general principle may be the
same. However, it is preferable that the rod 9 of
this embodiment is hollow, and it then carries therein
a rigid member containing the wiring for the spraying
head 16 and a hollow tube acting as a duct for sealant
to the spraying head.
However, Fig. 7 also shows that, for a large
pipe, it is desirable that the hole 3 in the pipe l
which permits the passage of the delivery tube 5, has
a under-pressure angled entry fitting 25 thereon, to
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simplify the entry of the delivery tube.
For large pipes it has also been found that it is
possible to omit the rod 9, and mount the spraying
means 16 directly on the end of the delivery tube 5 so
that the delivery tube 5 forms a conduit directly to
the spraying means 18. Although that delivery tube 5
is more rigid than the rod 9, the large diameter of
the pipe means that the delivery tube 5 can
accommodate the change in direction needed from the
angled entry fit-ting 25 to the direction extending
axially of the pipe 1, and its relatively greater
rigidity means that it is less likely to twist or coil
within the pipe 1, so that the problems discussed
above do not apply. The use of an angled entry
fitting 25 also means that the delivery tube can be
inserted so as to extend in either direction along the
pipe 1. Preferably, the delivery tube 5 comprises a
plurality of separable sections (this may also be used
in e.g. the embodiment of Fig. 7), to make insertion
of those sections easier. The sections may be
connected by spigoted joints.
Thus, both the embodiments of Figs. 7 and 8 can
move a spraying means 16 providing a directional spray
to a pipe joint 26 to be sealed, and then the
orientation detection means 18 ensures that the
spraying means 16 is positioned so tha-t spraying
outlets 17 are directed upwardly. Spraying may then
be carried out, as was described with reference to
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Fig. 6.
Although the present invention has been developed
primarily for use with large diameter pipes, it is
applicable to smaller diameter pipes, although there
the problems of buckling and folding may be less
acute. However, a standard kit comprising spraying
means, delivery tube and rod may then be used for the
majority of applications.
