FR2521688A1 - Sealant lining large and branching small pipes - with excess sealant from small pipe returned to large and spread as top layer - Google Patents

Abstract

The pipes are lined with sealant in succession by introducing liquid sealant and passing an appropriately sized pig through the pipe. Sealant forced into the small pipe when lining the large is returned into the large pipe using fluid or a pig and is then used by applying as a top layer to the existing lining by using a second pig of slightly smaller diameter than the first used for the large pipe. The second pig may be deformable to the required dia. by adjusting the back pressure used for running. A pig may consist of one or a pair of spherical foam rubber members and partic. for pipes with considerable bends, a pair of pigs is used with each consisting of two members interconnected by a flexible linear connector.

Description

 The invention relates to a method for the internal coating of gas, water, etc. supply pipes.

and, in particular, pipes with ramifications1
piping systems comprising a large diameter pipe (hereinafter called "large pipe") and a small diameter pipe (hereinafter called "small pipe") are generally covered with an internal coating after separation of the pipes at the point of connection, so as to carry out the internal coating of each of the pipes separately0
This process requires a lot of work to separate the pipes and then reweld them after coating, so that the efficiency of the operation is very poor. As a result, a method has recently been proposed making it possible to effectively re-internalize the large pipe and the small pipe without separating them.

This process comprises a first step consisting in internally lining a small pipe by passing a corresponding movable body of small diameter through it, and a second step consisting in internally drawing a large pipe by charging a body therein corresponding mobile of large diameter, one of these two stages being carried out before the other. However, as the coating or the waterproof coating composition is partially pushed into the small pipe during the stage of coating the large pipe, the above process has the disadvantage that the excess coating composition must be pushed back to 8tre evacuated by the large pipe. ~
when this method is used for piping comprising a large number of small branch pipes, the excess quantities of coating composition pushed back back up accumulate in a considerable mass,
Economically, it is very disadvantageous to discard all this mass given the loss of coating composition which results therefrom and the process to be carried out to get rid of it.

In addition, the coating composition returning from the small pipe in the upstream position is likely to flow into another small pipe in the downstream position. To avoid this problem, it is necessary to limit the length of the coating that can be formed on each pass, or to repeat the operation of return and evacuation of the excess composition. However, this way of proceeding inevitably imposes a yield limitation.

 The invention aims to overcome the above drawbacks of the prior art by creating a method of coating pipes with branches, characterized in that the sealing coating composition returning from a small pipe, as described above, is recovered to be effectively used without being discarded.

 Another object of the invention is to create a method of coating pipes comprising a large pipe and a small pipe, characterized in that the part going backwards of the coating composition is effectively used, and in that a special movable body is also used capable of gently and gradually coating the pipe with the sealing coating composition, especially when the large pipe and / or the small pipe have strongly bent L or T parts.

 To this end, the invention relates to a method for the internal lining of a pipe provided with branch pipes, by advancing a movable body in the pipe comprising a large pipe and a small pipe branching out, so as to thus coat the tubing of a waterproof coating composition in the form of a tube, a process characterized in that it comprises the various stages consisting in coating the small pipe by causing a corresponding movable body to pass through it small diameter, to cover the large pipe by passing a corresponding large diameter mobile body through it, thus forming a coating layer, one of the coating steps being carried out before the other, to be recovered in the large pipe the part of the coating composition pushed into the small pipe during the coating step of the large pipe, and to use the recovered part of the composition to revote the coating layer in downstream of the discharge point by passing a mobile body having a diameter slightly smaller than that of the large mobile body, after # recovery stage.

 Thus, the method according to the invention makes it possible to effectively consume the coating composition recovered, for coating the large pipe. This allows the waste which was produced in conventional processes to be eliminated or greatly reduced resulting in throwing the coating composition back into the large pipe. It is thus possible to eliminate or considerably simplify the process of evacuating the coating composition, which makes the process according to the invention much more efficient and much more economical.

 The recovered coating composition is thus completely or almost completely consumed by being pushed forward when leaving the coating from which it returns, before reaching the next branch. As a result, the coating composition absolutely cannot penetrate the next small pipe. There is no longer any limitation on the length of coating that can be performed on each pass. In fact, it is even possible to coat a long pipe system by a continuous operation with remarkably good performance, without the need to separate the small pipes from the large pipe.

 the special movable body mentioned above, intended for additionally used for bent X or li pipes comprises several elements and, preferably, two elements, connected to each other. More particularly, the movable body consists of elements symmetrical with respect to a plane perpendicular to the direction of movement, so as to carry out a coating or any other similar work inside the pipe, these elements being conform or approximately conform l 'to each other, and connected by a flexible linear element.

The invention will be described in detail with the help of the drawings attached, in which:
FIGS. 1A to 1D are diagrams representing a sequence of operating steps according to a first embodiment of the invention,
- Figures 2A to 2C are diagrams showing a sequence of operating steps according to a second embodiment of the invention
FIG. 3 is a sectional view, partially cut away, schematically showing another embodiment of the invention,
FIGS. 4A and 4B are sectional views showing how a movable body moves forward,
- Figure 5 is a partial sectional view showing a variant of Figure 3.

 Figures 1A to 1D show the case where the step of coating a small pipe precedes the step of coating a large pipe, and Figures 2A to 2C show the opposite case.

 We will first describe the operating process of the figures at ID.

I - A fluid-tight coating composition 14 and a
pair of small diameter mobile bodies 16 16 intended
to maintain between them the coating composition, are in
products in a small pipe 12 of a pipe 10, as
indicated in figure lA. Back pressure is applied to
movable bodies for advancing in the piping 12
by internally coating this pipe with a coating composition in the form of a tubular layer.

I do certain amount 20 of the same fluid composition
waterproof coating than that indicated above, and a
pair of large diameter mobile bodies 22, 22 intended for
maintain between them the coating composition, are in
products in a large pipe 18 of pipe 10, as
indicated in figure 13. Rear pressure is applied to the
movable bodies 22, 22 for advancing them in the pipe
18 by internally coating this pipe with a composition of
coating in the form of a tubular layer
re.At the same time, the small moving bodies 16, 16 and the
part 14 'of the waterproof coating composition previously
pushed into the large pipe 18 during stage I
are sent forward. Part 14 'is used for
coating the large pipe 18 and the mobi bodies
the 16, 16 are evacuated from the pipe 18.

 the rear movable bodies 16, 22 used in steps I, they have smaller radii than those of the corresponding pipes, the respective radii differences being equal to the thickness of the coating layers.

Iff-The 20 'part of the coating composition pushed into
the small pipe 12 during step 1, is forced back into
the large pipe 18 by simple injection of a fluid into the former
open end of the small pipe 12 or by pushing the body
mobile of small diameter 16 ′ in the pipe 12, as shown in FIG. The latter method is preferable for obtaining a coating of uniform thickness.

IV - The 20 'part of the waterproof coating composition re
stride during stage III is driven downstream
in the large pipe 18 by pushing a body into it
large diameter mobile 22 ', as shown in the figure
ID. The movable body 22 'has a slightly diameter
smaller than that of the large mobile bodies 22 used
for lining the large pipe 18 internally during
step it. As a result, the repressed part 20 'of the component
coating, used to coat the layer
coating 24 formed during step II.

 We will now describe the operating mode shown in Figures 26 to 2C.

la - The large diameter moving bodies 22, 22 are pushed
in the large pipe 18 to cover it with a portion
20 of the waterproof coating composition, as indicated
in Figure 2A.

IIa- The small diameter mobile bodies 16, 16 are pushed
in the small pipe 12 to revote it with a part
14 of the waterproof coating composition, as shown
in figure 23. part 20 'of the revOte composition
tightly pushed into the small pipe 12 during the
tap it, is simultaneously pushed back into the large pipe
18 at the end of this step.

Illa-The 22 'large diameter mobile body, slightly smaller
tit that the movable body 22, as indicated above, is
pushed into the big pipe 18 to get the little ones out
movable bodies 16, 16, as shown in Figure 2C. At this time
ment, the coating composition part 20 'pushed back
during step lia, is used to coat the neck
che coating 24 formed during 1 ~ tape.

 The mobile body 22 'used to use the repressed waterproof coating composition in the case of FIGS. 1A to 1D and of FIGS. 2A to 2C, has, in the free state, a diameter slightly smaller than that of the large mobile body 22 used to make the coating. It is thus possible to use a rigid metallic body, a hard resin or the like, to produce the body 22. In an alternative embodiment, it is possible to use a movable body of variable volume and / or shape as a function of variations in the discharge pressure. , this movable body thus being able to have a diameter slightly smaller than that of the covering body 22.

 Although the method according to the invention has been described above in the case of coating a pipe 10 comprising only one small pipe 12, this method can also be used in the following manner in the case of piping systems with a large number of small pipes.

 The coating step I or 11a of a small pipe, or the delivery step lila of the coating composition, are carried out simultaneously for a whole group of small pipes or successively for each of the small pipes taken one after the other. . The step coating it or there of a large pipe, or step IIIc of using the repressed composition are carried out at once for the entire length of the large pipe 18.

 However, the piping system can be divided into sections, each comprising a single small pipe 12 or a suitable number of small pipes 12, so as to carry out steps I to IV or la to IIIa for each section.

 FIG. 3 represents an embodiment usable for piping systems comprising parts with strong curvature, such as bent T-shaped parts or the like, on small pipes and / or on large pipes. FIG. 3 only shows part of a large or a small pipe which can be covered with an internal coating by the same methods as those already described, for large and small pipes, according to FIGS. 1A to 1D or FIGS. 2A to 2C .

 In FIG. 3, a pipe 12 or 18 comprises opposite open ends allowing the coating to be effected.

Movable bodies 30 are introduced into the pipes through an open end. A pneumatic pressure produced by a blower 35 and transmitted via a pressure regulating device 36 and a stop valve 37, is applied to the movable bodies so as to push them towards the other open end pipe. The movable body 30 is made up of two elements 32, 32 symmetrical with respect to a plane perpendicular to the direction of movement, and conforming or approximately conforming to each other. These elements are, for example, spherical, regular hexagonal , elliptical, oval or hexagonal irregular; and these elements 32, 32 are connected by a flexible linear element 33 such as a fabric wire, a cable, a spring or a plastic cord.

 The movable body 30 which can be used for implementing the method according to the invention passes as described below through a T-bend fitted with a plug. The two elements 32a, 32b move forward, in the front-rear position of Figure 4A. The front element 32a begins by entering the blocked gap 34 and comes to water at the entrance or in the vicinity of the entrance to the blocked space, so as to close the latter. As the T-bends present approximately an L shape, the rear element 32b then comes into contact with the front element 32a against which it stops and then continues to advance in the downstream pipe section, as shown in Figure 43.

 Then, the element 32b pulls the element 32a when stopped to drive it by means of the linear element 532 so that the two elements cross the elbow in the reverse front-rear position represented by dotted lines in FIG # e 42. As the two elements 32a, 32b are conforming or approximately conforming to each other, and symmetrical with respect to a plane perpendicular to the direction of movement, the reverse front-rear relation practically does not disturb the subsequent movement of the mobile body in itself, and allows it to perform the inner coating of the pipe.

 The two movable bodies 30 are placed at a suitable distance from each other in the pipes 12 or 18.

Through a hole 38 drilled in the pipe near the above-mentioned open end, a relatively low viscosity sealing coating composition 39 is injected into the space between the two movable bodies. The blower 35 is then started so that the pneumatic pressure thus produced pushes the bodies 30, 30 along the inner surface of the pipe, which allows the pipe to be coated internally with a coating composition in the form of 'a continuous tube.

 Whereas a conventional mobile body with a single element instead of the two associated elements according to the invention, is blocked in the pipes at the location of the elbows and even at the location of the bifurcations, the mobile body according to the invention can , on the contrary, easily overcome these obstacles in a very reliable way by moving slowly and gradually. As a result, it is possible to carry out in continuous regime and with excellent efficiency, the interior coating of a desired length of piping comprising elbows, this operation being obtained by means of a single pass of the movable body according to the invention.

In other words, the use of this movable body makes it very easy to make coatings of this type for a very large number of applications corresponding to the various conditions encountered, such as, for example, the various configurations of the pipe. In addition, the movable body is easy to manipulate since its constituent elements are symmetrical, as described above, and can therefore be introduced inside the pipe in any front-rear configuration.

 Preferably, the movable body is made of elastic material. The length of the flexible linear element is such that the face to face distance between the two movable elements is of the order of half the diameter of the pipe to be coated. Natural or synthetic rubber, and in particular foam rubber, is preferably used as elastic material, because when the two elements produced in such a material are subjected to a back pressure of approximately 1 to 1, 2 kg / cm2 and at the pressure of the air confined between the elements, they stretch radially with respect to the pipe and come into intimate contact with the internal surface of the latter. Another reason for this choice is that the elements move around and are unlikely to locally reduce the thickness of the coating layer below them due to their weight.

 it is preferable to use as a linear element a stainless steel film of sufficient flexibility and solidity. Preferably, the diameter of this rope is of the order of 1.6 mm for pipes of 50 to 75 mm, or of the order of 1 unit for pipes of 25 to 38 mm. If the distance face to face between the two elements clearly exceed half the diameter of the pipe to be coated, to reach, for example, the value of this diameter or If, on the contrary, this distance is significantly smaller than the diameter of the pipe, the elements no longer rotate smoothly and regularly in I or T bends. It has been found that the best results are obtained for a length of the flexible linear element such as that indicated above (i.e. the distance face to face above ), and for a rigidity suitable for the curvature.

 Although FIG. 3 represents two mobile bodies 30, 50 intended to hold the waterproof coating composition between them 39, since this composition is of relatively low viscosity, it is obvious that a single mobile body 30 may be sufficient to push this composition towards the front, as indicated in FIG. 5, when its viscosity is relatively high and when the mobile body is pushed at relatively high speed.

Claims (9)

 1.- Method for the internal coating of a pipe provided with branch pipes, by advancing a movable body in the pipe (10) comprising a large pipe (18) and a small pipe (12) leaving in diversion, so thus coating the piping with a waterproof coating composition in the form of a tube, process characterized in that it comprises the various stages consisting in coating the small pipe (12) by passing a corresponding movable body (16) of small diameter, to coat the large pipe (18) by passing therein a corresponding movable body (22) of large diameter, thereby forming a coating layer (24), one of the steps of coating being carried out before the other, recovering in the large pipe (18) the part (20 ') of coating composition pushed into the small pipe (12) during the step of coating the large pipe, and using the recovered part (20 ') of the composition to coat the covering layer (24) downstream of the discharge point, passing a large moving body (22 ') through the large pipe (18) having a diameter slightly smaller than that of the large large moving body (22).  2.- Method according to claim 1, characterized in that the movable body (22 ') intended to use the recovered part of the waterproof coating composition, has a slightly smaller diameter in the free state.  3.- Method according to any one of claims I and 2, characterized in that the movable body (22 ') using the recovered part of the composition, can deform to take its slightly smaller diameter, by adjusting the rear pressure thrust.  4.- Method according to any one of claims 1 to 3, characterized in that the step of coating the small pipe precedes the step of coating the large pipe, and in that the step of recovering the composition of waterproofing is carried out separately after the step of coating the large pipe.  5.- Method according to any one of claims 1 to 3, characterized in that the step of coating the large pipe precedes the step of coating the small pipe, and in that the step of recovering the composition of waterproof coating is carried out Just at the end of the step of coating the small pipe.  6.- Method according to any one of claims 1 to 5, characterized in that a pressurized fluid is applied to the rear of the movable body (30) placed in the piping (i0), so as to push it- ci in the direction of flow of the pipe by applying the waterproof coating composition on the inner wall of this pipe, the movable body (30) being made up of several elements (32) symmetrical with respect to a plane perpendicular to the direction of movement, these elements (32) being conforming or approximately conforming to each other, and connected by a flexible linear element 433).  7.- Method according to any one of claims 1 to 6, characterized in that the movable body (30) consists of spherical elements (32).  8.- Method according to any one of claims 1 to 7, characterized in that the elements (52) of the movable body (30) are made of an elastic material.  9.- Method according to any one of claims I to 8, characterized in that the dlémeets (32) of the movable body (30) are made of foam rubber.