FR2715084A1 - Method and device for applying a coating in a buried pipe - Google Patents

Abstract

The object of the invention is the production of a coating in curable resin with two components, for example an epoxy resin, over a great length (up to 150 m) of a buried pipe (1), in order to limit the work. excavation. The coating (3) is applied and smoothed by means of a coating head (4) continuously supplied and drawn by a flexible hose (5) wound up on a winch (8) of a base unit (6 ) placed near an access point (2) to the pipe. The two resin components are heated in the base unit and maintained at the optimum temperature by electrically heating the hose (5). They are mixed in the coating head and applied immediately by centrifugal spraying. The invention applies in particular to the rehabilitation of cast iron drinking water pipes.

Description

METHOD AND DEVICE FOR APPLYING A COATING IN A

BUSHING ENTERREE

  The present invention relates to a method for applying a two-component resin-based coating in a buried pipe,

  especially in a drinking water pipe made of cast iron.

  The invention also relates to a device for implementing this method, comprising a base unit intended to be placed outside the pipe near an access point to this pipe, a movable head of coating intended to be placed in the pipe, and at least one flexible connecting the coating head to

the basic unit.

  The invention applies in particular, but not exclusively, to the rehabilitation or improvement of old cast iron drinking water pipes. When new drinking water pipes are laid, cast iron pipes with a synthetic coating are now used, which guarantees high resistance to corrosion, low resistance to flow and low risk of deposition. solids. In old cast iron pipes, with or without traces of corrosion, there is increasing interest in economically applying a sheath or lining offering the same advantages, by performing

  as little as possible of civil works.

  However, the methods proposed so far are unsatisfactory, whether technically or economically. A known method, for example illustrated in document FR-A-2,445,220, consists in adhering a flexible tubular sheath applied by

  air pressure against the inner face of the buried pipe.

  However, sheaths of this kind have insufficient long-term strength. In addition, the method of application requires connecting a large pneumatic apparatus at one end of each section of the pipe to be treated, that is to say to excavate a large well at each access point. Therefore, it is preferable to make a coating with a curable product, applied directly into the buried pipe. The present invention aims to achieve this from a

  efficient and relatively inexpensive way.

  The rehabilitation of drinking water pipes requires the use of special coatings with very specific characteristics, such as: - absence of solvents (regulations for food products), - correct adhesion to metal surfaces previously cleaned by means conventional, - rapid drying for rapid water return of pipes, with minimum time of immobilization, homogeneous and waterproof coating, - high hardness to ensure resistance to abrasion and facilitate future cleaning, - possibility of application by coating on long lengths (100 to 150 m) and pipe diameters ranging from 80 to 500 mm, - moderate price of the coating components, ensuring a high competitiveness of the process compared to the conventional technique by opening trenches and replacing pipes by

new ducts.

  Currently, some epoxy resins with two components meet all the above criteria, but there is no known method to apply them properly and economically at a distance greater than ten meters to

from the access point.

  The invention makes it possible to solve this problem by a method of the type indicated above, characterized in that a mobile coating head and at least one hose connecting said head to a point of access to the pipe, said head being arranged to apply a curable mixture on the inner wall of the pipe to form the coating, in that the coating head is continuously fed with both components hot, at a temperature appropriate to rapid hardening of the curable mixture, by means of heated conduits housed in said hose, in that the two components are continuously mixed in the coating head to form the curable mixture and in that said head is moved continuously along the pipeline

  while applying said mixture.

  Preferably, the coating head is moved by pulling on the hose. The coating head can be moved at a rate proportional to the feed rate of the components. For a given flow rate, the thickness of the layer will be proportional to the

  speed of movement of the head.

  In an advantageous form of the process, to apply the curable mixture, the coating head performs a projection operation of the mixture, forming a coating layer on the inner wall of the pipe, and simultaneously a mechanical finishing operation of said layer behind the projection zone, particularly by

hammering and / or smoothing.

  For the implementation of this method, the invention provides a device of the type indicated above, characterized in that: - the coating head comprises a mixer for mixing the two components, rotary coating means for applying the mixing the components on the inner periphery of the pipe, and at least one motor for operating the mixer and said coating means, - said at least one hose comprises two supply ducts for said components, a power transmission duct for the motor of the head, heating means for heating at least the supply ducts, and a flexible traction member for pulling the coating head by means of the hose to advance it, - the basic unit comprises two heated tanks for said components, at least one pump for transferring the tank components to the corresponding supply lines of the hose, a drum winch on which is fixed a rear end of the hose, means for adjusting the speed of the winch and / or the pump, and control and regulating means

hose heating.

  In a preferred embodiment, the motor of the coating head is a pneumatic motor and said energy transmission duct is a compressed air duct which is heated by means of

hose heating.

  Preferably, the rotary coating means comprise a centrifugal turbine arranged to receive said mixture leaving the

  mixer and distribute it on the inner wall of the pipe.

  The rotary coating means may further comprise at least one rotary brush, rotatably connected to the turbine and disposed axially behind the latter relative to the direction of advance of the coating head. The mixer, the turbine and the rotating brush may have a common shaft driven by the motor of the head

of coating.

  According to an advantageous embodiment, the hose heating means are electrical and comprise at least one resistive element extending substantially over the entire length of the hose. The compressed air duct may also be heated by the electric heating means. Preferably, the hose comprises at least one temperature sensor which is connected to the control means and

  heating regulation of the hose.

  In the base unit, the two component tanks can be provided with heating means. They may include each

  a pneumatic or electric mixer.

  In addition, the pump and the winch can both have pneumatic drive means. The speed adjusting means may comprise a pneumatic synchronization device which

  controls the pump according to the speed of rotation of the winch.

  The pump may advantageously be a two-cylinder pump operating in synchronism for pumping respectively said components. The method and the device according to the invention have the great advantage of allowing the application of a coating by means of a relatively simple moving head, which can easily be exchanged or adapted to work in pipes of different diameters, with a Versatile flexible power and traction unit and a base unit that can stay on the surface near an access glance at the

  pipeline, in the form of a small vehicle easy to carry.

  An essential aspect of the invention is to bring the components to the hot coating head and mix them only in this head, which allows to operate over a long driving distance from a point of access, this length being limited in practice only by the volume of the winch drum when the hose is completely wound therein. The hardening of the resin can not be initiated in the hose, since the components are still separated there. On the other hand, it is carried out quickly from the exit of the coating head after passing through the rotary mixer and thanks to

  at the relatively high temperature of the curable mixture.

  Other features and advantages of the invention will become apparent

  in the description of a preferred embodiment, given below.

  below by way of nonlimiting example, with reference to the accompanying drawings, in which: - Figure 1 shows schematically the use of a device according to the invention, comprising a base unit, a heated umbilical hose and a head of FIG. 2 is a schematic side view of the base unit along the arrow II of FIG. 3; FIG. 3 is a plan view of the base unit, partially broken away; FIG. 4a is a cross-sectional view of the heated hose; FIG. 4b is a cross-sectional view of an alternative embodiment of the heated hose; FIG. 5 is a longitudinal sectional view of the coating head; FIG. 6 is a diagram of the members of the base unit that deliver the two components of the resin to the hose, and FIG. 7 is a diagram of the units of the base unit that move the coating head by winding. of the hose on a winch, and - Figure 8 is a schematic my heating organs and

  temperature regulation of the hose.

  Referring to Figure 1, a buried pipe constituted by a cast iron water pipe 1 opens into an access shaft 2 and is subject to an improvement treatment by applying a coating 3 of a 2-component curable epoxy resin after appropriate preparatory operations such as cleaning, rust removal, drying, etc. The coating is applied by means of a device according to the invention, composed of a coating head 4, a supply and traction hose 5, called flexible umbilical, and a base unit 6 preferably placed on the ground surface 7, near the access well 2. The unit 6 comprises a drum winch 8 on which the hose 5 winds to pull the coating head in the direction of the arrow A during work. One or more idlers 9 are supported by a temporary frame (not shown) to guide the hose 5 into the well area. The hose can be set up beforehand in line 1 by pulling in the opposite direction to A from a second access point where it will be fixed

the head 4.

  Figures 2 to 4 show in more detail the base unit 6 and the hose 5. The latter can be made flat as shown in Figure 4a or twisted as shown in Figure 4b. It comprises in all cases two ducts 11 and 12 respectively for the first and second liquid component of the epoxy resin (base resin and hardener), and a third duct 13 for compressed air, each duct being defined by a flexible polyethylene tube 14 surrounded by a steel braid 15 to withstand a high pressure, for example 200 bar for conduits 11 and 12 of 3/8 "(9.5 mm), and a protective sheath 16. A copper braid 17, for electric resistance heating, respectively surrounds the ducts 11 and 12, the electrical connection between the two being provided by a loop at one end of the ducts. An electrically insulating polyurethane coating 18. In FIGURE 4a, the assembly is surrounded by a heat-insulating layer 19 made of glass fibers and an outer sheath 20 of heat-shrinkable synthetic material. The existing gap between the conduits 11, 12, 13 and the layer 19 can be filled by an electrically insulating polyurethane filler. In FIG. 4b, the thermal insulation layer 19 is provided individually around each duct and is protected by a polyurethane sheath 100. Three wedging tubes 101 are also provided between the three ducts to position them. The assembly is surrounded by a retaining band 102, covered with a polyurethane protective envelope 103. A signal cable 90, connected to a temperature sensor, is placed inside said hose. This hose 5 preferably has a length of 150 m. Alternatively, it would be possible to use multiple separate hoses each having a conduit, but the unit solution provided herein is better thermally and for convenience of use. The steel braids allow the hose to transmit sufficient tensile force to the coating head. In the variant embodiment illustrated in FIG. 4b, an additional traction cable 15 ', arranged along the central axis of said hose, is

  provided to assist in transmitting said pulling force.

  As shown in Figures 2 and 3, the base unit 6 is in the form of a carriage having a frame 21, wheels 22 and a drawbar 23. It comprises an electric block 24 transformer which is powered by the sector and delivers a low voltage of 48 V for heating. It further contains a pneumatic circuit 25 supplied with compressed air through an inlet valve 26 and a filter 27. A reservoir 28 for the base resin and a reservoir 29 for the hardener are heated to a temperature of 60 to 80 ° C. by electric heating belts 30 and each have a pneumatic mixer 31; they are wrapped with an insulating mass 32 and connected to a two-cylinder pneumatic pump 33 which delivers the two separate components of the resin in a given proportion to rotary unions respectively 34 and 35 on a

hollow shaft 36 of the winch 8.

  The hose 5 is wound on a drum 37 of the winch 8, between two side cheeks 38, and its rear end (not shown) is attached to the drum. Through the hollow shaft 36, its ducts 11 and 12 for the liquid components are connected to the rotary connectors 34 and 35, its compressed air duct 13 is connected to a pneumatic rotary coupling 40 provided with a valve 41, and its Electrical circuits are connected to corresponding rotary connectors 42. The shaft 36 of the winch, carrying the drum 37, is rotated by a pneumatic geared motor 43 via chain transmissions 44 and 45, a limiter torque 46 and a clutch 47. All functions of the device are controlled and controlled in a conventional manner from a

  control panel 48, as will be described later.

  The construction of the coating head 4 is illustrated in FIG. 5. This head comprises a cylindrical body 50 equipped with three guide brackets 51 arranged to slide in the pipe and to center the head 4. At its front end connected to the hose 5 (Not shown), there is provided an inlet connector 52 for the compressed air which feeds a pneumatic motor 53 and escapes laterally through a ring of orifices 54. The motor 53 rotates a shaft 55 actuating a mixer 56 a centrifugal turbine 57 and a smoothing brush 58 forming the rear end of the head 4. An inlet fitting 60 receives the base resin of the conduit 11 of the hose, which is fed to the mixer 56 through a channel 61 and A check valve 62. Identical organs driving the hardener to the mixer 56 o the two hot components will form a curable liquid mixture which is ejected by a ring of axial nozzles 63 on the turbine 57, for here a slightly conical disc. Thanks to the progressive advancement of the head 4, the projected liquid lines the entire inner wall of the pipe and forms a thin coating, for example

  0.3 to 1 mm for an application of 0.5 to 1.5 kg / m2.

  The preferred thickness of the epoxy coating is 0.3 to 0.4 mm. Curing begins immediately due to the relatively high temperature of the mixture and the ambient heat provided by the heated compressed air. The brush 58 provides a final smoothing of the coating; where appropriate, it may be preceded by a

  hammering favoring the elimination of any air bubbles.

  The operation of the device according to the invention will be better understood by referring to the diagrams of the circuits shown in the figures.

6-8.

  With reference to FIG. 6, the pump 33 comprises a pneumatic motor 65 which synchronously drives a plunger in a first cylinder 66, to deliver the base resin from the reservoir 28 to the rotating connection 34 through a valve 67, and a piston plunger in a second cylinder 68 for delivering the hardener from the reservoir 29 to the swivel 35 through a valve 69. Bypass valves 70 allow recycling to the tanks if necessary. The pressure of the pumped liquid components is displayed by manometers 78. The compressed air circuit 25 supplies, through a filter 79, a distribution line 71 whose pressure is displayed by a pressure gauge 72. The pump 33 receives the air compressed through an adjustable flow restrictor 73, a pressure modulator 74 and a shut-off valve 75. The pipe 71 directly feeds the mixers 31 through shut-off valves 76 and also makes it possible to pressurize the tanks 28 and 29 through regulators 77. The elements 72 to 78 are in the

control panel 48.

  FIG. 7 shows that the pneumatic motor 43, which drives the shaft 36 of the winch 8 via a gearbox 43a, the clutch 47 and the torque limiter 46, is fed by the compressed air circuit 25 through an adjustable flow restrictor 80 and a pressure modulator 81 for varying the speed of the winch, and therefore the speed of movement of the coating head 4, by controlling the pressure by means of a pressure gauge 82. elements 80 to 82 are in the control panel 48. To adjust the amount of curable mixture applied per linear meter of pipe, that is to say to adjust the thickness of the coating 3 taking into account the diameter of In line 1, a pneumatic timing device (not shown) uses output pulses from winch motor 43 to control the speed of pump 33 by means of pressure modulator 74 (FIG. 6). The flow of the components of the resin is then

  proportional to the speed of movement of the coating head.

  FIG. 8 illustrates the means for heating and regulating the temperature of the hose 5, in order to maintain the components of the resin and the compressed air at the desired temperature. In the electrical block 24 (FIG. 3), a four-stage 220/48 V single-phase transformer 84 is associated with a five-position switch 85 for delivering a stepped secondary voltage of 12 to 48 V, indicated by a voltmeter 86. the rotating couplings 42, this tension is applied to the forward and return strands of the heating braid 17 of the hose 5, extending between a rear insulating seal 87 and a front insulating seal 88 of the hose 5. Close to the latter is the temperature sensor 89 which, by a signaling cable 90, a swivel 42 'and an amplifier 91, acts on a thyristor 92 regulating the primary of the transformer

  84 to limit heating if necessary.

  The present invention is not limited to the embodiment described above, but extends to any modification or variant

obvious to a person skilled in the art.

Claims (17)

claims   A method for applying a two-component resin-based coating in a buried pipe, especially in a drinking water pipe made of cast iron, characterized in that a mobile coating head (4) is placed in the pipeline and at least one hose (5) connecting said head to an access point to the pipe, said head being arranged to apply a curable mixture to the inner wall of the pipe (1) to form the coating (3), in continuously supplying the coating head (4) with both hot components, at a temperature suitable for rapid hardening of the curable mixture, by means of heated conduits housed in said hose (5), that the two components are continuously mixed in the coating head to form the curable mixture and in that said head (4) is continuously displaced along the pipe (1) while it applies said mixed. 2. Method according to claim 1, characterized in that one   moves the coating head (4) by pulling on the hose (5).   3. Method according to claim 1, characterized in that one moves the coating head (4) at a proportionally adjustable speed   at the feed rate of the components.   4. Method according to claim 1, characterized in that, to apply the curable mixture, the coating head (4) performs a projection operation of the mixture, forming a coating layer (3) on the inner wall of the channeling, and simultaneously a mechanical finishing operation of said layer behind the   projection zone, in particular by hammering and / or smoothing.   5. Device for applying a two-component resin-based coating in a buried pipe, in particular in a cast iron drinking water pipe, for carrying out the method according to claim 1, comprising a base unit (6) intended to be placed outside the pipe (1) near an access point (2) to the pipeline, a mobile coating head (4) intended to be placed in the pipeline, and at least a hose (5) connecting the coating head to the base unit, characterized in that: - the coating head (4) comprises a mixer (56) for mixing the two components, rotary coating means (57, 58) for applying the mixture of components on the inner wall of the pipe, and at least one motor (53) for operating the mixer and said coating means, - said at least one hose (5) comprises two pipes supply (11, 12) for said components, a transmission path energy supply (13) for the motor of the head, heating means (17) for heating at least the supply ducts, and a flexible traction member (15, 15 ') for pulling the head of coated with the hose to advance it, the base unit (6) has two heated tanks (28, 29) for said components, at least one pump (33) for transferring the tank components to the corresponding supply ducts of the hose, a drum winch (8) to which is fixed a rear end of the hose (5), means for adjusting the speed of the winch and / or the pump, and   means for controlling and regulating the heating of the hose.   6. Device according to claim 5, characterized in that the motor (53) of the coating head is a pneumatic motor and in that said energy transmission duct (13) is a duct of compressed air.   7. Device according to claim 5, characterized in that the rotary coating means comprise a centrifugal turbine (57) arranged to receive said mixture leaving the mixer and the   spread on the inside wall of the pipe.   8. Device according to claim 7, characterized in that the rotary coating means further comprise at least one rotary brush (58), rotatably connected to the turbine (57) and disposed axially behind the latter relative to the direction. progress of the coating head.   9. Device according to claim 8, characterized in that the mixer, the turbine and the rotating brush have a common shaft   (55) driven by the motor (53) of the coating head.   10. Device according to claim 5, characterized in that the hose heating means are electrical and comprise at least one resistive element (17) extending substantially over the entire hose length.   11. Device according to claims 6 and 10, characterized in that   the compressed air duct (13) is heated by, - X electric means of heating.   12. Device according to claim 10, characterized in that the hose (5) comprises at least one temperature sensor (89) which is connected to the heating control and control means. of the hose.   13. Device according to claim 5, characterized in that the two component tanks (28, 29) are provided with means of heating (30).   14. Device according to claim 13, characterized in that said   reservoirs each comprise a pneumatic mixer (31).   Device according to claim 5, characterized in that the pump (33) and the winch (8) both have drive means tires.   16. Device according to claim 15, characterized in that the speed adjusting means comprise a pneumatic synchronization device which controls the pump (33) as a function of the speed of rotation of the winch (8). 17. Device according to claim 15 or 16, characterized in that the pump (33) is a two-cylinder pump operating in   synchronism for respectively pumping said components.