EP0667188A1 - Method and device for applying an internal coating to underground pipes - Google Patents

Abstract

The coating is applied by a mobile coating head (4) that is inserted through an access chamber (2). A flexible pipe (5) connects the head to the access point. The mobile head is inserted in the pipe and travels along the pipe under the action of a pneumatic motor fitted in the head and supplied through the flexible pipe. To apply the coating the head is supplied, through the flexible pipe, with the two components of the epoxy resin, heated to reduce the drying time. The resin is applied to the inside of the pipe by a rotary brush, driven from the compressed air line. The head is drawn along the pipe, at a speed determined by the rate of application of resin, by winding the flexible pipe back onto a drum (8) on a vehicle parked at the top of the access chamber.

Description

The present invention relates to a method for applying a two-component resin-based coating in a buried pipe, in particular in a cast iron drinking water pipe, according to which a mobile coating head and at least one are placed in the pipe. flexible connecting this head to an access point to the pipeline, said head being arranged to apply a hardenable mixture on the interior wall of the pipeline to form the coating and said head is continuously moved along the pipeline while it applies said mixture, this displacement being effected by traction on the hose at an adjustable speed proportional to the feed rate of the components.

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

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

However, the methods proposed so far are not satisfactory, whether technically or economically. A known method, illustrated for example in document FR-A-2 445 220, consists in gluing a flexible tubular sheath applied by air pressure against the internal face of the buried pipe. However, sheaths of this kind have insufficient resistance in the long term. In addition, the application process requires connecting a large pneumatic device to one end of each section of the pipe to be treated, that is to say to excavate a large well at each access point. This is why it is preferable to make a coating with a hardenable product, applied directly to the buried pipe. The present invention aims to achieve this in an efficient and relatively inexpensive manner.

Publication GB-A-2,024,051 describes an embodiment, in which a coating is applied to the interior walls of a pipeline by means of a coating head moved by traction along the pipeline and connected to the component tanks by flexible hoses wound on a drum. The applied coating comprises a solvent, which allows it to be applied without temperature constraint. However, solvents are generally prohibited products for food applications, such as drinking water pipes. Consequently, the device described could not be suitable for the intended use.

Another publication, DE-A-24 34 920, describes a device for spraying a polyurethane foam used in the building. The two components of the foam are brought from the tanks to the spray gun by ducts heated by means of a circulation of hot water. This type of heating requires a large size of the conduits and does not guarantee the uniformity of the temperature along these conduits. Consequently, this device would not be suitable for the rehabilitation of buried pipelines.

• absence de solvants (réglementation pour produits alimentaires),
• adhésion correcte sur les surfaces métalliques nettoyées préalablement par des moyens classiques,
• séchage rapide pour remise en eau rapide des conduites, avec durée minimale d'immobilisation,
• enduction homogène et étanche,
• dureté élevée pour assurer la résistance à l'abrasion et faciliter les nettoyages futurs,
• possibilité d'application par enduction sur de grandes longueurs (100 à 150 m) et des diamètres de conduites allant de 80 à 500 mm,
• prix modéré des composants d'enduction, assurant une grande compétitivité du procédé par rapport à la technique classique par ouverture de tranchées et remplacement des tuyauteries par des conduites neuves.

The rehabilitation of drinking water pipes requires the use of special coating products with specific characteristics, such as:

• absence of solvents (regulations for food products),
• correct adhesion to metal surfaces cleaned beforehand by conventional means,
• quick drying for rapid re-filling of pipes, with minimum downtime,
• homogeneous and waterproof coating,
• high hardness to ensure abrasion resistance and facilitate future cleaning,
• possibility of application by coating over long lengths (100 to 150 m) and pipe diameters ranging from 80 to 500 mm,
• moderate price of coating components, ensuring a high competitiveness of the process compared to the conventional technique by opening trenches and replacing pipes with new pipes.

Currently, some two-component epoxy resins meet all of the above criteria, but there is no known process for applying them properly and economically at a distance greater than ten meters from the access point.

The invention makes it possible to solve this problem by a method of the type indicated above, characterized in that the coating head is continuously supplied with the two components when hot, at a temperature suitable for rapid hardening of the curable mixture. , by means of conduits heated uniformly over their entire length and housed in said hose and in that the two components are continuously mixed in the coating head to form the curable mixture.

In an advantageous form of the process, to apply the curable mixture, the coating head performs a spraying 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 area, in particular by hammering and / or smoothing.

• la tête d'enduction comporte un mélangeur pour mélanger les deux composants, des moyens rotatifs d'enduction pour appliquer le mélange des composants sur le pourtour intérieur de la canalisation, et au moins un moteur pour actionner le mélangeur et lesdits moyens d'enduction,
• ledit au moins un flexible comporte deux conduits d'alimentation pour lesdits composants, un conduit de transmission d'énergie pour le moteur de la tête, des moyens de chauffage électrique entourant les conduits d'alimentation pour les chauffer uniformément sur toute leur longueur, et un organe souple de traction permettant de tirer la tête d'enduction au moyen du flexible pour la faire avancer,
• l'unité de base comporte deux réservoirs chauffés pour lesdits composants, au moins une pompe pour transférer les composants des réservoirs aux conduits d'alimentation correspondants du flexible, un treuil à tambour sur lequel est fixée une extrémité arrière du flexible, des moyens de réglage de vitesse du treuil et/ou de la pompe, et des moyens de commande et de régulation du chauffage du flexible.

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 mixture of components to the inner periphery of the pipe, and at least one motor for actuating the mixer and said coating means,
• said at least one flexible hose comprises two supply conduits for said components, an energy transmission conduit for the head motor, electric heating means surrounding the supply conduits to heat them uniformly over their entire length, and a flexible traction member making it possible to pull the coating head by means of the hose to make it advance,
• the base unit comprises two heated tanks for said components, at least one pump for transferring the components from the tanks to the corresponding supply lines of the hose, a drum winch on which is fixed a rear end of the hose, adjustment means speed of the winch and / or the pump, and means for controlling and regulating the heating of the hose.

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

Preferably, the rotary coating means comprise a centrifugal turbine arranged to receive the said mixture leaving the mixer and distribute it over the interior wall of the pipeline.

The rotary coating means may further comprise at least one rotary brush, linked in rotation 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 rotary brush can have a common shaft driven by the motor of the coating head.

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

In the basic unit, the two component tanks can be provided with heating means. They may each include a pneumatic or electric mixer.

In addition, the pump and the winch may both have pneumatic drive means. The speed adjustment means may include a pneumatic synchronization device which controls the pump as a function of the speed of rotation of the winch.

The pump can advantageously be a two-cylinder pump operating in synchronism to pump said components respectively.

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 movable head, which can easily be exchanged or adapted to work in pipes of different diameters, with a versatile supply and traction hose and a base unit that can stay on the surface near a manhole access port, in the form of a small, easy-to-transport vehicle.

An essential aspect of the invention consists in bringing the components hot to the coating head and mixing them only in this head, which makes it possible to operate over a long length of pipe 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 there. Curing of the resin cannot begin in the hose, since the components are still separated there. On the other hand, it takes place quickly as soon as it leaves the coating head after passing through the rotary mixer and thanks to the relatively high temperature of the curable mixture.

• la figure 1 représente schématiquement l'utilisation d'un dispositif selon l'invention, comprenant une unité de base, un flexible ombilical chauffé et une tête d'enduction,
• la figure 2 est une vue latérale schématique de l'unité de base, suivant la flèche II de la figure 3,
• la figure 3 est une vue en plan de l'unité de base, partiellement coupée,
• la figure 4a est une vue en coupe transversale du flexible chauffé,
• la figure 4b est une vue en coupe transversale d'une variante de réalisation du flexible chauffé,
• la figure 5 est une vue en coupe longitudinale de la tête d'enduction,
• la figure 6 est un schéma des organes de l'unité de base qui délivrent au flexible les deux composants de la résine,
• la figure 7 est un schéma des organes de l'unité de base qui déplacent la tête d'enduction par enroulement du flexible sur un treuil, et
• la figure 8 est un schéma des organes de chauffage et de régulation de température du flexible.

Other characteristics and advantages of the invention will appear in the description of a preferred embodiment, given below by way of nonlimiting example, with reference to the appended drawings, in which:

• FIG. 1 schematically represents the use of a device according to the invention, comprising a base unit, a heated umbilical hose and a coating head,
• FIG. 2 is a schematic side view of the base unit, along arrow II of FIG. 3,
• FIG. 3 is a plan view of the base unit, partially cut 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 view in longitudinal section of the coating head,
• FIG. 6 is a diagram of the organs of the base unit which deliver the two resin components to the hose,
• FIG. 7 is a diagram of the components of the base unit which move the coating head by winding the hose on a winch, and
• FIG. 8 is a diagram of the heating and temperature regulation members of the hose.

Referring to Figure 1, a buried pipe consisting of a cast iron water pipe 1 opens into an access well 2 and is subject to an improvement treatment by applying a coating 3 of a two-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 an umbilical hose, and a base unit 6 preferably placed on the ground surface 7, near the access shaft 2. The unit 6 comprises a drum winch 8 on which the hose 5 is wound to pull the coating head in the direction of arrow A during work. One or more return pulleys 9 are supported by a temporary frame (not shown) for guiding the hose 5 in the area of the well. The hose can be put in place in line 1 beforehand by pulling it in the opposite direction to A from a second access point where the head 4 will be fixed to it.

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 respectively il and 12 for the first and the second liquid component of the epoxy resin (base resin and hardener), as well as a third duct 13 for compressed air, each duct being defined by a flexible tube in polyethylene 14 surrounded by a steel braid 15 to withstand high pressure, for example 200 bars for conduits 11 and 12 of 3/8 '' (9.5 mm), and a protective sheath made of polyethylene 16. A copper braid 17, for electrical resistance heating, respectively surrounds the conduits 11 and 12, the electrical connection between the two being provided by a loop at one end of the conduits. Each copper braid 17 is covered with an electrically insulating coating 18 made of polyurethane. In FIG. 4a, the assembly is surrounded by a thermal insulation layer 19 made of glass fibers and an outer sheath 20 made of heat-shrinkable synthetic material. The interior air volume existing between the conduits 11, 12, 13 and the layer 19 can be filled by an electrically insulating filling of polyurethane. 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 strip 102, covered with a polyurethane protective envelope 103. A signaling cable 90, connected to a temperature sensor, is placed inside said hose. This hose 5 preferably has a length of 150 m. As a variant, it would be possible to use several separate hoses each having a conduit, but the unit solution provided here is better, thermally and for convenience of use. The steel braids 15 allow the hose to transmit a sufficient tensile force to the coating head. In the alternative embodiment illustrated in FIG. 4b, an additional traction cable 15 ′, disposed along the central axis of said hose, is provided to assist in the transmission of said traction 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 electrical block 24 with transformer which is supplied by the mains and delivers a low voltage of 48 V for heating. It also contains a pneumatic circuit 25 supplied with compressed air through an inlet valve 26 and a filter 27. A tank 28 for the base resin and a tank 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 in an insulating mass 32 and connected to a two-cylinder pneumatic pump 33 which delivers the two separate components of the resin in a predetermined proportion to rotary connections 34 and 35 respectively 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 fixed to the drum. Through the hollow shaft 36, its conduits 11 and 12 for the liquid components are connected to the rotary couplings 34 and 35, its compressed air conduit 13 is connected to a pneumatic rotary coupling 40 provided with a valve 41, and its electrical circuits are connected to corresponding rotary couplings 42. The shaft 36 of the winch, carrying the drum 37, is rotated by a pneumatic gear motor 43 via chain transmissions 44 and 45, a limiter of torque 46 and of a clutch 47. All the functions of the device are commanded 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 center the head 4. At its front end connected to the hose 5 (not shown), there is 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 impeller 57 and a smoothing brush 58 forming the rear end of the head 4. An inlet connector 60 receives the base resin from the conduit 11 of the hose, which is led to the mixer 56 at through a channel 61 and a non-return valve 62. Identical members leading the hardener to the mixer 56 where the two hot components will form a curable liquid mixture which is ejected by a ring of axial nozzles 63 on the turbine 57, formed here of 'a slightly conical disc. Thanks to the progressive advancement of the head 4, the sprayed liquid lines the entire inner wall of the pipe and forms a thin coating, for example from 0.3 to 1 mm approximately 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 ensures a final smoothing of the coating; if necessary, it can be preceded by a hammering member promoting the elimination of any air bubbles.

The operation of the device according to the invention will be better understood by referring to the circuit diagrams shown in FIGS. 6 to 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 rotary union 34 through a valve 67, and a piston plunger in a second cylinder 68 to deliver the hardener from the tank 29 to the rotary union 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 pipe 71 whose pressure is displayed by a manometer 72. The pump 33 receives the air compressed through an adjustable flow limiter 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. Elements 72 to 78 are found in the control panel 48.

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

FIG. 8 illustrates the heating and temperature regulation means of the hose 5, in order to maintain the components of the resin and the compressed air at the desired temperature. In the electric block 24 (FIG. 3), a transformer 84 monophase 220/48 V with four steps is associated with a switch 85 with five positions to deliver a staggered secondary voltage of 12 to 48 V, indicated by a voltmeter 86. Through the rotary couplings 42, this voltage is applied to the strands going and returning from the heating braid 17 of the hose 5, extending between a rear insulating joint 87 and a front insulating joint 88 of the hose 5. Near the latter is the temperature sensor 89 which, by a signal cable 90, a rotary connector 42 'and an amplifier 91, acts on a thyristor 92 regulating the primary of the transformer 84 to limit the 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 (15)

Method for applying a two-component resin-based coating in a buried pipe, in particular in a cast iron drinking water pipe, according to which a mobile coating head (4) and at least one flexible pipe are placed in the pipe ( 5) connecting this head to an access point to the pipe, said head being arranged to apply a hardenable mixture on the inner wall of the pipe (1) to form the coating (3), said head (4) is moved continuously along the pipe (1) while it applies the said mixture, by pulling on the hose (5) at an adjustable speed proportional to the supply flow of the components, characterized in that the supply is continuously coating head (4) with the two components hot, at a temperature suitable for rapid hardening of the curable mixture, by means of conduits heated uniformly over their entire length and housed in said flexible hose (5) and in that the two components are continuously mixed in the coating head to form the curable mixture. Method according to claim 1, characterized in that, in order to apply the curable mixture, the coating head (4) performs an operation of spraying the mixture, forming a layer of coating (3) on the internal wall of the pipeline, and simultaneously a mechanical finishing operation of said layer behind the projection area, in particular by hammering and / or smoothing. Device for applying a two-component resin-based coating in a buried pipe, in particular in a cast iron drinking water pipe, for implementing the method according to claim 1, comprising a base unit (6) intended for be placed outside the pipe (1) near an access point (2) to the pipe, a mobile coating head (4) intended to be placed in the pipe, and at least one flexible (5) connecting the coating head to the base unit, characterized in than : - the coating head (4) comprises a mixer (56) for mixing the two components, rotary coating means (57, 58) for applying the mixture of components to the inner wall of the pipe, and at least one motor (53) for actuating the mixer and said coating means, - Said at least one flexible (5) comprises two supply conduits (11, 12) for said components, an energy transmission conduit (13) for the motor of the head, electric heating means (17) surrounding the supply conduits to heat them uniformly over their entire length, and a flexible traction member (15, 15 ') enabling the coating head to be pulled by means of the flexible hose to make it advance, - the base unit (6) comprises two heated tanks (28, 29) for said components, at least one pump (33) for transferring the components from the tanks to the corresponding supply lines of the hose, a drum winch (8 ) on 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. Device according to claim 3, characterized in that the motor (53) of the coating head is a pneumatic motor and in that said energy transmission duct (13) is a compressed air duct. Device according to claim 3, characterized in that the rotary coating means comprise a centrifugal turbine (57) arranged to receive said mixture leaving the mixer and distribute it over the interior wall of the pipeline. Device according to claim 5, characterized in that the rotary coating means further comprise at least one rotary brush (58), linked in rotation to the turbine (57) and arranged axially behind it with respect to the direction of advance of the coating head. Device according to claim 6, characterized in that the mixer, the turbine and the rotary brush have a common shaft (55) driven by the motor (53) of the coating head. Device according to claim 3, characterized in that the heating means of the hose are electric and comprise at least one resistive element (17) extending substantially over the entire length of the hose. Device according to claims 4 and 8, characterized in that the compressed air duct (13) is heated by the electrical heating means. Device according to claim 8, characterized in that the hose (5) comprises at least one temperature sensor (89) which is connected to the means for controlling and regulating the heating of the hose. Device according to claim 3, characterized in that the two component tanks (28, 29) are provided with heating means (30). Device according to claim 11, characterized in that said reservoirs each comprise a pneumatic mixer (31). Device according to claim 3, characterized in that the pump (33) and the winch (8) both have pneumatic drive means. Device according to claim 13, characterized in that the speed adjustment means comprise a pneumatic synchronization device which controls the pump (33) according to the winch rotation speed (8). Device according to claim 13 or 14, characterized in that the pump (33) is a two-cylinder pump operating in synchronism to pump said components respectively.

Images