CA1276783C - Apparatus for internally coating pipes - Google Patents
Apparatus for internally coating pipesInfo
- Publication number
- CA1276783C CA1276783C CA000526279A CA526279A CA1276783C CA 1276783 C CA1276783 C CA 1276783C CA 000526279 A CA000526279 A CA 000526279A CA 526279 A CA526279 A CA 526279A CA 1276783 C CA1276783 C CA 1276783C
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- compressed air
- coating material
- pigs
- spraying device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Coating Apparatus (AREA)
- Spray Control Apparatus (AREA)
Abstract
Abstract:
The invention provides an apparatus for coating the internal surfaces of pipes. The apparatus comprises two pigs which engage against the internal pipe surfaces and are movable through the pipe. The pigs define an intermediate zone between them for receiving the coating material. A spraying device capable of spraying material in the radial direction communicates with the intermediate zone via a material feed line. Upon being drawn through the pipe, the coating material is fed from the inter-mediate zone to the spraying device which atomizes the material and sprays it onto the internal surfaces of the pipe. This assures complete coating of the internal surfaces but avoids the need for coating material feed lines leading to a material reservoir outside the pipe.
The invention provides an apparatus for coating the internal surfaces of pipes. The apparatus comprises two pigs which engage against the internal pipe surfaces and are movable through the pipe. The pigs define an intermediate zone between them for receiving the coating material. A spraying device capable of spraying material in the radial direction communicates with the intermediate zone via a material feed line. Upon being drawn through the pipe, the coating material is fed from the inter-mediate zone to the spraying device which atomizes the material and sprays it onto the internal surfaces of the pipe. This assures complete coating of the internal surfaces but avoids the need for coating material feed lines leading to a material reservoir outside the pipe.
Description
~276783 Apparatus for internall~_coating pipes The invention relates to an apparatus for the internal coating of pipes.
In the chemical field, in particular in natural gas and oil transportation, water containing corrosive components (sulfur, salt) occurs in considerable quantities in materials being transported by pipeline.
Such water is often transported through welded steel pipes at times under very high pressures (up to 200 bar). If the pipes are not protected on the inside, they are quickly destroyed by corrosion, which adversely affects the operation of the transmission system and considerably endangers the environment.
To reduce such corrosion it has been suggested to install plastic tubes within the steel pipes. This, however, leads to an undesirable reduction of the cross sectional area of the pipes.
For the prevention of corrosion, it is also known to coat the interior of pipes with a material which is resistant to the accumulated corrosive media. Such coating is carried out in pipes of large diameters by means of mobile vehicles which move through the pipes spraying the coating material onto the internal walls.
This i5 not possible for pipes of small diameter.
Instead, they may be coated, ~or example, by a plug consisting of two "pigs" between which the normally fluid coating material is located, and which is drawn back and ~.~76783 forth through the pipe. Incidentallv, the term "pig" is used in this art as the name for a type of movable sealing element which completely blocks the pipe and usually has an elastic material at its edges to form a seal where the edges meet the pipe interior. Such a procedure has the disadvantage that weak points occur in the coating in the region of uneven parts of the internal pipe surface, particularly at the weld seams, where the coating material is stripped off by the second pig and thus form points where the corrosive media may attack the pipes.
Another process for coating is airless paint spraying (the so-called airless-process~. In this, the coating material from a tank located outside the pipe is pumped to a nozzle in the pipe by means of a high pressure pump and a high pressure tube. The high pressure in the tube causes the material to be sprayed and coat the internal surface of the pipe. The disadvantage of such a system is that, as a result of the considerable pressure loss caused by friction in the high pressure pipe, only very limited pipe lengths may be coated.
Particularly in oil and natural gas transmission pl pe~7cs systems, pipline often extend underground for long stretches and so the new coatings of the inner tube sur-faces re~uired at regular yearly or half-yearly intervals causes a considerable expenditure. In order to effect the periodic coating by one of the known apparatuses, stretches of about 300 m have to be dug up and then the pipe cut into.
An object of the invention is therefore to provide an apparatus which enables very long thin pipes to be uni-formly and reliably coated on the inside without permit-ting the coating to become too thin or completely broken at irregularities of the internal pipe surface.
According to the invention there is provided apparatus for coating the internal surfaces of pipes, comprising:
first and second pigs which are movable through the pipe and engage the internal pipe surfaces at their peripheral ~767a3 edges, said pigs defining an intermediate zone between them; a spraying device movable through the pipe with said pigs; and a coating material feed line interconnecting the intermediate zone with the spraying device so that coating material located in the intermediate zone may be fed the spraying nozzle for coating said internal surfaces.
By the use of such an apparatus, the coating material is carried along in the immediate vicinity of the spraying device so that practically no pressure loss takes place during the delivery of the coating material to the spraying device. At the same time, the atomizing spraying device creates, without direct contact, an even inner coating on the pipe even at the weld seams and other uneven parts of the inner surface of the pipe.
Moreover, the pigs, which engage elastically with the pipe inner surface, spread the coating material located in the intermediate zone onto the pipe inner surface as a thin base film so that pores and indentations that are difficult for the spraying device to access are prior-coated with the coating material when the spraying device reaches them.
Regions, particularly at the weld seams, from which the second pig removes the coating right down to a base film, are further covered with additional coating material by the spraying device, which normally acts radially.
Using the apparatus of the invention pipes having lengths several times those which may be sprayed with conventional equipment, can be accommodated. The number of expensive excavation points, in the case of pipes extending underground, can thus be reduced. By reason of the even internal coating which is achieved, it is also possible, if desired, to increase the time interval between two successive coating operations without risking serious corrosion.
A particular advantage is obtained when the spraying device has a spinning disc or a rotating nozzle which is caused to rotate by compressed air from a compressed air ~276783 reservoir. Alternatively, an electric motor can be used as the drive or a non-rotating spray nozzle may be provided.
In order to atomize the coating material, the material may be pressurized either by compressed air from the com-pressed air reservoir or by feed pressure from an electric feed pump which, by means of a feed element which projects into the intermediate zone, forces coating material through a material feed line to the spray nozzle.
Preferably, pull cords are attached to the second pig and extend through the intermediate zone and the first pig and are coupled to a cord winch located outside the pipe.
By pulling the pull cords, the coating material in the intermediate zone is pressurized and fed to the spraying ~ device through a material feed tube by the consequent increased pressure. A feed pump for the transportation of the coating material to the nozzle of the spraying device is not necessary in this embodiment of the invention.
It is advantageous, if the compressed air tube in the intermediate zone and between the compressed air reservoir and the first pig is intrinsically elastic and spirally wound. It can then adapt itself to the reducing distance between the two pigs.
In order to allow for rotational movement of the pigs, the attachments of the compressed air feed tube may be via rotatable couplings.
In the following, three preferred embodient~ of the invention are described in detail with reference to the accompanying drawing, in which:
Fig. 1 is a longitudinal cross-section of a pipe containing a first embodiment of the apparatus of the invention;
Fig. 2 is a longitudinal cross-section of a pipe containing a second embodiment of the apparat U5 of the invention; and ~276783 Fig. 3 a longitudinal cross-section of a pipe containing a third embodiment of the equipment.
A pipe 10 is to be provided on its inner surface with an internal layer of coating material 16.
The apparatus used for the internal coating according to Fig. 1 has a compressed air reservoir 20 with a pressure of, for example, 200 bar which is secured by slide collars 21. It is provided with a high pressure shutoff valve 22 to which a pressure reducer 23 is connected. The outlet of the pressure reducer is located on the axis of the axially symmetrical apparatus and consequently also on the axis of the pipe.
An elastic, spirally-wound section 30a of a pressure tube 30 is attached to the pressure reducer 23. The spiral winding is concentric with the axis of the apparatus and the pipe. The section 30a may also eotate freely since it is attached to the pressure reducer via a rotatable coupling 31a.
The end of the section 30a of the pressure tubing 30 opposite to the compressed air reservoir 20 is connected via a rotatable coupling 31b to a solid conduit section 32a in a first pig 40. The pig 40 consists of several spaced layers which completely occupy the cross sectional area of the pipe and have elastic outer edges which engage against the inner surface of the pipe.
The solid conduit section 32a of the pressure tubing 30 runs along the axis of the first pig 40. On the other side of the pig 40, a further spirally-wound section 30b of the pressure tubing 30 is located concentrically to the axis of the apparatus and is attached to the conduit section 32a via a rotatable coupling 31c. This leads to a solid conduit section 32~ located in a second pig 41, and is attached thereto via a rotatable coupling 31d. The second pig 41 is constructed in the same way as the first ~276783 pig 40 and likewise occupies the entire cross sectional area of the pipe. An intermediate zone 42 is located between the two pigs 40, 41 which is occupied by coating material 16.
Two pull cords SOa, 50b are attached to the second pig 41 by means of eyelets 51. The pull cords 50a, 50b extend symmetrically parallel but non-centrally from the second pig 41, through the intermediate zone 42 to the first pig 40 through which they extend via sealing bushings but to which they are not attached. The pull cords 50a, 50b then extend further to eyelets 53 on the compressed air reservoir 20. From there the pull cords 50a, 50b separ-ately extend from further eyelets 53 to a common eyelet 54 located on the axis of the apparatus, and from this an axially-extending pull cord 50c extends to a cord winder (not shown) at the end of the pipe 10.
The solid conduit 32b of the pressure tubing 30 which extends through the second pig 41 is provided with a shut-off valve 33 on the side of the pig 41 opposite to the intermediate zone 42. From there, the compressed air tubing 30 extends to spray apparatus 70, 71 which is rigidly fixed to the second pig 41 and which comprises a compressed air turbine 70 carrying a rotational nozzle 71.
The pig 41 additionally has coating material feed tubes 60a, 60b extending through it and the open ends of the tubes communicate with the intermediate zone 42 and with the rotational nozzle 71.
The internal coating of the pipe 10 takes place in the following manner:
After cleaning of the internal surface 11 of the pipe the entire apparatus is pulled through the pipe by means of a cord winch in the direction opposite to the coating direction larrow 15). Alternatively, the pull cord 50 may be shot or pulled through the pipe 10. Next, the individual parts are then combined with each other in a separate, additional pipe piece (not shown) and the 1~76783 intermediate zone between the pigs 40 and 41 filled with coating material 16.
A preferably steplessly acting winch pulls the compressed air reservoir 20 and the second pig 41 through the pipe 10 via pull cords 50c, 50a, 50b at a predeter-mined speed. The first pig 40 is not pulled by any of the pull cords but it is pushed in the direction of pull by the coating material 16 which dams up in front of the second pig 41 in the intermediate zone 42. The pressure thereby generated drives the coating material 16 through the material feed tubes 60 into the rotary nozzle 71 of the compressed air turbine 70. The compressed air drives the compressed air turbine 70 upon corresponding actuation of the shutoff valves 22, 23 at a rotational speed of, for example, 20,000 rpm. The high rotational speed causes the coating material 16 to be atomized. A stream of atomized coating material 16 is then sprayed from the rotary nozzle 71 onto the internal surface 11 of the pipe.
upon movement of the apparatus through the pipe 10, the second pig 41 spreads further coating material behind it from the intermediate zone 42 directly onto the internal surface of the pipe, and the spray coating from the spray equipment then forms on this primer layer.
As coating proceeds, the supply of coating material 16 in the intermediate zone 42 between the two pigs 40, 41 diminishes. The coating space 42 thus becomes smaller, and the two pigs 40, 41 draw closer to each other. The section 30b of the pressure tube 30 in the intermediate zoné 42 then has a smaller axial length to traversé; the spiral windings are thereby pressed together.
Conversely, the distance between the two rotatable couplings 31a, 31b, and therefore the distance between the pressure reducer 23 of the compressed air reservoir 20 and the first pig 40 increases, because the distance between the compressed air reservoir 20 and the second pig 41 remains constant. The section 30a of the compressed air t ~7~78~
tube 30 must consequently bridge a longer axial distance, and its spiral windings are therefore drawn apart.
The rotational couplings 31 in the compressed air tubing 30 are provided to accommodate forces which may arise as a result of rotary motions of the pigs 40, 41.
The second embodiment shown in Figure 2 is largely similar to the first embodiment. Instead of the compressed air supply, an electric motor 70' is located in the spray device 70', 71. This is provided with current through an electrical lead 57, which is provided as a core in the pull cord 50. The pull cord 50 extends through sealing bushings in the first pig 40, through the intermediate zone 42, and is attached to the second pig 41 at the attachment point 56.
Metering valves 61 are provided in the coating material feed tubes 60 for better matching of the coating material flow with the coating speed (speed of progression of the apparatus through the tube) and adjustment of the coating thickness on the internal surface 11. A normally desirable coating thickness is about 400~ m.
The embodiment shown in Fig. 3 comprises, if necessary, a first pig 40 and a second pig 41, between which the intermediate zone 42 is provided and which is filled with the coating material 16. A central eyelet 56 is located on the second pig 41 on which the pull cord 50 is fastened.
The pull cord extends through the intermediate zone 42, through a central, sealing bushing 52 in the first pig 40 and to an end of the pipe 10. The pull cord 50 is movable relative to the sealing bushing 52 so that the first pig 40 may approach the second pig 41 as the coating material 16 is depleted from the intermediate zone 42.
A booster pump 80 is located behind the second pig in the pùlling direction by means of coupling links 85. ~he pump is driven by an electric motor 81 and is centrally positioned in pipe 10 by sliding elements 21. A booster element 82 of the booster pump 80 extends rearwardly from ~76783 the electric motor 81 through the second pig 41 and feeds the coating material 16 into the opening of the material feed line 60, which in turn extends through the second pig 41, via a metering valve 61 for the coating material to the nozzle 71 of the spray device. The spray device 70', 71 is coupled via coupling links 85 behind the booster pump 80, 81 and is positioned centrally in the tube 10, if necessary, by means of sliding elements 21. The nozzle 71, which is rotated by an electric motor 70', then sprays the coating material uniformly against internal surface of the pipe.
In the chemical field, in particular in natural gas and oil transportation, water containing corrosive components (sulfur, salt) occurs in considerable quantities in materials being transported by pipeline.
Such water is often transported through welded steel pipes at times under very high pressures (up to 200 bar). If the pipes are not protected on the inside, they are quickly destroyed by corrosion, which adversely affects the operation of the transmission system and considerably endangers the environment.
To reduce such corrosion it has been suggested to install plastic tubes within the steel pipes. This, however, leads to an undesirable reduction of the cross sectional area of the pipes.
For the prevention of corrosion, it is also known to coat the interior of pipes with a material which is resistant to the accumulated corrosive media. Such coating is carried out in pipes of large diameters by means of mobile vehicles which move through the pipes spraying the coating material onto the internal walls.
This i5 not possible for pipes of small diameter.
Instead, they may be coated, ~or example, by a plug consisting of two "pigs" between which the normally fluid coating material is located, and which is drawn back and ~.~76783 forth through the pipe. Incidentallv, the term "pig" is used in this art as the name for a type of movable sealing element which completely blocks the pipe and usually has an elastic material at its edges to form a seal where the edges meet the pipe interior. Such a procedure has the disadvantage that weak points occur in the coating in the region of uneven parts of the internal pipe surface, particularly at the weld seams, where the coating material is stripped off by the second pig and thus form points where the corrosive media may attack the pipes.
Another process for coating is airless paint spraying (the so-called airless-process~. In this, the coating material from a tank located outside the pipe is pumped to a nozzle in the pipe by means of a high pressure pump and a high pressure tube. The high pressure in the tube causes the material to be sprayed and coat the internal surface of the pipe. The disadvantage of such a system is that, as a result of the considerable pressure loss caused by friction in the high pressure pipe, only very limited pipe lengths may be coated.
Particularly in oil and natural gas transmission pl pe~7cs systems, pipline often extend underground for long stretches and so the new coatings of the inner tube sur-faces re~uired at regular yearly or half-yearly intervals causes a considerable expenditure. In order to effect the periodic coating by one of the known apparatuses, stretches of about 300 m have to be dug up and then the pipe cut into.
An object of the invention is therefore to provide an apparatus which enables very long thin pipes to be uni-formly and reliably coated on the inside without permit-ting the coating to become too thin or completely broken at irregularities of the internal pipe surface.
According to the invention there is provided apparatus for coating the internal surfaces of pipes, comprising:
first and second pigs which are movable through the pipe and engage the internal pipe surfaces at their peripheral ~767a3 edges, said pigs defining an intermediate zone between them; a spraying device movable through the pipe with said pigs; and a coating material feed line interconnecting the intermediate zone with the spraying device so that coating material located in the intermediate zone may be fed the spraying nozzle for coating said internal surfaces.
By the use of such an apparatus, the coating material is carried along in the immediate vicinity of the spraying device so that practically no pressure loss takes place during the delivery of the coating material to the spraying device. At the same time, the atomizing spraying device creates, without direct contact, an even inner coating on the pipe even at the weld seams and other uneven parts of the inner surface of the pipe.
Moreover, the pigs, which engage elastically with the pipe inner surface, spread the coating material located in the intermediate zone onto the pipe inner surface as a thin base film so that pores and indentations that are difficult for the spraying device to access are prior-coated with the coating material when the spraying device reaches them.
Regions, particularly at the weld seams, from which the second pig removes the coating right down to a base film, are further covered with additional coating material by the spraying device, which normally acts radially.
Using the apparatus of the invention pipes having lengths several times those which may be sprayed with conventional equipment, can be accommodated. The number of expensive excavation points, in the case of pipes extending underground, can thus be reduced. By reason of the even internal coating which is achieved, it is also possible, if desired, to increase the time interval between two successive coating operations without risking serious corrosion.
A particular advantage is obtained when the spraying device has a spinning disc or a rotating nozzle which is caused to rotate by compressed air from a compressed air ~276783 reservoir. Alternatively, an electric motor can be used as the drive or a non-rotating spray nozzle may be provided.
In order to atomize the coating material, the material may be pressurized either by compressed air from the com-pressed air reservoir or by feed pressure from an electric feed pump which, by means of a feed element which projects into the intermediate zone, forces coating material through a material feed line to the spray nozzle.
Preferably, pull cords are attached to the second pig and extend through the intermediate zone and the first pig and are coupled to a cord winch located outside the pipe.
By pulling the pull cords, the coating material in the intermediate zone is pressurized and fed to the spraying ~ device through a material feed tube by the consequent increased pressure. A feed pump for the transportation of the coating material to the nozzle of the spraying device is not necessary in this embodiment of the invention.
It is advantageous, if the compressed air tube in the intermediate zone and between the compressed air reservoir and the first pig is intrinsically elastic and spirally wound. It can then adapt itself to the reducing distance between the two pigs.
In order to allow for rotational movement of the pigs, the attachments of the compressed air feed tube may be via rotatable couplings.
In the following, three preferred embodient~ of the invention are described in detail with reference to the accompanying drawing, in which:
Fig. 1 is a longitudinal cross-section of a pipe containing a first embodiment of the apparatus of the invention;
Fig. 2 is a longitudinal cross-section of a pipe containing a second embodiment of the apparat U5 of the invention; and ~276783 Fig. 3 a longitudinal cross-section of a pipe containing a third embodiment of the equipment.
A pipe 10 is to be provided on its inner surface with an internal layer of coating material 16.
The apparatus used for the internal coating according to Fig. 1 has a compressed air reservoir 20 with a pressure of, for example, 200 bar which is secured by slide collars 21. It is provided with a high pressure shutoff valve 22 to which a pressure reducer 23 is connected. The outlet of the pressure reducer is located on the axis of the axially symmetrical apparatus and consequently also on the axis of the pipe.
An elastic, spirally-wound section 30a of a pressure tube 30 is attached to the pressure reducer 23. The spiral winding is concentric with the axis of the apparatus and the pipe. The section 30a may also eotate freely since it is attached to the pressure reducer via a rotatable coupling 31a.
The end of the section 30a of the pressure tubing 30 opposite to the compressed air reservoir 20 is connected via a rotatable coupling 31b to a solid conduit section 32a in a first pig 40. The pig 40 consists of several spaced layers which completely occupy the cross sectional area of the pipe and have elastic outer edges which engage against the inner surface of the pipe.
The solid conduit section 32a of the pressure tubing 30 runs along the axis of the first pig 40. On the other side of the pig 40, a further spirally-wound section 30b of the pressure tubing 30 is located concentrically to the axis of the apparatus and is attached to the conduit section 32a via a rotatable coupling 31c. This leads to a solid conduit section 32~ located in a second pig 41, and is attached thereto via a rotatable coupling 31d. The second pig 41 is constructed in the same way as the first ~276783 pig 40 and likewise occupies the entire cross sectional area of the pipe. An intermediate zone 42 is located between the two pigs 40, 41 which is occupied by coating material 16.
Two pull cords SOa, 50b are attached to the second pig 41 by means of eyelets 51. The pull cords 50a, 50b extend symmetrically parallel but non-centrally from the second pig 41, through the intermediate zone 42 to the first pig 40 through which they extend via sealing bushings but to which they are not attached. The pull cords 50a, 50b then extend further to eyelets 53 on the compressed air reservoir 20. From there the pull cords 50a, 50b separ-ately extend from further eyelets 53 to a common eyelet 54 located on the axis of the apparatus, and from this an axially-extending pull cord 50c extends to a cord winder (not shown) at the end of the pipe 10.
The solid conduit 32b of the pressure tubing 30 which extends through the second pig 41 is provided with a shut-off valve 33 on the side of the pig 41 opposite to the intermediate zone 42. From there, the compressed air tubing 30 extends to spray apparatus 70, 71 which is rigidly fixed to the second pig 41 and which comprises a compressed air turbine 70 carrying a rotational nozzle 71.
The pig 41 additionally has coating material feed tubes 60a, 60b extending through it and the open ends of the tubes communicate with the intermediate zone 42 and with the rotational nozzle 71.
The internal coating of the pipe 10 takes place in the following manner:
After cleaning of the internal surface 11 of the pipe the entire apparatus is pulled through the pipe by means of a cord winch in the direction opposite to the coating direction larrow 15). Alternatively, the pull cord 50 may be shot or pulled through the pipe 10. Next, the individual parts are then combined with each other in a separate, additional pipe piece (not shown) and the 1~76783 intermediate zone between the pigs 40 and 41 filled with coating material 16.
A preferably steplessly acting winch pulls the compressed air reservoir 20 and the second pig 41 through the pipe 10 via pull cords 50c, 50a, 50b at a predeter-mined speed. The first pig 40 is not pulled by any of the pull cords but it is pushed in the direction of pull by the coating material 16 which dams up in front of the second pig 41 in the intermediate zone 42. The pressure thereby generated drives the coating material 16 through the material feed tubes 60 into the rotary nozzle 71 of the compressed air turbine 70. The compressed air drives the compressed air turbine 70 upon corresponding actuation of the shutoff valves 22, 23 at a rotational speed of, for example, 20,000 rpm. The high rotational speed causes the coating material 16 to be atomized. A stream of atomized coating material 16 is then sprayed from the rotary nozzle 71 onto the internal surface 11 of the pipe.
upon movement of the apparatus through the pipe 10, the second pig 41 spreads further coating material behind it from the intermediate zone 42 directly onto the internal surface of the pipe, and the spray coating from the spray equipment then forms on this primer layer.
As coating proceeds, the supply of coating material 16 in the intermediate zone 42 between the two pigs 40, 41 diminishes. The coating space 42 thus becomes smaller, and the two pigs 40, 41 draw closer to each other. The section 30b of the pressure tube 30 in the intermediate zoné 42 then has a smaller axial length to traversé; the spiral windings are thereby pressed together.
Conversely, the distance between the two rotatable couplings 31a, 31b, and therefore the distance between the pressure reducer 23 of the compressed air reservoir 20 and the first pig 40 increases, because the distance between the compressed air reservoir 20 and the second pig 41 remains constant. The section 30a of the compressed air t ~7~78~
tube 30 must consequently bridge a longer axial distance, and its spiral windings are therefore drawn apart.
The rotational couplings 31 in the compressed air tubing 30 are provided to accommodate forces which may arise as a result of rotary motions of the pigs 40, 41.
The second embodiment shown in Figure 2 is largely similar to the first embodiment. Instead of the compressed air supply, an electric motor 70' is located in the spray device 70', 71. This is provided with current through an electrical lead 57, which is provided as a core in the pull cord 50. The pull cord 50 extends through sealing bushings in the first pig 40, through the intermediate zone 42, and is attached to the second pig 41 at the attachment point 56.
Metering valves 61 are provided in the coating material feed tubes 60 for better matching of the coating material flow with the coating speed (speed of progression of the apparatus through the tube) and adjustment of the coating thickness on the internal surface 11. A normally desirable coating thickness is about 400~ m.
The embodiment shown in Fig. 3 comprises, if necessary, a first pig 40 and a second pig 41, between which the intermediate zone 42 is provided and which is filled with the coating material 16. A central eyelet 56 is located on the second pig 41 on which the pull cord 50 is fastened.
The pull cord extends through the intermediate zone 42, through a central, sealing bushing 52 in the first pig 40 and to an end of the pipe 10. The pull cord 50 is movable relative to the sealing bushing 52 so that the first pig 40 may approach the second pig 41 as the coating material 16 is depleted from the intermediate zone 42.
A booster pump 80 is located behind the second pig in the pùlling direction by means of coupling links 85. ~he pump is driven by an electric motor 81 and is centrally positioned in pipe 10 by sliding elements 21. A booster element 82 of the booster pump 80 extends rearwardly from ~76783 the electric motor 81 through the second pig 41 and feeds the coating material 16 into the opening of the material feed line 60, which in turn extends through the second pig 41, via a metering valve 61 for the coating material to the nozzle 71 of the spray device. The spray device 70', 71 is coupled via coupling links 85 behind the booster pump 80, 81 and is positioned centrally in the tube 10, if necessary, by means of sliding elements 21. The nozzle 71, which is rotated by an electric motor 70', then sprays the coating material uniformly against internal surface of the pipe.
Claims (11)
1. Apparatus for coating the internal surfaces of pipes, comprising:
first and second pigs which are movable through the pipe and engage the internal pipe surfaces at their peripheral edges, said pigs defining an intermediate zone between them;
a spraying device movable through the pipe with said pigs; and a coating material feed line interconnecting the intermediate zone with the spraying device so that coating material located in the intermediate zone may be fed the spraying nozzle for coating said internal surfaces.
first and second pigs which are movable through the pipe and engage the internal pipe surfaces at their peripheral edges, said pigs defining an intermediate zone between them;
a spraying device movable through the pipe with said pigs; and a coating material feed line interconnecting the intermediate zone with the spraying device so that coating material located in the intermediate zone may be fed the spraying nozzle for coating said internal surfaces.
2. Apparatus according to Claim 1 wherein said spraying device is attached to one of said pigs and said material feed lines passes through said one pig.
3. Apparatus according to Claim 1, further comprising a pull cord for pulling said apparatus through said pipe, said pull cord being attached to one of said pigs and passing through the other via sealing bushings and being connected to a cord winch at one end of the pipe.
4. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein said spraying device is operated by compressed air and is attached to a compressed air reservoir located in said apparatus via a compressed air tube.
5. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein said spraying device comprises a rotary nozzle which is rotatably driven by compressed air or by an electric motor.
6. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein said spraying device is operated by compressed air from a compressed air reservoir, and wherein said reservoir is located outside said intermediate zone and is provided with sliding elements which permit it to slide through the pipe.
7. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein said spraying device is operated by compressed air, a compressed air reservoir is located at the front of the apparatus in the direction of travel, said nozzle is located at a rear of the apparatus in the direction of travel and a compressed air tube interconnecting said reservoir and said nozzle extends through said pigs and said intermediate zone and has spirally wound sections to allow for changes in the spacing between the two pigs.
8. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein a booster pump is provided for enhancing the flow of coating material from the intermediate zone to the spraying device through said feed line.
9. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein a booster pump is attached to one of said pigs and comprises a feed element which projects into said inter-mediate zone and forces coating material from said zone into said coating material feed line.
10. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein a watering valve is provided in said coating material feed line so that the amount of coating material supplied to the spraying device may be regulated.
11
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000526279A CA1276783C (en) | 1986-12-24 | 1986-12-24 | Apparatus for internally coating pipes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000526279A CA1276783C (en) | 1986-12-24 | 1986-12-24 | Apparatus for internally coating pipes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1276783C true CA1276783C (en) | 1990-11-27 |
Family
ID=4134639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000526279A Expired - Fee Related CA1276783C (en) | 1986-12-24 | 1986-12-24 | Apparatus for internally coating pipes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1276783C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104428072A (en) * | 2012-07-12 | 2015-03-18 | 国际壳牌研究有限公司 | A pipeline pig and method for using the pig |
| US11703176B2 (en) | 2017-11-06 | 2023-07-18 | Warren Peterson | Apparatus and method for loading a pig into a pipeline |
-
1986
- 1986-12-24 CA CA000526279A patent/CA1276783C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104428072A (en) * | 2012-07-12 | 2015-03-18 | 国际壳牌研究有限公司 | A pipeline pig and method for using the pig |
| CN104428072B (en) * | 2012-07-12 | 2017-08-04 | 国际壳牌研究有限公司 | Wiper and the method using wiper |
| US11703176B2 (en) | 2017-11-06 | 2023-07-18 | Warren Peterson | Apparatus and method for loading a pig into a pipeline |
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