CA1257178A - Method and apparatus for removing pipe coatings - Google Patents
Method and apparatus for removing pipe coatingsInfo
- Publication number
- CA1257178A CA1257178A CA000455779A CA455779A CA1257178A CA 1257178 A CA1257178 A CA 1257178A CA 000455779 A CA000455779 A CA 000455779A CA 455779 A CA455779 A CA 455779A CA 1257178 A CA1257178 A CA 1257178A
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- nozzles
- pipe surface
- discs
- circumferential direction
- 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
Links
Abstract
ABSTRACT OF THE DISCLOSURE
Bituminous or other coatings are removed from a pipe surface by directing one or more powerful water jets against such pipe surface. The water jets have a pressure of between 300 and 600 bars, are directed against the pipe surface under an acute angle, when seen in circumferential direction of the pipe, and are moved in longitudinal as well as in circumferential direction along the pipe surface.
Bituminous or other coatings are removed from a pipe surface by directing one or more powerful water jets against such pipe surface. The water jets have a pressure of between 300 and 600 bars, are directed against the pipe surface under an acute angle, when seen in circumferential direction of the pipe, and are moved in longitudinal as well as in circumferential direction along the pipe surface.
Description
- - \
Br/lh/l ~257~78 Method and apparatus for removing pipe coatings.
This invention relates to the field of remo~ing pipe coatings and more in particular to a method and apparatus for removin~ bituminous or other coatings from a pipe surface, e.g. a portion of a pipeline.
Pipes in the ground are often provided with an exterior bituminous coating comprising a fiber web wound around the pipe and impregnated with bituminous material.
While such a bituminous coating may provide suf:Eicient corrosion r~sistance for a long period of time, it may be damaged after the lapse of such period in consequence~ of roots ingrowth or the li~e. Therefore, pipes should be excavated or exposed after a predetermined time period, e.g.
after 20 or 30 years and the bituminous coating thereon should be removed and replaced by a fresh coating prior to reburying the pipes or re-covering them with earth.
The removal of a bituminous coating and of a primer undercoating is effected up till now by meanq of hand tools like e.g. knifes and it will be clear that such is a time-consuming and laborious operation.
~22~i7~ 21766-430 Therefore, the invention has for its object to remove the disadvantages of the prior art and to provide a method and apparatus which are suitable for effecting the re~oval of bituminous as well as other coatings in an easy and efficient way.
In accordance with the invention, it has been found that an efficient and fast removal of bituminous coatings, may be e~fected by ~he use of water jets. If one or more powerful water jets are directed against the pipe surface, the bituminous coating will be rapidly released at the places of impact and will be discharged in flake form with the water used ~or the jets. If moreover, the water jets are allowed to travel along the pipe surface in longitudinal and circumferentlal direction, then a vast pipe area can be treated within a short period of time. The water as used is harmless to the envlronment and the flakes carried thereby will cause only minor environmental problems although they may be collected and recovered later on, if desired.
Thus, according to one broad aspect of the inventlon there is provided a method of removing bituminous or other coating from an exterior pipe surface, by directing one or more powerful water jets against such pipe suriace, characterized in that the water jets are directed against the pipe surface under an acute angle, when seen in circumferential direction of the pipe, and that each of the water jets is moved in longitudinal as well as in circumferential direction along the pipe surface in a zig-zag path, such zig-zag path having the longitudinal direction of the pipe as its main direction, and wherein the paths of adjacent water jets are closely spaced in circumferential direction, said water jets having a pressure of between 30 and 60 MPa.
The term "powerful water jets" is meant to define water jets of high impelling p.ressure. This impelling pressure may in general be between 300 and 600 bars although a pressure of 300 bars will be sufficient in manY cases. The number of water jets is not critical although two or four water jets, suitably distributed around the circumference of the pipe are often used in practice.
According to another broad aspect of the invention there is provided an apparatus for removing bituminous or o~her coatings from an exterior pipe surface, essentially comprising a frame adapted for being mounted around the pipe to be treated, one or more nozzles directed against the pipe surface on such frame, and means for feeding pressurized water to said nozzles, characterized in that said nozzles are directed ayainst the pipe surEace under an acute angle when measured in circumferential direction of the pipe and that means are present for moving the nozzles in longitudinal as well as in circumferential direction along the pipe surface, said means being adapted for moving the nozzles in a zig-zag path along the pipe surface, said zig-zag path haviny the longitudinal direction of the pipe as its main direction, and the paths of adjacent nozzles being closely spaced in circumferential direction.
Such apparatus is suitable for effecting the aforesaid method and may be advantageous in removing bituminous coatings from endless pipes in the open air.
3a 21766-430 In principle~ the frame is needed only for carrying the other parts such as nozzles, driving means and water feeding means. It should be capable of being mounl;ed quite easily to the pipe to be treated and preferably, it is as n?uch open as possible in order to permlt an easy discharge of wat;er supplied by the nozzles. The number o~ nozzles is not critical.
The means for moving the nozzles in longitudinal direction will preferably comprise travelling wheels and driving rollers carried by the frame and engaging the pipe. Means for moving the nozzles in circumferential direction will preferably comprise one or more rotatable annular discs positioned in planes perpendicular to the longitudinal axis of the pipe and surrounding the pipe concentrically with some spacing, said discs carrying the nozzles in ~?
V
~;~5~
`, ~
~ 21766-430 groups, and means for rotating the discs around their axes.
Such a construction is easy to realize and may serve to reach the desired purpose in an efficient way provided that the means for moving in longitudinal and circumferential direction are suitably coordinated.
It may be desirable in many cases that the nozzles are unable to perform a complete revolution of 360 during -their travel in circumferential direc-tion of the ~257~
pipe, because there is a risk then that the water feeding means such as e.g. water hoses would get en-tanglsd around the pipe. Therefore, in a preferred embodiment of the invention, arrangements have been made to move the nozzles in a zigzag path along the pipe surface, such ziyzag path having the longitudinal direction of the pipe as its main direction, and to ensure that the paths of adjacent no~zles are closely spaced in circumferential direction. With such an embodiment, any entanglement of hoses o~ other water feeding means can be positively prevented~ Such embodiment can be realised e.g. by adapting the means for rotation of the nozzle-carrying amular discs in such a way that the discs will get a reciprocating rotary movement along a restricted rotation angle. Further, in order to prevent that unwanted reaction forces are acting on the frame or pipe in that case, the rotational means of two adjacent discs may be coupled in such way that the discs will always rotate in mutually opposi.te directions. This will lead to a balanced high speed apparatus suitable for treating pipes : 20 in an efficient manner.
With regard to the travelling movement of the nozzles in longitud.inal direction, it is preferable to have the travelling wheels adjustably supported. Further, it is preferable that the driving rollers are supported by hinged levers which are biased to engage the pipe by means of e.g.
a spring mechanism or a hydraulic cylinder, in such a way that treatment of an angular pipe sect.ion is possible.
In total, the invention provides a method and apparatus suitable for fast and effective removal o:E a bituminous or other pipe coating.
The invention will now be described with reference to the drawings which show an embodiment of the invented apparatus by way of example. Such embodiment is intended for removing a bituminous coating from a pipe surface.
Fig. 1 is a side view of this embodiment.
Fig. 2 is a plan view of this embodiment along the line II-II of fig. 1.
Fig. 3 is a front view of this embodiment, alon~
~L257~71~
the lines III-III o~ fig. 1.
Fig. 4 shows the rotational system of the annular discs in this embodiment on a larger scale.
Fig. 5 is a view showing the invented apparatus in operation.
The appara-tus of figs. 1 to 3 has a frame 1 which is open from below and which may rest on the ground, if necessary, by means of a sledge 2. During operation, it is mounted around a pipe 3 to be treated and will be supported by that pipe then. Presuming that pipe 3 is an endless pipe, e.g. an exposed portion of a pipeline, frame 1 may be lifted easily by engaging eyes 4 thereon and may be lowered from above onto the pipe 3.
Frame 1 is resting on the pipe 3 by means of travellin~ wheels 5, for the major part arranged in pairs, which further act as guides during travel of the frame along the pipe in longitudinal direction. The travelling wheels are adjustable in position (compare e.g. the adjusting bolts 6) for the sake of centration.
Frame 1 further carries a pair of knurled drivin~
roller~ 7,7 driven by a hydromotor 8, for travel of the frame along the pipe in longitudinal direction. The driving rollers 7~7 are fixed to the free ends of a pair of hinged levers 9,9 which are pulled together by means of a hydraulic cylinder 10 so as to ensure that the driving rollers 7,7 will firmly engage pipe 3.
Within the fra~eare two annular discs 11,11, carrying nozzles 12,12. The discs 11,11 are rotatably mounted and positioned in planes which are perpendicular to the longitudinal direction of the pipe during operation.
Furthex, the discs ll,ll will surround the pipe 3 concen-trically and with some spacing. Each disc 11 has a detachable portion 13 in order to permit mounting the disc around pipe 3, and is provided with a guard hood 14 for the water to be sprayed.
The nozzles 12,12 have been mounted in such a way on discs 11,11 that they are direc-ted towards pipe 3 and that water jets from ~hese nozzles wi.ll hit the plpe 5~
under an acute impact angle, when seen in clrcumferen~ial direction. Both the mounting position and the angular position of the nozzles are adjustable, however.
Each of -the nozzles 12 has ~een connected by means of hoses 15 to a distxibution system 16 for pressurised water, said distribution system having a central feed 17.
The annular discs 11,11 are freely rotatable in frame 1 by means of a series of guiding rollers 18,18.
They are driven by a rope 19 passing along a driving roller 20 and further along guiding rollers 21,21, such guiding rollers being positioned in such a way that the rope will engage a portion of the circumference of each annular disc.
According to fig. 4, only a single rope 19 and a single driving roller 20 are used for driving both annular discs 11,11, although two series of guiding rollers 21,21 are present and locking clamps 22 are used for preventing the rope from slipping off the driving roller or the annular discs. The driving roller 20 is driven by a rack-and-pinion sy~tem 23,24 and the rack 23 is driven by two hydraulic cylinders 25,25. In consequence of this driving system, the annular discs 11,11 and the driving roller 20 will ge-t a reciprocating rotary movement and both discs will always simultaneously rotate in mutually opposite directions. The rotation angle of each annular disc 11 is less than 360 and in the case of two annular discs, each carrying two nozzles (like shown), the rotation angle will be somewhat more than 90, like for instance 110-120.
The apparatus as shown i5 prepared for operation by positioning it on the pipe 3 to be treated and mounting detachable portions 13 onto the annular discs 11. Fur~her, the travelling wheels 5 are adjusted in posi-tion and care is taken that the driving rollers 7 will engage pipe 3 correctly. Thereafter, the various moving systems as well as the nozzles are put into operation. Activa-tion of hydromotor 8 will ensure through driving rollers 7,7 that fra~ 1 is moved with a certain speed in longitudinal direction along pipe 3, and activation of cylinders 25,25 will result irlto a reciprocating move~ent of the annular discs 11,11 in ~ii7~7~
`~
circumferential direction of the pipe. If both types of movement are effected simultaneously, the nozzles 12,12 will each follow alzigzag path along the pipe surface, such zigzag path having its main direction in longitudinal direction of the pipe and having closely contiguous path sections. Since 4 nozzles are present in the apparatus as shown, each of them having a rotation angle in circumferen-tial direction of more than 90, the pa-thsof adjacent nozzles ; will be closely spaced and run in correspondence with each-other.
Pressurised water is fed to the nozzles 12,12 so as to direct powerful water jets against the surface of pipe 3 to remove a bituminous coatinq and a primer under-coating (if any) from that surface. Such removal of a bituminous coating may be effected very efficiently, due to -the force of the water jets, and the whole surEace of the pipe may be -treated Eor great lengths, due to the movement of nozzles in longitudinal and circumferential direction.
In a practical example, the apparatus as shown is moved at a speed of 15 to 20 m/hour along a pipe of 150 mm in diameter. The annular discs are reciprocating 15 times per minute and the four nozzles discharge water jets of 15 tot 25 mm in width under an adjustable pressura of 300 to 600 bars. Under such circumstances, the whole pipe surface may he freed from its bituminous coating in a rapid and efficient way.
In the foregoing description, it has been shown that the sys-tems for movement in longitudinal and circum-ferential direction are driven by hydromotor 8 and hydraulic cylinders 25,25, resp. These driving members have ac-tuatin~
means (not shown) which may be positioned on the apparatus itself but are preEerably positioned on auxiliary equipment, such as e.g. a truck running with the apparatus along the pipe. The actuating means for hydromotor 8 and for hydraulic cylinders 25,25 may be separate but have preferably been coupled, such as e.g. by a common swi-tch on a switch board, in order to ensure tha-t both driving members are actuated simultaneously and that -the nozzles will follow a zi(lzag ~25~7~7~3 path along the pipe surface.
In fig. 5, the invented apparatus is shown in operation during the removal of a bituminous coating from a pipeline. Pipeline 26 is resting in position and is not divided into separate sec-tions meaning that a flow of fluids through the pipeline need not be interrupted. In stead thereof, a groove 27 of sufficient ~imensions to permit installation and operation of the invented apparatus is cut around the pipeline.
1~ Apparatus 28 is lifted by means vf a crane 30 standing on a truck 29 and is placed onto the exposed portion of the pipeline whereupon the driving members for movement in longitudinal and circumferential direction are actuated simultaneously by ac-t~ating means on truck 29 throu~h the intermediary of hydraulic pipes 31. The truck will keep the apparatus 28 in balance through crane 30 and will run with apparatus 23 along the pipeline. The water needed for removal of the bituminous coating is contained in a tank lorry 32 and is fed through a pump 34 and flexible hoses 33 to appa-ratus 23 where it is distributed among the nozzles and directed against the surface of the pipeline in the form of powerful water jets. In thi~s way, a pipeline section of unrestricted length may be freed of a bituminous or other coating in continuous operation.
Thanks to the fact that the travelling wheels 5 are adjustable and that driving rollers 7 are hingedly supported, it is possible with the invented apparatus to treat angular sections having a curvature radius of 5 meters at minimum, without any need for additional measures of special nature.
In the foregoing description, the invention hasbeen shown for utilisation in the removal of bituminous coatings. It should be noted, however, that the invention is not limited to such utilisa~.ion and may also be used for removal of other types of coating such as for instance polyethylene coatings.
Br/lh/l ~257~78 Method and apparatus for removing pipe coatings.
This invention relates to the field of remo~ing pipe coatings and more in particular to a method and apparatus for removin~ bituminous or other coatings from a pipe surface, e.g. a portion of a pipeline.
Pipes in the ground are often provided with an exterior bituminous coating comprising a fiber web wound around the pipe and impregnated with bituminous material.
While such a bituminous coating may provide suf:Eicient corrosion r~sistance for a long period of time, it may be damaged after the lapse of such period in consequence~ of roots ingrowth or the li~e. Therefore, pipes should be excavated or exposed after a predetermined time period, e.g.
after 20 or 30 years and the bituminous coating thereon should be removed and replaced by a fresh coating prior to reburying the pipes or re-covering them with earth.
The removal of a bituminous coating and of a primer undercoating is effected up till now by meanq of hand tools like e.g. knifes and it will be clear that such is a time-consuming and laborious operation.
~22~i7~ 21766-430 Therefore, the invention has for its object to remove the disadvantages of the prior art and to provide a method and apparatus which are suitable for effecting the re~oval of bituminous as well as other coatings in an easy and efficient way.
In accordance with the invention, it has been found that an efficient and fast removal of bituminous coatings, may be e~fected by ~he use of water jets. If one or more powerful water jets are directed against the pipe surface, the bituminous coating will be rapidly released at the places of impact and will be discharged in flake form with the water used ~or the jets. If moreover, the water jets are allowed to travel along the pipe surface in longitudinal and circumferentlal direction, then a vast pipe area can be treated within a short period of time. The water as used is harmless to the envlronment and the flakes carried thereby will cause only minor environmental problems although they may be collected and recovered later on, if desired.
Thus, according to one broad aspect of the inventlon there is provided a method of removing bituminous or other coating from an exterior pipe surface, by directing one or more powerful water jets against such pipe suriace, characterized in that the water jets are directed against the pipe surface under an acute angle, when seen in circumferential direction of the pipe, and that each of the water jets is moved in longitudinal as well as in circumferential direction along the pipe surface in a zig-zag path, such zig-zag path having the longitudinal direction of the pipe as its main direction, and wherein the paths of adjacent water jets are closely spaced in circumferential direction, said water jets having a pressure of between 30 and 60 MPa.
The term "powerful water jets" is meant to define water jets of high impelling p.ressure. This impelling pressure may in general be between 300 and 600 bars although a pressure of 300 bars will be sufficient in manY cases. The number of water jets is not critical although two or four water jets, suitably distributed around the circumference of the pipe are often used in practice.
According to another broad aspect of the invention there is provided an apparatus for removing bituminous or o~her coatings from an exterior pipe surface, essentially comprising a frame adapted for being mounted around the pipe to be treated, one or more nozzles directed against the pipe surface on such frame, and means for feeding pressurized water to said nozzles, characterized in that said nozzles are directed ayainst the pipe surEace under an acute angle when measured in circumferential direction of the pipe and that means are present for moving the nozzles in longitudinal as well as in circumferential direction along the pipe surface, said means being adapted for moving the nozzles in a zig-zag path along the pipe surface, said zig-zag path haviny the longitudinal direction of the pipe as its main direction, and the paths of adjacent nozzles being closely spaced in circumferential direction.
Such apparatus is suitable for effecting the aforesaid method and may be advantageous in removing bituminous coatings from endless pipes in the open air.
3a 21766-430 In principle~ the frame is needed only for carrying the other parts such as nozzles, driving means and water feeding means. It should be capable of being mounl;ed quite easily to the pipe to be treated and preferably, it is as n?uch open as possible in order to permlt an easy discharge of wat;er supplied by the nozzles. The number o~ nozzles is not critical.
The means for moving the nozzles in longitudinal direction will preferably comprise travelling wheels and driving rollers carried by the frame and engaging the pipe. Means for moving the nozzles in circumferential direction will preferably comprise one or more rotatable annular discs positioned in planes perpendicular to the longitudinal axis of the pipe and surrounding the pipe concentrically with some spacing, said discs carrying the nozzles in ~?
V
~;~5~
`, ~
~ 21766-430 groups, and means for rotating the discs around their axes.
Such a construction is easy to realize and may serve to reach the desired purpose in an efficient way provided that the means for moving in longitudinal and circumferential direction are suitably coordinated.
It may be desirable in many cases that the nozzles are unable to perform a complete revolution of 360 during -their travel in circumferential direc-tion of the ~257~
pipe, because there is a risk then that the water feeding means such as e.g. water hoses would get en-tanglsd around the pipe. Therefore, in a preferred embodiment of the invention, arrangements have been made to move the nozzles in a zigzag path along the pipe surface, such ziyzag path having the longitudinal direction of the pipe as its main direction, and to ensure that the paths of adjacent no~zles are closely spaced in circumferential direction. With such an embodiment, any entanglement of hoses o~ other water feeding means can be positively prevented~ Such embodiment can be realised e.g. by adapting the means for rotation of the nozzle-carrying amular discs in such a way that the discs will get a reciprocating rotary movement along a restricted rotation angle. Further, in order to prevent that unwanted reaction forces are acting on the frame or pipe in that case, the rotational means of two adjacent discs may be coupled in such way that the discs will always rotate in mutually opposi.te directions. This will lead to a balanced high speed apparatus suitable for treating pipes : 20 in an efficient manner.
With regard to the travelling movement of the nozzles in longitud.inal direction, it is preferable to have the travelling wheels adjustably supported. Further, it is preferable that the driving rollers are supported by hinged levers which are biased to engage the pipe by means of e.g.
a spring mechanism or a hydraulic cylinder, in such a way that treatment of an angular pipe sect.ion is possible.
In total, the invention provides a method and apparatus suitable for fast and effective removal o:E a bituminous or other pipe coating.
The invention will now be described with reference to the drawings which show an embodiment of the invented apparatus by way of example. Such embodiment is intended for removing a bituminous coating from a pipe surface.
Fig. 1 is a side view of this embodiment.
Fig. 2 is a plan view of this embodiment along the line II-II of fig. 1.
Fig. 3 is a front view of this embodiment, alon~
~L257~71~
the lines III-III o~ fig. 1.
Fig. 4 shows the rotational system of the annular discs in this embodiment on a larger scale.
Fig. 5 is a view showing the invented apparatus in operation.
The appara-tus of figs. 1 to 3 has a frame 1 which is open from below and which may rest on the ground, if necessary, by means of a sledge 2. During operation, it is mounted around a pipe 3 to be treated and will be supported by that pipe then. Presuming that pipe 3 is an endless pipe, e.g. an exposed portion of a pipeline, frame 1 may be lifted easily by engaging eyes 4 thereon and may be lowered from above onto the pipe 3.
Frame 1 is resting on the pipe 3 by means of travellin~ wheels 5, for the major part arranged in pairs, which further act as guides during travel of the frame along the pipe in longitudinal direction. The travelling wheels are adjustable in position (compare e.g. the adjusting bolts 6) for the sake of centration.
Frame 1 further carries a pair of knurled drivin~
roller~ 7,7 driven by a hydromotor 8, for travel of the frame along the pipe in longitudinal direction. The driving rollers 7~7 are fixed to the free ends of a pair of hinged levers 9,9 which are pulled together by means of a hydraulic cylinder 10 so as to ensure that the driving rollers 7,7 will firmly engage pipe 3.
Within the fra~eare two annular discs 11,11, carrying nozzles 12,12. The discs 11,11 are rotatably mounted and positioned in planes which are perpendicular to the longitudinal direction of the pipe during operation.
Furthex, the discs ll,ll will surround the pipe 3 concen-trically and with some spacing. Each disc 11 has a detachable portion 13 in order to permit mounting the disc around pipe 3, and is provided with a guard hood 14 for the water to be sprayed.
The nozzles 12,12 have been mounted in such a way on discs 11,11 that they are direc-ted towards pipe 3 and that water jets from ~hese nozzles wi.ll hit the plpe 5~
under an acute impact angle, when seen in clrcumferen~ial direction. Both the mounting position and the angular position of the nozzles are adjustable, however.
Each of -the nozzles 12 has ~een connected by means of hoses 15 to a distxibution system 16 for pressurised water, said distribution system having a central feed 17.
The annular discs 11,11 are freely rotatable in frame 1 by means of a series of guiding rollers 18,18.
They are driven by a rope 19 passing along a driving roller 20 and further along guiding rollers 21,21, such guiding rollers being positioned in such a way that the rope will engage a portion of the circumference of each annular disc.
According to fig. 4, only a single rope 19 and a single driving roller 20 are used for driving both annular discs 11,11, although two series of guiding rollers 21,21 are present and locking clamps 22 are used for preventing the rope from slipping off the driving roller or the annular discs. The driving roller 20 is driven by a rack-and-pinion sy~tem 23,24 and the rack 23 is driven by two hydraulic cylinders 25,25. In consequence of this driving system, the annular discs 11,11 and the driving roller 20 will ge-t a reciprocating rotary movement and both discs will always simultaneously rotate in mutually opposite directions. The rotation angle of each annular disc 11 is less than 360 and in the case of two annular discs, each carrying two nozzles (like shown), the rotation angle will be somewhat more than 90, like for instance 110-120.
The apparatus as shown i5 prepared for operation by positioning it on the pipe 3 to be treated and mounting detachable portions 13 onto the annular discs 11. Fur~her, the travelling wheels 5 are adjusted in posi-tion and care is taken that the driving rollers 7 will engage pipe 3 correctly. Thereafter, the various moving systems as well as the nozzles are put into operation. Activa-tion of hydromotor 8 will ensure through driving rollers 7,7 that fra~ 1 is moved with a certain speed in longitudinal direction along pipe 3, and activation of cylinders 25,25 will result irlto a reciprocating move~ent of the annular discs 11,11 in ~ii7~7~
`~
circumferential direction of the pipe. If both types of movement are effected simultaneously, the nozzles 12,12 will each follow alzigzag path along the pipe surface, such zigzag path having its main direction in longitudinal direction of the pipe and having closely contiguous path sections. Since 4 nozzles are present in the apparatus as shown, each of them having a rotation angle in circumferen-tial direction of more than 90, the pa-thsof adjacent nozzles ; will be closely spaced and run in correspondence with each-other.
Pressurised water is fed to the nozzles 12,12 so as to direct powerful water jets against the surface of pipe 3 to remove a bituminous coatinq and a primer under-coating (if any) from that surface. Such removal of a bituminous coating may be effected very efficiently, due to -the force of the water jets, and the whole surEace of the pipe may be -treated Eor great lengths, due to the movement of nozzles in longitudinal and circumferential direction.
In a practical example, the apparatus as shown is moved at a speed of 15 to 20 m/hour along a pipe of 150 mm in diameter. The annular discs are reciprocating 15 times per minute and the four nozzles discharge water jets of 15 tot 25 mm in width under an adjustable pressura of 300 to 600 bars. Under such circumstances, the whole pipe surface may he freed from its bituminous coating in a rapid and efficient way.
In the foregoing description, it has been shown that the sys-tems for movement in longitudinal and circum-ferential direction are driven by hydromotor 8 and hydraulic cylinders 25,25, resp. These driving members have ac-tuatin~
means (not shown) which may be positioned on the apparatus itself but are preEerably positioned on auxiliary equipment, such as e.g. a truck running with the apparatus along the pipe. The actuating means for hydromotor 8 and for hydraulic cylinders 25,25 may be separate but have preferably been coupled, such as e.g. by a common swi-tch on a switch board, in order to ensure tha-t both driving members are actuated simultaneously and that -the nozzles will follow a zi(lzag ~25~7~7~3 path along the pipe surface.
In fig. 5, the invented apparatus is shown in operation during the removal of a bituminous coating from a pipeline. Pipeline 26 is resting in position and is not divided into separate sec-tions meaning that a flow of fluids through the pipeline need not be interrupted. In stead thereof, a groove 27 of sufficient ~imensions to permit installation and operation of the invented apparatus is cut around the pipeline.
1~ Apparatus 28 is lifted by means vf a crane 30 standing on a truck 29 and is placed onto the exposed portion of the pipeline whereupon the driving members for movement in longitudinal and circumferential direction are actuated simultaneously by ac-t~ating means on truck 29 throu~h the intermediary of hydraulic pipes 31. The truck will keep the apparatus 28 in balance through crane 30 and will run with apparatus 23 along the pipeline. The water needed for removal of the bituminous coating is contained in a tank lorry 32 and is fed through a pump 34 and flexible hoses 33 to appa-ratus 23 where it is distributed among the nozzles and directed against the surface of the pipeline in the form of powerful water jets. In thi~s way, a pipeline section of unrestricted length may be freed of a bituminous or other coating in continuous operation.
Thanks to the fact that the travelling wheels 5 are adjustable and that driving rollers 7 are hingedly supported, it is possible with the invented apparatus to treat angular sections having a curvature radius of 5 meters at minimum, without any need for additional measures of special nature.
In the foregoing description, the invention hasbeen shown for utilisation in the removal of bituminous coatings. It should be noted, however, that the invention is not limited to such utilisa~.ion and may also be used for removal of other types of coating such as for instance polyethylene coatings.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of removing bituminous or other coating from an exterior pipe surface, by directing one or more powerful water jets against such pipe surface, characterized in that the water jets are directed against the pipe surface under an acute angle, when seen in circumferential direction of the pipe, and that each of the water jets is moved in longitudinal as well as in circumferential direction along the pipe surface in a zig-zag path, such zig-zag path having the longitudinal direction of the pipe as its main direction, and wherein the paths of adjacent water jets are closely spaced in circumferential direction, said water jets having a pressure of between 30 and 60 MPa.
2. Apparatus for removing bituminous or other coatings from an exterior pipe surface, essentially comprising a frame adapted for being mounted around the pipe to be treated, one or more nozzles directed against the pipe surface on such frame, and means for feeding pressurized water to said nozzles, characterized in that said nozzles are directed against the pipe surface under an acute angle when measured in circumferential direction of the pipe and that means are present for moving the nozzles in longitudinal as well as in circumferential direction along the pipe surface, said means being adapted for moving the nozzles in a zig-zag path along the pipe surface, said zig-zag path having the longitudinal direction of the pipe as its main direction, and the paths of adjacent nozzles being closely spaced in circumferential direction.
3. Apparatus as claimed in claim 2, wherein the means for moving the nozzles in longitudinal direction comprise travelling wheels and driving rollers carried by said frame and engaging the pipe, and wherein the means for moving the nozzles in circum-ferential direction comprise one or more rotatable annular discs positioned in planes perpendicular to the longitudinal axis of the pipe and surrounding the pipe concentrically with some spacing, said discs carrying the nozzles in groups, and said means further comprising means for rotating the discs around their axes.
4. Apparatus as claimed in claim 3, wherein the travelling wheels are adjustably supported.
5. Apparatus as claimed in claim 3, wherein the driving rollers are supported by hinged levers which are biased to engage a pipe surface.
6. Apparatus as claimed in claim 3, wherein the means for rotating the annular discs are adapted for giving the discs a reciprocating rotational movement with a limited rotation angle.
7. Apparatus as claimed in claim 6, wherein the rotation means comprise a rope passing over a driving roller, as well as a rack-and-pinion system acting on the driving roller.
8. Apparatus as claimed in claim 3 or 7, wherein the rotation means of two adjacent discs are coupled so as to cause the discs to rotate at any time in mutually opposite directions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000455779A CA1257178A (en) | 1984-06-04 | 1984-06-04 | Method and apparatus for removing pipe coatings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000455779A CA1257178A (en) | 1984-06-04 | 1984-06-04 | Method and apparatus for removing pipe coatings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1257178A true CA1257178A (en) | 1989-07-11 |
Family
ID=4128019
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000455779A Expired CA1257178A (en) | 1984-06-04 | 1984-06-04 | Method and apparatus for removing pipe coatings |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1257178A (en) |
-
1984
- 1984-06-04 CA CA000455779A patent/CA1257178A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |