CA1092768A - Method and apparatus for checking the inner surface of tubes by resin casting - Google Patents
Method and apparatus for checking the inner surface of tubes by resin castingInfo
- Publication number
- CA1092768A CA1092768A CA275,008A CA275008A CA1092768A CA 1092768 A CA1092768 A CA 1092768A CA 275008 A CA275008 A CA 275008A CA 1092768 A CA1092768 A CA 1092768A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- resilient
- duct
- rigid
- ribs
- 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
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000010125 resin casting Methods 0.000 title abstract 2
- 229920005989 resin Polymers 0.000 claims abstract description 20
- 239000011347 resin Substances 0.000 claims abstract description 20
- 239000012530 fluid Substances 0.000 claims abstract description 16
- 230000002093 peripheral effect Effects 0.000 claims abstract description 11
- 239000012858 resilient material Substances 0.000 claims abstract description 4
- 238000007789 sealing Methods 0.000 claims description 15
- 229920003023 plastic Polymers 0.000 claims description 10
- 239000004033 plastic Substances 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 4
- 229920001971 elastomer Polymers 0.000 claims description 4
- 239000000806 elastomer Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 229920000728 polyester Polymers 0.000 claims description 2
- 229920002635 polyurethane Polymers 0.000 claims description 2
- 239000004814 polyurethane Substances 0.000 claims description 2
- 125000005442 diisocyanate group Chemical group 0.000 claims 1
- 239000000088 plastic resin Substances 0.000 claims 1
- 229920002379 silicone rubber Polymers 0.000 claims 1
- 238000006116 polymerization reaction Methods 0.000 abstract description 4
- 229920002050 silicone resin Polymers 0.000 abstract description 2
- 210000000614 rib Anatomy 0.000 description 14
- 230000007547 defect Effects 0.000 description 9
- 239000007788 liquid Substances 0.000 description 3
- 239000000446 fuel Substances 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 235000011483 Ribes Nutrition 0.000 description 1
- 241000220483 Ribes Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- -1 diisocyanate compounds Chemical class 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
An apparatus for checking the inner surface of tubes by resin casting comprises a rigid tube fitted into a tube made of resilient material of which the end sections are sealingly mated to the respective end sections of the rigid tube. The resilient tube is provided at the end sections of its outer surface with peripheral seals of which the outer diameter is slightly smaller than the inner diameter of the tube being ins-pected. Between the seals the resilient tube is provided with a plurality of peripheral ribs regularly spaced from one another and with dovetail cross-section. A duct connectible to a pres-surized fluid vessel communicates with the outer surface of-the rigid tube, a duct connectible to a vessel containing a pres-surized polymerizable resin communicates with the outer surface of the resilient tube and a duct connectible to a vacuum vessel or to the atmosphere also communicates with the outer surface of the resilient tube. Also disclosed is a method whereby a replica is made by flowing a silicone resin into the space between the tube being inspected and the outside of the apparatus. After polymerization, the resilient tube contracts and while contracting draws the replica therewith. Thus between the tube being copied and the replica a clearance is formed great enough for permitting the withdrawal of the apparatus from the tube along with the replica of the latter.
An apparatus for checking the inner surface of tubes by resin casting comprises a rigid tube fitted into a tube made of resilient material of which the end sections are sealingly mated to the respective end sections of the rigid tube. The resilient tube is provided at the end sections of its outer surface with peripheral seals of which the outer diameter is slightly smaller than the inner diameter of the tube being ins-pected. Between the seals the resilient tube is provided with a plurality of peripheral ribs regularly spaced from one another and with dovetail cross-section. A duct connectible to a pres-surized fluid vessel communicates with the outer surface of-the rigid tube, a duct connectible to a vessel containing a pres-surized polymerizable resin communicates with the outer surface of the resilient tube and a duct connectible to a vacuum vessel or to the atmosphere also communicates with the outer surface of the resilient tube. Also disclosed is a method whereby a replica is made by flowing a silicone resin into the space between the tube being inspected and the outside of the apparatus. After polymerization, the resilient tube contracts and while contracting draws the replica therewith. Thus between the tube being copied and the replica a clearance is formed great enough for permitting the withdrawal of the apparatus from the tube along with the replica of the latter.
Description
109;~768 The object of this invention are a method and an apparatus for detecting any faults in the inner surface of a tube.
Specifically the method and apparatus of this invention are useful in defectoscopy of the core tubes of a nuclear reactor.
The known techniques for detecting the surface defects of metal structures and specifically the defects of the inner surface of a tube include the following :
a) Optical methods comprising the visual inspection-of a suitably lighted surface ;
b) Magnetoscopy methods whereby any surperficial or internal defects of an object being examined are made visible through the perturbations caused by said defects to a magnetic field induced on the object ;
c) Methods based on eddy currents whereby the changes are measured of the eddy currents in the object being examined due to the changes of the chemical composition, microstruct-ure, size, or to surface or inside discontinuities, etc, ;
d) Ultrasonic methods which are based on the behaviour of mechanical vibrations at frequency higher than the audible range induced on the objects being examined ;
e) Radiographic methods based on the attenuation of X or Y
radiation passing through an object. By this method any discontinuities inside an object are considered which may comprise either physical or chemical discontinuities ;-f) The method of making a replica of the object surface. This method comprises making a print or copy as faithful as possible of the area to be examined by casting against it a polymerizable , ~, . .
. ,, . : ~ : : :
''` ' - : ' '`' ' .. `' `'`
resin and subsequently observing and measuring the defective areas on the replica.
The above methods as developed up to now according to the prior art, all suffer from limitations and drawbacks. By the optical methods the position and extension of the defects can be detected but not their depth. The same applies to magneto- ~
scopic methods. The methods based on eddy currents provide only the position of a defect and moreover they are very complicate and expensive; the methods based on ultrasonic waves are also complicate and expensive. The radiographic methods are dis-turbed by environmental radiation and imply the use of expensive equipment.
Further, all the above methods, when used for defectos-copy purposes of the inner surfaces of tubes particularly in the case of small diameter tubes, are not applicable due to the diffi-culty of reaching the inner surfaces of the tubes.
In these cases, the replica method is more advanta-geous.
Resins with low surface tension - that is adapted for , 20 penetrating very narrow fissures - have been recently developed whereby very faithful replicas can be produced.
The apparatus of the prior art for defectoscopy by replica of the inner surfaces of tubes are adapted only for inspecting small areas of said surfaces because the replicas obtained by said apparatus cover only a portion of the tube inner circumference. In such apparatus the mold into which the resin is cast for obtaining the replica comprises a cup made of resi-lient material. Such cup is introduced into the pipe to be inspectea and forced against the tube inner surface at the position where by previous inspections a surface defect has been located. Various means can be used for forcing the cup against the wall such as for instance a toggle lever. The inside of the ,.~
1~ 768 cup is connected to the outside of the tube by two pipes; while the tube is kept up~ight a liquid resin is fed through the lower pipe until it outflows from the upper pipe after filling the cup. Subsequent to the resin setting, the means which forces the cup against the tube wall is released and the cup is with-drawn from the tube. Thus a replica is obtained of a limited region of the tube and by inspecting it the damage can be - evaluated. Such method in addition to requiring a very skilled operator, does not give positive results because of the diffi-culty of locating the defect to be inspected and consequently accurately positioning the replica mold.
This invention is therefore directed to overcoming some of the above mentioned drawbacks of the methods of the prior art.
In fact, by the method of this invention replicas can be made of a tube inner surface area which extends not only over the whole inner circumference of the tube but also over sizable longitudinal sections of the tube. As an indication, the area covered by the apparatus of this invention can be estimated of the order of thirty times the area covered by the apparatus of the prior art.
Furthermore, by the method of this invention, well defined sections of the tube can be replicated. In fact, the position of the apparatus along the tube and consequently the boundaries of the replicated surface can be easily determined.
Thus replicas can be made of the whole tube without overlappings by successively displacing the apparatus along the tube.
According to the method of this invention, the replica is removed away from the surface to be inspected in a direction perpendicular thereto, no damage being caused to the replica when this is detached from the tube surface.
Much more the plastic being resilient, even the under-7t;8cut details of the tube surface can be reproduced on the replica. ~en a defect such as a pitting of the inner surface of the tube has an undercut profile, that is when the pitting `
is smaller at its opening than at a depth thereof, the plastic material which has crept thereinto could not be withdrawn from the pitting after the plastic setting. But because according to the invention the plastic is resilient after setting, the borders of the resin expanded in the pitting are inflected when a force is applied thereto, whereby the resin replica of the pitting can pass through the pitting opening.
The apparatus of this invention comprises a rigid tube fitted into a tube made of resilient material of which the end sections are sealingly mated to the respective end sections of the rigid tube.
The resilient tube is provided at the end sections of its outer surface with peripheral sealing means of which the outer diameter is slightly smaller than the inner diameter of the tube being inspected.
Between said sealing means, the resilient tube is ,20 provided with a plurality of peripheral ribs regularly spaced from one another and with dovetail cross-section. A duct con-nectible to a pressurized fuel vessel communicates with the outer surface of said rigid tube, a duct connectible to a vessel containing a pressurized polymerizable resin communicates with the inner surface of said resilient tube and a duct connectible to a vacuum vessel or to the atmosphere also communicates with ¦
the outer surface of said resilient tube.
According to the method of this invention, a replica is made by flowing a silicone resin into the space between the tube , lO9Z768 being inspected and the outside of the apparatus of this inven-tion. After polymerization said resilient tube contracts and while contracting draws the replica therewith.
Thus, between the tube being copied and the replica a clearance is formed great enough for permitting the withdrawal of the apparatus from the tube along with the replica of the latter.
This invention will be better understood from the following detailed description and attached drawing which illustrates by way of example a preferred embodiment thereof.
The single figure shows a longitudinal cross-section of the apparatus of this invention.
With reference to this figure the apparatus of this invention comprises a resilient tube made of a relatively stiff turnable material. A thick backing tube 2 substantially indeformable is fitted into tube 1 with the least possible clearance. Tube 2 has the same length as tube 1 but is provided with two threaded extensions 2' which project from the respective ends of tube 1 for a relatively short distance. At their end sections - lower and upper in the figure - tubes 1 and 2 are sealed together. The sealing means comprises, at each end of the assembly comprising the rigid and resilient tubes, a circular plate 12 with a flange 12" projecting at ,.
right angles towards the other end of said assembly, which plate is fitted on said extension of tube 2 and engages the end of tube l; a ring nut 14 threadingly engages extensions
Specifically the method and apparatus of this invention are useful in defectoscopy of the core tubes of a nuclear reactor.
The known techniques for detecting the surface defects of metal structures and specifically the defects of the inner surface of a tube include the following :
a) Optical methods comprising the visual inspection-of a suitably lighted surface ;
b) Magnetoscopy methods whereby any surperficial or internal defects of an object being examined are made visible through the perturbations caused by said defects to a magnetic field induced on the object ;
c) Methods based on eddy currents whereby the changes are measured of the eddy currents in the object being examined due to the changes of the chemical composition, microstruct-ure, size, or to surface or inside discontinuities, etc, ;
d) Ultrasonic methods which are based on the behaviour of mechanical vibrations at frequency higher than the audible range induced on the objects being examined ;
e) Radiographic methods based on the attenuation of X or Y
radiation passing through an object. By this method any discontinuities inside an object are considered which may comprise either physical or chemical discontinuities ;-f) The method of making a replica of the object surface. This method comprises making a print or copy as faithful as possible of the area to be examined by casting against it a polymerizable , ~, . .
. ,, . : ~ : : :
''` ' - : ' '`' ' .. `' `'`
resin and subsequently observing and measuring the defective areas on the replica.
The above methods as developed up to now according to the prior art, all suffer from limitations and drawbacks. By the optical methods the position and extension of the defects can be detected but not their depth. The same applies to magneto- ~
scopic methods. The methods based on eddy currents provide only the position of a defect and moreover they are very complicate and expensive; the methods based on ultrasonic waves are also complicate and expensive. The radiographic methods are dis-turbed by environmental radiation and imply the use of expensive equipment.
Further, all the above methods, when used for defectos-copy purposes of the inner surfaces of tubes particularly in the case of small diameter tubes, are not applicable due to the diffi-culty of reaching the inner surfaces of the tubes.
In these cases, the replica method is more advanta-geous.
Resins with low surface tension - that is adapted for , 20 penetrating very narrow fissures - have been recently developed whereby very faithful replicas can be produced.
The apparatus of the prior art for defectoscopy by replica of the inner surfaces of tubes are adapted only for inspecting small areas of said surfaces because the replicas obtained by said apparatus cover only a portion of the tube inner circumference. In such apparatus the mold into which the resin is cast for obtaining the replica comprises a cup made of resi-lient material. Such cup is introduced into the pipe to be inspectea and forced against the tube inner surface at the position where by previous inspections a surface defect has been located. Various means can be used for forcing the cup against the wall such as for instance a toggle lever. The inside of the ,.~
1~ 768 cup is connected to the outside of the tube by two pipes; while the tube is kept up~ight a liquid resin is fed through the lower pipe until it outflows from the upper pipe after filling the cup. Subsequent to the resin setting, the means which forces the cup against the tube wall is released and the cup is with-drawn from the tube. Thus a replica is obtained of a limited region of the tube and by inspecting it the damage can be - evaluated. Such method in addition to requiring a very skilled operator, does not give positive results because of the diffi-culty of locating the defect to be inspected and consequently accurately positioning the replica mold.
This invention is therefore directed to overcoming some of the above mentioned drawbacks of the methods of the prior art.
In fact, by the method of this invention replicas can be made of a tube inner surface area which extends not only over the whole inner circumference of the tube but also over sizable longitudinal sections of the tube. As an indication, the area covered by the apparatus of this invention can be estimated of the order of thirty times the area covered by the apparatus of the prior art.
Furthermore, by the method of this invention, well defined sections of the tube can be replicated. In fact, the position of the apparatus along the tube and consequently the boundaries of the replicated surface can be easily determined.
Thus replicas can be made of the whole tube without overlappings by successively displacing the apparatus along the tube.
According to the method of this invention, the replica is removed away from the surface to be inspected in a direction perpendicular thereto, no damage being caused to the replica when this is detached from the tube surface.
Much more the plastic being resilient, even the under-7t;8cut details of the tube surface can be reproduced on the replica. ~en a defect such as a pitting of the inner surface of the tube has an undercut profile, that is when the pitting `
is smaller at its opening than at a depth thereof, the plastic material which has crept thereinto could not be withdrawn from the pitting after the plastic setting. But because according to the invention the plastic is resilient after setting, the borders of the resin expanded in the pitting are inflected when a force is applied thereto, whereby the resin replica of the pitting can pass through the pitting opening.
The apparatus of this invention comprises a rigid tube fitted into a tube made of resilient material of which the end sections are sealingly mated to the respective end sections of the rigid tube.
The resilient tube is provided at the end sections of its outer surface with peripheral sealing means of which the outer diameter is slightly smaller than the inner diameter of the tube being inspected.
Between said sealing means, the resilient tube is ,20 provided with a plurality of peripheral ribs regularly spaced from one another and with dovetail cross-section. A duct con-nectible to a pressurized fuel vessel communicates with the outer surface of said rigid tube, a duct connectible to a vessel containing a pressurized polymerizable resin communicates with the inner surface of said resilient tube and a duct connectible to a vacuum vessel or to the atmosphere also communicates with ¦
the outer surface of said resilient tube.
According to the method of this invention, a replica is made by flowing a silicone resin into the space between the tube , lO9Z768 being inspected and the outside of the apparatus of this inven-tion. After polymerization said resilient tube contracts and while contracting draws the replica therewith.
Thus, between the tube being copied and the replica a clearance is formed great enough for permitting the withdrawal of the apparatus from the tube along with the replica of the latter.
This invention will be better understood from the following detailed description and attached drawing which illustrates by way of example a preferred embodiment thereof.
The single figure shows a longitudinal cross-section of the apparatus of this invention.
With reference to this figure the apparatus of this invention comprises a resilient tube made of a relatively stiff turnable material. A thick backing tube 2 substantially indeformable is fitted into tube 1 with the least possible clearance. Tube 2 has the same length as tube 1 but is provided with two threaded extensions 2' which project from the respective ends of tube 1 for a relatively short distance. At their end sections - lower and upper in the figure - tubes 1 and 2 are sealed together. The sealing means comprises, at each end of the assembly comprising the rigid and resilient tubes, a circular plate 12 with a flange 12" projecting at ,.
right angles towards the other end of said assembly, which plate is fitted on said extension of tube 2 and engages the end of tube l; a ring nut 14 threadingly engages extensions
2' and forces plate 12 in the direction of the other end of said assembly. The inner surface of flange 12' is tapered and therefore the end section of tube 1 is forced against tube 2 when ring nut 14 is tightened.
For a more effecting sealing an O-ring 16 is provided in a peripheral groove 16' of the outer surface of backing tube 2.
. .
.. ..
109;~768 A duct 18 longitudinally extends along the wall thickness of tube 1 to reach the end surface of extension 2' of tube 2, which duct leads into space 10 between tube 1 and tube 2 at a position between the end sections of tube 2 where this is sealed against tube 1. Duct 18 from extension 2' of tube 2 is prolonged by a pipe 3 connectible to a supply - not shown -of pressurized fluid through control valve 3'.
Two peripheral ribs 4 poject from the outer surface of tube 1 each one at a position close to each end of the tube.
Ribs 4 - intended for functioning as seals - are defined by undercut side surfaces and concave outer surface whereby two symmetrical sharp ridges are formed by said side surfaces and outer surface joining together.
The outer diameter of ribs 4 is slightly less than the inner diameter of the tube 5 being copied.
Between ribs 4 a plurality of smaller peripheral ribs 6 are provided at regular distances along the apparatus. Ribs 6 have dovetail cross-sections and an outer diameter substantially smaller than the inner diameter of tube 5 and smaller also than the outer diameter of ribs 4. Thus a space 9 is provided between tube 5 and tube 1 which space is defined by the facing surfaces of said tubes and the two seals 4. Into space 9 two ducts 7 and 8 open each one close to one of seals 4.
Duct 7 is connectible to a vacuum pump not shown, through a control valve 7' and to the atmosphere through valve 7", while duct 8 is connectible to a supply of liquid resin not shown, through a control valve 8". Duct 8 from its opening to space 9 extends through the thickness of tube 1 in a direction perpendicular to the axis of the apparatus and then parallel thereto to reach the end surface of tube 1. From said end duct 8 extends into a tube 8' which crosses plate 12 and passes within the bore of tube 2 along its axis and connects to said , . . . .
189;~76~
supply of liquid resin through valve 8".
OPeration The apparatus of the invention is introduced into tube 5 to extend over the area to be copied.
By opening valve 3' a pressurized fluid is fed between the outer surface of tube 2 and the inner surface of resilient tube 1. The fluid pressure is increased until tube 1 is expanded to a predetermined diameter, such that a gap is left between each rib 6 and the facing surface of tube 5. Valve
For a more effecting sealing an O-ring 16 is provided in a peripheral groove 16' of the outer surface of backing tube 2.
. .
.. ..
109;~768 A duct 18 longitudinally extends along the wall thickness of tube 1 to reach the end surface of extension 2' of tube 2, which duct leads into space 10 between tube 1 and tube 2 at a position between the end sections of tube 2 where this is sealed against tube 1. Duct 18 from extension 2' of tube 2 is prolonged by a pipe 3 connectible to a supply - not shown -of pressurized fluid through control valve 3'.
Two peripheral ribs 4 poject from the outer surface of tube 1 each one at a position close to each end of the tube.
Ribs 4 - intended for functioning as seals - are defined by undercut side surfaces and concave outer surface whereby two symmetrical sharp ridges are formed by said side surfaces and outer surface joining together.
The outer diameter of ribs 4 is slightly less than the inner diameter of the tube 5 being copied.
Between ribs 4 a plurality of smaller peripheral ribs 6 are provided at regular distances along the apparatus. Ribs 6 have dovetail cross-sections and an outer diameter substantially smaller than the inner diameter of tube 5 and smaller also than the outer diameter of ribs 4. Thus a space 9 is provided between tube 5 and tube 1 which space is defined by the facing surfaces of said tubes and the two seals 4. Into space 9 two ducts 7 and 8 open each one close to one of seals 4.
Duct 7 is connectible to a vacuum pump not shown, through a control valve 7' and to the atmosphere through valve 7", while duct 8 is connectible to a supply of liquid resin not shown, through a control valve 8". Duct 8 from its opening to space 9 extends through the thickness of tube 1 in a direction perpendicular to the axis of the apparatus and then parallel thereto to reach the end surface of tube 1. From said end duct 8 extends into a tube 8' which crosses plate 12 and passes within the bore of tube 2 along its axis and connects to said , . . . .
189;~76~
supply of liquid resin through valve 8".
OPeration The apparatus of the invention is introduced into tube 5 to extend over the area to be copied.
By opening valve 3' a pressurized fluid is fed between the outer surface of tube 2 and the inner surface of resilient tube 1. The fluid pressure is increased until tube 1 is expanded to a predetermined diameter, such that a gap is left between each rib 6 and the facing surface of tube 5. Valve
3' is then closed.
By opening valve 8" fluid resin is admitted into space 9 through pipe 8. At the same time, while valve 3' is still closed and valve 7" is also closed, valve 7' is opened to connect space 9 to a vacuum pump not shown. Valve 7' is subsequently closed when the resin, after filling space 9, begins to outflow therefrom such outflowing being detected by a means not shown. Valve 8" is then closed and valve 7" is opened for connecting space 9 to the atmosphere. Thë resin is left to polymerize thereafter .. '. ::;., ~ , . ~ , . ., . .
. . . .. . . .
- - , . :
- - - - ~ .. , :
:. .. . `
: '. :
`: lO9Z768 The polymerization time may vary from some hours to a few tens of minutes depending on the resin type and on the temperature of the surface being copied. After polymerization the fluid in space 9 is discharched by opening valve 3'. Thus the inner sur-face of resilient tube 1 is caused to contact throughout the outer surface of tube 2. In other words,resilient tube 1 con-tracts and pulls therewith the replica by means of ribs 6; ribs
By opening valve 8" fluid resin is admitted into space 9 through pipe 8. At the same time, while valve 3' is still closed and valve 7" is also closed, valve 7' is opened to connect space 9 to a vacuum pump not shown. Valve 7' is subsequently closed when the resin, after filling space 9, begins to outflow therefrom such outflowing being detected by a means not shown. Valve 8" is then closed and valve 7" is opened for connecting space 9 to the atmosphere. Thë resin is left to polymerize thereafter .. '. ::;., ~ , . ~ , . ., . .
. . . .. . . .
- - , . :
- - - - ~ .. , :
:. .. . `
: '. :
`: lO9Z768 The polymerization time may vary from some hours to a few tens of minutes depending on the resin type and on the temperature of the surface being copied. After polymerization the fluid in space 9 is discharched by opening valve 3'. Thus the inner sur-face of resilient tube 1 is caused to contact throughout the outer surface of tube 2. In other words,resilient tube 1 con-tracts and pulls therewith the replica by means of ribs 6; ribs
4 are also moved away from tube 5 whereby the whole apparatus can be withdrawn from tube 2 with no effort.
It should be noted that in the above process the filling up of space 9 is facilitated by the vacuum in space 9; also any air bubbles within the fluid plastic are readily extracted there-from by said vacuum whereby a more faithful replica can be prod-uced.
The casting of the plastic can be carried out with tube
It should be noted that in the above process the filling up of space 9 is facilitated by the vacuum in space 9; also any air bubbles within the fluid plastic are readily extracted there-from by said vacuum whereby a more faithful replica can be prod-uced.
The casting of the plastic can be carried out with tube
5 in upright position,as shown in the figure, or inclined or even horizonta,l. When tube 1 is in inclined or horizontal position the apparatus should be inserted into tube 1 with the inlet of the fluid plastic into space 9 at the lowermost po-sition.Example.
An apparatus has been constructed according to this invention ~for making replicas of the inner surfaces-of tubes with 106 mm ID.
In the particular case, the apparatus was adapted for making replicas 360 mm long.
Resilient tube 1 was made of Vulkolan with a Shore hardness of about 90. Tube 1 was then turned to obtain a series of ribs 6 .
* (A registered trademark. It is an elastomer of the polyurethane group obtained by polyaddition of polyester and diisocyanate compounds). - 8 -,. : ~ . . .
at intervals of 20 mm from one another. Tube 2 was made ofalum1nlum.
Into space 9 an alastomeric resin was cast particularly adapted for replica work. The setting time of the cast resin was 8 - 10 hours.
The apparatus was tested on nuclear reactor tubes both unused and irradiated. The copied areas were at a distance of 4 m from the tube end.
The replicas have been made with the tube in vertical position the apparatus being introduced from the top into the tube.
Into space 10 water was fed at such a pressure that the outer peripheries of the dovetail ribes 6 were brought to a distance of 3 mm from the inner surface of tube 5.
With the above apparatus the exact dimensions have been measured of wear traces by fuel elements which traces had -been previously detected by other means.
Thanks to the extension and continuity of the area observable by means of the replica so obtained such traces, scratched and erosions have been detected which had escaped precedent inspections of the inner surface of the tube.
It is to be noted that the above materials employed forconstructing this apparatus can be replaced by others, provided that they are equivalent from the point of view of the effectiveness of the apparatus.
More speclfically any other turnable elastomer having a Shore hardness of about 90 can be used for making tube 1. As a material for making tube 2, steel or other materials can be used in addition to aluminium provided that the tube is rigid enough to firmly stand without deformation the water pressure within space 10.
Other modifications and variants to the above preferred lV9~768 embodiment can be envisaged by those skilled in the art. For instance, ribs 4 may comprise rings not integral with tube 1 but inserted into grooves of the same tube and they may also be suppressed when the sealing of space 9 is ensured by other means.
As for the length of the apparatus, it can obviously be made much greater than in the above example.
All the above modifications and variants should be considered to be within the scope of the appended claims when-ever made in the true spirit of the invention.
An apparatus has been constructed according to this invention ~for making replicas of the inner surfaces-of tubes with 106 mm ID.
In the particular case, the apparatus was adapted for making replicas 360 mm long.
Resilient tube 1 was made of Vulkolan with a Shore hardness of about 90. Tube 1 was then turned to obtain a series of ribs 6 .
* (A registered trademark. It is an elastomer of the polyurethane group obtained by polyaddition of polyester and diisocyanate compounds). - 8 -,. : ~ . . .
at intervals of 20 mm from one another. Tube 2 was made ofalum1nlum.
Into space 9 an alastomeric resin was cast particularly adapted for replica work. The setting time of the cast resin was 8 - 10 hours.
The apparatus was tested on nuclear reactor tubes both unused and irradiated. The copied areas were at a distance of 4 m from the tube end.
The replicas have been made with the tube in vertical position the apparatus being introduced from the top into the tube.
Into space 10 water was fed at such a pressure that the outer peripheries of the dovetail ribes 6 were brought to a distance of 3 mm from the inner surface of tube 5.
With the above apparatus the exact dimensions have been measured of wear traces by fuel elements which traces had -been previously detected by other means.
Thanks to the extension and continuity of the area observable by means of the replica so obtained such traces, scratched and erosions have been detected which had escaped precedent inspections of the inner surface of the tube.
It is to be noted that the above materials employed forconstructing this apparatus can be replaced by others, provided that they are equivalent from the point of view of the effectiveness of the apparatus.
More speclfically any other turnable elastomer having a Shore hardness of about 90 can be used for making tube 1. As a material for making tube 2, steel or other materials can be used in addition to aluminium provided that the tube is rigid enough to firmly stand without deformation the water pressure within space 10.
Other modifications and variants to the above preferred lV9~768 embodiment can be envisaged by those skilled in the art. For instance, ribs 4 may comprise rings not integral with tube 1 but inserted into grooves of the same tube and they may also be suppressed when the sealing of space 9 is ensured by other means.
As for the length of the apparatus, it can obviously be made much greater than in the above example.
All the above modifications and variants should be considered to be within the scope of the appended claims when-ever made in the true spirit of the invention.
Claims (12)
1. An apparatus for making replicas of the inner surface of a cylindrical circular tube over a length thereof by casting a plastic material for replicas upon the same surface, which apparatus comprises a rigid tube inserted into a tube of resilient material, the inner end sections of the latter tube being forced against the corresponding outer end sections of said rigid tube to form a seal therebetween, said resilient tube being provided on its outer surface with two circular sealing ribs with outer diameter adapted for sealingly fit into the tube to be copied which ribs are each at a short distance from one of said end sections of the resilient tube, the latter tube being being also provided with a series of peripheral ribs regularly spaced along the outer surface of said resilient tube between said sealing ribs, said peripheral ribs having a dove-tall cross-section and an outer diameter less than said sealing ribs; said apparatus being also provided with a first duct connectible to a supply of pressurized fluid which duct opens at the outer surface of said rigid tube; a second duct connectible to a supply of said plastic material in its fluid state, which second duct leads to an opening on the outer surface of said resilient tube close to one of said sealing ribs; a third duct alternatively connectible to a vacuum supply or to the atmosphere which duct opens at the outer surface of said resilient tube close to the sealing rib at the end of said resilient tube opposite to the opening of said second duct.
2. An apparatus as claimed in claim 1 wherein said first and second ducts are provided with a valve between the respective supply and the respective openings on the outer surface of said rigid tube and of said resilient tube and said third duct is provided with a valve between its opening on the outer surface of said resilient tube and the atmosphere and between the same opening and said supply of vaccum.
3. An apparatus as claimed in claim 1 wherein said plastic material comprises a silicone elastomer.
4. An apparatus as claimed in claim 1 wherein the cross-section of said sealing ribs has a pair of cuspidal projections at its outer perphery and the ribs are integral with said resilient tube.
5. An apparatus as claimed in claim 1 wherein each of the sealing means between said rigid and resilient tube comprises a circular plate provided with a tapering flange projecting at right angles towards the other ends of the tubes and by a ring nut which threadingly engages an extension of said rigid tube to force said plate against the end of said elastic tube.
6. An apparatus as claimed in claim 1, wherein an "O" ring is provided between said rigid and said resilient tube for ensuring the sealing therebetween.
7. An apparatus as claimed in claim 1, wherein said first duct connected to a supply of pressurized fluid extends within the thickness of said rigid tube in a direction parallel to the apparatus axis and then perpendicular thereto for reaching its opening on the outer surface of the rigid tube; said second duct passes within the bore of said rigid tube through the whole length thereof and then through the thickness of said resilient tube in a direction parallel to the apparatus axis and lastly for a short distance in a direction perpendicular thereto for reaching the opening on the surface of the same tube, said third duct extends for a length through the thick-ness of said resilient tube in a direction parallel to the apparatus axis and then in a direction perpendicular thereto for reaching its opening on the outer surface of said resilient tube.
8. An apparatus as claimed in claim 1 wherein said resilient tube is made of an elastomer with Shore hardness of about 90.
9. An apparatus as claimed in claim 8 wherein said resilient tube is made of an elastomer of the polyurethane group obtained by polyaddition of polyester and diisocyanate compounds.
10. An apparatus as claimed in claim 1 wherein said circular tube is included in a core of a nuclear reactor.
11. A method for making replicas of the inner sur-face of a cylindrical circular tube by casting a fluid plastic resin against said surface which method comprises:
introducing into the tube whose inner surface is to be copied an apparatus comprising a rigid tube fitted into an elastic tube of which tubes the end sections are sealed together, said elastic tube being provided at its ends with peripheral ribs adapted for forming a seal between said elastic tube and the tube to be copied and a plurality of peripheral ribs with outer diameter smaller than said sealing ribs, which smaller ribs have a dovetail cross-section and are regularly spaced from one another over the distance between said sealing ribs;
inletting a pressurized fluid between said rigid tube and said elastic tube whereby the latter tube is biased towards the inner surface of the tube to be copied;
increasing the pressure of said fluid to such a level that said smaller ribs are brought to a predetermined distance from the inner surface of the tube to be copied;
supplying under pressure said fluid resin into the space between said elastic tube deformed as above and the tube to be copied through an inlet at one end of the apparatus and simultaneously connecting to a vacuum source said space through an outlet at the other end of the apparatus;
disconnecting said space between the elastic tube and the tube to be copied from said vacuum source and connecting it to the atmosphere;
leaving the resin to polymerize;
relieving the pressure between said rigid tube and said elastic tube whereby the latter tube resumes its normal position and pulls therewith the polymerized resin carrying the replica on its surface.
introducing into the tube whose inner surface is to be copied an apparatus comprising a rigid tube fitted into an elastic tube of which tubes the end sections are sealed together, said elastic tube being provided at its ends with peripheral ribs adapted for forming a seal between said elastic tube and the tube to be copied and a plurality of peripheral ribs with outer diameter smaller than said sealing ribs, which smaller ribs have a dovetail cross-section and are regularly spaced from one another over the distance between said sealing ribs;
inletting a pressurized fluid between said rigid tube and said elastic tube whereby the latter tube is biased towards the inner surface of the tube to be copied;
increasing the pressure of said fluid to such a level that said smaller ribs are brought to a predetermined distance from the inner surface of the tube to be copied;
supplying under pressure said fluid resin into the space between said elastic tube deformed as above and the tube to be copied through an inlet at one end of the apparatus and simultaneously connecting to a vacuum source said space through an outlet at the other end of the apparatus;
disconnecting said space between the elastic tube and the tube to be copied from said vacuum source and connecting it to the atmosphere;
leaving the resin to polymerize;
relieving the pressure between said rigid tube and said elastic tube whereby the latter tube resumes its normal position and pulls therewith the polymerized resin carrying the replica on its surface.
12. A method as claimed in claim 10 wherein said pressurized fluid is water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT4877676A IT1057454B (en) | 1976-03-30 | 1976-03-30 | Checking the inner surface of tubes - by forming a resin casting, e.g. of silicone rubber |
| IT48776A/76 | 1976-03-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1092768A true CA1092768A (en) | 1981-01-06 |
Family
ID=11268493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA275,008A Expired CA1092768A (en) | 1976-03-30 | 1977-03-29 | Method and apparatus for checking the inner surface of tubes by resin casting |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1092768A (en) |
| IT (1) | IT1057454B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4659530A (en) * | 1985-06-17 | 1987-04-21 | Vetco Gray Inc | Method of taking an impression with an internal bore impression tool |
-
1976
- 1976-03-30 IT IT4877676A patent/IT1057454B/en active
-
1977
- 1977-03-29 CA CA275,008A patent/CA1092768A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4659530A (en) * | 1985-06-17 | 1987-04-21 | Vetco Gray Inc | Method of taking an impression with an internal bore impression tool |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1057454B (en) | 1982-03-10 |
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