FR2623279A1 - Method and device for marking a tubular panel heat exchanger tube - Google Patents

Abstract

The invention relates to a method of marking an end 90 of a tubular heat exchanger tube and to the corresponding marking device. Through the end 91 of a heat exchanger tube there is introduced a flexible rod 19 provided with a marking head 10 having a median portion which is radially expandable and on which are fixed marking means up to a head position extending beyond the end 90 to be marked of the tube; the said median portion is radially and remotely expanded and the flexible rod is pulled until the head enters into contact, via these marking means, with the end 90 to be marked; the median portion of the head is then contracted and the flexible rod 19 is withdrawn.

Description

Method and apparatus for marking a tube plate heat exchanger tube
The present invention relates to a method and an apparatus for marking an end of a tube plate type heat exchanger tube.

 It finds a particularly important although not exclusive application in the field of marking tubes in a heat exchanger between the primary coolant of a reactor, such as a pressurized water reactor or PWR, and water in liquid phases. and vapor constituting the secondary refrigerant.

 It is important to identify the leaking tubes by marking them so that they can then be closed off without risk of error on the tube to be condemned, the obturation being necessary to avoid any contamination by the primary circuit possibly loaded with radioactive elements from the secondary circuit which must imperatively remain inactive.

 The known methods and apparatuses for marking heat exchanger tubes of this type are unsatisfactory. The markings are in fact carried out manually in a long, tedious manner and with risks of errors very detrimental to safety.

 The invention aims to provide a method and an apparatus for marking heat exchanger tubes with a tubular plate which respond better than those previously known to the requirements of practice, in particular in that the marking method makes it possible to quickly identify one and / or the other of the ends of the same leaking tube without risk of error, by using only simple means, easily adaptable to a machine commonly used in the detection of leaks from a nuclear reactor heat exchanger .

The machine can in particular be of the type commonly called 'spider'. One can find possible constitutions of spiders by referring in particular to documents US-A-4,018,345 (COMBUSTION ENGINEERING) and
FR-A-2 309 314 (FRAMATOME).

The invention provides a method of marking one end of a tubular heat exchanger tube accessible from the other end of said tube, characterized in that
- Introducing through said other end of the tube a hose provided with a marking head having an expandable middle portion and on which are fixed marking means1 to a position of the head extending beyond the end to spot tube,
the said middle portion is expanded until a cross section of the head is obtained at the level of the marker means greater than the section of the tube,
- a pull is exerted on the hose until said head comes into contact by its marking means with said end to be identified on the tube, stopping the pull when the pulling force becomes greater than a predetermined value for marking said end ,
- Then contract the middle portion of the head and remove the hose from the tube.

The process is advantageously completed by marking the other end, characterized in that
the head of the hose is placed opposite said other end of the tube to be identified,
the middle portion of the head is expanded until a cross section of the head is obtained at the level of the marker means greater than the section of the tube,
- a push is exerted on the hose until the head comes into contact with said other end of said tube by stopping the push when the push force becomes greater than a predetermined value to mark said other end and then the head is removed said other end and the middle portion is contracted to return to an initial state.

The invention also provides an apparatus for marking a tube plate heat exchanger tube, characterized in that it comprises
- a marking head elongated around an axis comprising a middle portion on which are fixed marking means, said portion being provided to expand and contract radially between a contracted state and an expanded state where said middle portion has a radial bulk greater than that of the terminal parts in the axial direction of the head,
- a hose axially connected to the marking head,
- an engine assembly designed to exert a pulling or pushing force on the hose and,
- control means of the engine assembly comprising a module providing a signal when the pulling or pushing force on said marking head is greater than a predetermined value.

In advantageous embodiments, use is also made of one and / or the other of the following arrangements.
the middle portion comprises a hollow core elongated around the axis of the marking head, provided with a sealed outer membrane, deformable under the pressure of a fluid and on which the marking means are mounted, the flexible being tubular, connected on one side to the internal volume delimited by said hollow core and on the other side to means for producing a pressurized fluid capable of radially expanding the membrane,
the hollow core comprises a rigid central pipe, of substantially tubular shape, closed on one side and capable of being connected to the hose on the other side, said pipe being covered with the deformable membrane fixedly held on the pipe in a sealed manner its ends and delimiting with the external face of said pipe an expandable volume under the pressure of a fluid in communication with the inside of said pipe by at least one passage orifice,
- the end parts of the marking head are frustoconical, ensure the fixing of the deformable wall on the rigid central pipe of the hollow core and include stops to stop the radial expansion of the membrane,
the marking means comprise at least one marking ring made of deformable foam capable of deforming with the middle portion of the marking head,
- the module providing a signal is stretched around an axis; it includes a central piston suitable for sliding on the cylindrical end of a support element between two extreme positions and two rings mounted to slide respectively on the piston and the cylindrical end, each of the rings being held in a predetermined position by a spring resting on a part integral with the support element, each ring being adapted to cooperate with the piston coming to bear on one or the other of said rings when a pulling or pushing force is exerted on the head marking; the module also includes electrical signaling means indicating the movement of a sliding ring following the application of a predetermined stress on the spring associated with said ring,
the module providing a signal is connected to the hose between the engine assembly and the marking head, the piston and the element of said module each being extended at one of their ends by a connection piece with the hose,
- the marking head being able to expand under the action of a pressurized fluid and the flexible being tubular, the piston and the element provided with a cylinder end are longitudinally hollow so as to allow the passage of the fluid under clean pressure to expand the head.

 The invention will be better understood on reading the following description of a particular embodiment, given by way of non-limiting example.

The description refers to the accompanying drawings in which
- Figure 1 shows a block diagram of an apparatus according to the invention,
FIG. 2 is a sectional view of the main elements of the invention,
FIG. 3 is an enlarged view in two longitudinal half-sections of the marking head of FIG. 2, a half-section in the expanded position and a half-section in the contracted position,
FIG. 4 is an enlarged view, in section, of the signaling module of FIG. 2.

 The heat exchanger shown in Figure 1 is of a type commonly used in pressurized water reactors. It comprises an envelope 1 which contains a bundle of U-shaped tubes 2, the end portions of which pass through a tubular plate 3 The plate 3 delimits, with a partition 4, a cold water box 5 and a hot water box 6, provided respectively an outlet pipe and an inlet pipe for the primary coolant of the reactor (not shown).

 Valves, also not shown, equip these pipes and make it possible to isolate the part of the primary circuit contained in the exchanger and to empty it.

 The part of the exchanger between the tubes 2 and the casing 1 is occupied, during operation, by the secondary coolant of the reactor and therefore belongs to the secondary circuit.

 The apparatus according to the invention comprises a marking head 10 (FIG. 3) elongated around an axis 11, having a middle portion 12 on which the marking means are fixed comprising a mounting 13 for supporting two elastic washers 14 for marking . The washers are coated with a grease-dye mixture. The frame 13 is constituted by a rigid mandrel in several rigid sectors not fixed to each other, held in place by the washers 14.

 The middle portion 12 is designed to expand and contract radially between a contracted state and an expanded state where the middle portion has a radial bulk greater than that of the end portions 15 of the head and of the section of the end to be marked.

In the contracted state, the middle portion 12, on the other hand, has a smaller radial dimension than that of the parts 15 which are themselves of dimensions compatible with their free passage in the U-shaped tubes 2.

 The overall longitudinal dimensions of the head and the longitudinal dimensions of this latter are also compatible with the passage of the head in the curves of the tubes 2.

 The middle portion 12 comprises a hollow core elongated around the axis 11 comprising a rigid central pipe 16 of stainless steel of substantially tubular shape, closed on one side 17 and capable of being connected on the other side 18 forming a grooved end piece a hose 19 connected axially to the head.

 The central pipe 16 is pierced with orifices 20 and covered with a sealed external membrane 21, deformable under the pressure of a fluid. The membrane 21 is for example made of elastomer. It is maintained - on the pipe 16 in a sealed manner at its two ends and defines with the external face of the pipe 16 an expandable volume 23 under the pressure of a fluid in communication with the inside of the pipe 24 through the orifices 20 .

 The membrane 21 is fixed to the duct by the end portions 15 of substantially frustoconical shape. The parts 15 include stops 22 capable of stopping the radial expansion of the membrane 21 by blocking the movement of the frame 13 held on the membrane 21 by a spring ring 25 (spring seal type) and by the two marking washers 14 in elastic foam.

 The hose 19 is constituted by a hose made of relatively flexible material such as that known under the name RILSAN. It is axially connected to the head 10 by the splined end piece 18 and displaceable by a motor assembly 27 designed to exert a pulling or pushing force on the hose. The motor assembly 27 comprises in particular a drum 28 suitable for winding or unwinding the hose 19 of around thirty meters and a motor 29, the control of which is connected via a controller 30 to a control and command console 31, suitable for controlling moving the hose.

 The hose is connected to a compressed air supply source. The arrival of compressed air controlled by a remote-controlled valve 32 deforms the membrane 21 and pushes the frame 13 constituted by a mandrel expandable in several sectors to the expanded position where the frame comes into contact with the stops 22. A valve remotely controlled venting 33 brings the middle portion 12 into contracted portion.

 A stainless steel spring 34 around the tube 19 facilitates the passage of the tube in difficult places (small radius elbows of the U-shaped tubes for example).

An olive 35 retains the spring on the hose and also serves as a stop when the hose is retracted into the drive means 27.

 The apparatus according to the particular embodiment of the invention described here also comprises a module 40 (see Figure 4) elongated around an axis 41 connected to the hose 19 between the motor assembly 27 and the marking head 10 The module 40 is capable of supplying an electrical signal via a cable 42 circulating inside the flexible 19, to the automatic device 30 when the pulling or pushing force on the marking head where the flexible is greater than a value predetermined.

 To do this, the module 40 comprises a central piston 43, capable of sliding on the cylindrical end 44 of an element 45, and the end of which can take two extreme positions 46 and 47 shown in dashed lines in FIG. 4. A seal 48 ensures the sealing of the piston. The piston 43 and the element 45 are tubularly hollow; they are terminated at their opposite side each by a grooved end on which the flexible hose is connected on one side 50 towards the source of compressed air and on the other side 49 towards the marking head so that the air tablet can pass through the module 40 to supply the marking head 10.

 Two guide cones 51 and 52 are respectively fixed on the end pieces 49 and 50 of the piston 43 and of the element 45.

 The module includes two rings. 53 and 54 mounted sliding on the piston 43 and on the cylindrical end 44 of the element 45 respectively.

 Each ring is held in a predetermined position compressed against stops making contact 80 by a spring 55, 56 bearing on the other side respectively on a part 57 secured to the element 45 or on the element 45 itself. The two electric wires 58, 59 of the cable 42 are mounted on the latter.

 In the equilibrium position as in FIG. 4, the module ensures contact formed between the two wires, for example supplied with 24 V direct current.

 When a force sufficient to compress the springs 55, 56 by pushing one of the rings 53, 54 is applied to the piston 43, the contact opens and a signal is therefore transmitted to the controller 30.

 The marking head is advantageously placed in front of the tube to be identified by a machine 60 of the type commonly known by the name of "spider" suitable for also guiding the hose during its introduction or its exit.

 The machine comprises a table with crossed movements carrying expandable fingers insertable in the terminal part of other tubes. The different movements of the spider can be automatic or controlled from the console 31 via the automaton 30 connected to the spider's motor by electrical or pneumatic conductors 61.

 The method is implemented in the following manner using the device which has just been described.

Tube marking
The spider is introduced into the box 6 and placed on the tube plate 3.

 After checking the tightness of a tube and identifying it as a leaking tube by means 70, 71, shown schematically in phantom in Figure 1 and of the type described in application FR 84 13798, the marking is carried out. tube.

 The marker assembly, the marking washers of which have been previously coated with marker product, is placed in front of the tube identified by displacement of the spider 60 on which it has been previously mounted. The movement of the spider is for example automatically controlled by the automaton 30 which has recorded the position of the leaking tube.

 The marking head is then introduced and the hose is pushed back by the motor means 27 to a position of the head extending outside the end 90 to be located of the tube in the cold box 5.

The length of the hose to be unwound is assessed, for example visually or automatically, by marks (not shown) placed on the hose. A margin is taken on the unwound length to be certain that the end is exceeded by the head.

 Automatically or manually, the compressed air supply valve 33 is then opened, the operating pressure being for example of the order of 4 bars.

 The middle portion 12 of the head 10 expands and makes it possible to obtain, at the level of the marking washers 14, a transverse bulk greater than the section of the tube.

 A traction is exerted on the hose 19 until the head 10 comes into contact then in compression with the end 90 to be marked. This contact is detected by the module 40 which sends a signal to stop traction as soon as the head 10 wider than the section of the orifice 90 to be marked is blocked on the latter by opening the contact of the wires 58 and 59 of the module 40.

 The end 90 is then marked by rubbing the marking washers coated with a greasy-coloring mixture on the walls of the orifice of the tube.

 The compressed air supply valve 32 is then closed and the air valve 33 open, which causes the median portion 12 of the head 10 to contract, which again becomes smaller in section than that of the tube.

 The springs 55, 56 to the module 40 then close the contact between the wires 58 and 59, no more sufficient resistant force being exerted on the hose.

 The hose is then removed from the tube and prepared for a new marking operation.

When we want to mark the end of a tube in a hot box, for example of the same tube as the one whose end has already been marked, we proceed as follows:
After having brought back the marking head in a hot box (it is therefore facing the tube to be marked), the middle portion is dilated by sending compressed air, as described above, then the flexible hose is pushed until the head comes into contact then in compression with the end 91 to be marked.

 The push opens the contact of the module 40 and stops the movement of the head.

 The marking is then carried out as described above, then the head is contracted and removed.

 The marked tubes can be closed later, for example by fitting a mechanical stopper.

Claims (10)

 1. A method of marking one end (90) of a tube (2) of tubular heat exchanger accessible from the other end (91) of said tube, characterized in that  a flexible hose (19) fitted with a marking head (10) having a median portion (12) which can be expanded radially and on which are fixed marking means (13, 14), is introduced via said other end (91) of the tube; up to a position of the head extending outside the end (90) to be identified of the tube,  - said central portion (12) is radially and remotely expanded until a cross section of the head is obtained at the level of the marking means greater than the section of the tube (2),  - traction is exerted on the hose until said head comes into contact by its marking means with said end to be identified from the tube, stopping traction when the traction force becomes greater than a predetermined value to mark said end,  - Then we contract the middle portion of the head and we remove the hose (19) from the tube.  2. Marking method according to claim 1 characterized in that, in addition,  - the head (10) is placed facing said other end (91) of the tube to be located,  - the middle portion (12) of the head (10) is expanded until a cross section of the head is obtained at the level of the marker means (13, 14) greater than the section of the tube,  - a push is exerted on the hose until the head comes into contact with said other end (91) of said tube by stopping the push when the pushing force becomes greater than a predetermined value,  - We mark said other end then we remove the head from said other end and we contract the middle portion to return to an initial state.  3. Apparatus for marking one end of a tube plate heat exchanger tube, characterized in that it comprises  - a marking head (lob) elongated around an axis (11l comprising a middle portion (12) on which are fixed marking means (13, 14), said portion being provided with means that can be actuated remotely making it possible to expand and contract it radially between a contracted state and an expanded state where said middle portion (12) has a radial bulk greater than that of the end portions in the axial direction of the head,  - a hose (19) connected axially to the marking head,  a motor assembly (27) designed to exert a pulling or pushing force on the flexible pipe (19) and,  - control means (30, 31, 40) of the engine assembly comprising a module (40) providing a signal when the pulling or pushing force on said marking head (10) is greater than a predetermined value.  4. Apparatus according to claim 3, characterized in that the middle portion (12) of the marking head comprises a hollow core, elongated around the axis (11) of said marking head and provided with an outer membrane ( 21) sealed, deformable under the pressure of a fluid and on which the marking means (13, 14) are mounted, and in that the flexible (19) is tubular, connected on one side to the internal volume delimited by the core hollow and on the other side to means for producing a pressurized fluid capable of radially expanding said membrane.  5. Apparatus according to claim 4, characterized in that the hollow core comprises a rigid central pipe (16), of substantially tubular shape, closed on one side (17) and able to be connected to the hose on the other (13 ), said pipe (16) being covered with the deformable membrane (21) fixedly held on said pipe in a sealed manner at its ends and delimiting with the external face of said pipe an expandable volume under the pressure of a fluid and in communication with the interior of the pipe (16) by at least one orifice (20) for passage.  6. Apparatus according to claim 5, characterized in that the end parts (15) of the marking head (10) are frustoconical, ensure the fixing of the deformable wall (21) on the rigid central pipe (16) of the hollow core and comprise stops (22) for the radial expansion of the membrane.  7. Apparatus according to any one of the preceding claims, characterized in that the marking means (13,14) comprise at least one marking washer of deformable foam capable of deforming with the middle portion (12) of the marking head .  8. Apparatus according to any one of the preceding claims, characterized in that the module (40) providing a signal is elongated around an axis (41) and in that it comprises a central piston (43) capable of sliding on the cylindrical end (44) of a support element (45) between two extreme positions (46, 47), two rings (53, 54) slidably mounted respectively on the piston (43) and said cylindrical end (44) , each of the rings being held in a predetermined position by a spring (55, 56) bearing on the support element, each ring (53, 54) being able to cooperate, with the piston (43) coming to bear on either of these rings when a pulling or pushing force is exerted on the marking head (10), and electrical signaling means (42, 80) indicating the movement of a sliding ring following applying a predetermined stress to the spring associated with said ring.  9. Apparatus according to claim 8, characterized in that the module (40) providing a signal is connected to the hose (19) between the engine assembly (27) and the marking head (10), the piston (43) and the element (45) of said module (40) each being extended at one of their ends by a connecting end piece (48, 49) with said flexible pipe (19).  10. Apparatus according to claim 9, characterized in that the marking head (10) being able to expand under the action of a pressurized fluid and the hose (19) being tubular, the piston (43) and l 'support element (45) are internally tubular so as to allow the passage of pressurized fluid to expand the head (10).