EP0180892B1 - Apparatus for electropolishing the inner surfaces of tubes - Google Patents

Apparatus for electropolishing the inner surfaces of tubes Download PDF

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Publication number
EP0180892B1
EP0180892B1 EP85113706A EP85113706A EP0180892B1 EP 0180892 B1 EP0180892 B1 EP 0180892B1 EP 85113706 A EP85113706 A EP 85113706A EP 85113706 A EP85113706 A EP 85113706A EP 0180892 B1 EP0180892 B1 EP 0180892B1
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EP
European Patent Office
Prior art keywords
tube
heat exchanger
electrode
electropolishing
supporting frame
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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
Application number
EP85113706A
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German (de)
French (fr)
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EP0180892A1 (en
Inventor
Ludwig Dipl.-Ing. Voggenthaler (Fh)
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Siemens AG
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Siemens AG
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Publication of EP0180892A1 publication Critical patent/EP0180892A1/en
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/002—Component parts or details of steam boilers specially adapted for nuclear steam generators, e.g. maintenance, repairing or inspecting equipment not otherwise provided for
    • F22B37/003—Maintenance, repairing or inspecting equipment positioned in or via the headers
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
    • G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
    • G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces

Definitions

  • the invention relates to a device for electropolishing the inner surface of pipes with an electrode connected to a DC voltage source, which can be inserted into and removed from the pipe to be electropolished, according to the preamble of claim 1.
  • the electrode comprises a tubular body which can be connected to an electrolyte supply pump and which is metallically conductive on its outer surface carries, is provided in the vicinity of the plug with at least one outflow opening and is guided axially displaceably on a support device.
  • a support device is also shown, which is attached to the outside of the housing of the heat exchanger. The upper ends of the heat exchanger tubes are inserted into an open collecting container for the electrolyte liquid, which is connected to a storage container which feeds the supply line for the electrolyte supply via a pump.
  • a device for electropolishing the inner surface of U-shaped heat exchanger tubes has also become known, in which an electrode connected to a DC voltage source is inserted into one end of a heat exchanger tube. Here, electrolyte liquid is supplied from the other end of the heat exchanger tube. The electrode is then pulled out of the heat exchanger tube at a constant speed with the DC voltage switched on.
  • this known device for electropolishing the inner surface of U-shaped heat exchanger tubes the entire inner surface of such heat exchanger tubes can be cleaned and also decontaminated. It is a peculiarity of such a device that it is attached to both ends of a heat exchanger tube, i.e. must be connected in both bottom caps of a heat exchanger at the same time.
  • relatively large amounts of electrolyte liquid are required simply because of the filling of the entire heat exchanger tube and the relatively long hose lines.
  • the invention is therefore based on the object of developing a device for electropolishing the inner surface of pipes, in particular the ends of heat exchanger pipes, the handling of which is as simple as possible and whose electrolyte consumption can also be limited to smaller amounts in accordance with the smaller surfaces to be electropolished.
  • the total amount of electrolyte required is greatly reduced by the inventive design.
  • the device need only be connected to a single end of a heat exchanger tube. This alone halves the preparation time or set-up time compared to the known device.
  • the axial displaceability of the electrode on a carrying device at the same time facilitates the setting of the electropolishing depth and also the assembly of the device at the place of use.
  • a drainage tube can be passed concentrically through the electrode and through the stopper in a particularly expedient development of the invention. This ensures that excess electrolyte liquid can leak out of the section of the heat exchanger tube located above the pipe plug and that at the same time the attention of the operating personnel is drawn in this way to the leakage of the sealing plug. It is advantageous for the tight fit of the stopper in the tube to be electropolished if the stopper carries a seal which is in contact with the tube to be electropolished.
  • the electrode When electropolishing heat exchanger tubes, the electrode is protected against tilting, since it is guided on a support device that can be anchored to the tube plate of the heat exchanger. This measure also creates a prerequisite for the operating personnel to be able to move away from the vicinity of the tube sheet during electropolishing.
  • the carrying device forms the prerequisite for being able to fasten a leakage collecting container under the tube to be electropolished in an advantageous further development of the invention. This prevents dripping electrolyte liquid from getting into the bottom cap of the heat exchanger.
  • the figure shows a section of the tube sheet of a heat exchanger with the heat exchanger tubes opening into the tube sheet and the device according to the invention, introduced in one of these heat exchanger tubes, for electropolishing the inner surface of this heat exchanger tube.
  • the figure shows a section of the tube sheet 1 of a heat exchanger 2, which is not shown in the rest, with the heat exchanger tubes 3, 4, 5, 6 inserted into the bores of the tube sheet 1 and welded there with their ends.
  • the weld seams 7, 8, 9, 10 are shown clearly exaggerated.
  • the device 11 according to the invention for electropolishing is fastened to the tube sheet (1) by means of three pneumatic clamping fingers 12 (only one shown), each of which is inserted and clamped in a heat exchanger tube 3.
  • These pneumatic clamping fingers 12 are attached to a common adapter plate 13.
  • This adapter plate has a central opening 14 into which a guide bush 15 is inserted.
  • An insulating flange 16 which surrounds the guide bush 15 and is made of an insulating material, is also fastened on the adapter plate 13.
  • a holding flange 17 for the electrode 18 is fastened to this insulating flange 16.
  • This holding flange 17 has a central bore (19) in which one end of the electrode 18 is guided.
  • This electrode 18 comprises a metallically conductive tube piece 20 which is inserted into the heat exchanger tube 5 to be electropolished as far as the latter is to be electropolished.
  • the tube piece 20 carries a stopper 21.
  • This stopper 21 consists of two approximately discus-shaped halves 22, 23 made of insulating material.
  • a seal 24, an O-ring in the exemplary embodiment, is clamped between them.
  • the 0-ring lies against the inside diameter of the heat exchanger tube 5 to be electropolished.
  • These two halves 22, 23 of the plug 21 are pierced.
  • a drainage pipe 25 is guided through it and carries a tension nut 26 at its end.
  • the tube piece has a plurality of small holes 27, 28, 29, 30 at the end facing the stopper 21.
  • annular cavity 31 Between the tube piece 20 and the inside diameter of the holding flange 17 there is an annular cavity 31.
  • a further auxiliary flange 33 is seated on the holding flange 17 and likewise has a central bore of smaller diameter, in which the drainage tube 25 passing through the electrode is guided.
  • an electrolyte inlet fitting 35 opens into the auxiliary flange.
  • a clamping sleeve 38 with clamping nut 39 is screwed onto the drain pipe. The latter is supported on the clamping plate 37 of the clamping flange 36.
  • a return sleeve 41 which can be brought into contact with an O-ring 40 on the tube sheet 1 on the circumference of the tube 5 to be electropolished, can be seen between the adapter plate 13 and the tube sheet.
  • This return sleeve is guided in the guide bushing 15 in a liquid-tight manner and is pressed against the tube sheet 1 by a compression spring 42 supported on the adapter plate 13 with its tube sheet mouthpiece 43 carrying the 0-ring (40). It consists of electrically non-conductive material. It surrounds the pipe section 20 of the electrode with a predetermined distance and opens into the holding flange 17.
  • the return sleeve 41 is surrounded by an electrolyte collecting chamber 44 which is concentrically surrounding it and is fastened to the adapter plate 13. This electrolyte collection chamber 44 is connected to an electrolyte drainage nozzle 45 attached to the adapter plate.
  • the electrolyte return pipe 32, the electrolyte drain pipe 45 and the drain pipe 25 are each connected to an electrolyte reservoir 49 via a hose 46, 47, 48.
  • a circulating pump 50 for the electrolyte liquid is connected to this electrolyte reservoir, which is connected to the electrolyte inlet connection 35 via a further hose 51.
  • the DC voltage source 52 is also shown schematically with its positive pole connected to the tube sheet 1 and the negative coil connected to the holding flange 17.
  • a heat exchanger pipe If a heat exchanger pipe has leaked due to corrosion at one point, it can be repaired, among other things, by inserting a smaller SLEEVE pipe that bridges the damaged section.
  • the two ends of the SLEEVE pipe must be connected liquid-tight to the inner wall of the heat exchanger pipe.
  • Another repair measure would be to cut off this heat exchanger tube at its damaged end, to detach it from the tube sheet by grinding the weld seam on the tube sheet, to pull it out of the tube sheet and by means of a correspondingly long piece of replacement tube which would have to be welded to both the cut end of the heat exchanger tube and to the tube sheet, to replace. In both cases, welding has to be carried out and consequently the area of the weld seam has to be cleaned.
  • the oxide layer on the inner surface of the heat exchanger tube has to be separated here and cut open.
  • the electropolishing of the inner surface of the heat exchanger tube is suitable for this. Even if the radiation exposure for performing other work in the vicinity of the tube sheet of a heat exchanger, for example in the subsequent primary chamber of the steam generator, is to be reduced, the electropolishing of the ends of one or more heat exchanger tubes in the area of the tube sheet is expedient.
  • the device 11 for electropolishing is fastened to the tube sheet 1 by inserting the clamping fingers 12 located on the adapter plate 13 into the adjacent heat exchanger tubes 3 and bracing them in these heat exchanger tubes.
  • the adapter plate is pressed immediately before the hydraulic or electromechanical expansion of the clamping fingers 12 so far against the tube sheet 1 that the tube sheet mouthpiece 43 of the return sleeve 41 rests resiliently on the tube sheet 1, namely centrally to the heat exchanger tube 5 to be electropolished.
  • the electrode 18 together with the insulating flange 16, holding flange 17, auxiliary flange 33 and clamping flange 36 can be inserted into the heat exchanger tube 5 to be electropolished and screwed onto the adapter plate 13.
  • the length of the electrode 18 has already been adapted to the length of the electropolishing tube section. Also, the clamping nuts 26, 39 have been preloaded so far that the drainage pipe 25 with its clamping nut 26 pulls the two halves 22, 23 of the sealing plug 21 against the intermediate seal 24 and the metallically conductive pipe section 20 of the electrode 18.
  • the electropolishing can be started by switching on the DC voltage source 52.
  • fresh electrolyte is conveyed from the electrolyte reservoir 49 via the electrolyte circulation pump, via the electrolyte inlet connection 35, the cavity 34 of the auxiliary flange 33 and from there between the drain pipe 25 and the pipe section 20 of the electrode 18 up to the stopper 21.
  • the fresh electrolyte liquid emerges through the holes 27 to 31 located directly in front of the plug 21 in the pipe section 20 and now flows back between the pipe section 20 and the wall of the heat exchanger pipe 5 to be electropolished.
  • the oxide layer on the inner wall of the heat exchanger tube 5 is removed and the removed particles, together with the downward flowing electrolyte liquid, reach the electrolyte return nozzle and from there the hose 46 into the electrolyte reservoir 49.
  • Electrolyte liquid emerging at the 0-ring (40) of the tube plate mouthpiece 43 also runs back into the electrolyte collecting chamber 44 and via the electrolyte drainage connection connected to the electrolyte collecting chamber back into the electrolyte collecting container 49. From there it can be pumped again into the electrolyte inlet connection by the circulation pump 50.
  • the electropolishing process i.e. After a period of time which is dependent on the layer thickness to be removed and the current intensity switched on, the DC voltage source 52 and the circulation pump 50 are switched off. As soon as the pneumatic clamping fingers 12 are relaxed, the entire electropolishing device 11 can be pulled out of the tube sheet 1 from below and, in the same way, brought back to another heat exchanger tube to be electropolished and locked there.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Metallurgy (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)

Description

Die Erfindung bezieht sich auf eine Vorrichtung zum Elektropolieren der inneren Oberfläche von Rohren mit einer an einer Gleichspannungsquelle angeschlossenen, in das zu elektropolierende Rohr einschiebbaren und wieder herausziehbaren Elektrode gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a device for electropolishing the inner surface of pipes with an electrode connected to a DC voltage source, which can be inserted into and removed from the pipe to be electropolished, according to the preamble of claim 1.

Aus der US-A-2 764 540 ist eine Vorrichtung dieser Art bekannt, bei der die Elektrode einen an eine Elektrolytversorgungspumpe anschließbaren, an seiner Außenoberfläche metallisch leitenden rohrartigen Körper umfaßt, welcher an seinem in Einschubrichtung vorderen Ende eine das zu elektropolierende Rohr flüssigkeitsdicht verschließenden Stopfen trägt, in der Nähe des Stopfens mit mindestens einer Ausströmöffnung versehen und an einer Tragvorrichtung axial verschiebbar geführt ist. In der genannten US-A-2 764 540 ist auch eine Tragvorrichtung gezeigt, die außen am Gehäuse des Wärmetauschers befestigt ist. Dabei sind die oberen Enden der Wärmetauscherrohre in einen offenen Sammelbehälter für die Elektrolytflüssigkeit eingeführt, der mit einem Vorratsbehälter verbunden ist, welcher die Zuleitung für die Elektrolytzuführung über eine Pumpe speist.From US-A-2 764 540 a device of this type is known, in which the electrode comprises a tubular body which can be connected to an electrolyte supply pump and which is metallically conductive on its outer surface carries, is provided in the vicinity of the plug with at least one outflow opening and is guided axially displaceably on a support device. In the said US-A-2 764 540 a support device is also shown, which is attached to the outside of the housing of the heat exchanger. The upper ends of the heat exchanger tubes are inserted into an open collecting container for the electrolyte liquid, which is connected to a storage container which feeds the supply line for the electrolyte supply via a pump.

Es ist auch bereits eine Vorrichtung zum Elektropolieren der Innenoberfläche von U-förmigen Wärmetauscherrohren bekannt geworden, bei der eine an einer Gleichspannungsquelle angeschlossenen Elektrode in das eine Ende eines Wärmetauscherrohres eingeschoben wird. Hierbei wird Elektrolytflüssigkeit von dem anderen Ende des Wärmetauscherrohres zugeführt. Sodann wird die Elektrode bei eingeschalteter Gleichspannung mit konstanter Geschwindigkeit aus dem Wärmetauscherrohr wieder herausgezogen. Mit dieser bekannten Vorrichtung zum Elektropolieren der Innenoberfläche von U-förmigen Wärmetauscherrohren läßt sich die gesamte Innenoberfläche solcher Wärmetauscherrohre reinigen und auch dekontaminieren. Es ist eine Eigenart einer solchen Vorrichtung, daß sie an beiden Enden eines Wärmetauscherrohres, d.h. in beiden Bodenkalotten eines Wärmetauschers zugleich angeschlossen werden muß. Darüberhinaus werden bei einer solchen Vorrichtung allein schon wegen der Füllung des gesamten Wärmetauscherrohres und der relativ langen Schlauchleitungen relativ große Mengen an Elektrolytflüssigkeit benötigt.A device for electropolishing the inner surface of U-shaped heat exchanger tubes has also become known, in which an electrode connected to a DC voltage source is inserted into one end of a heat exchanger tube. Here, electrolyte liquid is supplied from the other end of the heat exchanger tube. The electrode is then pulled out of the heat exchanger tube at a constant speed with the DC voltage switched on. With this known device for electropolishing the inner surface of U-shaped heat exchanger tubes, the entire inner surface of such heat exchanger tubes can be cleaned and also decontaminated. It is a peculiarity of such a device that it is attached to both ends of a heat exchanger tube, i.e. must be connected in both bottom caps of a heat exchanger at the same time. In addition, in such a device, relatively large amounts of electrolyte liquid are required simply because of the filling of the entire heat exchanger tube and the relatively long hose lines.

Für diverse Aufgaben, wie etwa der Verminderung der Strahlenbelastung in der Primärkammer eines Dampferzeugers oder bei der Vorbereitung von Rohrteil-Austauschmaßnahmen brauchen aber nicht komplette Wärmetauscherrohre sondern nur kleine Wärmetauscherrohrabschnitte, häufig jene, die unmittelbar am Rohrboden des jeweiligen Wärmetauschers anschließen, gereinigt bzw. dekontaminiert zu werden.For various tasks, such as reducing the radiation exposure in the primary chamber of a steam generator or preparing pipe part replacement measures, it is not necessary to clean or decontaminate complete heat exchanger pipes, but only small heat exchanger pipe sections, often those that connect directly to the tube plate of the respective heat exchanger will.

Der Erfindung liegt daher die Aufgabe zugrunde, eine Vorrichtung zum Elektropolieren der Innenoberfläche von Rohren, insbesondere der Enden von Wärmetauscherrohren zu entwickeln, deren Handhabung dafür möglichst einfach ist und deren Elektrolytverbrauch entsprechend der kleineren zu elektropolierenden Oberflächen auch auf kleinere Mengen begrenzt werden kann.The invention is therefore based on the object of developing a device for electropolishing the inner surface of pipes, in particular the ends of heat exchanger pipes, the handling of which is as simple as possible and whose electrolyte consumption can also be limited to smaller amounts in accordance with the smaller surfaces to be electropolished.

Die gestellte Aufgabe wird erfindungsgemäß durch die im Kennzeichen des Anspruchs 1 angegebenen Merkmale gelöst. Vorteilhafte Weiterbildungen sind in den Ansprüchen 2 bis 5 beschrieben.The object is achieved according to the invention by the features specified in the characterizing part of claim 1. Advantageous further developments are described in claims 2 to 5.

Durch die erfindungsgemäße Ausbildung wird die gesamte erforderliche Menge an Elektrolytflüssigkeit stark vermindert. Ferner braucht die Vorrichtung nur an einem einzigen Ende eines Wärmetauscherrohres angeschlossen zu werden. Allein hierdurch wird die Vorbereitungszeit bzw. Rüstzeit gegenüber der bekannten Vorrichtung halbiert. Die axiale Verschiebbarkeit der Elektrode an einer Tragvorrichtung erleichtert zugleich die Einstellung der Elektropoliertiefe als auch die Montage der Vorrichtung am Einsatzort.The total amount of electrolyte required is greatly reduced by the inventive design. Furthermore, the device need only be connected to a single end of a heat exchanger tube. This alone halves the preparation time or set-up time compared to the known device. The axial displaceability of the electrode on a carrying device at the same time facilitates the setting of the electropolishing depth and also the assembly of the device at the place of use.

Um zu verhindern, daß bei undichtem Sitz des Stopfens in dem zu elektropolierenden Wärmetauscherrohr größere Mengen an Elektrolytflüssigkeit oberhalb der Elektrode in das Wärmetauscherrohr hineinsickern können, kann in besonders zweckmäßiger Weiterbildung der Erfindung ein Drainagerohr konzentrisch durch die Elektrode und durch den Stopfen hindurchgeführt werden. Hierdurch wird sichergestellt, daß überschüssige Elektrolytflüssigkeit aus dem oberhalb des Rohrstopfens befindlichen Abschnitt des Wärmetauscherrohres auslaufen kann und daß zugleich die Aufmerksamkeit des Bedienungspersonals auf diese Weise auf die Undichtigkeit des Dichtstopfens gelenkt wird. Dabei ist es für den dichten Sitz des Stopfens in dem zu elektropolierenden Rohr vorteilhaft, wenn der Stopfen eine an dem zu elektropolierenden Rohr anliegende Dichtung trägt.In order to prevent large amounts of electrolyte liquid from seeping into the heat exchanger tube above the electrode when the plug is leaking in the heat exchanger tube to be electropolished, a drainage tube can be passed concentrically through the electrode and through the stopper in a particularly expedient development of the invention. This ensures that excess electrolyte liquid can leak out of the section of the heat exchanger tube located above the pipe plug and that at the same time the attention of the operating personnel is drawn in this way to the leakage of the sealing plug. It is advantageous for the tight fit of the stopper in the tube to be electropolished if the stopper carries a seal which is in contact with the tube to be electropolished.

Beim Elektropolieren von Wärmetauscherrohren wird die Elektrode vor Verkantungen geschützt, da sie an einer am Rohrboden des Wärmetauschers verankerbaren Tragvorrichtung geführt wird. Mit dieser Maßnahme wird auch eine Voraussetzung dafür geschaffen, daß sich das Bedienungspersonal während des Elektropolierens aus der Nähe des Rohrbodens entfernen kann.When electropolishing heat exchanger tubes, the electrode is protected against tilting, since it is guided on a support device that can be anchored to the tube plate of the heat exchanger. This measure also creates a prerequisite for the operating personnel to be able to move away from the vicinity of the tube sheet during electropolishing.

Zugleich bildet die Tragvorrichtung die Voraussetzung dafür, um in vorteilhafter Weiterbildung der Erfindung einen Leckagesammelbehälter unter dem zu elektropolierenden Rohr befestigen zu können. Dieser verhindet, daß austropfende Elektrolytflüssigkeit in die Bodenkalotte des Wärmetauschers gelangen kann.At the same time, the carrying device forms the prerequisite for being able to fasten a leakage collecting container under the tube to be electropolished in an advantageous further development of the invention. This prevents dripping electrolyte liquid from getting into the bottom cap of the heat exchanger.

Weitere Einzelheiten der Erfindung werden anhand eines in der Figur dargestellten Ausführungsbeispiels erläutert. Es zeigt:Further details of the invention will be explained with reference to an embodiment shown in the figure. It shows:

Die Figur einen Ausschnitt aus dem Rohrboden eines Wärmetauschers mit den im Rohrboden mündenden Wärmetauscherrohren und der in einem dieser Wärmetauscherrohre eingeführten erfindungsgemäßen Vorrichtung zum Elektropolieren der Innenoberfläche dieses Wärmetauscherrohres.The figure shows a section of the tube sheet of a heat exchanger with the heat exchanger tubes opening into the tube sheet and the device according to the invention, introduced in one of these heat exchanger tubes, for electropolishing the inner surface of this heat exchanger tube.

Die Figur zeigt einen Ausschnitt aus dem Rohrboden 1 eines im übrigen nicht weiter dargestellten Wärmetauschers 2 mit den in den Bohrungen des Rohrbodens 1 eingeschobenen und dort mit ihren Enden verschweißten Wärmetauscherrohren 3,4, 5, 6. Die Schweißnähte 7., 8, 9, 10 sind deutlich überhöht eingezeichnet. In der Figur ist die erfindungsgemäße Vorrichtung 11 zum Elektropolieren über drei pneumatische Spannfinger 12 (nur einer dargestellt), die in je einem Wärmetauscherrohr 3 eingeführt und dort eingespannt sind, am Rohrboden (1) befestigt dargestellt. Diese pneumatischen Spannfinger 12 sind an einer gemeinsamen Adapterplatte 13 befestigt. Diese Adapterplatte besitzt einen zentralen Durchbruch 14, in den eine Führungsbuchse 15 eingesetzt ist. Auf der Adapterplatte 13 ist außerdem ein die Führungsbuchse 15 umschließender Isolierflansch 16 aus einem isolierenden Material befestigt. An diesem lsolierflansch 16 ist ein Halteflansch 17 für die Elektrode 18 befestigt. Dieser Halteflansch 17 besitzt eine zentrale Bohrung (19), in der das eine Ende der Elektrode 18 geführt ist.The figure shows a section of the tube sheet 1 of a heat exchanger 2, which is not shown in the rest, with the heat exchanger tubes 3, 4, 5, 6 inserted into the bores of the tube sheet 1 and welded there with their ends. The weld seams 7, 8, 9, 10 are shown clearly exaggerated. In the figure, the device 11 according to the invention for electropolishing is fastened to the tube sheet (1) by means of three pneumatic clamping fingers 12 (only one shown), each of which is inserted and clamped in a heat exchanger tube 3. These pneumatic clamping fingers 12 are attached to a common adapter plate 13. This adapter plate has a central opening 14 into which a guide bush 15 is inserted. An insulating flange 16, which surrounds the guide bush 15 and is made of an insulating material, is also fastened on the adapter plate 13. A holding flange 17 for the electrode 18 is fastened to this insulating flange 16. This holding flange 17 has a central bore (19) in which one end of the electrode 18 is guided.

Diese Elektrode 18 umfaßt ein metallisch leitendes Rohrstück 20, das soweit in das zu elektropolierende Wärmetauscherrohr 5 eingeschoben ist, wie letzteres zu elektropolieren ist. An seinem in das Wärmetauscherrohr eingeschobenen Ende trägt das Rohrstück 20 einen Stopfen 21. Dieser Stopfen 21 besteht aus zwei annähernd diskusförmigen Hälften 22, 23 aus Isoliermaterial. Zwischen diesen ist eine Dichtung 24, im Ausführungsbeispiel ein 0-Ring eingeklemmt. Der 0-Ring liegt am Innendurchmesser des zu elektropolierenden Wärmetauscherrohres 5 an. Diese beiden Hälften 22, 23 des Stopfens 21 sind durchbohrt. Durch die ist ein Drainagerohr 25 geführt, das an seinem durchgeführten Ende eine Spannmutter 26 trägt. Das Rohrstück besitzt an dem dem Stopfen 21 zugewandten Ende mehrere kleine Löcher 27, 28, 29, 30. Zwischen dem Rohrstück 20 und dem Innendurchmesser des Halteflansches 17 befindet sich ein ringförmiger Hohlraum 31. In diesen mündet ein in den Halteflansch 17 eingelassener Elektrolytrücklaufstutzen 32. Auf dem Halteflansch 17 sitzt ein weiterer Hilfsflansch 33, der ebenfalls eine zentrale Bohrung kleineren Durchmessers trägt, in der das die Elektrode durchsetzende Drainagerohr 25 geführt ist. In den ringförmigen Hohlraum 34 zwischen dem Innendurchmesser des Hilfsflansches 33 und dem Außendurchmesser des Drainagerohres 25 mündet ein in den Hilfsflansch eingelassener Elektrolytzulaufstutzen 35. Auf dem Hilfsflansch 33 ist ein Spannflansch 36 mit einer Spannplatte 37 befestigt, durch die das Drainagerohr 25 hindurchgeführt ist. Auf dem Drainagerohr ist eine Spannhülse 38 mit Spannmutter 39 aufgeschraubt. Letztere stützt sich an der Spannplatte 37 des Spannflansches 36 ab.This electrode 18 comprises a metallically conductive tube piece 20 which is inserted into the heat exchanger tube 5 to be electropolished as far as the latter is to be electropolished. At its end inserted into the heat exchanger tube, the tube piece 20 carries a stopper 21. This stopper 21 consists of two approximately discus-shaped halves 22, 23 made of insulating material. A seal 24, an O-ring in the exemplary embodiment, is clamped between them. The 0-ring lies against the inside diameter of the heat exchanger tube 5 to be electropolished. These two halves 22, 23 of the plug 21 are pierced. A drainage pipe 25 is guided through it and carries a tension nut 26 at its end. The tube piece has a plurality of small holes 27, 28, 29, 30 at the end facing the stopper 21. Between the tube piece 20 and the inside diameter of the holding flange 17 there is an annular cavity 31. A further auxiliary flange 33 is seated on the holding flange 17 and likewise has a central bore of smaller diameter, in which the drainage tube 25 passing through the electrode is guided. In the annular cavity 34 between the inner diameter of the auxiliary flange 33 and the outer diameter of the drain pipe 25, an electrolyte inlet fitting 35 opens into the auxiliary flange. A clamping sleeve 38 with clamping nut 39 is screwed onto the drain pipe. The latter is supported on the clamping plate 37 of the clamping flange 36.

Zwischen der Adapterplatte 13 und dem Rohrboden ist eine mit einem O-Ring 40 am Rohrboden 1 am Umfang des zu elektropolierenden Rohres 5 zur Anlage bringbare Rücklaufhülse 41 zu erkennen. Diese Rücklaufhülse ist in der Führungsbuchse 15 flüssigkeitsdicht geführt und wird durch eine sich an der Adapterplatte 13 abstützende Druckfeder 42 mit ihrem, den 0-Ring (40) tragenden Rohrbodenmundstück 43 gegen den Rohrboden 1 gedrückt. Sie besteht aus elektrisch nichtleitendem Material. Sie umhüllt mit einem vorgegebenen Abstand das Rohrstück 20 der Elektrode und mündet im Halteflansch 17. Die Rücklaufhülse 41 ist von einer sie konzentrisch umgebenden auf der Adapterplatte 13 befestigten Elektrolytsammelkammer 44 umgeben. Diese Elektrolytsammelkammer 44 steht mit einem an der Adapterplatte befestigten Elektrolytabflußstutzen 45 in Verbindung.A return sleeve 41, which can be brought into contact with an O-ring 40 on the tube sheet 1 on the circumference of the tube 5 to be electropolished, can be seen between the adapter plate 13 and the tube sheet. This return sleeve is guided in the guide bushing 15 in a liquid-tight manner and is pressed against the tube sheet 1 by a compression spring 42 supported on the adapter plate 13 with its tube sheet mouthpiece 43 carrying the 0-ring (40). It consists of electrically non-conductive material. It surrounds the pipe section 20 of the electrode with a predetermined distance and opens into the holding flange 17. The return sleeve 41 is surrounded by an electrolyte collecting chamber 44 which is concentrically surrounding it and is fastened to the adapter plate 13. This electrolyte collection chamber 44 is connected to an electrolyte drainage nozzle 45 attached to the adapter plate.

Im unteren schematischen Teil der Figur ist zu erkennen, daß der Elektrolytrücklaufstutzen 32, der Elektrolytabflußstuzten 45 und das Drainagerohr 25 über je einen Schlauch 46, 47, 48 an einen Elektrolytvorratsbehälter 49 angeschlossen sind. An diesem Elektrolytvorratsbehälter ist eine Umwälzpumpe 50 für die Elektrolytflüssig angeschlossen, die über einen weiteren Schlauch 51 mit dem Elektrolytzulaufstutzen 35 verbunden ist. Schematisch ist noch die Gleichspannungsquelle 52 mit ihrem am Rohrboden 1 angeschlossenen Pluspol und am Halteflansch 17 angeschlossenen Minuspul dargestellt.In the lower schematic part of the figure it can be seen that the electrolyte return pipe 32, the electrolyte drain pipe 45 and the drain pipe 25 are each connected to an electrolyte reservoir 49 via a hose 46, 47, 48. A circulating pump 50 for the electrolyte liquid is connected to this electrolyte reservoir, which is connected to the electrolyte inlet connection 35 via a further hose 51. The DC voltage source 52 is also shown schematically with its positive pole connected to the tube sheet 1 and the negative coil connected to the holding flange 17.

Ist ein Wärmetauscherrohr etwa durch Korrosion an einer Stelle leck geworden, so kann es unter anderem durch Einschieben eines kleineren SLEEVE-Rohres, das den beschädigten Abschnitt überbrückt, repariert werden. Dabei müssen die beiden Enden des SLEEVE-Rohres flüssigkeitsdicht mit der Innenwand des Wärmetauscherrohres verbunden werden. Eine andere Reparaturmaßnahme bestünde darin, dieses Wärmetauscherrohr an seinem beschädigten Ende abzuschneiden, durch Aufschleifen der Schweißnaht am Rohrboden vom Rohrboden zu lösen, aus dem Rohrboden herauszuziehen und durch ein entsprechend langes Ersatzrohrstück, das sowohl am abgeschnittenen Ende des Wärmetauscherrohres als auch am Rohrboden anzuschweißen wäre, zu ersetzen. In beiden Fällen muß geschweißt werden und muß folglich der Bereich der Schweißnaht gereinigt werden. Insbesondere muß hier die Oxydschicht an der Innenoberfläche des Wärmetauscherrohres vor dem Abtrennen und Aufschneiden entfernt werden. Hierzu eignet sich das Elektropolieren der Innenoberfläche des Wärmetauscherrohres. Auch wenn die Strahlenbelastung zur Durchführung anderer Arbeiten in der Nähe des Rohrbodens eines Wärmetauschers etwa in der anschließenden Primärkammer des Dampferzeugers vermindert werden soll, ist das Elektropolieren der Enden eines oder mehrerer Wärmetauscherrohre im Bereich des Rohrbodens zweckmäßig.If a heat exchanger pipe has leaked due to corrosion at one point, it can be repaired, among other things, by inserting a smaller SLEEVE pipe that bridges the damaged section. The two ends of the SLEEVE pipe must be connected liquid-tight to the inner wall of the heat exchanger pipe. Another repair measure would be to cut off this heat exchanger tube at its damaged end, to detach it from the tube sheet by grinding the weld seam on the tube sheet, to pull it out of the tube sheet and by means of a correspondingly long piece of replacement tube which would have to be welded to both the cut end of the heat exchanger tube and to the tube sheet, to replace. In both cases, welding has to be carried out and consequently the area of the weld seam has to be cleaned. In particular, the oxide layer on the inner surface of the heat exchanger tube has to be separated here and cut open. The electropolishing of the inner surface of the heat exchanger tube is suitable for this. Even if the radiation exposure for performing other work in the vicinity of the tube sheet of a heat exchanger, for example in the subsequent primary chamber of the steam generator, is to be reduced, the electropolishing of the ends of one or more heat exchanger tubes in the area of the tube sheet is expedient.

Zur Durchführung dieser Arbeiten wird die Vorrichtung 11 zum Elektropolieren durch Einführen der an der Adapterplatte 13 befindlichen Spannfinger 12 in die benachbarten Wärmetauscherrohre 3 und Verspannen derselben in diesen Wärmetauscherrohren am Rohrboden 1 befestigt. Dabei wird die Adapterplatte unmittelbar vor dem hydraulischen oder elektromechanischen Spreizen der Spannfinger 12 soweit gegen den Rohrboden 1 gedrückt, daß das Rohrbodenmundstück 43 der Rücklaufhülse 41 federnd an dem Rohrboden 1 und zwar zentrisch zu dem zu elektropolierenden Wärmetauscherrohr 5 anliegt. Nunmehr kann die Elektrode 18 mitsamt dem Isolierflansch 16, Halteflansch 17, Hilfsflansch 33 und Spannflansch 36 in das zu elektropolierende Wärmetauscherrohr 5 eingeführt und an der Adapterplatte 13 angeschraubt werden. Dabei ist die Länge der Elektrode 18 schon zuvor an die Länge des elektropolierenden Rohrabschnitts angepaßt worden. Auch sind bereits vorher die Spannmuttern 26, 39, soweit vorgespannt worden, daß das Drainagerohr 25 mit seiner Spannmutter 26 die beiden Hälften 22, 23 des Dichtstopfens 21 gegen die zwischenliegende Dichtung 24 und das metallisch leitende Rohrstück 20 der Elektrode 18 zieht. Nach Anschluß des Elektrolytzulaufschlauchs 51 des Elektrolytrücklaufschlauchs 46, des Elektrolytabflußschlauches 47, des Lecktageschlauches 48 und in die Inbetriebnahme der Umwälzpumpe 50 für den Elektrolyten kann durch Einschalten der Gleichspannungsquelle 52 mit dem Elektropolieren begonnen werden.To carry out this work, the device 11 for electropolishing is fastened to the tube sheet 1 by inserting the clamping fingers 12 located on the adapter plate 13 into the adjacent heat exchanger tubes 3 and bracing them in these heat exchanger tubes. The adapter plate is pressed immediately before the hydraulic or electromechanical expansion of the clamping fingers 12 so far against the tube sheet 1 that the tube sheet mouthpiece 43 of the return sleeve 41 rests resiliently on the tube sheet 1, namely centrally to the heat exchanger tube 5 to be electropolished. Now the electrode 18 together with the insulating flange 16, holding flange 17, auxiliary flange 33 and clamping flange 36 can be inserted into the heat exchanger tube 5 to be electropolished and screwed onto the adapter plate 13. The length of the electrode 18 has already been adapted to the length of the electropolishing tube section. Also, the clamping nuts 26, 39 have been preloaded so far that the drainage pipe 25 with its clamping nut 26 pulls the two halves 22, 23 of the sealing plug 21 against the intermediate seal 24 and the metallically conductive pipe section 20 of the electrode 18. After connecting the electrolyte feed hose 51, the electrolyte return hose 46, the electrolyte drain hose 47, the leakage hose 48 and after starting the circulation pump 50 for the electrolyte, the electropolishing can be started by switching on the DC voltage source 52.

Während des Elektropolierens wird über die Elektrolytumwälzpumpe frischer Elektrolyt aus dem Elektrolytvorratsbehälter 49 über den Elektrolytzulaufstutzen 35, den Hohlraum 34 des Hilfsflansches 33 und von dort zwischen dem Drainagerohr 25 und dem Rohrstück 20 der Elektrode 18 bis hin zum Stopfen 21 gefördert. Durch die unmittelbar vor dem Stopfen 21 im Rohrstück 20 befindlichen Löcher 27 bis 31 tritt die frische Elektrolytflüssigkeit aus und strömt nun zwischen dem Rohrstück 20 und der zu elektropolierenden Wandung des Wärmetauscherrohres 5 zurück. Da das Rohrstück am negativen Pol der Gleichspannungsquelle 52 und der Rohrboden 1 mit den Wärmetauscherrohren am positiven Pol der Gleichspannunsquelle angeschlossen ist, wird die Oxydschicht an der Innenwandung des Wärmetauscherrohres 5 abgetragen und gelangen die abgetragenen Partikel mitsamt der abwärtsströmenden Elektrolytflüssigkeit in den Elektrolytrücklaufstutzen und von da über den Schlauch 46 in den Elektrolytvorratsbehälter 49.During the electropolishing process, fresh electrolyte is conveyed from the electrolyte reservoir 49 via the electrolyte circulation pump, via the electrolyte inlet connection 35, the cavity 34 of the auxiliary flange 33 and from there between the drain pipe 25 and the pipe section 20 of the electrode 18 up to the stopper 21. The fresh electrolyte liquid emerges through the holes 27 to 31 located directly in front of the plug 21 in the pipe section 20 and now flows back between the pipe section 20 and the wall of the heat exchanger pipe 5 to be electropolished. Since the pipe section is connected to the negative pole of the DC voltage source 52 and the tube sheet 1 with the heat exchanger tubes to the positive pole of the DC voltage source, the oxide layer on the inner wall of the heat exchanger tube 5 is removed and the removed particles, together with the downward flowing electrolyte liquid, reach the electrolyte return nozzle and from there the hose 46 into the electrolyte reservoir 49.

In den Fällen, in denen der Stopfens 21 nicht dicht schließt und Elektrolytflüssigkeit im Wärmetauscherfohr 5 am Stopfen 21 vorbei nach oben steigt, fließt es durch das durch den Stopfen 21 hindurchgeführte Drainagerohr 25 wieder ab und über den am Drainagerohr angeschlossenen Schlauch 48 in den Elektrolytvorratsbehälter 49 zurück. Auch am 0-Ring (40) des Rohrbodenmundstückes 43 austretende Elektrolytflüssigkeit läuft in die Elektrolytsammelkammer 44 und über den an der Elektrolytsammelkammer angeschlossenen Elektrolytabflußstutzen in den Elektrolytsammelbehälter 49 zurück. Von dort kann es durch die Umwälzpumpe 50 wieder erneut in den Elektrolytzulaufstutzen gepumpt werden.In the cases in which the plug 21 does not close tightly and the electrolyte liquid in the heat exchanger tube 5 rises past the plug 21, it flows through the drainage pipe 25 passed through the plug 21 and via the hose 48 connected to the drainage pipe into the electrolyte reservoir 49 back. Electrolyte liquid emerging at the 0-ring (40) of the tube plate mouthpiece 43 also runs back into the electrolyte collecting chamber 44 and via the electrolyte drainage connection connected to the electrolyte collecting chamber back into the electrolyte collecting container 49. From there it can be pumped again into the electrolyte inlet connection by the circulation pump 50.

Nach Beendigung des Elektropoliervorganges, d.h. nach einer der abzutragenden Schichtstärke und des eingeschalteten Stromstärke abhängigen Zeitspanne werden die Gleichspannungsquelle 52 und die Umwälzpumpe 50 abgeschaltet. Sobald die pneumatischen Spannfinger 12 entspannt sind, kann die gesamte Elektropoliervorrichtung 11 von unten aus dem Rohrboden 1 abgezogen und in gleicher Weise an ein anderes zu elektropolierendes Wärmetauscherrohr erneut zur Anlage gebracht und dort arretiert werden.After the electropolishing process, i.e. After a period of time which is dependent on the layer thickness to be removed and the current intensity switched on, the DC voltage source 52 and the circulation pump 50 are switched off. As soon as the pneumatic clamping fingers 12 are relaxed, the entire electropolishing device 11 can be pulled out of the tube sheet 1 from below and, in the same way, brought back to another heat exchanger tube to be electropolished and locked there.

Claims (5)

1. Device for electropolishing the inner surface of tubes with an electrode connected to a direct- current supply able to be inserted into the tube to be electropolished and extracted again, the electrode (18) enveloping a tube-like body (20) metallically conductive on its outer surface, able to be connected to an electrolytic supply pump (50), which body carries, on its front end in the plugging-in direction, a stopper (21) sealing in a liquid-tight manner the tube (5) to be electropolished, is equipped in the vicinity of the stopper with at least one outlet opening (27 to 30) and is guided in an axially displaceable manner on a supporting frame (12 to 17), characterised in that the supporting frame (12 to 17) is able to be anchored on the tube plate (1) of the heat exchanger (2) for electropolishing heat exchanger tubes (3 to 6) and that a return motion casing (41) encasing the electrode (18) is guided in a fluid-tight manner on an adapter plate (13) of the supporting frame and is pressed by way of a spring (42) supported on the supporting frame (12 to 17) with a mouth piece (43) against the tube plate (1).
2. Device for electropolishing according to claim 1, characterised in that a drainage tube (25) is led concentrically through the electrode (18) and through the stopper (21).
3. Device according to claim 1, characterised in that a leakage storage tank (44) is able to be fastened centrally to the electrode (18) on the supporting frame (12 to 17).
4. Device according to claim 1, characterised in that the supporting frame (12 to 17) is able to be fastened to the tube plate (1) by means of damping fingers (12), able to be wedged, in the apertures of neighbouring heat exchanger tubes (3 to 6).
5. Device according to claim 1, characterised in that for shortening the operating time those areas of the metallically conductive tube-like body (20) of the electrode (18), which lie opposite the wall areas of the heat exchanger tube (5) which do not need to be electropolished, are previously wrapped with an insulating tape.
EP85113706A 1984-11-09 1985-10-28 Apparatus for electropolishing the inner surfaces of tubes Expired EP0180892B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3440956 1984-11-09
DE3440956 1984-11-09

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EP0180892A1 EP0180892A1 (en) 1986-05-14
EP0180892B1 true EP0180892B1 (en) 1988-08-31

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DE (1) DE3564708D1 (en)
ES (1) ES8701243A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8719816D0 (en) * 1987-08-21 1987-09-30 Sb Plating Ltd Electro-plating techniques
FR2652191B1 (en) * 1989-09-15 1991-12-13 Framatome Sa DEVICE FOR BRINGING A TREATMENT LIQUID INTO A ZONE ON THE INTERIOR SURFACE OF A TUBE AND METHOD FOR PLACING THIS DEVICE IN THE TUBE.
US5225645A (en) * 1990-07-02 1993-07-06 Combustion Engineering, Inc. Electron discharge machining tool
FR2705825B1 (en) * 1993-05-28 1995-08-18 Framatome Sa Device for decontaminating the internal surface of an end section of a pipe.
JP2012040674A (en) * 2010-08-23 2012-03-01 Mitsubishi Heavy Ind Ltd Clamper, working device in water chamber, and clamp method
CN107151816B (en) * 2017-06-02 2019-07-02 无锡市鹏振智能科技有限公司 A kind of electrolytic polishing method

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2764540A (en) * 1952-09-10 1956-09-25 William G Farin Method and means for electropolishing inner surfaces
CH396561A (en) * 1960-10-06 1965-07-31 Nyby Bruk Ab Process for the electrolytic polishing of surfaces of metallic objects
US3202598A (en) * 1963-03-22 1965-08-24 Titanium Metals Corp Electrolytic polishing tool
DE1496757A1 (en) * 1965-06-04 1969-08-14 Contimet Gmbh Tool for electrolytic smoothing of the inner surface of metallic pipes
CH567581A5 (en) * 1971-09-18 1975-10-15 Siemens Ag
DE3136187C2 (en) * 1981-09-12 1988-08-18 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Method and device for cleaning the inner walls of metallic pipe systems by electropolishing with the aid of moving electrodes
FR2544343A1 (en) * 1983-04-18 1984-10-19 Sfermi Apparatus for decontaminating the end of a hollow metal tube by electropolishing

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ES8701243A1 (en) 1986-11-16
DE3564708D1 (en) 1988-10-06
EP0180892A1 (en) 1986-05-14
ES548722A0 (en) 1986-11-16

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