GB2065717A - Installation for the liquid surface treatment of tubes - Google Patents

Abstract

Tubes, particularly of the type used in the nuclear field, are surface- treated e.g. pickled in an installation consisting of a tube feed, a transport unit, two treatment stations and a collecting tank, the transport unit comprising entry flaps (3), transport rollers (4) and guide ledges (5) for the tubes (2), one treatment station (25) being equipped with twin rollers (18) for guiding the tubes (2), with a collecting tank (9) for treatment medium connected to a hinged funnel (8) and with a take-up unit (6) for the tubes (2) consisting of an elastomeric plug provided with holes in a steel die with a force plunger provided with distributing bores, and the other treatment station (26) being provided with further twin rollers (18) for guiding the tubes (2), with sprinkler lances (10) for treating the inside of the tubes, with sprinkler collars (11) for treating the outer surface of the tubes and with one or more collecting tanks (13) for treatment medium. <IMAGE>

Description

SPECIFICATION Installation for the surface-treatment of tubes This invention relates to an installation for the surface treatment of tubes.

More particularly the invention relates to an installation for the surface treatment of tubes, consisting of a tube feed, a transport unit, one or two treatment stations and a collecting tank for the treatment medium.

In known surface treatment processes, such as pickling and rinsing, cleaning and degreasing with detergents or solvents or coating with lacquers or plastic coverings, the tubes are introduced in bundles into dipping baths. By repeated dipping in baths generally arranged one behind the other, the required surface quality is obtained with more or less acceptable reproducibility.

In the nuclear field for example, fuel element cans are internally cleaned by blowing manually solvent-impregnated plugs of felt or cotton wool through the tubes, the degree of cleanness achieved being subjectively assessed on the basis of the level of soiling of the plugs used.

It is generally not possible with these known processes to obtain a uniform and reproducible cleaning effect inside the tube. In addition, large quantities of the treatment liquids are in danger of being entrained through the various dipping baths.

Furthermore, considerable effort and care is required to achieve a specified surface quality.

Apparatus for the surface treatment of rods, sections and components are also known which consist of transport units, treatment stations and collecting tanks for the treatment medium and by which adhering impurities may be removed.

However, these known apparatus are not suitable for the surface treatment of tubes, particularly tubes of the type used in the nuclear field.

Accordingly, an object of the present invention is to provide an installation for the surface treatment of tubes comprising a tube feed, a transport unit, one or two treatment stations and a collecting tank for the treatment medium, with which it is possible to obtain a specified optimal surface quality, particularly in the case of tubes of the type used in the nuclear field.

The present invention provides an installation for the surface treatment of tubes, comprising a tube feed, a transport unit comprising entry flaps, transport rollers and guide ledges for the tubes, a first treatment station equipped with twin rollers for guiding the tubes, a collecting tank for treatment medium to a hinged funnel and means for taking up the tubes consisting of an elastomeric plug provided with holes in a steel die with a force plunger provided with distributing bores and a second treatment station equipped with twin rollers for guiding the tubes, with sprinkler lances for treating the inside of the tube, with sprinkler collars for treating the outer surface of the tubes and with one or more collecting tanks for treatment medium.

The installation according to the invention consists of a transport unit on which several tubes are simultaneously transported into the individual different treatment stations, being taken up at one end, sealed and rinsed or coated with the treatment medium at least once.

Figures 1 and 2 of the accompanying drawings diagrammatically illustrate by way of example, one embodiment of the installation according to the invention.

A number of tubes (2) corresponding to the capacity of the installation is taken from a tube feed (1) and delivered by means of several hinged entry flaps (3) to a transport unit (24) which is equipped with transport rollers (4). The tubes (2) are positioned on the transport rollers (4) by means of adjustable guide ledges (5) which are arranged throughout the entire transport unit (24) and by lowering the entry flaps (3).

The transport unit and two treatment stations (25, 26) are mounted in a collecting tank (15) so that treatment liquids can be quantitatively collected. The tubes are first transported into one (25) of the treatment stations where they are guided by twin rollers (18) and introduced into a take-up unit (6) in which they are sealed and rinsed with the treatment liquid. Figure 2 shows this take-up unit (6) in detail. It consists of a plug (22) of an elastomeric materials which is provided with holes (23) for accommodating the tubes (2) and which is situated in a steel die (19). By pressing on a force plunger (20) provided with distributing bores (21), the elastomeric plug (22) is deformed in such a way that it applies itself to the inserted tube ends and seals them off from the outside.From a central supply (7), the treatment liquids, for example a pickling solution, is passed through the tubes via the distributing bores (21).

The treatment liquid flowing out at the other end of the tubes is collected in a hinged funnel (8) and delivered by a pump (17) to the collecting tank (9).

The plug (22) is then expanded, the collecting funnel (8) is folded away and the tubes (2) withdrawn from the treatment station (25).

The tubes then pass via the transport unit (24) into the second treatment station (26) where the tubes are treated not only internally but also externally. To this end, the tubes (2) again guided by twin rollers (18) are pushed over lances (10) provided with sprinkler jets. These sprinkler jets are preferably situated at the tips of the lances from where the treatment liquid is sprayed onto the inner surface of the tubes. The same treatment liquid may also be sprayed onto the outer surface of the tubes through sprinkler collars (11). The supply of this liquid may be shut off, for example at the end of the advance of the tube, and another treatment liquid sprayed on during the return of the tube. A deflection plate (12) then ensures that the various liquids are guided into various collecting tanks (13) from which they may be circulated by means of a pump (16).

The spray treatment may be repeated several times and thus adapted to meet requirements. In addition, the sequence of the rinsing and spraying treatments may be selected as required.

On completion of the treatment, the tubes return to the entry position from which they are removed from the transport unit (24) by means of the entry flaps (3) and roll down an inclined plane (14).

In the case of a surface treatment where the tubes have to be rotated about their longitudinal axis, the transport rollers (4) and the twin rollers (18) may be replaced by rotating discs which are arranged obliquely of the tube axes.

The treatment stations (25,26) are preferably inclined to ensure that the residues of liquid run off cleanly. An angle of inclination of from 0.2 to 150 has proved to be particularly suitable.

In addition, it is of advantage for the sprinkler lances (10) to be supported by fold-away holders at the tube entry end.

The installation according to the invention is eminently suitable for the surface treatment of tubes and particularly for the surface treatment (for example pickling and rinsing, cleaning and degreasing or coating) of tubes of the type used in the nuclear field.

The following Examples in conjunction with the drawings are intended further to illustrate the treatment of tubes in an installation according to the invention: 1. Aluminium tubes 15 x 1.5 mm in diameter and 8 m long (heat-exchanger tubes) are placed in position on the transport unit (24), pushed into the take-up unit (6), sealed and then rinsed for 5 minutes with NaOH-pickling solution.

The funnel (8) let down at the end of the tubes ensures that the outflowing pickling agent is collected and flows back into the pickling agent container (9). The take-up unit (6) is then relaxed and the tubes withdrawn. They are then pushed over lances (10) provided at their ends with slots.

At the same time, they move through sprinkler collars (11). Fresh water is sprayed onto the inner surfaces through the sprinkler lances (10) and onto the outer surfaces through the sprinkler collars (11) so that the tubes are freed from residues of the pickling liquid. The rinsing cycle consists of the advance and return movements.

When the tubes have been pushed back into their starting position, they are raised and roll down an inclined plane (14) into a collecting magazine. 10 Tubes are treated at the same time.

The advance and return speed is 5 m/minute.

Both the treatment liquid and also the rinsing water are circulated by means of suitable pumps, the liquid being circulated at a rate of 1.2 m3/h and the rinsing water at a rate of 10 m3/h.

2. 10 Zircaloy tubes 16 mm in diameter and 7 m long are positioned on the transport unit (24).

They pass immediately into the treatment station (26) via the lance (10) and through the sprinkler collar (11) where they are sprayed with a washing agent consisting of water, phosphate cleaner and surfactant and heated to a temperature of 900 C.

The high-pressure spray jets (20 bars) detach the adhering, partly cracked oil residues. Dirt and fats are also removed. During their return, the tubes are rinsed with fresh water and completely cleaned.

The tubes then pass into the other treatment station (25) where they are sealed in the take-up unit (6) and blown dry in 1 minute with warm air.

The tubes are then withdrawn from the take-up unit (6) and raised by means of a pivoting system from the transport unit (24). They roll down the inclined plane (14) into a magazine where they may be externally dried by means of warm air.

The advance and return speed is 2 m/minute.

Washing and rinsing liquid are circulated. The circulation rates are 10 m3/h for both media. In addition, 3000 m3/h or air at 300C are blown through the tubes to blow dry the inner surfaces.

3. For treating their inner surfaces, C-steel tubes are coated with a primer liquid. One treatment station only (25) is required for this purpose and the transport rollers (4) and twin rollers (18) are replaced by rotating discs which are arranged obliquely of the tubes.

The tubes, which are 6 m long and 35 mm in diameter for a wall thickness of 2 mm, pass into the elastomeric take-up unit (6), are sealed and rinsed for 30 seconds with the primer solution.

Thereafter they emerge from the take-up unit (6) after a distance of 6 metres, simultaneously rotating about their longitudinal axis. The direction of rotation is reversed so that the tubes pass back into the starting position. During transport, the primer is uniformly distributed and dried through the rotation. The tubes are then raised from the transport unit (24) and roll into a magazine where they dry completely. The layer thickness in the inner tube is adjusted through the viscosity of the primer. In this way, layer thickness of from 5 to 50 ,um are applied according to requirements.

The speed of linear travel of the tubes during drying is 2 m/minute while they rotate at 100 r.p.m. about their longitudinal axes.

Claims (5)

1. An installation for the surface treatment of tubes, comprising a tube feed, a transport unit comprising entry flaps, transport rollers and guide ledges for the tubes, a first treatment station equipped with twin rollers for guiding the tubes, a collecting tank for treatment medium connected to a hinged funnel and means for taking up the tubes consisting of an elastomeric plug provided with holes in a steel die with a force plunger provided with distributing bores and a second treatment station also equipped with twin rollers for guiding the tubes, with sprinkler lances for treating the inside of the tubes, with sprinkler collars for treating the outer surface of the tubes and with one or more collecting tanks for treatment medium.

2. An installation as claimed in Claim 1, wherein the treatment stations are provided with discs rotating obliquely of the axes of the tubes for transporting the tubes along a helical path.

3. An installation as claimed in Claim 1 or 2, wherein the treatment stations are inclined at an angle of from 0.2 to 150.

4. An installation as claimed in any of Claims 1 to 3, wherein the sprinkler lances are supported by fold-away holders.

5. An installation for the surface treatment of tubes substantially as described with particular reference to the accompanying drawings.