DE29807792U1 - Device for blasting the inner surfaces of pipes - Google Patents

Description

TER MEER STEINMBSTER &' PARTNER GBR

PATENT ATTORNEYS - EUROPEAN PATENT ATTORNEYS

Dr. Nicolaus ter Meer, Dipl.-Chem. Helmut Steinmeister. Dipl.-Ing.

Peter Urner, Dipl.-Phys. Manfred Wiebusch

Gebhard Merkle, Dipl.-Ing. (FH)

Mauerkircherstrasse 45 Artur-Ladebeck-Strasse

D-81679 MUNICH D-33617 BIELEFELD

KIP P01/97/G2 30.4.1998

Jens Werner Kipp

Klashofsiedlung 3 33659 Bielefeld

DEVICE FOR BLASTING THE INTERNAL SURFACES OF

PIPES

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DESCRIPTION

The invention relates to a device for blasting the inner surfaces of pipes, with a nozzle aligned coaxially to the pipe, which emits the blasting medium and a deflection body which directs the blasting medium onto the pipe wall.

WO 96/39 277 describes a method for cleaning the inside of pipes, in which the pipe wall is blasted with a blasting medium, for example compressed air, with the aid of a robot moving through the pipe, to which dry ice is preferably added as a blasting agent.

In DE 296 22 088 U, a device according to the preamble of claim 1 is described for carrying out this method, which has an annular nozzle aligned coaxially to the pipe and movable through the pipe. The mouth of the annular nozzle is conically widened and contains a conical deflector which, together with the outer wall of the nozzle, forms an outlet channel in the shape of a conical shell, so that the emerging jet takes on a funnel-shaped shape and evenly sweeps over the pipe wall over its entire circumference.

The object of the invention is to provide a device of this type which is particularly suitable for smaller pipe diameters.

This object is achieved according to the invention in that the deflection body lies with the largest part of its length axially behind the mouth of the nozzle and can be moved through the pipe alone or together with the nozzle.

With this arrangement, the outer diameter of the nozzle itself does not need to be larger than the outer diameter of the deflector, so that a slim design is achieved that is also suitable for pipes with a small inner diameter.

If the deflector is connected to the nozzle, this connection must be tensile, but it can otherwise be relatively unstable or flexible, since the deflector centers itself in the pipe through dynamic effects. This can also improve the guidance of the nozzle in the pipe.

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Since the deflection of the blasting medium and the blasting agent is caused by the deflection body, there is a high degree of design freedom with regard to the design of the actual nozzle. In particular, the nozzle can be designed as a Laval nozzle, with which high flow velocities of the blasting medium, possibly even supersonic flows, can be achieved.

If the deflector moves through the pipe alone, i.e. without the nozzle, the movement of the deflector must be slowed down so that its speed is always lower than the flow velocity of the jet medium and the desired deflection effect is achieved.

The subclaims specify special embodiments of the invention, including various possibilities for delaying the movement of the deflecting body.

In the following, preferred embodiments are explained in more detail with reference to the drawing.

Show it:

Figure 1 is an axial section of a blasting device; and
25

Figure 2 is a partially broken side view of the essential element of a blasting device according to another embodiment.

The blasting device shown in Figure 1 is used to clean the inner surfaces of a pipe 10 by means of a solid or liquid blasting medium with or without blasting agent.

A nozzle 12 in the form of an adapter that can be coupled to the end of the pipe serves to introduce the blasting medium into the pipe under high pressure. In the example shown, the nozzle 12 simply has an external cone 14 at the front end, which engages in the end of the pipe and fits tightly against the inner wall

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of the pipe when the nozzle is held with light pressure against the end of the pipe. A pressure hose (not shown) can be connected to the opposite end of the nozzle, through which the blasting medium is supplied.

The jet device also includes a deflection body 16 that is separate from the nozzle 12. In the example shown, the deflection body 16 has an elongated, boat-like shape with a conical upstream end 18. The cross-sectional shape of the deflection body 16 is adapted to the cross-sectional shape of the pipe 10 and is therefore circular in the case of round pipes. The outer diameter of the deflection body is slightly smaller than the inner diameter of the pipe 10.

A traction cable 22 is fastened in an axial bore 20 of the deflector body 16, which runs through the pipe 10 and through the mouth of the nozzle 12 and exits the nozzle 12 outside the pipe 10 through an oblique lateral opening 24. The free end of the traction cable 22 is held by hand or unwound from a winding device (not shown).

The blasting medium emitted by the nozzle 12 flows at high speed through the pipe 10 and hits the conical end 18 of the deflector 16, thereby being deflected radially outwards so that it hits the pipe wall at an angle and cleans the inner surface of the pipe. A blasting medium with a moderately abrasive effect, such as dry ice, can be mixed into the blasting medium. The nozzle 12 can be provided with openings corresponding to the opening 24 for feeding the blasting medium. Other additives to the blasting medium can also be fed through these openings, for example to chemically treat the pipe wall or to "coat" it with lime or dirt repellent.

The blasting agent is deflected by the deflector 16 in the same way as the blasting medium, so that an intensive cleaning of the pipe wall is achieved. It has been shown that the particles of the blasting agent hardly hit the surface of the deflector due to fluid dynamic effects, but are deflected by the flow so that they hit the pipe wall directly. The blasting medium and the blasting agent, as well as any material removed from the pipe wall, pass through the annular intermediate

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space between the deflector and the pipe wall and are discharged via the pipe end opposite the nozzle 12.

When the traction cable 22 is gradually released, the deflector body 16 moves self-centeringly through the pipe so that the pipe 10 can be gradually cleaned over its entire length.

Figure 2 shows an embodiment of the deflection body 16 which is suitable for even smaller pipe diameters.

The deflector according to Figure 2 has a boat-shaped upstream part 26 and a conical downstream part 28 designed as a separate component. The two parts 26, 28 can be screwed together or fastened to one another in some other way. The upstream part has a conically widening section 30, a shorter cylindrical section 32 and a conically tapering section 34, which follow one another in the direction of flow in the order given. Together with the cylindrical pipe wall, part 26 forms an annular nozzle, the cross-section of which initially narrows and then widens again like a Laval nozzle. In this way, a very high flow velocity, possibly supersonic speed, can be achieved downstream of part 26 due to the Laval effect. The conical part 28 forms the actual deflection body, which then directs the blasting medium and the particles of the blasting medium at high speed 5 onto the pipe wall. However, the blasting medium can also be directed onto the pipe wall for the first time through the section 30.

The deflection body 16 according to Figure 2 has the axial bore 20 and also has in its cylindrical section 32 a transverse bore 36 provided with an internal thread, which allows the traction cable 22 to be fixed with a grub screw.

If a highly abrasive blasting agent is used, the traction cable may be damaged and break. In this case, it is advisable to slow down the movement of the deflector 16 by means of a rod 38 which is inserted into the pipe 10 from the opposite end and guided by hand or machine. The section 34 and the conical part 28 of the deflector

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steering body have an axial bore 40 with a larger diameter into which the rod 38 can be inserted or screwed.

Finally, the deflection body 16 can also have a friction body or scraper 42, which is shown in dash-dotted lines in Figure 2. The scraper 42 rests with its blades against the inner wall of the pipe, preferably under elastic pre-tension, and thus creates a braking effect which slows down the movement of the deflection body 16. This means that the rod 38 or the traction cable 22 can be dispensed with if necessary. At the same time, the scraper 42 loosens any contaminants adhering to the pipe wall. In the example shown, the scraper 42 is used for pre-cleaning, loosening the contaminants before they are completely removed by the jet deflected by the deflection body. Alternatively or additionally, however, a trailing scraper can also be provided on the deflection body for subsequent cleaning of the blasted surface. The blades of the scraper 42 can be set slightly helically so that the deflection body rotates about its longitudinal axis during its movement through the pipe.

Claims (9)

1. Device for blasting the inner surfaces of pipes ( 10 ), with a nozzle ( 12 ) which is aligned coaxially to the pipe and emits the blasting medium and a deflector body ( 16 ) which directs the blasting medium onto the pipe wall, characterized in that the deflector body ( 16 ) lies with the largest part of its length axially behind the mouth of the nozzle ( 12 ) and can be moved through the pipe ( 10 ) alone or together with the nozzle. 2. Device according to claim 1, characterized in that the nozzle ( 12 ) is designed as an adapter which can be coupled to the end of the pipe for introducing the blasting medium into the pipe and that the deflection body ( 16 ) is movable through the pipe relative to the nozzle. 3. Device according to claim 2, characterized in that a traction cable is attached to the deflection body ( 16 ). 4. Device according to claim 3, characterized in that the nozzle ( 12 ) has a lateral opening ( 24 ) outside the tube ( 10 ) through which the traction cable exits. 5. Device according to claim 2, characterized in that the deflection body ( 16 ) is supported with its end opposite the nozzle ( 12 ) on a rigid or flexible rod ( 38 ) extending through the pipe ( 10 ). 6. Device according to one of claims 2 to 5, characterized in that the deflection body ( 16 ) has a widening section ( 30 ) at the upstream end and a tapering section ( 34 ) further downstream. 7. Device according to claim 6, characterized in that the widening and tapering sections ( 30 , 34 ) of the deflector body ( 16 ) together with the wall of the tube ( 10 ) form an annular Laval nozzle. 8. Device according to claim 6 or 7, characterized in that the tapering section ( 34 ) is followed downstream by a part ( 28 ) which widens in the direction of flow. 9. Device according to one of the preceding claims, characterized in that the deflection body ( 16 ) or optionally the unit consisting of deflection body ( 16 ) and nozzle ( 12 ) has a friction body ( 42 ) which is in frictional contact with the inner wall of the pipe ( 10 ).