Method for maintaining a turbomachine

1. A method for maintaining an axial-flow turbomachine, which has a support structure and a plurality of axially adjacent guide vane rings, each having a plurality of guide vanes, wherein the guide vanes are each provided with at least one platform, which is fastened to the support structure by means of retaining elements, wherein mutually facing platform end faces of axially adjacent guide vanes define mutually associated seal sections made of a metal material, which in each case jointly form a seal assembly, the method comprising:

a) removing a defective guide vane to be replaced and at least one axially adjacent intact guide vane with which the guide vane to be replaced forms a seal assembly, wherein the seal sections forming the seal assembly each have a projection which extends in a circumferential direction, projects axially and engages in an associated recess in the other seal section, the recess extending in the circumferential direction;

b) making available a replacement guide vane that is configured to replace the removed defective guide vane, the platform of which replacement guide vane defines at least one replacement seal section made from a metal material, wherein the at least one replacement seal section comprises two axially projecting projections of equal length which extend in the circumferential direction and are separated from one another by a groove extending in the circumferential direction; and

c) mounting the removed intact guide vane and the replacement guide vane on the support structure, wherein the seal section of the removed intact guide vane and the facing replacement seal section of the replacement guide vane are connected to one another by a sealing strip to form a functional seal assembly.

2. The method as claimed in claim 1 , wherein the sealing strip is produced from metal.

3. The method as claimed in claim 1 , wherein at least one main surface of the sealing strip has a ridged surface.

4. The method as claimed in claim 1 , wherein the sealing strip is fastened by means of a plurality of fastening means at least to the seal section of the removed intact guide vane, further wherein the fastening means are rivets.

5. The method as claimed in claim 1 , wherein the seal section of the removed intact guide vane is machined in such a way before mounting in step c) that, in a manner corresponding to the replacement seal section, it has two projections which extend in the circumferential direction, project axially and are separated from one another by a groove extending in the circumferential direction.

6. The method as claimed in claim 5 , wherein the machining of the seal section of the removed intact guide vane is performed in step c) by closing the recess by the application of material and then introducing the groove.

7. The method as claimed in claim 6 , wherein a deposition welding or spraying method is used to close the recess.

8. The method as claimed in claim 6 , wherein an erosion method is used to form the groove.

9. The method as claimed in claim 5 , wherein the machining of the seal section of the removed intact guide vane is performed by removing part of the seal section and fastening a replacement piece to the remaining part of the seal section, the piece defining the two projections and the groove.