On the safe side: Siemens refurbishment process

Rotating blades have a specific feature that is called the tip. During operation in some cases the tip may touch its counterparts, the guide ring segments and the opposite root platform areas of the stationary vanes.

This may result in a loss of material on the tip, as well as at the surfaces of the guide ring segments and the root platform areas. Therefore, for rotating blades that have some tip loss, a tip welding procedure is recommended during refurbishment to help avoid loss of efficiency.

Further, the rotating blades of the first rows are facing the hot gas stream from the combustion chamber almost at turbine inlet temperature. Hence, those components should be protected in an effective manner.

SGT5-4000F Turbine blades

Stationary vanes have cooling inserts and undergo similar steps in the refurbishment process. Like the cast body, the assembled cooling inserts can experience high stresses during operation.

Therefore, for stationary vanes the replacement of cooling inserts may be recommended during refurbishment, depending on inspection findings. Similar to the moving blades, the stationary vanes should be protected in an effective manner from the hot gas stream.

The solution: an OEM thermal barrier coating system (TBC) applied on top of the standard metallic coating. Depending on the type of gas turbine and the maintenance and repair concept, a TBC layer is required for the blades and vanes of row one, two and three.

SGT5-8000H Turbine vanes

As the OEM, Siemens is uniquely positioned for refurbishment of SGT5/6-4000F/8000H guide ring segments to OEM standards – another of your unique refurbishment benefits. During refurbishment the parts may need to be inspected, repaired, straightened and recoated. The guide ring segments represent the new part configuration after refurbishment. As a result, the refurbished guide ring segment is also protected by a Siemens specified TBC system.

SGT5-4000F Guide ring segments