Generally correlate repair processes those of new parts production (volume 4) and so let expect also their failures and problems. However repairs are complicated because the processes must be executed at deteriorated/damaged or altered parts. With this often lack the optimal pre-conditions of the new parts production. Different are also special applications of usual processes. To this belongs the build up of worn component zones by welding. Examples are tips of labyrinth seals, blade tips, shrouds of compressor blades as well as blades of turbine rotors and stators. Especially repair specific are brazing repairs of hot parts. They serve the closure/filling of cracks up to the build up of whole zones of parts. Typical application are turbine vanes (nozzles).

Sub chapters of this chapter deal with typical repairspecific processes:

• Welding (chapter 21.2.1).
• High temperature brazing (chapter 21.2.2).
• Coating: Thermal sprying, diffusion coatings (chapter 21.2.3).
• Etching, “stripping” of coatings (chapter 21.2.4).
• Shot peening (chapter 21.2.5).
• Rework by machining , polishing/finshing and work off of damages (chapter 21.2.6).
• Straightening (chapter 21.2.7).
• Hot isostatic pressing (HIP, chapter 21.2.8).