Sealants as cured pastes or liquids are especially used for the sealing of flanges from gear boxes and casings, like in fhe front area of the compressor. For the purpose suitableprocessing and application, according the instructions in the specifications and manuals, a sufficient operation safety should be guaranteed. Problematic are rather the little, seemingly harmless deviations. To these belongs the change to a product which is evaluated as comparable.
Fig. "Correct amount of sealant is important" (Lit. 22.4-13): For the sealing of flanges from casings/boxes in the temperature region of -50 bis +250°C, anaerobc sealing componds (type Hylomar®) proved itself since long time. This is especially true for flanges of oil delivering/wetted casings (sketch above). Surplus sealant is squeezed during the compressing of the flanges out of the sealing gap (detail above right). This material can separate and block important flow cross sections. At the approachable outside, it is no problem to remove the rests, especially when not yet hardened. In contrast, sealant which escapes inwards, often can no more be removed. It hardens and than cen be transported by the oil stream. Larger amounts of these particles clogg filter sieves/screens (Fig. "Correct amount of sealant is important"), pipe lines for fuel drainage (Fig. "Excessive use of sealant") and oil jets/nozzles. A danger at which usually is poited in the manuals, respectively processing instructions. In the oil circuit especially the relative small cross sections of the sieves are concerned (frame below). In Fig. "Excessive use of sealant" the case is described, during which after an aborted start fire of an APU occurred, because the drainage pipe line was blocked. So the fuel could accumulate.