This paper discusses recent developments within the DIALOGS project which are aimed at implementing a range of advanced fault detection techniques in real industrial applications. The DIALOGS methodology of representing the plant's physical and functional structure as a hierarchy is presented. The mechanism to map the target faults onto this hierarchy is discussed resulting in the choice of appropriate fault detection algorithm. An example fault detection system design is presented for a heat exchanger pilot plant application. This design example shows the complementary relationships between the analytically derived fault detection algorithms such as Static Characteristics and Parity Space, statistical residual evaluation using GLR and CUSUM, and logic based reasoning to make the final diagnostic hypothesis. A possible mechanism to present this information to the operators is also presented.