Digraph-based causal models are widely used to model the cause and effect behavior of process systems. Signed digraphs (SDG) capture the direction of the effect as well. SDG reasoning can identify the propagation path of the deviation at a certain node over the whole SDG

and as a result

plays an important role not only in online fault diagnosis

but also in offline hazard and operability (HAZOP) analysis. In recent years

various packages have been developed to use SDG reasoning as an auxiliary tool in the chemical process and process safety analysis. This paper describes how existing open source components can be used to construct a browser and server architecture for an SDG inference framework. A small example is used to illustrate how this framework can be utilized to construct an SDG system for the given process. Thereafter

SDG systems for two complicated processes are created to demonstrate the effectiveness of the framework.