Process engineers design industrial process plants using piping and instrumentation diagrams (P&IDs). Today, data analysts who diagnose plant disturbances based on historical signal trends usually analyze these complex diagrams manually on paper, which is time-consuming and error-prone. In the last 15 years, researchers have thus proposed several approaches and tools to turn these diagrams into machine-readable models that can be processed by software tools. Yet, these tools lack sophisticated query interfaces and intuitive visualizations. We propose the method TOPNAV to navigate plant topology models and aid data analytics. The method supports systematic searching for elements and paths in topology models and feeding the results into analytical tools to facilitate statistical analyses. In a user study, an up to 90% time reduction was observed compared to manual P&ID analysis, while reducing errors significantly.