This case study chronicles ASME’s pioneering development of a systems-based standard for plant systems design, using a Model-Based Systems Engineering (MBSE) approach to fill gaps in how design and construction specifications are currently handled. Drafted by a geographically dispersed volunteer committee, ASME leverages the cloud-native MBSE tool Innoslate to ensure transparency, consistency, and collaboration across disciplines and stages. The standard aims to unify practices across nuclear, chemical, oil & gas, and other process plants, with a strong emphasis on safety, reliability, and lifecycle impact. Key features include a clear taxonomy, defined boundaries for design phases (conceptual, preliminary, detailed), rigorous requirements management, risk-based probabilistic methods, and process hazard analysis early in design.