What is a Blockflow Diagram? | Blog No. 88

A block flow diagram (BFD) is a high-level process diagram used to represent the major steps in a chemical or industrial process. As the name suggests, it utilizes simple blocks to represent each step in a process, connected by arrows that indicate the flow of material or energy.

Unlike PFDs (Process Flow Diagrams) or P&IDs (Piping and Instrumentation Diagrams), a BFD doesn’t show specific equipment, valves, piping, or instruments. Its purpose is to provide a basic understanding of the system without overwhelming the viewer with technical details.

Why Use a BFD?

We typically use BFDs to see the overall structure of the process. It helps engineers, designers, operators, and managers visualize the system before diving into all the details. At Macha PSM, we always start with the BFD to create a baseline for how the system works before we begin developing P&IDs. Even during the middle of a P&ID project, I’ll often refer back to the BFD to make sure I am still on the right track. 

Why It Matters

BFDs are more than just a helpful starting point; they are also an important tool for every facility. They support process safety management (PSM) efforts and are required under OSHA’s PSM standard 29 CFR § 1910.119(d)(2)(i)(A). This regulation states that facilities must include either a BFD or a PFD as part of their Process Safety Information (PSI).

Beyond compliance, BFDs make it easier for someone to quickly understand a complex system, especially when introducing new team members or presenting the process to individuals unfamiliar with the chemical or industrial process.

Coming Up Next: Implementing LOTOTO Best Practices in Ammonia Systems. {Part 3 of 3}

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