Performing hazards analyses and fire risk assessments on oxygen systems is critical to ensure that a system design has a low probability of ignition and a low consequence of ignition. Historically several different methods have been used to identify and evaluate fire hazards in oxygen systems. Most of these methods, however, are designed for detailed materials or component analyses, and can be impractical for large-scale oxygen systems with many components and even multiple end processes. Wendell Hull & Associates, Inc. (WHA), in conjunction with Oxygen Safety Consultants, Inc. and INCO Ltd., has developed an efficient approach to identify and evaluate hazards in large-scale oxygen systems. The WHA oxygen hazards and fire risk assessment process considers the important aspects of oxygen system safety as they relate to design, cleaning, operations and maintenance, and uses ASTM Standard Guide G 88 as a basis for quickly identifying and ranking system-level oxygen hazards. ASTM G 88 is a standard guide for oxygen system design containing many system-level factors known to contribute to ignition and propagation of fires. The WHA analysis process applies ASTM G 88 at the system level, using both schematic analysis and visual inspection to systematically assign a hazard severity ranking to all system components, allowing components that possess the greatest risk of ignition and fire propagation to be quickly identified and further evaluated. This paper describes the WHA oxygen hazards and risk assessment method, using ASTM G 88 to quickly identify and assign a hazards severity ranking to components in large-scale oxygen systems.