(146c) Oleum Release - When the Hose Breaks

Oleum, also known as “fuming sulfuric acid,” is chemical commonly used for a variety of processes, such as sulfonation, nylon manufacturing, dye production, nitration, and hydrofluoric acid production. It is also a highly hazardous material regulated under both the Environmental Protection Agency (EPA) Risk Management Program (RMP) and the Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) Standard guidance. This paper is based on an oleum release incident that occurred during a bulk unloading process from railcar to chemical reactor via flexible hosing, resulting in injury to operating personnel. A post-incident investigation determined that the release had several contributory causes, including non-standard operating conditions, improper management of change, improper transfer hose selection and maintenance, absence of training and process documentation, and inability to recognize signs of imminent equipment failure. This case study describes the sequence of events and decision-making that led to the subject oleum release and also provides lessons learned. This study then applies PHAST, an important tool for definition of minimum safe working zones, to evaluate hazard zones associated with a series of characteristic hose leak and rupture scenarios for uncontrolled liquid/vapor release of sulfur trioxide and sulfuric acid, the constituent components of oleum. The paper will then use those outputs in a LOPA / HAZOP approach to compare to a Quantitative Risk Analysis for a model facility. The results will be used to provide guidance for applying simplified LOPA / Consequence Analysis approaches to loading and unloading releases of highly hazardous materials.