(189b) Cold Safety Considerations for C3 Services

Previous presentations on cold safety have provided an overview of hazard recognition and mitigations, including piping assessment and mitigations, and cold flare system monitoring and sustainment. Further work indicates that scenarios associated with C3 system may be difficult to identify. At normal operating pressures of C3 refrigeration systems and C3 recovery equipment in olefins plants, C3s can condense at near-ambient temperatures, which can introduce cold safety risks during maintenance activities and abnormal operations of systems that normally operate with vapor-phase C3s. Recognizing the risk of brittle fracture in such scenarios may not be intuitive, since liquid hydrocarbon is not expected to be present. However, condensation of C3s can be influenced by factors such as weather conditions, starting temperature of the vessel or catalyst bed, and duration of time that a line is left stagnant. This paper provides learnings on C3-service equipment during clearing, commissioning and abnormal operations, and potential approaches for better recognition and mitigation of these scenarios. In addition, incidents will be presented to serve as examples of scenarios and mitigations to be considered.