Tank Overfill Protection - API 2350 and IEC 61511 Safety Considerations

摘要

For overfill protection on tanks holding volatile, petroleum fluids, the industry best practice has been documented in API 2350. Recent events have begun to cause the industry to rethink the overfill protection requirements and to move to a more functional safety approach. For the process industry, the standard for designing a Safety Instrumented System (SIS) is IEC 61511. The IEC 61511 standard for Safety Instrumented Systems (SIS) has been widely adopted to evaluate risk associated with safety related systems in the process industry. Many companies want to apply the IEC standard, in addition to the API Standard. This creates consistency in their approach to safety and helps verify the specific risks associated with their facilities. This paper examines trends in the industry, particularly related to the Buncefield incident and the report of the Major Incident Investigating Board, and the issues and possible solutions to designing Tank Overfill Protection Systems that can meet both the API Recommended Practice and the IEC standard.