Strengthening Risk Control Measures Through Mapping of Potential Accident Scenarios: A Refinery and Petrochemical Site Case Study

Abstract for 5^thCCPS Latin American Conference on Process Safety

Suggested session: Hazard Identification and Risk Management

A large number of refineries and petrochemical sites worldwide (and indeed in Latin America) are over 30 years old. They were built according to design criteria and process safety philosophies which differ greatly from those adopted in recent plants and new projects.  The safety standards of new units are more stringent, partly as a result of accidents which have occurred (and have highlighted faults in plants’ design and operation) and partly because of society’ increased expectations for safer and cleaner industrial activities.

Old installations are unlikely to maintain their original configuration throughout their life. Additional units are built, other units are debottlenecked, new equipment and lines are installed, offices, warehouses, control rooms are altered or relocated. Furthermore over the last few years increased plant automation and delegation of labour intensive activities to subcontractors has changed – even dramatically – number and location of own and contractors’ personnel in the process areas.

A potential accident occurring at an old installation may have devastating effects, potentially much higher than at a new  one, not only because of the inferior safety standards  adopted for their design and lay out, but also because of the following:

• The combination of physical and organisational changes intervened during the life of the site may result in new accident scenarios and/or more severe consequences (e.g. a plant originally built in a secluded area and now surrounded by other installations; permanent and temporary occupied buildings placed next to process areas;  outsourcing of services, resulting in large number of contractors entering the site, etc.)

• Number, size and location of fire & gas detection and suppression systems may be insufficient or inadequate for some potential accident scenarios

• Equipment and occupied buildings may not be adequate to withstand the effect of  accidents such as UVCE (Unconfined Vapour Cloud Explosion)

• The Emergency Response Team might not be  aware of the size of the accidents impact area, hence  precious time might be lost in deciding the best course of actions

This paper discusses  a large study conducted at a major Latin America refinery and petrochemical site, aimed at reviewing in a systematic way what accident scenarios – associated to old, revamped and new units – may occur and what effects  they may have on people’ safety and equipment integrity.

The study also reviewed if the existing engineering protections and organisational arrangements were sufficient to minimise the escalation of such accidents and provided practical recommendations for improvement. These ranged from design considerations to relocation of working areas, protection of normally occupied buildings, re-routing of internal traffic, upgrade and maintenance of active and passive fire protection, emergency response arrangements, etc.

This paper wishes to illustrate how identification of accident scenarios, consequence modelling and critical review of study results with key site functions (Safety, Emergency Response, Process and Operations) leads to concrete and effective safety improvements.

Note: the study has been developed as part of the implementation of the “Risk Assessment” element of Process Safety Management at the Ecopetrol Refinery in Barrancabermeja, Colombia