Understanding the Importance of OBRA in Process Safety
An Occupied Buildings Risk Assessment (OBRA)is crucial in process safety assessments for high hazard sites. While these assessments typically focus on unplanned events in process areas, history has shown that major incidents can have devastating effects on people within buildings. Catastrophic events such as Flixborough, Hickson & Welch, and BP Texas City resulted in fatalities to building occupants, highlighting the need for a more comprehensive approach to risk assessment. May process safety studies focus on the process risk to operators and personnel within plant areas, however OBRA takes a wider view and looks at potential societal impact of hazards.
An OBRA determines whether the people inside buildings on a facility are exposed to unnecessary risk from hazards such as:
- Explosions
- Fires
- Chemical reaction fallout
- Toxic releases
Assessing Risk: Key Factors to Consider
While ‘unnecessary risk’ is often assessed qualitatively, we can also apply quantitative methods to predict the potential impact of fire, explosion, or other hazards originating from nearby process areas. OBRA also evaluates whether access and egress routes would be impacted under various defined event scenarios.
When Should an OBRA Be Conducted?
OBRA is essential for addressing Major Accident Hazards (MAHs) and their effects on building occupants and emergency response. OBRA is an expectation of the Health and Safety Executive in the UK for Upper Tier COMAH sites, and in other European countries it is a requirement in some cases for Lower Tier COMAH sites as well. If any of the following conditions change at your site, it is crucial to revisit the assessment:
- Changes in inventory levels
- Modifications to site layout
- Alterations to access routes
- Fluctuations in occupancy numbers
While OBRA can be performed as a standalone assessment, it is often integrated with or complements other process safety studies to provide a more comprehensive safety evaluation. Typically the OBRA would sit within the predictive risk assessment section of an COMAH safety report, assessing the full risk of the MAHs on a site to all personnel who may be affected.
Key Benefits of OBRA for Your Facility
For businesses handling hazardous materials or operating within high-risk environments, an Occupied Buildings Risk Assessment offers several key advantages:
- Reduction of hazards and risks to building occupants by implementation of safe design and mitigation measures
- Identification of safe site areas
- Evaluation of occupied building or process storage/plant options
By implementing OBRA as part of a proactive safety management strategy, facilities can enhance the protection of personnel, ensure regulatory compliance, and minimize risks associated with major accident hazards.
Would you like to learn more about how an Occupied Buildings Risk Assessment can benefit your facility? Get in touch with our team today.