Fire and Explosion Risk analysis

Fire and Explosion Risk Assessment (FERA) involves quantification of the probability of fire & explosion accidental events, and their consequences. The main objective of FERA is:

• To identify and quantitatively evaluate all credible fire and explosion events associated with flammable inventories that could have an impact on the facilities.
• To provide input to decisions relating to the design of systems and equipment, Layout of main areas and equipment, Requirement to barriers.
• To provide suitable recommendations on the design and operation of the facilities that would bring about a reduction in fire risks.

Specific FERA objectives can be distinguished depending on the different design phases for which it is applied.

1. Concept Selection Phase
   During Concept Selection phase, different project options (e.g. onshore versus offshore processing and platform versus subsea installation) could have associated risks significantly different. For this reason, a comparison of risks associated to different options may be effectively studied using a FERA and could be useful in the decision process. During early design phases, when most data are not available, comparative coarse FERA may be applied.
2. Concept Definition Phase
   The FERA shall exhaustively address the identification of all risk reduction actions (first preventive and then mitigating) required to minimize escalation effects, due to incident scenarios. The execution of a systematic FERA during this phase will avoid negative impacts on the project schedule and costs.
3. Execution Phase
   At the end of the detailed engineering, i.e. when all optimization has been completed, FERA is intended to demonstrate and confirm to management, shareholders and the Regulator that all risk reduction actions (first preventive and then mitigating) identified during Concept Definition phase have been implemented and risk criteria have been achieved.
4. Existing facilities
   For existing facilities, in case some modifications of design are assessed to potentially cause Incident Scenarios, an additional or revalidated FERA shall be developed. The study shall demonstrate that the modifications introduced are subject to a proper Risk Management Process.

The FERA shall quantify risks to the asset related to incident scenarios derived from Loss of Containments (LOCs). Loss of Containments include hydrocarbon releases from process equipment, gathering systems.

The main steps in this preliminary FERA are summarised below. They provide the framework to fulfilling the objectives of the study:

• Identify all potential LOC that could lead to potential fire and explosion hazards on the facilities;
• Determine the physical properties of flammable inventory (e.g. volume, mass flow rates, pressure, temperature, etc.);
• Identify the potential release types and subsequent fire / explosion scenarios (e.g. pool fire, jet fire, flash fire, explosion, etc.);
• Develop the fire / explosion characteristics for each of the identified fire / explosion scenarios (e.g. flame sizes, radiation distances, explosion overpressure distances, etc.);
• Determine the leak frequencies associated with each fire / explosion scenario;
• Determine the potential escalation scenarios and consequences of each event, with consideration of the control and mitigation measures proposed; and
• Propose additional measures for control and mitigation of the fire/explosion hazards for review as part of ALARP demonstration process.

• IP, HSE, UKOOA, “Ignition Probability Review, Model Development and Lookup Correlations”, IP Research Report, 2006.
• OGP Risk Assessment Data Directory Doc.

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