Quantitative Risk Analysis (QRA) for the Al SEEF Petrol Station

iFluids Engineering and Consultancy WLL was awarded to perform Quantitative Risk Analysis QRA for the Al SEEF Petrol Station

What is Quantitative Risk Analysis (QRA)?

Quantitative Risk Assessment (QRA) is a tool used for risk analysis of a system or process in a systematic manner.

• It’s employed in several industries, including Power generating, Oil and gas, and Transportation.
• QRA defines hazards to employees working on various systems, which are then compared to safety requirements and evaluated for acceptability. QRA is often used to predict public safety threats.
• The project aimed to evaluate the potential hazards involved in the processes of unloading, storing, and dispensing of Petrol (premium) and Petrol (super), which are classified as hazardous materials at the site.

The Al SEEF Petrol station includes the following:

• Super / Premium Petrol Fuel Delivery Truck and Offloading Area;
• Super / Premium Petrol storage tanks with all necessary fitting and piping work;
• The submersible pump used for underground storage tanks, specifically the Red Jacket Pump, is a commonly employed device in various industries.
• Petrol filling island and Dispensers; and
• Interconnection piping between equipment.

Quantitative Risk Analysis (RA) study includes,

• Identification of Hazards using Event Tree Analysis (ETA) and Fault Tree Analysis (FTA) for identifying Loss of Containment scenarios, risk-prone areas, various failure modes, etc.
• The evaluation of potential risks stemming from various hazards and the examination of their acceptability to individuals, infrastructure, and the natural surroundings encompass the following aspects. 
• The present study involves the computation of the physical ramifications resulting from accidental scenarios.
• This includes conducting a frequency analysis to determine the likelihood of incident scenarios leading to various hazards such as flammable gas, fire, smoke, explosion overpressure, and toxic gas hazards.
• Additionally, the study aims to assess the probability of failure for tanks, piping, and other equipment, based on internationally recognised databases.
  • Damage limits the identification and quantification of the risks and contour mapping on the layouts.
  • Individual risk quantification and contour mapping.
  • Societal risk quantification and contour mapping
  • Assessment of risk to predetermined acceptable thresholds
  • Hazard Risk mitigation measures & recommendations to prevent incidents, to control accidents.

QRA Methodology

The Methodology to carry out Quantitative Risk Analysis (QRA) associated with the storage terminal can assess the consequence of fires initiated by various events and quantify the risk in terms of risk to personnel and petrol Station.

• Data / Information Collection:
  • Collection of relevant data on operating conditions and selection/evaluation of accident scenarios for the storage and pumping facilities at terminals and along the pipelines.
• Hazard Identification:
  • Identify hazards associated with the storage and operation of the proposed terminal using expert judgment. Hazard identification is done to identify, Maximum Credible accident scenarios, Various failure modes, causes & effects, and Risk prone areas in petroleum storage installation/depots
• Frequency/Probability Analysis:
  • Assess the likelihood of occurrence of the identified hazardous scenarios by reviewing historical accident data and internationally accepted databases.
• Consequence Analysis:
  • The consequences of each outcome resulting from an initial event are determined using the SAFETI consequence model, a widely recognised international framework developed by DNV in the United Kingdom. This model is utilized to evaluate the effects of gas leaks, fires, explosions, toxicity, and other process hazards.
    • The overall damage potential of identified scenarios is calculated by taking into account the following:-
      • Hazard Substances released
      • Process Conditions
      • Location of hazardous substances released & where it is likely to spread
      • Degree of confinement
      • Meteorological conditions
      • Ignition sources available
• Risk Determination:
  • Risk determination involves the consideration of both the severity of the consequences of an identified hazard and the probability of its occurrence.
• Risk Assessment:
  • Evaluates the risks level, in terms of individual and societal risks associated with the identified hazardous scenarios. The overall risk level is compared with the criteria as stipulated in international guidelines to determine their acceptability
• Recommendations:
  • Mitigation measures will be identified where the risk is considered in the ALARP (As Low as Reasonably Practicable) region will be recommended.

• Fire and explosion hazards from the proposed facility were modelled using the DNV PHAST/SAFETI 7.2 modelling software.
• The software developed by DNV is utilised for conducting risk assessment studies on flammable and toxic hazards, with a focus on identifying both individual and societal risks.
• This tool provides the user with the capability to evaluate the physical ramifications resulting from inadvertent discharges of hazardous substances that possess toxicity or flammability properties.
• PHAST v7.2 is used for consequence calculations and Safeti v7.2 is used for risk calculations.
• The software package comprises a range of contemporary models that enable comprehensive modelling and quantitative evaluation of various phenomena, including the evaporation of release rate pools, atmospheric dispersion, vapour cloud explosions, combustion, and the heat radiation effects caused by fires, among others.
• The software has been developed using the hazard model outlined in the TNO Yellow Book as its foundation.
• Modelling runs were completed for each isolatable section of the petrol station to assess the potential consequences and risks of a small, medium, large and catastrophic release from within that section.
• The ramifications of the discharge of combustible substances are primarily contingent upon the prevailing meteorological conditions.
• In the evaluation of significant scenarios about the discharge of combustible substances, the meteorological parameters of utmost significance are those that exert an influence on the dispersion of the released material within the atmosphere.
• The key factors encompass wind speed, wind direction, atmospheric stability, and temperature.  Rainfall does not have any bearing on the results of the risk analysis; however, it can have beneficial effects by absorption/washout of released materials.
• The observed behaviour of a release is primarily influenced by the specific weather conditions present at the time of the release.
• Petrol (premium) and petrol(super) are offloaded from road tankers to underground storage tanks, and from there, fuel is pumped to a fuel filling station.

A summary of the consequence analysis is as follows:-

• In the case of full-bore rupture of the Petrol (Premium) Fuel Delivery Truck Unloading pipeline to the Storage Tank, the hydrocarbon vapour cloud produced, as a result of the release disperses within 308.9m (0.2 LFL) of the release under calm wind (1.5 m/sec) and stable atmospheric stability conditions (Pasquill-Gifford Atmospheric Stability Class F)
• Consequence modelling indicated that the lowest heat radiation contour of interest, (4.7kW/m²) heat radiation contour resulting from a jet fire scenario for the case of full-bore rupture of Petrol (Super) Fuel Delivery Truck Unloading Pipeline to storage Tank extends to a distance of 111.4 m under 1.5F wind and atmospheric conditions
• In the case of a full-bore rupture of the Petrol (Premium) Fuel Delivery Truck Unloading pipeline to the Storage Tank, the distance to the LFL (50%) contour is 203.4m under 1.5F wind and atmospheric conditions
• In the case of catastrophic rupture of Underground Petrol (Premium) Storage Tank failure, the distance to the VCE overpressure level of 0.1 bar is 215.5m under 1.5F wind and atmospheric conditions, and
• In the case of catastrophic rupture of Underground Petrol (Super) Storage Tank failure, the distance for pool fire heat radiation of 4.7kW/m² is 140.4 under 3D wind and atmospheric conditions.
• The flash fire envelope, Over-explosion effect caused by truck unloading, tank discharge line, and Tank or Truck failure cases of Al Seef Petrol Station activities will reach up to Qrail station and it is tabulated in detail under section 5.4 consequence analysis results.

Quantitative Risk Analysis (QRA) Summary for Al SEEF Petrol Station

• The risk analysis was carried out using DNV SAFETI software version 7.2 to obtain risk results in the form of LSIR contours F-N Curve and it is presented in section 7 of the report.
• These risk results were assessed based on the Risk Acceptance Criteria in line with the Qatar Petroleum Philosophy for HSE Risk Management and concluded that the IRPA for the people in the Petrol Station, Tanker Area, and General Area was found to lie in the ALARP region, for the people in the Shops and Office area it was found to lie in the ACCEPTABLE region and the societal risk for the Al SEEF Petrol station population considered for the study was to found lie partly in the UNACCEPTABLE region for numbers of fatalities less than 4 persons and partly lies in the ALARP region for number fatalities less than 35 people and partly lies in the ACCEPTABLE region.
• The individual and societal risk for the people at the Qrail station lies within the acceptable region.
• The main objective of this QRA study is to quantify and assess risk from the hazards associated with the Al SEEF Petrol Station. To fulfil the assessment objective, the identification and evaluation of potential scenarios have been conducted.
• The probability and impact of potential accidental releases within the facility have been analysed and reported.
• Moreover, in light of the findings obtained from the assessment, suitable recommendations have been furnished as measures to mitigate risks.
• Among the Risk Ranking locations considered for the study, for the following Risk Ranking locations Petrol Station, Tanker, and General Area the LSIR values lie in the ALARP Region for Combination.
• The Risk for various locations was studied and found that the people in the Petrol Station, Tanker, and General Area lie in the ALARP region.
• The individual risk for the people in the Qrail station lies within the acceptable region.
• It is concluded from the study that the societal risk for the overall population considered for the study falls partly in the UNACCEPTABLE, ALARP and the UNACCEPTABLE region.
• Risk reduction measures to be incorporated into the design and/or operation of the petrol station are given to reduce risks from unacceptable to ALARP or Acceptable region and also to manage the safe operation of the facility.

Conclusion

The Quantitative Risk Analysis (QRA) for the Al SEEF Petrol Station has provided valuable insights into the potential risks associated with its operations. Using DNV SAFETI software, the assessment quantified individual and societal risks, ensuring alignment with Qatar Petroleum’s HSE Risk Management philosophy. The analysis concluded that individual risk for personnel in the petrol station, tanker area, and general area lies within the ALARP region, with the shops and office area falling within the acceptable risk range. However, certain societal risks fall partially within the unacceptable and ALARP regions, emphasizing the need for mitigation.

Recommendations from this study focus on implementing risk control measures to reduce risks to as low as reasonably practicable (ALARP) or acceptable levels. These measures will not only address immediate safety concerns but also contribute to long-term operational safety. By integrating these controls, the Al SEEF Petrol Station can enhance safety standards, align with regulatory requirements, and safeguard both employees and the public, ensuring sustainable and secure operations.