Quantitative Risk Assessment

HAZAN/Fault Tree Analysis

Hazard Analysis (HAZAN) is quantification of the identified risks. Fault Tree Analysis is one of the techniques used for Quantitative Risk Assessment. A fault-tree analysis (FTA) is conducted to understand all the underlying causes of a particular failure, so that the root causes can be eliminated. The outcome of an FTA is a better understanding of the layers of causes for a particular failure, and action plans for eliminating the root causes. This also helps in estimating the overall failures and risks associated with the failures. The faults and their effects will be presented diagrammatically. The trees will be developed based on the information collected during discussions and studied from documents.

Event Tree Analysis

Event Tree Analysis is done based on the possible outcomes arise from the event of interest and considers the barriers and enabling events also. Customized spread sheets will be used by consultants to develop the ETA.

Failure Mode & Effects Analysis

Failure Modes and Effects Analysis (FMEA) is methodology for analyzing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design. FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions to mitigate the failures. A crucial step is anticipating what might go wrong with a product. While anticipating every failure mode is not possible, the development team should formulate as extensive a list of potential failure modes as possible. JRB consultants carry out Design and Process FMEAs. Software tools such as FMEAPro are used for FMEA studies.

Consequence Analysis

Consequence Analysis is carried out to estimate the damage distances due to flammable and toxic gas dispersions, fires and explosions. Consequence Analysis involves source term modeling, physical impact modeling and impact assessment. Consequence Analysis is carried out by using the internationally reputed software tools such as PHAST. The results of the study can be used as input for Quantitative Risk Assessment, Critical equipment and structure design and Emergency Response Planning.

The other studies falling under the category include:

• Flammable and toxic gas dispersion
• Preliminary Analysis for Determination of Separation Distances

Quantitative Risk Assessment

QRA is done using the consequence analysis, failure frequency analysis and ignition probabilities. The Individual Risk (worker/ public), Societal risk and Potential Loss of Life indicators are estimated and evaluated against the risk acceptability criteria. Software tools such as PhastRisk are used for the QRA. Following are the various types of Risk Analysis carried out by the consultants:

• Onshore QRA studies
• Off Shore QRA
• Pipeline Risk Analysis
  • Blast and Overpressure
  • Analysis H2S Risk Assessment
• Riser and Topsides Risk Analysis

Dropped Objects Study

The objective of the Dropped Object Study is to determine whether dropped objects present a significant risk to hydrocarbon installations leading to a loss of containment during normal production operations and maintenance activities at platforms, manifold tower and wellhead towers and also to verify the design load of lay down areas, which could be affected by the dropped objects during the lifting activities within the facilities. Calculations are carried out by using the customised spreadsheets.

Helicopter Risk Analysis

Helicopter collision risks are detrimental to the safety of structure and people in the offshore platforms. Transportation risk for the people travelling in the helicopter is also covered under Helicopter risk analysis. The study helps in designing the layout of helipad and other safety measures to be adopted in the platforms and the helicopter.

Ship Collision study

The purpose of Ship Collision Study is to study the movement of various vessels which may visit the platforms and cargo/ merchant vessels which cruise to the nearby installations and assess the risk posed by them to installation in general and risers in particular . The impact energy due to all types of collision which may affect the platform structure is calculated by using customized spreadsheets and analyzed. The design collision protection measures which are available in each platform are also studied.

Occupational Risks / Non Hydrocarbon Hazard Analysis

All occupational risks applicable for those working in offshore platforms and other facilities cover electrical risks, accidentals risks such tripping/falling etc, transportation risks etc. Customised spreadsheets will be estimation of Non Hydrocarbon risks.

ALARP study

In all cases of medium and high risk levels the consideration shall be given to reducing risk to a level deemed ALARP reflecting among other factors local conditions and circumstances, the balance of cost and benefits and the current state of scientific and technical knowledge. To reduce a risk to an ALARP level involves balancing reduction in risk to a level, objectively assessed, where the trouble, difficulty and cost of further reduction measures becomes unreasonably disproportionate to additional risk reduction achieved. The overall approach taken in demonstrating ALARP is based on corporate requirements .The ALARP contributing scenarios are identified through the QRA. Existing risk reduction measures that were not considered in QRA, but still can bring down the risk are identified in the ALARP Workshop. Additional measures required to reduce the risk by considering the cost impacts are also analyzed.

COMAH (Control of Major Accident Hazards)

COMAH approach is a systematic procedure for the identification and recording of Major Accident Hazards and the risk levels of new projects and existing facilities and operations. It facilitates the preventive approach to risk management as appropriate risk control and mitigation measures can then be incorporated at an early stage in the design process.

COMAH report provides following information on the Major Accident Hazards:

• Hazard Identification methodology used Hazard Release scenarios
• Analysis and assessment of risk ( Hazards & Effect Register)
  • Demonstration of sufficiency of control, mitigation and recovery methods through techniques like Bow Tie Analysis
• Demonstration that the risk is acceptable or ALARP
  • Demonstration that all HSE Critical Equipment and Systems (or Safety Critical Element) are identified and that adequate management systems, procedures and competencies are in place to manage these
• On- Site & Off-site emergency response plans
  • Demonstration of controls for all hazards (Major, Medium or Low) via HSEMS

Software tools such as Thesis will be used for developing Bow Tie diagrams and PHAST, PHASTRISK for the estimation of risks.