Understanding Quantitative Risk Assessment
A Quantitative Risk Assessment (QRA) is known as a formal and systematic risk analysis approach which helps to quantify the risks associated with the operation of an engineering process. A QRA is an essential tool which supports and understands the kind of exposure and understands the risk to employees, the environment, company assets and its reputation. A QRA also helps to make cost effective decisions and manages the risks for the entire asset lifecycle.
Objectives of a QRA study
- Identifying the hazards associated with the facility
- Determining the potential frequency & consequence associated with the identified hazard.
- Determining the system availability of the protection systems
- To quantify the risks associated with a facility(Eg. Risk Contours, Individual Risk per Annum(IRPA), Potential loss of Life(PLL), F-N Plots).
Risk Analysis techniques provides advanced quantitative means to supplement other hazard identification, analysis, assessment, control and management methods to identify the potential for such incidents and to evaluate control strategies.
QRA is widely used in assessing the risk in Oil & Gas Installations especially refineries, tank farms, cross country pipelines, bottling plants, terminals etc.
Risk Assessment Procedure
Hazard Identification is a critical step in Risk Analysis which include a good set of aids which include What-If Analysis, Hazard & Operability (HAZOP) Studies, Failure Mode & Effects Analysis (FMEA) & Preliminary Hazard Analysis (PHA) etc.
Assessment of risks is based on the consequences & likelihood
- Consequence Estimation is a methodology used to determine the potential for the damage or injury from specific incidents.
- Likelihood Assessment is the methodology used to estimate the frequency or probability of occurrence of an incident.
Software’s such as PHAST RISK MICRO 6.7, WHAZANv2.0, and EFFECTS v2.0 are used to carry out the modeling of probable outcomes such as fire, explosion, vapor cloud explosion, BLEVE etc.
So finally concluding this, Risks are quantified using this study is ranked based on the severity & probability. Acceptability of the estimated risk must then be judged based upon criteria appropriate to the particular situation. Study report is used to understand the significance of existing control measures and to follow the measures continuously.