QUANTITATIVE RISK ASSESSMENT (QRA)
QRA is a tool that systematically analyses the risks from hazardous activities in order to quantify the risks to personnel working on the facility, and then compare the predicted risk levels against the QP risk criteria and assess their tolerability. In addition, QRA is also used to estimate the risks to public.
Risk assessment is an overall process of identifying and analyzing risk, and evaluating how it might be modified to maintain appropriate levels of safety and to meet the regulatory, company norms / criteria.
It is very important to identify risks in industrial workplaces in order to protect the plant workers, the people in the surrounding area, the environment and the plant assets. Demonstration of acceptable risk levels is often a requirement for any single or many facilities such as chemical production and processing facilities, high pressure pipelines or storage and transportation sites for gas / oil.
Why QRA Study is needed?
The QRA provides valuable insights into the risk profile of the plant, identifying and ranking the areas where failures may result harmful to the operators, members of the public /community in proximity, the environment and the asset itself. QRA provides a basis for decision making in the design and operation of the plant and may also be required to show that assets are fit for purpose of its intended operation.
What does QRA help you to know?
The most obvious service of a QRA are the two ingredients of risk: consequence and probability. For every accident scenario identified, there will be a specific hazard zone (as defined by the hazard endpoints) and a corresponding probability of occurrence. As separate pieces, the consequence modeling results are often more useful than the probability values. A QRA generates a large amount of consequence information, allowing extensive comparison between the effects of hole size(s), weather conditions, and many other variables. Although rarely used explicitly, each individual accident outcome has an associated probability of occurrence.
The most common and oftentimes most useful items provided by a QRA are individual risk contours.
When QRA should be done?
QRA techniques is carried out to identify potential hazards to an asset including plant, process and personnel; & the right time to go for QRA when;
- estimating risk levels and assessing their tolerability
- identifying main contributors to risk
- demonstrating acceptability of risks to regulators and the workforce
- evaluating risk reduction measures to determine effectiveness in reducing risks
- identifying safety and environmental critical equipment and procedures
- providing a basis for ongoing decision making on safety and operational issues
- comparing different design options
Approach / Methodology
A Typical QRA process includes:
A QRA study is made up of a number of steps:
INPUTS REQUIRED (not an exhaustive list)
- Latest Piping and Instrumentation Diagrams (P&IDs)
- Operating Philosophy and Process Conditions/ Operating Parameters
- Latest Scaled Layout/ Plot Plan
- Population Details (Location and Number)
- Site Meteorology & etc.
The study will comprise of a number of distinct but interrelated tasks as follows:
- Site visits; ( optional- subject to project case)
- Data collection and review of relevant documents for the project;
- Identification of potential hazardous events;
- Development of the QRA methodology and assumptions report;
- Consequence assessment including development of incident scenarios using event tree analysis (ETA);
- Failure frequency analysis;
- Risk evaluation and integration;
- ALARP demonstration;
- Provision of Risk Reduction Measures (RRMs); and
- Preparation of QRA report for project scope.
- QRA Assumption Register/Methodology Report
- QRA Study Report
iFluids Engineering expert team having sound experience in completing Qualitative Risk Assessments (QRAs), which is a structured approach to identifying and understanding the risk associated with hazardous activities such as the operation of the plant / operation facility…