Risk Assessment Techniques

Risk Assessment Techniques

• Risk is defined as the combination of severity and probability of an event.
• Risk is also defined as how often an event can happen and how bad it is when it does happen.
• Risk = Severity x Likelihood
• Likelihood is the chance that a hazard event may occur.
• Severity considers the extent of damage, fatalities, injuries, and losses.
• Risk score = (Probability x Exposure) x Consequence
• Likelihood values and consequence values must be agreed upon by the risk assessment team.
• Likelihood is the chance that a hazardous event will occur.
• Consequence is the outcome of a hazardous event.
• Risk can be evaluated qualitatively or quantitatively.
• Risk = Frequency x Consequence of hazard
• Risk analysis involves estimating risk based on engineering evaluation and mathematical techniques combining incident consequences and frequencies.
• Risk assessment steps include risk analysis, hazard identification, hazard & scenario analysis, likelihood, consequences, and identifying safety barriers.
• A risk assessment matrix uses a table format to determine risk levels based on likelihood (probability) and severity. Values for likelihood and severity vary depending on the system and are chosen by the team (e.g. "negligible," "minor," "major," "extreme").
• Likelihood and severity are used to produce an overall risk score.
• A risk matrix is a visual tool to aid in decision-making. It is not a risk assessment process.
• A hazard is an inherent physical or chemical characteristic that has the potential to cause harm to people, property, or the environment.
• In chemical processes, a hazard is a combination of hazardous material, the operating environment, and unplanned events that could result in an accident.
• HAZAN (Hazard Analysis) is a systematic method for identifying and assessing hazards in the workplace.
• HAZAN focuses on job tasks to identify hazards before they occur.
• HAZAN takes into account employee, task, tools, and environment.
• Steps to an effective HAZAN procedure include defining the scope of work, breaking down the job into tasks, identifying and documenting hazards with potential accident scenarios, evaluating the causes, impact and likelihood of hazardous events.
• HAZAN also involves identifying control measures, training requirements, and reviewing analysis with involved employees.
• HAZOP (Hazard and Operability Study) is a design review technique used for hazard identification.
• HAZOP identifies design deficiencies that may lead to operability problems in complex workplace operations.
• HAZOP benefits include identifying potential hazards, enhancing safety measures, and improving cost-effectiveness of risk reduction.
• HAZOP disadvantages include being time-consuming and requiring rigorous review of complex processes.
• The three objectives of HAZAN are hazard identification, cause identification, and risk determination.
• Consequence analysis models determine the extent of negative effects from undesired events (like fire and explosion).
• Consequence analysis considers expected number of injuries and material exposures.
• Consequence analysis is used to prevent harm or eliminate risks.
• Common hazards considered in consequence analysis include toxic materials, flammables, and explosives.
• Consequence analysis models have three steps: Identify all possible consequences, Rank them according to severity, Categorize them by probability of hazard effects.
• Consequence analysis assists when faced with uncertainty or risk by predicting the impact of complex events along an event chain pathway. Advanced techniques such as Fault tree analysis (FTA) and event tree analysis (ETA) quantify the likelihood, in addition to estimating the impact of specific outcomes.