Qualitative hazard analysis

Ref. 39 suggests an initial qualitative hazards analysis early in systems design, with only general levels of hazard probabilities identified, in addition to severity categories. An example of such a qualitative ranking from Ref. 39 appears in Table V. 

Layers-of-protection analysis (LOPA) is a semiquantitative methodology for analyzing and assessing risk. It is typically applied after a qualitative hazards analysis has been completed, which provides the LOPA team with a listing of hazard scenarios with associated safeguards for consideration. LOPA uses simplified methods to characterize the process risk based on the frequency of occurrence and consequence severity of potential hazard scenarios. The process risk is compared to the owner/operator risk criteria. When the process risk exceeds the risk criteria, protection layers are identified that reduce the process risk to the risk criteria. 

Hazard and operability analysis (HAZOP) A qualitative hazard analysis technique to identify and... 

M. Rousand, Preliminary Hazard Analysis, NTNU/Willey, October 2005. AuthorAnonymous, J.F. Shortle, Applying Qualitative Hazard Analysis to Support Quantitative Safety Analysis for Proposed Reduced Wake Separation ConOps, George Mason University, Fairfax, VA M. Allocco, FAA, Washington, DC. 

Usually these are completed after qualitative hazard analysis is over to address the following issues ... 

Many hazards may be identified and controlled or eliminated through use of qualitative hazard analysis as defined in Guidelines for Hazard Evaluation Procedures, Second Edition (AICHE/CCPS, 1992). Qualitative studies typically identify potentially hazardous events and their causes. In some cases, where the risks are clearly excessive and the existing safeguards arc inadequate, corrective actions can be adequately identified with qualitative methods. CPQRA is used to help evaluate potential risks when qualitative methods cannot provide adequate understanding of the risks and more information is needed for risk management. It can also be used to evaluate alternative risk reduction strategies. 

Define the potential event sequences and potential incidents. This may be based on qualitative hazard analysis for simple or screening level analysis. Complete or complex analysis is normally based on a full range of possible incidents for all sources. 

In June 1966, MIL-S-38130 was revised. Revision A to the specification once again expanded the scope of the SSP by adding a system modernization and retrofit phase to the defined life-cycle phases. This revision further refined the objectives of an SSP by introducing the concept of maximum safety consistent with operational requirements. On the engineering side, MIL-S-38130A also added another safety analysis the Gross Hazard Study (now known as the Preliminary Hazard Analysis). This comprehensive qualitative hazard analysis was an attempt to focus attention on hazards and safety requirements early in... 

Safety analyses principally comprise qualitative Hazard Analysis and probabilistic Safety Risk Assessment. Hazard Analysis models and evaluates the system s hazardous conditions and related system functions in order to identify the possible hazardous consequences which may occur as the result of initiating events such as failures or environmental aggressions. Probabilistic Safety Risk Assessment evaluates the... 

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