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Improvement of Risk Graph Method to Identify Important Operational Safety Indexes

Khalati, Elham | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50484 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Rashtchian, Davood
  7. Abstract:
  8. Safety integrity level that is a basis for relative risk reduction, is defined by the safety function assessment. Among risk assessment methods, risk graph is known as a qualitative method, which has been used by safety experts due to its simple structure. But this feature doesn't stop them from checking out the structure in a careful way. At first by specifying the basic parameters of the risk graph method, it has been defined that safety and control systems that their functions are independent from alarms and human consciousness, are not considered in this method, so a new parameter has been introduced to show the effects of mentioned control and safety systems. On the other hand, in order to reduce the uncertainty of risk graph method input parameters, a combination of fuzzy logic and risk graph has been used. After checking different parameters during fuzzification, a linear equation based on Sugeno inference system has been introduced. After improving the process and structure of risk assessment based on risk graph method, in order to calculate safety integrity level, appropriate risk tolerance criteria shall be selected. Mentioned criteria based on the consequence type, is composed of three outcomes: asset, time, and missing value. The new method for determining risk reduction factor can be used for most of the risk assessment methods
  9. Keywords:
  10. Fuzzy Logic ; Uncertainty ; Safety Integrity Level (SIL) ; Risk Graph ; Risk Tolerance Criteria

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