Sharif Digital Repository

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... 

In modern society, engineers, technical managers are responsible for planning, design, construction, exploitation of simplest to most complex systems. Crashes cause disruption of systems at different levels and can be considered as a serious threat to society and the environment, thus consumers and people expect reliable products and systems. There are different methods for increasing the reliability of systems, one of them is related to their quality and another way is related to use of standby systems. Also maintenance and repairing have major role for keeping up reliability or availability of systems. In the first part of project, optimization the reliability of system by standby... 

According to privileged risks existing in process industries and intensity of their consequences, Safety investigation and risk assessment are highly significant in these unites. Execution of risk assessment in process unites has been constituted from two qualitative and quantitative parts. The most crucial issue in risk assessment procedure is uncertainties related to data and needed information, besides of various models presented. This subject frequently relates to deficiency, ambiguity, and inaccessibility of necessary information for specifying of risk assessment characteristics i.e., event reproducibility and their intensities. In this work for overcome these constraints, bow-tie fuzzy... 

Domino accidents are those which are initiated from one equipment and extend to neighbor equipments or units and as a result the consequence of the primary accident is increased. Risk management is one of the tools for reducing risk of accidents and Quantitative Risk Analysis is a crucial stage in risk management. Despite the importance and severity of domino accidents, in most of QRA studies the effect of these accidents on risk is not considered. In the present work tools for Quantitative Risk Analysis with considering domino accidents has been developed. Two major methods for this reason are used; analytical method and simulation. First, software based on analytical method was developed... 

This research has been worked out in two main parts and it is tried to reach a high level of Safety Integrity in Safety Instrumented Systems using in Oil, Gas and Petrochemical industries. The first part involves an overview of system risk analysis and initial investigation of Safety Integrity Level as a new parameter in safety instrumented systems which are very important section of Safety engineering during last couple of years. According to the fact that the available papers and articles in this area are very limit; we have faced a lot of problem in doing research and actually to be honest; all available resources have been focused plus the related standards. The second part is about... 

Gas leak explosion is major risks in closed environment in the chemical industry. One of the fundamental principles of safety is control of ignition sources using special protective equipment in areas where possible flammable gases or vapors are there. Computational fluid dynamics is used in this project to evaluate and analyze the risks associated with gas distribution. Ventilation effect has been studied by computational fluid dynamics on gas cloud formed by leakage of flammable in hazardous areas. To demonstrate the accuracy of calculations performed by computational fluid dynamics, the results are validated by experimental data. The simulated results for gas dispersion are found to be in... 

Safety integrity level is a measure of performance and relibality of safety instrumented functions that may be used as a protection layer for processes. There are various methods for determining Safety integrity level, each of which has its own advantages and disadvantages. Of these methods, two methods of risk graph and layers of protection analysis are most used by different organizations and companies. A major disadvantages of these methods is uncertainty that users face in different steps of appling them. To overcome this problem using fuzzy logic has been suggested in literatures. This thesis was conducted in to parts, the first part includes principles of risk assessment and initial... 

The set processes of carbon dioxide capture, transfer and storage in underground water source, called CCS. Carbon dioxide capture and storage is a process consisting of the separation of carbon dioxide from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere. Carbon dioxide is the most important greenhouse gases, which causes global average temperature rise and controller institutions want the companies and refineries to follow this issue.Under normal circumstances, there is minor amounts of carbon dioxide gas in the air which its concentration is close to 0.04 percent. The concentration of between 7 to 10 percent is a serious...