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Protection through the use of safety layers. A process plant shutdown system is a functional safety countermeasure crucial in any hazardous process plant such as oil and gas production plants and oil refineries. The concept also applies to non-process facilities such as nuclear plants. These systems are used to protect people, assets, and the ...
Layers of protection analysis (LOPA) is a technique for evaluating the hazards, risks and layers of protection associated with a system, such as a chemical process plant. . In terms of complexity and rigour LOPA lies between qualitative techniques such as hazard and operability studies (HAZOP) and quantitative techniques such as fault trees and event trees.
Process safety is an interdisciplinary engineering domain focusing on the study, prevention, and management of large-scale fires, explosions and chemical accidents (such as toxic gas clouds) in process plants or other facilities dealing with hazardous materials, such as refineries and oil and gas (onshore and offshore) production installations.
Pressure in blanketed tanks is maintained by self actuating pressure control valves (PCVs). As liquid is withdrawn from the tank the pressure in the gas space falls. The blanket gas supply valve opens to maintain the pressure. As the tank fills with liquid the pressure rises and a vent gas valve open to vent gas to atmosphere or a vent system. [11]
The concept has important practical use in fire safety engineering. For instance, to safely fill a new container or a pressure vessel with flammable gases, the atmosphere of normal air (containing 20.9 volume percent of oxygen) in the vessel would first be flushed (purged) with nitrogen or another non-flammable inert gas, thereby reducing the ...
Unlike ATEX which uses numbers to define the safety "Category" of equipment (namely 1, 2, and 3), the IEC continued to utilise the method used for defining the safe levels of intrinsic safety namely "a" for zone 0, "b" for zone 1 and "c" for zone 2 and apply this Equipment Level of Protection to all equipment for use in hazardous areas since ...
Because an inert purge gas is used, the purge procedure may (erroneously) be referred to as inerting in everyday language. This confusion may lead to dangerous situations. Carbon dioxide is a safe inert gas for purging. Carbon dioxide is an unsafe inert gas for inerting, as it may ignite the vapors and result in an explosion. [2]
The essential service water system (ESWS) circulates the water that cools the plant's heat exchangers and other components before dissipating the heat into the environment. Because this includes cooling the systems that remove decay heat from both the primary system and the spent fuel rod cooling ponds, the ESWS is a safety-critical system. [7]