Emergency equipment process isolation valves

The incidents described could occur in many different types of plants and are therefore of widespread interest. Some of them illustrate the hazards involved in activities such as preparing equipment for maintenance and modifying plants. Others illustrate the hazards associated with widely used equipment, such as storage tanks and hoses, and with that universal component of all plants and processes people. Other incidents illustrate the need for techniques, such as hazard and operability studies, and protective devices, such as emergency isolation valves. 

Total Plant Shutdown A total plant BSD effectively shuts down the total plant or facihty under emergency conditions. Isolation valves are closed to stop the flow of combustible, flammable, or potentially toxic fluids and to stop heat input to process heaters or reboilers, and rotating equipment. Activation of a total plant BSD should not stop or impede the operation of fire protection or suppression systems, deluge systems, sump pumps, or critical utilities such as instrument or process air. 

Equipment Shutdown A system of equipment stoppage and emergency isolation valves that are used to isolate individual equipment within a process unit and prevent the release of potentially toxic material in the event of a fire, rupture, or loss of containment. 

Permanent gamma ray scanning equipment was installed on each separator along with foam density and level recorders in the process control room. An emergency trip system that automatically shuts a valve in the appropriate separator gas line to isolate the separator from the compressor suction drums when a high foam level occurs was added also. A similar trip system was insulted in the gas feed line from the HP separator to the power station... 

The primary system is intended to isolate the major equipment in order to prevent reverse flow and exhaust oxides in a gaseous state. It consists of a special restraint type valve (check) and two motorised shutdown valves, arranged in series. The system includes a low pressure detector on the main pipe that trips the sulphuric acid pumps, isolates the process and stops the helium flow into the reactor and heaters (emergency system EAS-200). 

Valves. Valves are key components in reactor systems, since they arc the means by which process gas and liquid streams are controlled [48,49]. In the HRE-2 system, which has no control rods, temperature and reactivity arc controlled by valves that control the concentration of the fuel solution, and the power is controlled by valves that control the rate of steam removal from the heat exchangers. "Dump valves perform an emergency scram and normal drain function by controlling the flow of fuel solution to low-pressure storage tanks. Other valves perform pressure-control functions, allotv noncondensablc ga.ses to be bled from the system, or ai ( used to isolate equipment. 

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