Equipment safety containment loss

The comparison of the safety of equipment is not straightforward. It depends on several features of both process and equipment themselves. It can be evaluated from quantitative accident and failure data and from engineering practice and recommendations. Experience has been used for layout recommendations and for the development of safety analysis methods such as the Dow E F Index (Dow, 1987). Statistics contain details, causes and rates of failures of equipment and data on equipment involved in large losses. 

Solvent Fractionation. This process is the most expensive because of solvent loss, solvent recovery equipment, much lower temperature requirement, and stringent safety features. The process involves the use of solvents such as hexane or acetone. The oil is first dissolved in the solvent followed by cooling to the desired temperatures to obtain the desired crystals. Cooling is effected by brine if very low temperature is required. The miscella containing the partially crystallized oil and solvent is then filtered under vacuum suction in an enclosed drum filter. The olein miscella and stearin miscella are then separately distilled to remove the solvent and recover the fractions. Yield of olein is about 80%. The solvent process nowadays is only viable in the production of high value products such as cocoa butter equivalent or other specialty fats. 

In the event of a malfunction of the reactor or safety related equipment, a condition known as a Loss of Coolant Accident (LOCA) may occur within the Primary Containment Structure. Should this happen, the environment would become dramatically altered in a matter of seconds and result in the escalation of temperature and pressure to dangerous levels. To counteract this condition, large quantities of water with chemical additives are automatically directed onto all surfaces by means of high pressure spray systems. 

Reducing the size of chemical process industry (CPI) equipment generally improves safety by reducing both the quantity of hazardous material that can be released in case of loss of containment and the potential energy contained in the equipment. This energy may derive from high temperature, high pressure or heat of reaction. 

After explaining in the preceding chapter the control of processes by means of process control engineering equipment, subsequently safety devices are treated. They should become effective if the process control engineering measures should fail. Since processes take place inside enclosures (vessels, pipework etc.) the objective is to avoid the loss of their integrity (loss of containment, LOC). An important reason for such a loss is a pressure which lies above the failure pressure of the enclosure. This can, for example, result from component failures. Frequently increased pressure is accompanied by increased temperature, which lowers the load limits of materials and hence their failure pressure. Further reasons for a loss of integrity of enclosures are fires and explosions which cause pressure and/or temperature increases. 

Generic Safety Issue (GSI) C-10 in NUREG-0933 (Reference 1) is concerned with the effectiveness of various containment spray solutions in removing airborne radioactive materials present in the containment after a loss-of-coolant accident (LOCA). Also of concern is the possible damage to equipment in the containment caused by the solutions in an inadvertent actuation of the spray system. 

The HSE study, Findings From Voiuntary Reporting of Loss of Containment Incidents 2004/05, reported that 32% of loss-of-containment events were caused by process and safety equipment failure, which occurred due to inadequate design and maintenance. SIS equipment performance is limited by the rigor, timeliness, and repeatability of mechanical integrity activities. Key performance indicators are recommended as a means to ensure that the various requirements of ANSI/ISA-84.00.01-2004 are implemented as expected. Sustainable operation is achieved by focusing on indicators that provide realtime indication of compliance to expectations. Example indicators are provided in Table 1 for the SIS. Additional recommended indicators have been published by CCPS in Guidelines for Process Safety Metrics. ... 

The APIOOO design process was directed at creating a fire protection system that requires no safety claims to be made on fire-fighting fluids at all. This was attempted by careful design of the plant layout into fire areas and zones, such that the equipment in a given fire area could be lost to tire fire without loss of overall plant safety functions. Within the Containment Vessel, additional spatial separation requirements were enforced for redimdant equipment, to make sure safety functions could be obtained in the event of a fire in the containment. This eliminated the requirement for a pumped fire protection system for internal fire hazards except for Beyond Design Basis fire events in the clean side of the Auxihary Building. 

Since 1960 the direct current for electrolysis has been provided exclusively by silicon rectifiers. A set of rectifiers can supply up to 450 000 A. Voltages up to 4.0 kV per diode are feasible, but usually for safety, a peak a.c. voltage of 1500 V, corresponding to a d.c. output of 1200 V, is not exceeded. Liquid cooling of the diodes permits a compact design, and self-contained equipment reduces leakage losses. Modem electrolysis cell plants also use continuously variable thyristor converters in place of silicon diodes [64]. 

ABSTRACT The first element in safety management is the possession of enough knowledge about what and how accidents happen. Evaluation of the layers of protection is important from both retrospective and predictive points of view. This article focuses on incident scenarios and potential causes of incidents in oil and gas plants, based on literature reviews of accident scenarios in one Middle Eastern case and comparing them with world accident scenarios in this sector. The result shows that accident scenarios in this case are similar to accident scenarios in this sector in the world. We argue that this is because they use similar equipment and facilities. Also, loss of containment and fire are the most popular accident in these industries. Finally, there is a repetitive pattern of accidents world-wide. 

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