Explosion protection design arrangements

Facilities that are deemed critical or highly manned should be relocated out of the overpressure circles or provided with explosion protection measures. Other systems within these overpressure zones should be evaluated for the specific benefits of providing explosive protective design arrangements. An example is provided in Figure 16.1. 

Most petroleum and chemical facilities rely on inherent safety and control features of the process, inherent design arrangements of the facility, and process safety ESD features as the prime loss prevention measures. These features are immediately utilized at the time of an incident. Passive and active explosion and fire protection measures are applicable after the initiating event has occurred and an adverse affect to the operation has been realized. These features are used until their capability has been exhausted or the incident has been controlled. 

Siting - The preferred arrangement of bulk transport pipeline systems is for burial underground. This provides for enhanced protection from overhead events. This is even the case for offshore pipelines where there have been numerous incidents of dragged anchors from fishing vessels to pipelines exposed on the seabed. A radius of exposure from a pipeline can also be easily calculated for fires and vapor explosions based on the commodity, pressure, release opening, etc. From these calculations a restricted zone or similar can be designated. 

Optical flame sensors can be used for detecting the initial explosion, provided interference of environmental conditions can be reliably prevented. Pressure transducers are often used because the pressure wave travels at the speed of sound and can be detected at various angles. Vibrations and other mechanical movements can interfere pressure sensors. Therefore, efforts have to be made to minimize the influence of these interferences. The suppressant must be effective in flame quenching and compatible with product and the material of the plant. The suppressors must be designed and arranged adequately, so that the suppressant is rapidly and uniformly injected to the gas mixture in the protected enclosure. 

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