Safety and Seperation Distances – Safety Engineering (SAFTENG)

From “facility siting” in a PHA to establishing emergency “assemble areas,” the methodology we use matters. Many of us use a RAGAGEP from The European Industrial Gases Association (EIGA) titled Methodology for Determination of Safety and Separation Distances. The “safety distance” is to provide a minimum separation that will mitigate the effect of any foreseeable event. The separation distance will also provide protection for the equipment from foreseeable external impacts such as roadway, flare, or activities outside the control of the operation, for example, a plant boundary and prevent it from escalating into a larger incident. Here is a peek at what this RAGAGEP can do for us…

In order to do so, the following steps shall be followed:

Identify the hazard sources and events, for example release of gas, taking into account the likelihood.
Calculate the effects on neighboring objects and population taking into account mitigating factors.
Determine the safe distance to each object or population to meet the minimum hazard criteria.
Consider additional prevention or mitigating factors and re-calculate safe distance

The safety and separation distances are NOT intended to provide protection against catastrophic events or major releases; these should be addressed by other means to reduce the frequency and/or consequences to an acceptable level.

The safety distance is a function of the following:

The nature of the hazard, for example, toxic, flammable, oxidizing, asphyxiant, explosive, and/or overpressure.
The equipment design and the operating conditions, for example, pressure and temperature and/or physical properties of the substance under those conditions.
Any external MITIGATING protection measures, for example, firewalls, blast walls, diking, or deluge system, that reduce the escalation of the incident.
The object protected by the safety distance is the harm potential, including, for example, people, exposure time, environment, or equipment.

The provision of adequate distance or separation zones around the equipment is a fundamental consideration for a safe layout. By understanding the protection afforded by increasing the safety distance, one can optimize the safety protection of a piece of equipment. In most cases, the safety distance to provide protection from all possible events is NOT practicable. Therefore, an assessment of the frequency of the event and the potential consequence is necessary to understand which risks can be reasonably mitigated by a safety distance. If the safety distance is too large, additional mitigating or prevention measures should be considered, and the safety distance should be re-calculated.

CLICK HERE for this RAGAGEP

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