Page 319 - CHEF Guide

Mitigating Safeguards and Protection Layers

Personal Protective Equipment (PPE) is safety gear that is worn to act as a barrier between a person and hazard
(Figure 20-8). It is often the LAST line of defense for on-site or emergency personnel.

Figure 20-8 Images of Personal Protective Equipment (PPE)
Some key considerations for PPE as a safeguard or protective layer include:
 The PPE will provide full protection against the consequence of concern.
 The operator wears PPE every time the procedure is executed.
 There is verification of the procedure, training, and control of human factors to ensure PPE is properly used.

Industry consensus guidance suggests Probability of Failure on Demand of 0.1 [78]. The evaluation team may need to
review the existing or proposed design to determine if the generic probability of failure on demand (PFD) of 0.1 is appropriate
for the specific application.

Drainage and Containment is used to minimize consequences for loss of containment events by controlling liquid
spills from process and storage operations (Figure 20-9).

Figure 20-9 Why spill containment is important

There are several design considerations in determining the type of containment that is most effective. For a
conventional design, leaks accumulate around tank. In case of fire, tank will be directly exposed to flames that can be
supplied by a large amount of fuel and will be hard to control. It may be better to direct leaks and spills away from tank to a
remote pit or containment (Figure 20-10). In case of fire, the tank will be shielded from most of the flames and fire will be
easier to fight. (If a fire pit if far enough away, a fire wall may be unnecessary.)

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