Page 405 - Offshore Electrical Engineering Manual

392 CHAPTER 1 Reliability

FIGURE 8.1.3
Typical criticality matrix.

to performing this kind of analysis). This is a graph with axes of severity of effect
against the probability of its occurrence.
The severity is given four arbitrary categories as follows:

(a) Category I: Catastrophic – A failure which may endanger the whole
installation and involve loss of lives.
(b) Category II: Critical – A failure which leads to prolonged loss of
production and may cause severe injury, major equipment and/or
system damage.
(c) Category III: Marginal – A failure which may cause minor injury and minor
system/equipment damage and will result in delays to or partial loss of
production.
(d) Category IV: Minor – A failure not serious enough to cause injury or any
equipment/system damage but which will result in an unscheduled outage
for maintenance or repair.