Page 13 - LOPC Survey

Unintended operation of equipment
Vents and drains, by design, are loss-of-containment points, as their normal function is to remove
material (in a controlled, intended fashion) from the process. When vents and drains are activated in a
manner other than intended, they become a source of LOPC events. In particular, pressure relieving
devices (e.g., safety relief valves, rupture discs, conservation vents) that relieve prematurely can be
treated as LOPC events, even if they are not treated as a tiered event (per API RP 754). While testing of
reseating devices (i.e., relief valves) may provide some preventive assurance, most responses to
unintended relief device activation will be mitigative.

Knock-on (domino) effects
For many scenarios considered in this monograph, the potential for significant knock-on or domino
effects is high. Practitioners are encouraged to formally include the potential for such effects in their
PHA or other types of analysis.

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