Event & target likelihood

Cause & likelihood

IPL (Integrated Protection Layers) and its PFD (Process Failure on Demand)

Mitigated likelihood

Liquid carried over from the top of the scrub tower by the gas causing hydrate formation

1E−5

Fail of the sensor

to read high level, or fail of the valve at bottom of the tower to open to drain liquid

1E−2

Human action

Alarms

SIS (PLC)

2.6E−7

Human response to the alarm and manually open the valve

1E−1

A noticeable Alarm that would start if the level did not decrease after the sensor’s read within a few minutes

2.6E−1

Logic in PLC once a change in the liquid composition detected after the scrubber with a reasonable amount, automatically MCHE would be pay passed to prevent Hydrate formation.

1E−3