Guide word

Deviation

Cause

Consequence

Safeguard

DMRA

Less

1) Level

1) LIC (liquid indicator controller)in the scrub tower fails to open, causing liquid drainage

1.1.1 Which may cause gas to flow through the bottom exit to unit 7 causing hammering

A low level trip at the scrub tower to prevent gas entering

Probability = 4

Severity = 3

Risk factor = P × S = 12

Type = undesirable

More

1) Level

1.1. Malfunction of flow valve at bottom of scrubber

1.1.1 Carry over at the scrubber as the gas flow would carry liquid with it, liquid may freeze with the low temperature causing dry ice on inner tubes causing lower production &corrosion

High alarm level at the scrubber

Probability = 4

Severity = 2

Risk factor = P × S = 8

Type = acceptable with controls

Change

Composition change

1.1. Loss of reflux in the scrubber

1.1.1 Heavy ends directed to MCHE-Main Cryogenic Heat Exchanger-, causing corrosion & freezing

Low reflux alarm at entry of scrub column

Probability = 3

Severity = 2

Risk factor = P × S = 6

Type = acceptable with controls