196
W. Li et al.
Table 1. Risk level matrix
Probability
Consequence
1
2
3
4
5
1
Low
Low
Low
Low
Low
2
Low
Low
Low
Medium Medium
3
Low
Low
Medium Medium
High
4
Low
Medium Medium
High
High
5
Medium Medium
High
High
High
Table 2. Part of HAZOP analysis results
Deviation Possible
cause
Consequence
Protection
measures
Risk
matrix
Suggestions
High oil
level
Content
gauge
failure
Tank boil-overs,
economic losses,
environment
pollution, fire,
casualties
1. High liquid
level
interlocking,
closing the
valve front
tank;
2. Regular
checking of
content
gauge;
3. Monitoring;
4. Combustible
gas detector;
5. Flame
detector;
6. Ignition
source
management;
7. Lightning rod
and
grounding
grid;
8. Calculating
liquid level
variation
regularly
(5:4)
High
1. Transferring the
signals of
content gauge
failure to the
station and
making alarms;
2. Recording the
oil level showing
by the content
gauge during the
process of
storing the oil
into the tank;
3. Mounting
equipment to
make alarm or
take interlock
action when the
content gauge
value remains
unchanged for a
certain time
period in the
process of
storing the oil
into the tank