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Copyright © 2014 by Cenbee Bullock PFS Consulting Ltd
PFS
Specialising
In Functional Safety
Minimising Systematic Failures in SIS Design
Statistics from Process Improvement Institute:
CCPS
– Centre for Chemical Process Safety
Examples:
CCPS 2012 – Relief Valve (PRV)
PHE =
0.01 to 0.04
for a Relief Valve being returned to normal
operation after maintenance due to leaving the block valves in
the bypass position
Refinery Shutdown
PHE =
0.2
for Straight 30 working days of 12 hour shift
Probability of Human Error (PHE) varies from
0.1 to 0.001
dependent on the industry and the control of Human Factors.