Risk Based Inspection (RBI) results using the API RBI software are presented for
calculating a risk value for each piece of plant fixed-equipment. Usually RBI implementation
results in fixed-equipment inspection program modification. Inspection is specified for
equipment items that exceed Owner acceptable risk criteria while it is waived for equipment
that is below acceptable risk levels.
In RBI analysis, equipment risk value consists of a Likelihood-of-Failure (LOF) and a
Consequence-of-Failure (COF) element. The sum of different equipment damage
mechanisms (internal corrosion, external corrosion, cracking mechanisms and mechanical
damage) is the LOF value. The COF value is the sum of the damage to the specific equipment
item, damage to surrounding equipment, lost production, serious injury to personnel and
environmental clean-up.
This paper describes benefits realized from applying RBI in gas plants as a reliabilityengineering
tool for guiding decisions in optimizing fixed-equipment mechanical integrity.
Utilizing the calculated LOF, COF and Risk values for each piece of fixed-equipment allows for
extracting maximum value from a RBI database.
Based on RBI calculated risk values, fixed-equipment relative risk ranking is established to:
–set priorities and focus attention on the critical areas
–justify capital investment for Lifetime Extension projects
–proactively address Loss of Primary Containment and Process Safety issues
Keywords: Risk-based inspection, RBI, mechanical integrity, gas plant