API RP 581 - 3rd Ed.2016 - Add.2-2020 - Risk-Based Inspection Methodology

3-52 API RECOMMENDED PRACTICE 581
Table 4.5—Detection and Isolation System Rating Guide
Type of Detection System
Instrumentation designed specifically to detect material losses by changes in
operating conditions (i.e. loss of pressure or flow) in the system.
Suitably located detectors to determine when the material is present outside the
pressure-containing envelope.
Visual detection, cameras, or detectors with marginal coverage.
Type of Isolation System
Isolation or shutdown systems activated directly from process instrumentation or
detectors, with no operator intervention.
Isolation or shutdown systems activated by operators in the control room or other
suitable locations remote from the leak.
Isolation dependent on manually operated valves.
Detection Classification
A
B
C
Isolation Classification
A
B
C
Table 4.6—Adjustments to Release Based on Detection and Isolation Systems
System Classifications
Detection
Isolation
Release Magnitude Adjustment Reduction Factor, fact
di
A A Reduce release rate or mass by 25 % 0.25
A B Reduce release rate or mass by 20 % 0.20
A or B C Reduce release rate or mass by 10 % 0.10
B B Reduce release rate or mass by 15 % 0.15
C C No adjustment to release rate or mass 0.00