290 / 1143
5
Conclusions
Fast developing hazards present a number of challenges throughout the whole Safety
Lifecycle. Several of these can be addressed through strong Functional Safety
management, and through the development of generic documents. At each stage of the
Safety Lifecycle these cases present specific challenges, and a number of different solutions
can be designed. The recommendations of this paper are as follows:
• Develop a RACI Matrix for each and every document in the Safety Lifecycle; this is
especially important where multi-discipline input is required.
• Develop SIL assessment Terms of Reference, with criteria and agreed figures for
parameters including human error rates and ignition probabilities.
• Before SIL assessment ensure that all scenarios are clearly described, especially for
complex scenarios where operator error is the Initiating Event; HAZOP may not fully
provide this.
• Process modelling of overpressures is often needed in advance of the SIL
assessment to avoid over conservative assumptions being made.
• Develop a Process Safety Time Terms Of Reference.
• Develop a SRS template applicable to your applications.
• Verification processes should check that Operating Procedures describe the same
procedure as assumed in SIL assessment.
• For high integrity Inhibit SIFs, consider a hardwired inhibit, or even both a soft and
hard inhibit.
6
References
[1]
HSE Human Factors Briefing Note No. 3
[2]
Swainn & Guttman – Handbook of Human Reliability Analysis with Emphasis on
Nuclear Power Plant Applications
[3]
CCPS Guidelines for Initiating Events and IPLs in LOPA
[4]
OGP Risk Assessment Data Directory – Ignition probabilities (Report 434-6.1 March
2010)
[5]
IP Research Report – Ignition probability review, model development and look-up
correlations
[6]
ISA-TR84.00.004 part 1
[7]
CCPS – Layer Of Protection Analysis
[8]
Trevor Kletz – What Went Wrong?
[9]
Degani and Wiener - Human Factors of Flight-Deck Checklists: The Normal Checklist