LOPA (Layer of Protection Analysis) is a semi-quantitative methodology used to assess the adequacy of safeguards. ( i.e. have you done enough to address the hazard?)

LOPA is particularly useful for analysis of scenarios of concern identified in the HAZOP.

SIL (Safety Integrity Level) is the degree of confidence in a given safeguard. This applies only to Safety Instrumented Functions (SIFs) and a SIL allocation for SIFs is a requirement of EN 61511.

Per EN 61511, a SIL assessment should be carried out for all Safety Instrumented Functions i.e. instrumented loops called up as safeguards or as recommendations in the HAZOP or similar exercise.

LOPA is just one way of carrying out a SIL assessment.

At Fleming Professional, we minimise under and over-specification and we ensure that the key risks of the process are addressed.

• Certified Functional Safety Expert (CFSE) qualified chairperson (www.cfse.org)
• Management of information flow from HAZOP through SIL assessment
• Effective SIL allocation and avoidance of under and overspecification
• Software packages for LOPA & SIL – PHA Pro, PHA Works and HAZOP Manager®
• Database of standard LOPA and SIL assessment values derived from literature and recognised sources
• Use of Irish HSA and UK HSE derived risk targets to ensure consistency with HAZOP and avoid under and overspecification

See our sample projects here