Definition:
Target SIL (or Target Safety Integrity Level) is the required SIL determined during the SIL allocation process. This is typically done via a LOPA or could be with a risk graph and a few other things.
Target SIL is the required level of risk reduction (SIL 1, 2, 3, or 4) identified during analysis, before design or implementation of the SIF. The design and validation teams must then verify that the SIF, as built and configured, meets or exceeds that target.
Key Points:
- Guides design and verification efforts.
- Based on the risk reduction needed to meet tolerable risk.
- The achieved SIL in the design must meet or exceed the target SIL.
Example:
A HAZOP/LOPA determined that a SIF requires a Target SIL of 2 to reduce the explosion risk to achieve company (or regulatory) levels. The design team then creates a solution to meet or exceed SIL 2.
Cited Source:
- IEC 61511-1:2016, Clause 9.2.