80-81 / 975
Hybrid applications of IEC61511 – Laurie Blackmore
§
For a typical offshore production facility with separation, gas compression, injection etc.
there might typically be 300 to 400 SIS “trips” based on API leading to a SIS with
maybe 1000 I/O
§
When an IEC61511 SIL analysis is carried out there may be as few as 40 safety
instrumented functions (SIF) rated at SIL1 or above for personnel safety or
environment leading to a SIS with maybe 100 I/O
§
This leads to simpler SIS directed at the high risk functions, with less exposure to
systematic failures and more focused testing
§
There is a big difference here so a hybrid contract needs clear definition
7
API SIS compared to IEC61511 SIS