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© ABB
Slide 8
October 24, 2016
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Safety Requirement Specification
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Critical document, but who owns it?
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See C&E is not enough
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Critical and Non Essential Actions
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Bypass Requirements
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Should the SIF be bypassed?
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What are the temporary mitigation
measures
Example 2
Over-engineered, unmaintainable SIS
Original
Downgraded Upgraded
SIL 1
402
83
4
SIL 2
161
9
Proof
Tests
1795 /
year
367 / year
f
1795 /