Prepare for a functional safety assessment.
From the SIS scope on the P&ID to the documents your functional safety assessor reviews
What this covers.
Preparing for a functional safety assessment, under IEC 61511 and ISA 84, means assembling every record the assessor reviews. The SIF list, every safety instrumented function on the facility, the SIL determination, target SIL per SIF, typically from LOPA, the SIL verification, achieved SIL per SIF from the actual sensor, logic-solver, final-element architecture, the SIS scope on the P&ID with voting architecture preserved, the cause-and-effect matrix, the SIS proof-test schedule, and the SIS impairment history. Your team assembles that set, and the assessment itself stays with your engineers and your assessor.
By Tagsight Team·Published Aug 6, 2026
Inputs.
- P&ID set, for SIS scope extraction
- HAZOP study, for SIF identification scope
- LOPA worksheets, for SIL target per SIF
- SIL verification calculation report, from exida exSILentia, SIS-PRO, or equivalent
- SRS, Safety Requirements Specification
- Cause-and-effect matrix
- FAT and SAT records
Outputs.
- SIF list with target SIL, achieved SIL, voting architecture per SIF
- P&ID SIS subset, the safety instruments on the drawings
- Cause-and-effect matrix in structured form
- Voting architecture per SIF preserved as drawn
- Cross-walk between SIF list, SIL verification, P&ID SIS subset, and cause-and-effect matrix
- PDF binder plus Excel workbook plus JSON for the functional safety assessment
IEC 61511 SIL evidence by lifecycle stage
| Lifecycle stage | Evidence required | Source artifact |
|---|---|---|
| Hazard and risk assessment | SIF list with hazardous event scope | HAZOP plus LOPA outputs |
| Allocation to protection layers | Risk reduction target per SIF | LOPA scenario set |
| Safety requirements specification | Safety Requirements Specification per SIF | SRS document, P&ID references |
| SIS design and engineering | Sensor plus logic solver plus final element per SIF | P&ID set, voting as drawn |
| SIL verification | PFDavg plus RRF per SIF, voting included | SIL verification calculation |
| SIS safety validation | Validation test records per SIF | FAT, SAT and commissioning records |
| Operation and maintenance | Per-SIF proof-test interval plus history | Operations records |
The procedure.
- 01Extract SIS scope from the P&IDTake the SIS instruments from the registers and confirm them against the safety requirements specification. Voting architecture printed on the drawing is carried per SIF.
- 02Cross-walk with the SIF listTie every SIF on the SIF list to its SIS instruments on the P&ID. An SIS instrument tied to no SIF is scope drift to resolve before the assessment.
- 03Bring in the SIL verificationPer-SIF target SIL, achieved SIL, PFDavg, RRF, voting architecture and proof-test interval come from the verification report your SIL calculation tool produced (exida exSILentia, SIS-PRO, Sphera). They are carried as calculated, never recalculated.
- 04Reconcile with the cause-and-effect matrixTie every SIF action on the cause-and-effect matrix to its SIL-verified SIF. A cause-and-effect row with no matching SIF is a gap to close.
- 05Assemble the SRS evidencePer-SIF SRS sections cross-reference to the P&ID page, the SIL verification row, and the cause-and-effect matrix entry. That is the traceability the assessor follows.
- 06Issue the assessment documentsYour team issues the PDF binder, Excel workbook and JSON, and the functional safety assessor reviews that same set.
Common questions
Does this produce the SIL determination.
No. The SIL determination is the LOPA output that sets the target SIL per SIF. The SIL determination calculation stays in your validated process-safety package. The documents your team assembles carry the determination as an input, not as an output.
Is Tagsight certified for functional safety use.
No. Tagsight is not certified, validated or qualified for use in functional safety applications under IEC 61508, ISA 84.00.01 / IEC 61511 or comparable standards. The registers it gives your team are drafts for your own review. The SIL determination, the SIL verification and the assessment stay with your validated tools, your engineers and your assessor.
Are exida exSILentia, SIS-PRO, and Sphera SafeTech calculation reports supported.
Yes. All three calculation tools produce SIL verification reports that can be brought into the workspace alongside the drawings.
Related.
Upload a drawing.
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