Safety Requirements Specification
The Safety Requirements Specification (SRS) is a core document, which is used as the main reference to be followed by designers, installers, and operators of a Safety Instrumented Function (SIF). The SRS details all the crucial functional and integrity requirements for each of the SIFs. Prior to commissioning, the SIF is normally validated against the SRS to ensure that all the stated requirements are met.
- What inputs are required by FSES in order to prepare the Safety Requirements Specification?
As a minimum the following information would be required in order to prepare the SRS:
- Existing PHA / HAZOP report
- Existing SIL Determination Report
- Existing SIL Verification Report
- What is the expected output?
FSES will prepare a SRS document describing the facility along with a description of each of the elements which make up the SRS.
As a minimum, as per IEC 61511 the SRS for each SIF shall include the following:
- SIF Description
- Safe State Definition
- Sources of Demand
- Demand Rates
- SIL Requirement
- Trip Points
- Proof Test Intervals
- SIF Configuration
- Process Safety Time
- Output Actions
- Shutdown requirements
- Spurious Trip Rates
- Failure modes
Presented below is an example SRS sheet for a SIF.