The Safety Requirement Specification (SRS) contains the functional and integrity requirements for each Safety Instrumented Function (SIF). The SRS is the main reference document in which the design, installation, validation and operation of the system must follow. To be fully effective the SRS must be clear, concise, complete and consistent.
Before the system goes live the safety system should be validated against the SRS to ensure all requirements are met
The SRS is normally completed in two stages. In the first Stage, the SRS should be completed with all the required information from the HAZOP/HAZID/LOPA. All the required trip points, field devices to be shut down and monitoring devices must be identified. In the second stage the SRS should be updated with any relevant information after commissioning. Any additional hazards that are identified must be reviewed by the HAZOP team.