The IEC 61511 prescribes that various Functional Safety Assessments (FSA) must be held at specific moments within a functional safety project. In the SIS safety life cycle as shown below, 5 different stages are named.
- Stage 1 – After the H&RA has been carried out, the required protection layers have been identified and the SRS has been developed.
- Stage 2 – After the SIS has been designed.
- Stage 3 – After the installation, pre-commissioning and final validation of the SIS has been completed and operation and maintenance procedures have been developed.
- Stage 4 – After gaining experience in operating and maintenance.
- Stage 5 – After modification and prior to decommissioning of a SIS.
It is important here that the FSA is carried out by an (sufficiently) independent and competent team. The IEC 61511 states about this:
188.8.131.52.2 The membership of the FSA team shall include at least one senior competent person not involved in the project design team (for stages 1, 2 and 3) or not involved in the operation and maintenance of the SIS (for stages 4 and 5).
The ultimate goal is to check whether all relevant steps from the SIS safety life cycle have been completed before introducing hazards to the installation.
184.108.40.206.5 Prior to the hazards being present the FSA team shall undertake functional safety assessment(s) and shall confirm:
• the H&RA has been carried out;
• the recommendations arising from the H&RA that apply to the SIS have been implemented or resolved;
• project design change procedures are in place and have been properly implemented;
• the recommendations arising from any FSA have been resolved;
• the SIS is designed, constructed and installed in accordance with the SRS, any differences having been identified and resolved;
• the safety, operating, maintenance and emergency procedures pertaining to the SIS are in place;
• the SIS validation planning is appropriate and the validation activities have been completed;
• the employee training has been completed and appropriate information about the SIS has been provided to the maintenance and operating personnel;
• plans or strategies for implementing further FSAs are in place.
Consiltant BV has experience in performing Functional Safety Assessments. For more information, please contact us.