A Functional Safety Assessment (FSA) is an external audit done to determine how well you have your affairs in order with regard to compliance with the IEC 61511 directive. The Functional Safety Assessment must be carried out at various stages of the lifecycle:

FSA Stage 1 – After the HAZOP has been carried out and the SRS is ready

FSA Stage 2 – After the SIS has been designed

FSA Stage 3 – After the installation of the SIS is complete and tested prior to commissioning

FSA Stage 4 – After experience has been gained during operation and maintenance

FSA Stage 5 – After a change to the SIS and before a SIS is permanently withdrawn from service

The IEC 61511 ed.2 “SIS safety life-cycle phases and Functional Safety Assessment stages” is shown in Figure 1 below.

Figure 1: SIS safety life-cycle stages and FSA stages

According to the directive, stages 3 and 5 are compulsory, but often the other stages are included. A combined FSA Stage 1-3 is often carried out prior to commissioning.

The Functional Safety Assessment is carried out on the basis of a checklist.

Before starting a Functional Safety Assessment, the customer must provide documentation (or alternatives) for General Functional Safety Management – Hardware design documents and Software design documents.

The checklist is a translation of standard IEC 61511. The checklist refers to the paragraphs in the standard. The checklist lists items per FSA Stage that are checked to see if the customer/project complies with them. A total of 300 items are checked. Respectively per FSA Stage 1-5: 84, 81, 51, 58 and 26 items.

The outcome of the various items may be:

Compliant

Not Compliant

Partial Compliant

If an item is not relevant to the project it is classified as Not Considered.

Functional Safety Assessment

After the Functional Safety Assessment, a report is issued for the Not Compliance and Partial Compliance items with a recommendation with a Due Date. For the items classified as “Not Compliant”, it is recommended that they are resolved before the start-up or that a Risk Assessment is performed to determine whether a safe start-up can be performed.

For an item classified as Compliant, a recommendation/remark for future improvement may be proposed. The completed checklist is an appendix to the Functional Safety Assessment (FSA) report.

The FSA report contains the following information:

• Summary

• Introduction

• Purpose of the document

• Purpose of the assessment

• Attendees and roles

• Method of the Functional Safety Assessment (FSA)

• References

• Definitions

• Abbreviations

• Results of the assessment

• Summary of results

• Recommendations for “Not compliant requirements

• Recommendations for Partial Compliance Requirements

• Recommendation/remark for future improvement

• Conclusion

• Attachments

• FSA verification checklist