The main objective of a functional safety assessment (FSA) is to demonstrate compliance with related IEC functional safety standards through an independent assessment of the development process. Hence, the FSA process is a fundamental tool to ensure that the Safety Instrumented System (SIS) fulfills its requirements as an active barrier to reduce the risk to acceptable levels. At least one FSA is typically required during a project phase. Nevertheless, it is highly recommended to perform at least 2 FSAs in order to anticipate potential non-conformances in due time.
The FSA team shall have some degree of independence to the project team. The degree of independence is dependent on the safety integrity level (SIL) of the functions being engineered. It is, however, normal to select external companies, such as ourselves, to perform FSAs due to specific expertise in this field combined with total independence.
An FSA stage 3 is performed prior to the start-up of operations. It shall cover the whole process with more or less detail depending if previous FSAs were performed. In this case, an FSA 1 had been performed so the focus was on FSA 2 and FSA 3 SIS lifecycle phases. Namely design and engineering phase and mostly on operation readiness of the SIS.
Generally, installation, commissioning and validation of the SIS appeared to be properly planned during the FSA. The signed commissioning procedures and commissioning preparation check records confirmed that the SIS was installed and commissioned in accordance with these procedures. The day-to-day operations of the SIS, including testing and maintenance, is to be handled by the existing team and within the existing systems. Hence, the modification would not, in itself, introduce any changes towards how the SIS is operated, tested and maintained. Minor findings, recommendations and lessons learned were the outcomes of this assessment. No major findings, that could potentially lead to operational delays, were identified.