SIL Determination

Velimor's experienced consultants can lead and facilitate SIL Determination studies, Safety Integrity Level Determination studies, ranging from calibrated Risk Graphs, to semi-quantitative Layers of Protection Analysis (LOPA) and fully-quantitative Fault Tree Analysis (FTA).

A SIL Determination study is required to determine the Safety Integrity Level requirements, SIL requirements, for Safety Instrumented Functions (SIFs). This involves determining the necessary risk reduction required to meet the tolerable risk for specific hazardous scenarios. This typically involves:

• Determining the potential frequency and consequence of a specific hazard;
• Determining the risk reduction provided by other measures and the resulting risk gap;
• Assignment of SIL requirements for SIFs based on any resulting risk gaps in accordance with IEC 61508 and IEC 61511.

Velimor has extensive experience in conducting SIL Determination studies across a variety of industries, such as the process and machinery sector in accordance with their respective standards, IEC 61511 and IEC 62061.

As well as the use of a LOPA as part of a SIL Determination study, other methods such as a calibrated risk graph or FTA can also be used to identify the risk gap and determine the SIL requirements for the SIF under consideration. These methods can be analyzed quantitatively or semi-quantitatively based on the outputs from the HAZOP / PHA study.

As part of the SIL Determination study, Velimor can provide:

• A SIL Determination workshop facilitated by one of Velimor's experienced SIL Determination consultants;
• Use of software package ProSet®, providing a traceable and consistent approach throughout the SIL Determination study;
• Calibration of client specific risk criteria;
• Demonstration of the As Low as Reasonably Practical (ALARP) principle using Cost Benefit Analysis (CBA) where appropriate;
• A record of the SIL Determination study through the production of a subsequent report, providing an overview of the target SIL for the specified SIF under study as well as detailing the study as a whole.

Following on from a SIL Determination study, Velimor can conduct a SIL Verification assessment to verify if the SIFs meets the specified targets, as per the requirements of IEC 61508 and IEC 61511.