SIL Determination

ESC’s experienced consultants can lead and facilitate SIL Determination studies

ESC’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.

ESC 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 analysed quantitatively or semi-quantitatively based on the outputs from the HAZOP / PHA study.

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

  • A SIL Determination workshop facilitated by one of ESC’s experienced SIL Determination consultants;
  • Use of ESC’s internally developed 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, ESC 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.

ESC has chaired and facilitated several LOPAs for the following clients (not exhaustive):

AMPCO, Equatorial Guinea; QAPCO; BG Group; BG Tunisia Gas; British Pipelines Agency (BPA); Clearfleu; Diageo; Dove Energy; Exeter Energy; Reliance Industries,Paraxylene Train 4 Project, Jamnagar Refinery, India: GlaxoSmithKline Pharmaceuticals; Health Protection Agency (HPA); Industrial Chemicals Limited (ICL), Land & Marine; Maersk Oil Kazakhstan, Maersk Oil Qatar, Marathon Oil UK; Merial Animal Health; Shell UK; Perenco; Marathon Oil & LNG Equatorial Guinea; Marathon UK / BP; Occidental Petroleum of Qatar (Oxy); Premier Oil: Queensland Curtis LNG; Salym Petroleum; Saudi Aramco; Scottish & Southern Energy (SSE); Tata Steel UK; Tenghizchervoil; Thames Water; Total UK; Unilever; Woodside Energy / KBR; BP.

For more information, see our ESC client map.

Further Information

Our Functional Safety FAQs are a great place to start if you have any questions.

If you’d like any further information or would like to talk to one of our consultants please Contact Us via our contact form and we’ll be glad to help.