3411 Guidance on safety integrity level determination for safety instrumented systems in support of IEC 61511

Overview:

Most process plants are controlled by complex process control systems; there is increasing dependence on safety instrumented systems (SISs) to carry out safety instrumented functions (SIFs).This technical publication focuses on quantitative and semi quantitative safety integrity level (SIL) determination techniques and supports practical application of the following clauses of IEC standard 61511-1:

• clause 8 Process H&RA, and
• clause 9 Allocation of safety functions to protection layers.

It does so by providing guidance on:

• SIL determination of SIFs associated with SISs within the scope of IEC 61511.
• Identifying the SIFs to be carried out by one or more SISs.
• Illustrating several SIL determination methods available for ensuring that an appropriate SIL is selected for each SIF.
• The team-based workshop methodology.

It is intended for application to onshore and offshore process plants and projects worldwide.