Two widely used methods in the O&G industry for SIL determination are Layer of Protection Analysis (LOPA) and Risk Graphs. Each of these methods has their own advantages and disadvantages. LOPA allows the required risk reduction to be incorporated into the SIL values with higher precision.

AIE has adopted a structured approach to execute SIL assessment by using the Risk Graph/ Layer of Protection Assessment (LOPA) methods in accordance with IEC-61508 & IEC-61511 standards.

Risk graphs combine the effective consequence with the effective frequency of the hazardous event to determine a SIL that will reduce the risk to a tolerable level (see Figure 1).

The safety integrity levels risk graph (sometimes called a SIL Tree) method is a common tool used in determining the safety integrity level rating of a sub-system. A SIL tree is shown below: Definitions of terms used on the SIL Tree table:

alitative methods for determining the SIL. Annex D outlines the risk graph method, and Annex E describe. a hazardous event severity matrix method. It should be noted that the PFDavg and the corresponding SIL must be computed for all safety functions requ.

Explore methods for determining the appropriate Safety Integrity Level (SIL) for safety instrumented functions (SIFs) in industrial processes. Going deep into the structured approaches such as Risk Graphs, LOPA, and FTA, providing insights into their methodologies.

This paper summarises the principles, content and experience of implementing a procedure for the first 5 steps of the safety life cycle in IEC 61508 that has been developed by AK EHS & Risk in association with its clients. The principles used in the procedure for calibration of …

The definition of target SIL for safety functions (SIFs) is an important step in the Safety Life Cycle as per IEC 61511. There are a number of methods to define SIL, ranging from qualitative (Risk-Matrix), semi-qualitative (calibrated Risk Graph), semi-quantitative (LOPA), to quantitative (QRA).

May 1, 2016 · Two widely used methods in the Oil & Gas industry for SIL determination are Layer of Protection Analysis (LOPA) and Risk Graphs. Each of these methods has their own advantages and disadvantages. LOPA allows the required risk reduction to be incorporated into the SIL values with higher precision.

Risk matrices and risk graphs are used to assess the tolerability of the risk of individual hazard scenarios. They suffer from similar difficulties: Use with hazardous events is difficult. SIFs protect against specific hazardous events and the IEC 61511 / ISA 84 standard describes the determination of SILs with reference to hazardous events.