Safety Integrity Level (SIL) Verification

What is SIL verification?

SIL verification is an important step in evaluating safety systems within hazardous industries to ensure that the appropriate level of safety integrity is achieved. This process includes assessing safety functions, reliability, and performance to determine the SIL rating.

Through verification, it is ensured that systems are designed and implemented correctly, aligning with industry standards and regulatory mandates for safe operations. By conducting SIL verification, organizations can confirm that their safety systems are reliable and effectively mitigate potential risks in hazardous environments.

Example of SIL verification method

There are various methods used in SIL verification. Some of the most common examples would include: 

1. Hazard and Operability (HAZOP) Studies: Involves a systematic examination of a system or process to identify potential hazards and operational deviations. And helps understand how these deviations can lead to hazardous situations. 

2. Safety Integrity Level (SIL) Assessments: Evaluates the safety functions within a system and determine their effectiveness in achieving the desired risk reduction. 

3. Fault Tree Analysis (FTA): It is a graphical method used to analyze and evaluate the various combinations of events or faults that can lead to a system failure. It helps identify the critical events that can cause safety hazards and quantifies their probability of occurrence.

4. Reliability Block Diagrams (RBD): RBD is a graphical representation of a system’s reliability, showing the interconnections between components and their failure probabilities. It helps assess the overall system reliability and identify critical components that may impact safety.

5. Markov Analysis: Markov analysis is a mathematical technique that models the transition probabilities between different states of a system. It helps assess the system’s reliability over time by considering the probabilities of moving from one state to another.

6. Bayesian Networks:  Bayesian networks are probabilistic graphical models that represent the dependencies between variables. They are used to analyze the reliability and safety of systems by considering the uncertainties and conditional probabilities associated with different events.

7. Petri Nets: Petri nets are graphical modeling tools used to analyze and represent the dynamic behavior of systems. They can help evaluate the interactions and dependencies between components, identify potential hazards, and assess the system’s safety.

8. Layer of Protection Analysis (LOPA):  LOPA is a semi-quantitative method that assesses the effectiveness of independent layers of protection in mitigating risks. It helps determine if the existing layers of protection are sufficient or if additional measures are required to achieve the desired safety integrity level.

What does a SIL verification service include?

There are a number of individual services that fall under SIL verification. Here are the most used ones. 

• Safety Instrumented Function (SIF) list Preparation
• SIL Verification in exSILentia software
• PIU Verification
• Input Checklist Preparation
• Logic Solver Checklist Preparation
• Output checklist Preparation
• Review of the Process Hazard Analysis (PHA) Report Preparation
• Review C&E Report Preparation 
• Review Functional Logic Diagram Report Preparation
• Safety Requirements Specification (SRS) Test Report Preparation
• Conducting Quality Checks of All Reports