SIL Workshops, SIL Verification & Validations
Process facilities are highly susceptible to risks such as leaks and Loss of Containment (LOC) leading to fire explosion, injuries and multiple fatalities etc. which could also cause environmental damage and financial losses. Hence ensuring the integrity of process systems is very important for the safe operation of process industries. Process safety systems are usually designed with various layer of protection and Safety Instrumented System (SIS) is one of the most important layers of protection against occurrence of accidents and hazards. In the process safety design, this activity is referred to as SIL Determination or SIL Assessment because the performance requirements of a safety function are expressed as a Safety Integrity Level (SIL) as per the requirements of IEC 61508 / IEC 61511.
The Layer of Protection Analysis (LOPA) study is one of most consistent widely used approaches to Safety Integrity Level (SIL) Assessment. Independent Protection Layers are identified that may provide risk reduction and can accurately define the performance requirements of the Safety Instrumented Function. LOPA is a quantitative risk assessment method providing a Target Probability of Failure on Demand (PFD), which is associated with the Integrity Level requirements (SIL) as per IEC 61511.
SIL Verification & Validations
Process Safety Management, for any process plant is about managing risks throughout the SIS Safety Lifecycle Process. The below sketch shows the SIS Safety Lifecycle process that is based on IEC 61511 approach for Safety Instrumented Systems in Process Applications usually found in Oil and Gas plants, Chemicals and Pharmaceutical plants.
SIL identification and SIL verification studies are carried out normally during detailed design engineering for any project. Whereas SIL validation is carried out at site after erection of all components of the SIL certified loop.
During the SIL validation stage, the SIS validated that, the systems are procured as per the safety requirement specifications, safe installation and commissioning and proof test interval for each element of SIF loop is defined.
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