The first day of training was quite boring. Yawn. I hope it’ll have more interactive stuff tomorrow.

But in the end, I’m glad to be part of this Safety Integrity Level (SIL) selection and verification training. At least I would be able to tell if a system is intact or underrated.


Risk graph method, a small part in the overall IEC 61508 and 61511.

The whole thing is more or less FUNCTIONAL SAFETY ENGINEERING. What is the acceptable level of plant design? How do you ensure the design does not let undetected failures cause injuries or worse, fatalities?

In laymen terms, SIL basically classifies your plant by its probability to detect dangerous failures that might lead to injuries, fatalities or a catastrophic disaster.

SIL1 your plan could fail to detect danger once in 10 times to 100 times. (0.1% to 0.01% fail on demand)

SIL2 your plan could fail to detect danger once in 100 to 1000 times (0.01% to 0.001% fail on demand)

If you know a plant that is SIL-3 certified (by appropriate authorities, with proofs of documentation & track records), feel free to roam around the plant. It’s fairly safe.