Five SIL tasks for each safety life cycle phase

2021-05-05

SIL LIFE CYCLE

We perform our work according to a safety life cycle in the functional safety world. Typical functional safety standards, like IEC 61508, IEC 61511, and so on, include safety life cycles, but they are usually impractical. The IEC 61508 standard even has three lifecycles. One for the end user, one for the hardware of the safety system and one for the software of the safety system.

There are easily five parties involved when dealing with safety systems. There is the end user, the engineering partner, the system integrator, the product manufacturer, and any third party or government. Each party has their own lifecycle to follow. In practice, they do not look the same. The end user has a different lifecycle compared to the product manufacturer. This makes sense as they do different work concerning the safety system.

FIVE SIL TASKS FOR EACH LIFE CYCLE PHASE

Besides the actual work that needs to be carried out for each safety life cycle phase, there are several other tasks involved that need to be performed for each lifecycle phase besides the work that needs to be carried out in that phase. For each phase:

1. The work needs to be performed;
   
2. The work needs to be managed;
   
3. The work needs to be documented;
   
4. The work needs to be verified; and
   
5. The work needs to be assessed.
   

Functional safety management makes sure that the right people do the right work at the right time with the right tools, procedures, guidelines etc. Functional safety assessment makes sure that really the right people did the right job at the right time with the right tools, procedures, guidelines, etc.