Safety Integrity Level (SIL)

Safety Integrity Level (SIL)

Today, most safety functions are built upon electrical and programmable electronic systems. They are complex and it is not fully possible to determine each error type. The challenge is to design the system in such a way that it prevents serious errors and/or to have them under control. Therefore the standard IEC 61508 is the main standard for SIL, Safety Integrity Level.

The standard IEC 61508 has four levels of safety. These are called safety integrity levels. Safety integrity level 1 (SIL 1) is the lowest level and Safety integrity level 4 (SIL4) is the highest.

The first step in working with SIL is a properly completed hazard analysis to identify the safety functions. The next step is to make a SIL Risk analysis for the identified functions to determine the integrity level for each function. From there you design the system and verify if the integrity level set in the requirement specification, from the hazard analysis, is achieved. When these parts are finished, you can start to build the safety system.

We can help you with the hazard analysis and the SIL Risk analysis.

In certain cases it is a demand that a notified body checks the verification of the safety functions; for instance, if the safety functions protect a pressure vessel that must be inspected by a notified body. Our notified body organization has the skills and tools to provide this service as a part of the inspection.


  • You get a well-functioning security system
  • SIL provides increased availability
  • You reduce the risk of down-time
  • You achieve a better economic situation in your operations

Related services

  • Risk analysis
  • P&ID Review