It is a distinct engineering discipline from general EHS work.

What functional safety means

A system may rely on an automatic safety function to detect a hazardous condition and move the equipment or process toward a safer state.

Functional safety asks whether that function is:

  • correctly specified;
  • appropriately designed;
  • independently verified;
  • validated;
  • maintained through its lifecycle.

Safety lifecycle

IEC's overview of IEC 61508 describes an overall safety lifecycle covering stages such as concept, specification, design, installation/commissioning, operation/maintenance, modification and validation.

The lifecycle perspective is central: safety is not proven by one test at the end.

Hazard and risk connection

Functional-safety work begins with understanding hazardous scenarios.

The engineer needs to know:

  • what can go wrong;
  • consequence;
  • required risk reduction;
  • which safeguards are independent;
  • what the safety function must achieve.

SIL concepts

Safety Integrity Levels are used in relevant standards to express required integrity of safety functions.

SIL selection and verification are specialist activities. Do not infer a SIL from intuition or a generic risk matrix.

Requirements and verification

Strong functional-safety work emphasizes clear requirements.

A safety requirement may define:

  • triggering condition;
  • response;
  • timing;
  • safe state;
  • integrity;
  • diagnostics;
  • test needs.

Verification checks whether lifecycle work meets specified requirements.

Validation checks that implemented safety functions meet the intended safety needs.

Industrial and automotive contexts

Functional safety appears in:

  • process industries;
  • machinery;
  • industrial automation;
  • automotive;
  • rail;
  • other safety-related control systems.

Sector standards differ.

Standards landscape

IEC 61508 is a foundational functional-safety standard. Sector standards build on or adapt similar lifecycle principles.

Use the applicable standard for the product/industry.

Skills and career path

Useful foundations include:

  • systems engineering;
  • controls/electronics;
  • hazard analysis;
  • requirements;
  • verification/validation;
  • reliability;
  • configuration/change control.

Possible backgrounds:

  • electrical/control engineering;
  • automotive electronics;
  • process control;
  • systems engineering;
  • safety engineering with strong technical depth.

Functional safety is not simply “safety plus PLC.” It is rigorous lifecycle engineering of safety-related functions.

Related content

Sources