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Designing for safety
Inherent safety, designed in


Complicated configuration of pipes

System safety is the application of engineering and management principles, criteria, and techniques to optimize all aspects of safety within the constraints of operational effectiveness, time, and cost. It is a planned, disciplined and systematic approach to preventing or reducing accidents throughout the lifecycle of a system.

Important principles applied in system safety include inherent safety and defence in depth (use of multiple, independent safety barriers).

This submodule is a part of the hazard analysis module.

Learning objectives

Upon completion of this module, you should be able to:

  • understand inherent safety techniques

  • be able to explain the principle of defence in depth

  • distinguish between passive and active safety mechanisms

Course material

Design for safety

Lecture slides (PDF)

Learn about the principles of safe design, including inherent safety (minimize/substitute/moderate/simplify), defence in depth, safety factors, negative feedback, and design for controllability. Distinguish between passive and active safety mechanisms.

Designing for safety involves the use of:

  • Design principles such as fail-safe design, reduction of the level of coupling between system components, designing for controllability (incremental control, negative feedback mechanisms, simplification), defence in depth, and following the hierarchy of controls.

  • Active protection mechanisms such as safety valves, rupture disks, interlock devices, safety instrumented systems and lock-out/tag-out or LOTO procedures.

Other resources

We recommend the following sources of further information on this topic:

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