Most formally educated or well-trained safety professionals are familiar with the Hierarchy of Controls. We use this approach daily in our work to reduce the likelihood of an event and/or the event’s severity. Mr. Kletz always had a different take on using this philosophy in process safety and as always – he nailed it!
INTENSIFICATION: Use so little hazardous material that it does not matter if it all leaks out. “What you don’t have, can’t leak.”
SUBSTITUTION: Use a less hazardous material – less flammable or less toxic.
ATTENUATION: If a hazardous material must be used, use it
- under less hazardous conditions or
- in the least hazardous form
LIMITATION OF EFFECTS: Limit the effects of failures by changing the design or conditions of use rather than by adding protective equipment that may fail or be neglected.
- Use a safer material instead (substitution). Use hazardous materials in the least hazardous form (attenuation).
- Simplify the design. Complexity means more opportunities for human error and more equipment that can fail.
- Limit effects, not by adding on protective equipment but by equipment design, by changing reaction conditions, by limiting the energy available or by eliminating hazardous phases, equipment or operations.
- Avoid knock-on or domino effects.
- Make incorrect assembly impossible.
- Make the equipment status (open or closed, on-line or off-line) clear.
- Use equipment that can tolerate poor operation or maintenance.
Source/Credit: An engineer’s view of human error, Trevor Kletz