Safety in Design, Operations, and Maintenance
This domain examines whether you can carry the safety hierarchy into design and then preserve protective measures through operations, maintenance, and change. Questions often present a real task or a temporary configuration and ask for the controlling safeguard.
Design controls
Inherent safety comes first: minimize inventory, substitute less hazardous material, simplify, and separate incompatible operations. Engineered controls include safety factors, fail-safe behavior, redundancy, segregation, interlocks, and relief systems. Human factors, maintainability, and accessibility should be designed in so that safe work is also practical work.
Operations and maintenance
Lockout/tagout requires energy isolation, verification of zero energy, and control of stored energy. Permit-to-work systems coordinate hot work, confined space, and simultaneous operations. Management of change must cover temporary and permanent changes, including interlock bypasses, software changes, and substitute materials. Pre-startup safety reviews confirm that controls are in place before introducing hazardous materials. Configuration control and inspection programs address aging and degradation.
Worked example
A pump must be maintained while the line remains connected. The correct sequence is to isolate all energy sources, apply locks and tags, verify zero energy by attempting start and testing for residual pressure, and control any stored energy. If a bypass is needed for troubleshooting, use a documented bypass permit with compensating controls, a time limit, and verification that the bypass is restored. Reasoning: a bypass is a temporary change, not a normal operating mode, and restoration must be proven.
Traps that cost marks
- Relying on warnings or training as the primary control for a significant hazard.
- Leaving an interlock bypassed after the task ends.
- Skipping management of change for a “minor” modification.
- Applying lockout without verifying zero energy.