Professional Practice and Safety
This domain tests applied process-safety practice: hazard identification, risk ranking, permit and isolation discipline, and the specific hazards of hot metal, dust and electrical work.
Core rules
- Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, then PPE. PPE is the last line and never the primary control.
- Risk = severity × likelihood, usually on a 5 × 5 matrix. Controls are selected to reduce the score, and residual risk is re-scored and accepted formally.
- HAZOP uses guide words (no, more, less, as well as, part of, reverse, other than) applied to nodes and process parameters to generate deviations and their consequences.
- Permit-to-work and lock-out/tag-out: isolate, de-energise, verify zero energy, lock, tag, then work. Try-out verification is mandatory before entry or maintenance.
- Confined-space entry requires atmospheric testing for oxygen, flammables and toxics, forced ventilation, a standby person and a rescue plan.
- Molten metal and water are a violent combination: water on the furnace floor, damp scrap or wet moulds cause steam explosions. Dust clouds of aluminium, magnesium or coal can deflagrate. SDS and dust-hazard classification drive controls.
Worked example
A task is scored severity 4 and likelihood 4 = 16, high risk. Adding an engineering control (a fixed guard and interlock plus a written procedure) lowers likelihood to 2, giving 4 × 2 = 8, medium risk, which is accepted with a review date. Removing PPE alone would not have changed the score legitimately.
Traps that cost marks
Listing PPE first. Treating a low-probability catastrophic event as low risk. Assuming a lock is effective without a try-out. Using HAZOP for a simple task where a job safety analysis is appropriate.