Tank Entry Supervision: Roles, Permits, and Attendant Duties
The supervisor's job in one sentence
A tank entry supervisor exists to make sure no one enters a permit-required confined space until the hazards are identified, controlled, and continuously watched - and to stop the job the moment those conditions break down.
Concepts you must know
- Permit-required confined space (PRCS): a space large enough to enter, with limited entry/egress, not designed for continuous occupancy, and containing (or potentially containing) a hazardous atmosphere, engulfment, entrapment, or other serious hazard. A tank that has held hydrocarbons is almost always a PRCS.
- The entry permit: issued before entry, posted at the entry point, and cancelled when the job ends or conditions change. It records atmospheric readings, isolation methods, attendants, and rescue provisions.
- Attendant (hole watch): stays outside, maintains an accurate count of entrants, monitors conditions, orders evacuation on alarm or change, and never leaves the post or enters the space to attempt rescue.
- Entry supervisor: verifies permit conditions, confirms tests and isolation, terminates entry when required, and closes out the permit.
- Rescue: a trained rescue service must be available; non-entry retrieval (tripod/winch) is preferred.
Traps to watch for
Questions love the "helpful attendant." The correct answer is almost always that the attendant does not enter, calls for rescue, and keeps the count. Another trap: treating a permit as valid indefinitely - it is not. Also watch for "test once at the start" - testing must be continuous for flammable/oxygen/toxic hazards in tanks.
Rule of thumb
No permit, no attendant, no rescue plan, no continuous monitoring = no entry. Any one missing ends the job.
Worked example
A reading shows 19.5% oxygen and 0% LEL, and the crew wants to skip the attendant because "it's clean." Correct call: the attendant is still mandatory - the space remains a PRCS by configuration, and conditions can change.