A verbal permit extension at shift change
A confined space entry is under way in a 6 m deep, 2 m diameter surge chamber at a water treatment works. The permit issued at 06:30 states entry authorised 07:00–13:00, gas test valid for two hours, maximum two entrants, one attendant at the top, rescue by tripod and harness, no breathing apparatus entry. At 12:25 the crew is 80% through removing a build-up of grit and the supervisor radios the permit issuer to extend to 15:30 because the day shift ends at 13:00 and the vessel has been stable all morning. The morning readings were oxygen 20.7%, LEL 0% and H2S 0 ppm. The permit issuer is off-site at another plant but replies over the radio that it can be considered extended and he will sign it when he gets back. The day-shift gas tester is due to hand over to a night-shift tester at 13:00, who on arrival notices that the rescue plan names a standby man who has gone home sick and that the tripod winch cable has a kink.
1. Can the permit be extended in this way? Justify your answer and state what a valid extension requires.
Read the worked answer
No. An extension is a re-issue, and a re-issue needs what the original needed.
- The gas test has lapsed. The permit makes a test valid for two hours; the last quoted set is from the morning. Conditions in a surge chamber change with flow, with the works upstream, and with the work itself. Grit removal disturbs deposits and can release hydrogen sulphide and methane from the sediment.
- The authorisation must come from the permit issuer against current conditions, either at the workplace or under whatever the site's written procedure permits - some sites allow a documented gas test by a competent tester plus a signature on return, but a radio aside is not that. A verbal extension leaves no signed record of who authorised what, for which period, on what evidence.
- The change is material. The entry period moves into the night shift, the entrants and attendant change, and the remaining 20% of the work is the part with the most disturbance. That deserves a risk assessment for the remaining work, not an extrapolation from the morning.
- The practical route: stop at 13:00, withdraw and secure the cover, take a fresh set of readings at all required levels, have the night-shift tester do the tests, and have the permit issuer or a formally delegated deputy sign a new permit with new names and a new period. If that cannot be arranged, the job waits.
Verbal extensions are one of the most common ways a permit system fails in practice, because nobody can later show what was decided, when, or on what evidence.
2. What must the incoming night-shift gas tester do at handover, and what should be recorded?
Read the worked answer
The incoming tester owns the next entry decision and cannot inherit the previous one.
- Read the permit, then verify it against the site: current period, names of authorised entrants and attendant, isolation list, gas test interval, rescue arrangements.
- Do his own gas test with his own bumped and calibrated instrument, at every level the permit requires, before anyone re-enters. Previous readings are information, not evidence; an atmosphere twelve hours old, or two hours old, is history.
- Walk the job: cover, access, ladder, tripod, harness, communications, barriers, ventilation, ignition sources. Physically inspect the rescue equipment rather than reading that it is in place.
- Verify emergency arrangements: the named standby and rescue people are present and trained, the means of summoning help works, and the access route is clear for a stretcher or ambulance.
- Cross-brief the entrants and attendant: what is done, what remains, what has changed, the alarm and evacuation signal.
- Record: the handover entry in the log, the gas test values with times and instrument serial, the names of everyone on site, the permit number and period, and any suspension or refusal with the reason.
If any element cannot be verified, the tester does not sign. In this scenario the night-shift tester should be refusing to inherit the extension, not accepting it.
3. The rescue plan names an absent standby man and the winch cable is kinked. What is the correct response, and where does the gas tester's role stop?
Read the worked answer
The entry cannot continue as planned.
- A rescue plan naming an absent person is not a rescue plan. It is a document that creates false confidence. The standby is the difference between a thirty-second recovery and a fatality, and an untrained bystander cannot be substituted at the last minute.
- A kinked winch cable compromises the primary non-entry rescue method. In a 6 m chamber, tripod and harness retrieval is what the attendant relies on; a winch that jams halfway leaves the entrant suspended and the attendant with no options.
- Correct response: stop the work and withdraw the entrants. If the atmosphere is currently sound they are not in immediate danger, but the situation must be regularised before work resumes. Replace or repair the winch and have it inspected, appoint a trained standby who is briefed and present, and confirm how the emergency services are called and how long they will take to reach a 6 m chamber. Then re-test and re-authorise.
- The tester's role stops at the entry point. He verifies and authorises the atmosphere and the entry conditions; he is not the rescuer, must not enter to attempt a rescue without breathing apparatus and training, and should not be used as the standby. Rescue from a 6 m chamber by BA team is a different capability from the one on site at 12:25.
- Record the suspension, the reasons, and the corrective actions before any new permit is issued.
If the standby cannot be replaced and the winch cannot be made good this shift, the correct answer is that the job stops, regardless of the 80% already completed.