Welded Mast Tie Repair and the Missing Re-examination
At a 28-storey residential project in Kowloon Bay, a builder's lift mast tie bracket at 14/F was found with a 40 mm crack in its weld. The site maintenance team cut out the cracked weld and welded on a 10 mm reinforcing plate overnight. At 07:30 the next morning the site agent tells the hoist operator, Mr Chan, to resume lifting because 'the engineer looked at it and it is fine'. The hoist's last certificate of test and thorough examination was issued five months earlier, and the repair has not been entered in the log book. Mr Chan's operator certificate is valid. The agent says the concrete gang will lose half a day if the hoist is not running by 08:00. There is no written repair method statement on site and the welder used a site arc welder.
1. Identify the statutory and safety issues Mr Chan must resolve before he operates the hoist, and explain how each affects his decision.
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The central issue is that the hoist has been structurally altered since its last statutory examination. A mast tie bracket carries mast loads; cutting out a weld and adding a reinforcing plate is not routine maintenance. It changes the load path and may affect the strength of the tie, the mast tube and the galvanic protection. The existing certificate of test and thorough examination describes the hoist before that repair, so it cannot be relied on as evidence that the hoist is now safe. Under the Factories and Industrial Undertakings Ordinance and the builder's lift regulations, a builder's lift must be tested and thoroughly examined by a competent examiner before use after substantial repair or alteration. A verbal assurance from an agent is not a substitute. Second, there is no repair method statement, no design check and no welding procedure; a site arc welder may not be qualified for structural welding on the mast. Third, the repair is not in the log book, so the hoist's history is incomplete. Mr Chan's own operator certificate does not authorise him to accept structural repairs. His duty is therefore to keep the hoist out of service until the repair is properly designed, inspected and examined.
2. What documents and approvals should exist before the hoist is returned to service, and who should provide them?
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Return to service should be evidence-based, not opinion-based. The site should first have a written repair method statement and a design check for the reinforcing plate, prepared or accepted by a suitably qualified structural engineer. The welder should be qualified for the welding process used, and the completed weld should be inspected, with non-destructive testing where the engineer specifies it. The repair should then be recorded in the hoist log book with the date, nature of repair, parts used and the names of the persons responsible. Most importantly, a competent examiner should carry out a test and thorough examination after the repair and issue a certificate covering the hoist in its repaired condition. The operator should see that certificate, not a copy of the old one. The site agent, principal contractor or plant owner should provide these documents; the operator should not be asked to judge the adequacy of the weld. If the repair is treated as a temporary measure, the examiner should state any restriction, and the hoist should not be used outside that restriction.
3. If the agent insists on running the hoist, outline what Mr Chan should do and what he should record.
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Mr Chan should refuse to operate and make the refusal practical rather than argumentative. He should switch off and isolate the hoist, apply his personal lock or a site lockout tag, and place a conspicuous 'Do Not Operate' notice on the cage control and at the ground landing. He should tell the agent clearly that the hoist will not be run until the post-repair certificate is available. He should then notify his employer and the site safety officer in writing, not only by phone. The record should include the time, the defect found, the repair he was told about, the names of the persons who gave the instruction, the fact that no method statement or certificate was produced, and the action he took. Photographs of the bracket and the isolation tag are useful. If pressure continues, he should escalate to the principal contractor's representative or the safety department, and he may report the matter to the Labour Department if there is a real prospect of the hoist being used without the required examination. The aim is to leave a clear audit trail that protects workers and shows that the operator exercised his duty.