Defect Found During Pre-Lift Inspection
During your pre-start inspection of a 300 t telescopic crane, you find a 40 mm long, 3 mm deep gouge on the outer section of the main boom, on the compression face, near a weld toe. The crane lifted 60 t yesterday without incident. The boom has been in service for 12 years. The lift planned for today is 45 t at 20 m radius, chart capacity 58 t. The site supervisor says the gouge is 'just paint damage' and the lift is on the critical path. You also notice the last monthly inspection record is missing and the annual certification is dated 13 months ago.
1. How do you classify and respond to the boom damage and the documentation gaps?
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The gouge is on the compression face near a weld toe - a stress concentration and a potential initiation point for cracking under cyclic loading. Depth relative to wall thickness matters, and you do not know the wall thickness; 3 mm could be a significant fraction. It is not paint damage until proven otherwise. The correct response is to stop, tag the crane out of service, and refer the damage to the manufacturer or a competent engineer for assessment against the manufacturer's damage tolerance criteria. Do not grind, fill or paint over it, and do not accept a supervisor's opinion as an engineering assessment.
The documentation gaps compound the problem. A missing monthly inspection record and an annual certification 13 months old mean you cannot demonstrate the crane is in a verified safe condition. Both must be resolved before the crane returns to service. The fact that it lifted 60 t yesterday is irrelevant - damage accumulates and yesterday's success is not evidence of today's fitness.
2. The supervisor asks whether the lift can proceed at reduced capacity to 'stay inside the damage'. How do you answer, and what is the return-to-service path?
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No. A capacity reduction does not address a possible crack initiation site, and no one on site has the data to say what reduction would be safe. The crane stays out of service until the damage is assessed. Return-to-service path: obtain the manufacturer's or engineer's written assessment, which may require non-destructive testing (magnetic particle or ultrasonic) around the gouge and weld toe, and may specify repair, blending or continued service limits. Complete the missing monthly inspection and current annual certification by a competent person. Record the defect, the assessment and the repair in the crane's log. Only then re-plan the lift and re-verify the chart for the confirmed configuration. Communicate the delay to the lift planner so the critical path is managed, not bypassed.