An incident occurred during the loading of a plate girder (weight approximately 12 tonnes) onto a cargo barge. As the girder was being lowered two out of the four certified Green Pin Plate Clamps, type 6.0 EH, parted causing the plate girder to drop onto the deck.
No-one was injured and no further damage was sustained at the time of the incident. However, since certified lifting gear parted during apparently normal operations, an investigation was carried out into the nature and cause of the fracture of the lifting clamps.
The investigation concluded that the basic cause of the fractured Green Pin Plate Clamp was a brittle fracture initiated by micro-cracks in combination with a fragile design.
The contractor involved proposes to initiate the following actions:
- Check the Safe Working Load for each single Green Pin Plate Clamp against the original certifications and Vendor’s documentation.
- Dismantle the Green Pin Plate Clamp and inspect the knife plate (= cam) for micro-cracks by using an adequate NDT method prior to using this kind of clamp for lifting plates, plate girders, etc.