According to IMCA, during a trans-pooling of an umbilical, a tensioner pad fell from 11 m height and landed to the under-deck carousel, in a close distance to the deck supervisor and, luckily, no injury occurred.
The incident
During the trans-spooling of an umbilical, a tensioner pad retaining bolt sheared, resulting in a 1.5kg tensioner pad dislodging and falling 11m to the under-deck carousel, where it struck the already trans-spooled umbilical. The pad dropped and bounced towards the starboard side, almost hitting the deck supervisor, and landed on a salt sack approximately 1 m from him.
Probable cause
- Due to resources, timescale and difficulty of access, the grade 8.8 bolts were not replaced with the 10.9 bolts.
- No inspection regarding the retaining bolt had taken place and the torque values were not checked due to the difficulty in accessing the tensioner.
- Risk assessments had not been conducted prior to the work activity, therefore there had been no consideration of potential dropped objects or mitigation thereof.
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Lessons learned
- Replace M10 x 25mm grade 8.8 retaining bolts with M10 x 25mm grade 10.9 on all equipment prior to mobilisation to vessels.
- Corrective work orders to be fully completed inclusive of inspection of tensioner pad retaining bolts and torque value checks, prior to mobilising equipment to vessels;
- Risk assessment of this type of work should take place before the beginning of the operation.
