IMCA has issued a Safety Flash, describing an incident in which an AC cover from a capstan electrical cabinet fell about 1.7 meters on a pipelay tower.
What happened
On a pipelay tower, the AC cover of a capstan electrical cabinet became detached and fell approximately 1.7 meters. The cover was found resting on a cable attached to the platform and diagonal tubular brace. There were no injuries. However, there was potential risk to individuals working nearby.
Crew were working in the pipelay tower when they heard an unknown noise. They stopped to investigate the source of the noise and found that an AC unit vent cover had become detached from the capstan winch PLC cabinet.
Work was stopped immediately under “Stop Work Authority”. The integrity and rivets of the remaining air conditioning units on the tower were inspected, along with a security assessment of the remaining covers. It was also confirmed that there was no damage to the electrical cable the cover contacted.
What went wrong
Initial investigations detected a failure of the securing rivets caused by galvanic corrosion. When aluminium and stainless steel are combined in an assembly, electrons from the aluminium migrate into the stainless steel causing the aluminium to weaken and deteriorate at an accelerated rate.
Lessons learned
- Inspect all similar cabinets / equipment and change out any incompatible fixings;
- Review existing dropped object checklists and/or work orders and update as required;
- Verify during routine dropped object inspections of equipment at height, that primary and secondary fixings and safety securing lanyards are all compatible;
- Update Planned Maintenance work orders where required.
