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AC vent unit cover dislodged and fell 1.7m

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. Our member, based on information from the industry “DROPS calculator”, has treated the incident as it if were a Lost Time Injury (LTI).

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.

Cover in its final resting place
Failed Aluminium rivets

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.

Actions

There is potential for a similar incident to occur on similar vessels.

  • 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.

Members may wish to refer to:

Safety Event

Published: 23 October 2024
Download: IMCA SF 21/24

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