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High potential dropped object – steel bar, 10m

A member has reported an incident in which a heavy steel bar fell 10m onto the deck. The incident occurred during ROV deployment, when a round steel bar weighing approximately 20 kg became detached from above the cursor frame umbilical drum mechanism and fell approximately 10m onto the deck (moonpool doors). The object fell and struck the deck and then rolled under the ROV transfer plinth. There were no injuries or damaged caused, though at the time one member of the ROV deployment crew was standing in the moonpool area approximately 2-3m away from the point of impact and the ROV was approximately 1.5m off the deck.

The ROV launch operation was immediately stopped, the ROV was lowered back to deck, the item recovered, operations were suspended and investigations began.

ROV umbilical winch drum from which steel bar fell
ROV umbilical winch drum from which steel bar fell
Looking to the top of the ROV hangar at the cursor and cursor winch
Looking to the top of the ROV hangar at the cursor and cursor winch

Our member’s investigation revealed the following:

  • The steel bar was identified as having come from above the cursor frame umbilical drum. It was used to stop the umbilical jumping on the drum;
  • During a maintenance period (5 months prior to this incident), to upgrade parts of the existing ROV launch & recovery system, the manufacturer had fitted a guide above the drum as an improvement to the incumbent system. The function of this steel bar was to stop the umbilical jumping and fouling;
  • The cause of the incident was found to be: three separate steel bars were fitted to a holding guide frame and held in place with bolts at each end. The ROV umbilical on the drum was rubbing against the guide causing the bolts to loosen over a 5 month period. This was due to there being insufficient clearance between the round steel bar and the umbilical when on the cursor drum.

Our member made the following recommendations:

  • Weekly inspection checks on the steel bar guides, inspection interval to be reviewed, confirmed and included in planned maintenance system;
  • Inspection to include confirming a minimum of 5mm clearance between the guide bar and umbilical;
  • Ensure that the securing bolts are tight and torqued on all guide bars;
  • A secondary securing device to be fitted to the round bars and this to be inspected during the planned inspection. Remedial hold back on all three guide bars as a temporary measure put in place;
  • All future alterations in plant and equipment plant to be suitably communicated, risk assessed and a management of change exercise conducted with all the interested parties;
  • Onboard inspection of work areas to identify potential dropped objects with particular reference to the following areas:
    • Below lifting operations;
    • Cranes;
    • Elevated work areas or platforms;
    • Work spaces where equipment is mounted overhead.

Members may wish to make use of additional IMCA resources as follows:

Safety Event

Published: 29 November 2013
Download: IMCA SF 17/13

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