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Uncontrolled ascent of lay-down head

A member has reported that a saturation diver in 120m of water, preparing to move a pipeline lay-down head (LDH) using a lift bag, was struck in the back by the uncontrolled ascent of the LDH. The LDH was being used as a deadman anchor to assist in aligning a pipeline.

The resulting investigation concluded that:

  • the lift bag affixed to the LDH had a higher rating than the load to be lifted – inaccurate use of LDH weight data provided in the procedure while making a field change;
  • there had been inadequate communication – offshore personnel had not been appraised regarding the LDH’s true weight;
  • there were inadequate guards/protective devices – due to the distances involved in moving the LDH, the lift bag dump line and safety strap were not connected;
  • there had been inadequate assessment of the level of change – the task had been carried out under a ‘minor’ management of change (MOC) procedure.

The company involved has made the following recommendations:

  • diving operations using lift bags should always follow the company’s guidelines;
  • anchors should have a known measured weight or have their weight calculated for the condition of use;
  • lift plans should include the weights, weight calculations and methods of those calculations;
  • the deletion of a dump valve’s safety line constitutes a significant change, requiring the use of an appropriate MOC procedure. When a safety device is disabled or a safe procedure is bypassed, a task must be further risk-assessed, brought to a higher level and fully documented. This is true even in situations where a safety device might increase the risk of incident or injury.

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