A member has reported an incident where a trapped diver umbilical resulted in his death. During the surface supplied diver operation, the diver was deployed to the bottom (56m) to locate fixing points for davits which required him to travel along the pipeline and for the barge to be moved into position.
During the diving operation the barge moved astern. It is thought that this movement caused the diver’s umbilical to become snagged on an object on the seabed cutting off his gas supply. On the diver’s umbilical there were two ‘D’ rings – one at 39m (~130′) and one at 50m (165′). The 50m ‘D’ ring was attached to the bell lift wire controlling the maximum excursion of the diver; it was the 39m ‘D’ ring that became snagged on the seabed. The diver went on to bail out, reported that his umbilical was fouled and made his way back to the wet bell where he appeared to have been attempting to put the bell pneumo tube into his helmet when he was found by the standby diver who had been deployed from the surface. Both video and audio communications were lost soon after the diver reported his umbilical was fouled. Soon after the standby diver arrived at the wet bell attempts were made to recover it and the divers to the surface. As the wet bell was being recovered, since the diver’s umbilical was fouled on the seabed, he was dragged out of the wet bell. This occurred twice before the standby diver freed the trapped umbilical and eventually the diver was recovered to the surface but was pronounced dead by the doctor on board the vessel.
Following the investigation of the incident, a number of actions were put in place by the company:
- Controlled barge movements while divers are on excursion umbilical and travelling along a pipeline;
- All divers to be tended in-water, i.e. two divers in the water with one diver tending from the wet bell;
- All divers to be briefed on all emergency dive operational procedures and re-familiarised with the wet bell emergency equipment;
- Thorough briefing to all divers on the emergency recovery procedures to recover a stricken diver; ensuring that always his umbilical is cleared of any fouling which may have occurred during the dive and recover all the umbilical slack back to the surface prior to the wet bell ascending;
- Use of a pre-dive survey by a remotely operated vehicle (ROV) to be carried out to check debris in the work location involving divers travelling up pipelines;
- Ensure that both video/communications for all divers involved in a dive are connected and working as part of the pre-dive checks;
- Ensure divers deploy their excursion umbilical in a safe manner from the bell, ensuring that it is clear of the counterweight or any foreign objects which may be in the area of the bell footprint where the deployed umbilical would lie.
Members attention is also drawn to the following IMCA guidelines:
- IMCA international code of practice for offshore diving – which sets out good practice guidance on all aspects of a diving operation including work planning, risk management including vessel movements and emergency and contingency plans.
- Surface supplied mixed gas diving operations – which sets out that a properly equipped wet bell (providing a gas bubble in the wet bell dome) is required for this type of operation; aspects which should be considered in the risk assessment including umbilical management and the recovery of an injured diver, that the dives for depths between 50m and 75m the bottom time should limited to a maximum of 30 minutes; that for dives greater than 50m the standby diver should be located in and tend the diver from the wet bell.
- DESIGN for surface supplied mixed gas diving systems – which sets out the equipment requirements for this type of diving operation.
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