Fatality during air diving operations

A member has reported an incident in which a diver was killed during air diving operations, whilst working from a four point dive support vessel moored alongside an offshore platform. The incident occurred when the diver was working on attaching a marker buoy near to a leak in a 12″ live high pressure (800psi-900psi) water injection pipeline. This was so that the leak could be located later for repairs. The diver was working in 29m of water.

The diver successfully attached the buoy to the pipeline but it became fouled under the vessel. In order to free the buoy the diver was asked to move it to the far side of the leak. At the time of the dive, visibility was reduced as it was approaching sunset; the diver used his hat-mounted light to navigate. In addition, the tremendous noise of the leak on the live pipeline severely hampered voice communications between the diver and diving supervisor.

Once the diver had detached the marker buoy he started to move along the seabed beside the pipeline. He was on the same side as the leak. The diver appeared to look down at some debris and, as he stepped over this material, he was struck by a jet of the high pressure water coming from the damaged pipeline. All communication with the diver was instantly lost.

The standby diver was deployed immediately using the second diving basket. Within 5 minutes he had located the stricken diver who was lying on the seabed. The dive helmet (KM37) was no longer on the diver’s head but was lying beside him with the neck dam still attached. Both divers were recovered to surface. All attempts to resuscitate the injured diver failed; he was later pronounced dead by a doctor who had been helicoptered offshore.

An independent investigation was conducted by an experienced third party Diving Accident Investigator and various findings were noted, including the following:

• The diving equipment was functional, in-date, certified and compliant with IMCA guidelines at the time of the incident. There is no suggestion that diving equipment failure played any part in this incident;
• A generic risk assessment was used;
• A toolbox talk was conducted verbally for the divers and the hazard was informally discussed;
• There was a flow of work instructions that started off via formal instructions contained in the Diving Service Order and email and was changed later via informal, verbal commands and radio communications between various parties as the work progressed which may have caused some confusion;
• Reduced visibility, poor ambient lighting conditions and extreme noise interfered with conduct of the dive.

The root cause of the incident was determined to be a lack of understanding of the level of risk posed by the leak.

Our member learnt the following lessons:

• All supervisory personnel should be conversant with industry guidelines and in this particular instance operations of this nature should be conducted in accordance with IMCA D 006 – Diving operations in the vicinity of pipelines:
  • In planning to undertake damage inspection on pressurised pipelines it is important that the assessment of hazards encompasses not only the possible failure modes but also the associated risks to the diver, diving support vessel (DSV) and environment. ROV inspection should be used to conduct any initial inspection. Diver access should not occur until the pipeline has been depressurised to a level which has been established as safe through the engineering hazard assessment;
• Hazard identification and risk analysis must be carried out before any hazardous activity. The results of the hazard identification (HAZID) should be used to inform a job safety analysis (JSA) before the diver, if required, is deployed.
• Toolbox talks should be informed by the HAZID and JSA and should include all members of the dive team;
• Care should be taken to ensure that all members of the dive team have fully understood the hazards and risks involved;
• A formal documentary record should be kept of the toolbox talks, including the name of the person conducting the toolbox talk, date, time, dive no., and names of persons attending;
• Communication of work instructions to and from the vessel needs to be formalised and if possible reduced in volume;
• Environmental conditions should be taken into account in any diving operation;
• Following a serious or fatal accident it might be appropriate to consider arranging psychological counselling for all those involved.

Members may wish to refer to the following similar incidents (key words: diver, pipeline, pressure):

• Negative pressure injury to a diver(when breaking containment on subsea pipework)
• Identification of differential pressures subsea during diving operations
• Fatality during diving operation (on a pipeline end manifold)