A member reports that a diver, whilst working on deck, suffered a severe head injury while attempting to align two 8″ flanges on the deck of a DSV. The assembly was a subsea buoyancy tank which was being connected to two flexible risers. The risers were coiled on a deployment reel and the tank was temporarily secured on a raised launch cradle on the opposite side of the vessel. In an effort to rotate the riser flange into alignment with the tank flange, three drift pins were placed through the 3, 6 and 9 o’clock bolt hole positions on the riser side and partially into the tank side flanges. In order to assist rotation, a come-along and nylon strop were attached to the pin at the 3 o’clock position and tension was applied in what was thought to be a controlled manner while the pin at 6 o’clock was knocked into place. The pin at 3 o’clock deformed, was forced from its position, bounced off of a structural member and the man who was working on the bottom pin was struck. The blunt end of the pin struck and tore a hole in the visor of his safety helmet before leaving a gash in his forehead. Diagnosis was a compound fracture of the skull and loss of integrity to the sinus cavity. Four hours of reconstructive surgery and ten days in hospital followed. A minimum of two months’ recuperation is required before any diving medical can be applied for.
This blow to the head by the drift pin was caused by the violent release of the pin from its position under tension. The misalignment of the flanges was not foreseen, so a specific job safety analysis (JSA) for the task had not been undertaken. Although the team had taken time out to discuss and agree upon an approach to the alignment, the method chosen held an unidentified risk. The behaviour of the pin under the tension of a side pull, applied in such a configuration (partial insertion into the tank flange bolt holes and against a shifting surface), was unpredictable and not under the full control of the men performing the task. Despite efforts to retain the pins with lanyards and hand holds, the forces developed and the destructive potential were not anticipated.
The evidence of the torn safety hat, in addition to the injury, points to a significant force at impact. Due to the fact that damage was sustained, a report and enquiry will be made to the manufacturer. The consequences of the casualty not having worn his personal protective equipment (PPE) in this instance would, no doubt, have been even more severe.
The root cause of the incident will also be reviewed by the company. It advises that likely subjects at the moment are:
- Was the use of a swivel flange considered at any time?
- The original installation schedule stipulated assembly of the flanges after the risers had been deployed from the reel. This would have allowed a greater degree of mobility to the risers as compared to when on the reel. Was a management of change procedure engaged at this juncture?
- Over the course of the engineering phase of the project several people were replaced for one reason or another. What effect did this have on the integrity of the procedures?
- The vessel was due to sail within 24 hours of the incident. Did this constraint place pressure on the crew to rush the task prior to heading to sea where hazards would have been magnified on a moving vessel?