Byford Dolphin incident autopsy: The investigation and findings

1. What is Byford Dolphin?

Byford Dolphin is a semi-submersible drilling rig with a stable column operated by Dolphin Drilling, a subsidiary of Fred Olsen Energy. It has conducted seasonal drilling for various companies in the North Sea regions of the United Kingdom, Denmark, and Norway. It is registered in Hamilton, Bermuda.

The drilling rig has experienced several serious accidents, notably the 1983 blowout that killed four divers and one diving supervisor and severely injured another diver.

Since March 2023, Byford Dolphin has been stationed at Rosfjord, Norway, near Agnefest.

Originally named Deep Sea Driller, it is the first in a highly successful Aker H-3 series, designed and completed by Aker Group at Aker Verdal shipyard in 1974.

Byford Dolphin has a total length of 108.2 meters (355 ft), a width of 67.4 meters (221 ft), and a depth of 36.6 meters (120 ft). It has a maximum drilling depth of 6,100 meters (20,000 ft) and can operate at a water depth of 460 meters (1,500 ft). [7] As a drilling rig, Byford Dolphin is equipped with advanced drilling equipment and initially met stringent certification requirements under Norwegian law, although it was later banned from Norwegian waters. Byford Dolphin can be self-propelled (to resist drifting and ocean currents), but for long distances, it must be towed by a specialized tugboat.

2. Byford Dolphin Accidents and Incidents

Byford Dolphin has been involved in several accidents and incidents throughout its operational history.

One of the most notable incidents occurred on April 5, 1983, when an explosive decompression accident happened while a diver was in a decompression chamber. The accident resulted in the death of four divers and one diving supervisor, while another diver was seriously injured. The incident was caused by a faulty valve on the diving bell, which caused a rapid decompression of the chamber. The incident resulted in significant changes to the diving industry’s safety regulations.

In 2002, a worker was killed and two others were injured when a piece of drilling equipment fell on them during a routine maintenance operation on the rig.

In 2009, two workers were killed and two others were injured in another accident when a section of the rig’s derrick collapsed during a drilling operation. The accident was caused by a failure in the rig’s hoisting system, which caused the derrick to fall onto the drilling floor.

In addition to these incidents, Byford Dolphin has also been involved in several minor accidents and incidents, such as fires and collisions with other vessels. Despite these incidents, Byford Dolphin remains in operation, with safety measures continuously being improved and updated to prevent similar incidents from occurring in the future.

1. Cause of Divers’ Death

The cause of death of the divers in the Byford Dolphin accident is believed to be an explosive explosion in one of the pressure equalizer tubes in the rig, which resulted in a rapid increase in pressure in the diver’s floating room. The high pressure sloughed off oil and fat molecules in the divers’ blood, causing air bubbles in their bodies. When air bubbles jump into the blood vessels, they can block blood vessels and prevent blood from reaching other parts of the body, causing death. In addition, one diver was killed by mutilation and fragmentation due to a terrifying explosion in the rig.

2. Byford Dolphin incident autopsy Report Result

After medical investigations into the remains of the four divers, the most notable finding was the presence of large amounts of fat in the arteries, great veins, heart chambers and liver. This fat is unlikely to be due to an embolism, but has certainly precipitated from the local blood, rendering the lipid insoluble. Autopsies showed that rapid bubble formation in the blood denatured the lipoprotein complex, stopping the divers’ blood circulation. One of the divers was dismembered and mutilated by the explosion, forcing him to escape through a partially blocked doorway and possibly died instantly. Coward, Lucas and Bergersen were exposed to the effects of explosive decompression and died at the locations indicated in the diagram. Investigation by forensic pathologists determined that Hellevik was forced through a 60 cm (24 in) crescent-shaped hole created by a jammed interior trunk door. The released pressure and air cut his thoracic and abdominal cavity in half, resulting in the fragmentation of the body and the expulsion of all internal organs in the chest and abdomen, except for the trachea and a segment of the small intestine. , and of the thoracic spine. The fragmented internal organs were projected at some distance and partially found 10 meters (30 ft) vertically above the external pressure inlet.

The investigation by the accident investigation commission concluded that the accident was caused by human error on the part of the diver who opened the clamp. The hatch was designed with a hinge in the middle, similar to a butterfly valve, and was rotated too far to the left, causing the edge of the hatch to fall inward and into the open hatch. This created a wide gap of 24 inches horizontally, resembling an open manhole cover but fixed in place. It is unclear whether the contractor opened the clamp before the pressure vessel was depressurized at the direction of his supervisor, on his own initiative, or due to inaccurate information. At that time, the only means of communication for the outside bidders was through a loudspeaker attached to the wall surface, which made it difficult to hear what was happening amidst the loud noise of drilling and the sea. The exhaustion after long hours of strenuous work also affected the divers, who usually worked in shifts of 16 hours.

The incident was also attributed to technical malfunction. The Byford Dolphin diving system was outdated, dating back to 1975, and was not equipped with a safety hatch, an external pressure gauge, or an interlocking mechanism that could prevent the hatch from opening while the system was under pressure. Before the accident occurred, Norske Veritas issued the following certification rule: “The mechanisms connecting the bell to the chamber must be arranged so that they cannot operate when the chamber is pressurized,” thus requiring such systems to have safety rings and interlocking mechanisms. One month after the accident, Norske Veritas and the Norwegian Oil Directorate issued the final regulations for all bell systems.

Among others, former crew members of Byford Dolphin and NOPEF (a Norwegian oil and petrochemical union) have come forward to allege that the investigation was a cover-up. They claimed that the accident investigation commission did not address in their report the distribution of responsibility for important equipment by Comex, authorized by the diving department of the Norwegian Petroleum Directorate, a key agency in the accident. They also alleged that the accident was caused by a lack of appropriate equipment, including clamps equipped with interlocking mechanisms (unable to open while the chamber system was still under pressure), external pressure gauges, and safety communication systems, all of which had been delayed due to budget constraints.

The Byford Dolphin Incident is a famous diving accident that occurred in 1983 when part of the Byford Dolphin rig in the North Sea exploded, killing four workers and causing serious injuries to several others. After the incident, there were many lawsuits filed by divers and relatives of the victims.

These lawsuits focus on investigating the liability of companies involved in accidents, including insurance and safety certificate issuers and prime contractors. Many people believe that, if these companies had complied with safety and strict regulations in managing and operating the rig, the accident could not have happened.

However, these lawsuits have faced many difficulties and obstacles, including identifying and proving the responsibility of the parties involved. Making the settlement of this case take a lot of time and effort, and also create controversies between the parties involved.

Currently, this case has been settled and the parties involved have reached an out-of-court settlement of suppression. However, it has become one of the most famous diving accidents in history and is a wake-up call for companies and workers in the industry.