What Is The Byford Dolphin Accident? Why Is Decompression Sickness So Bad?

As the first of her kind in the hugely popular Aker H-3 series, Deep Sea Driller was constructed in 1974 at the Aker Verdal shipyard. The Aker Group developed it.

Overall, the Byford Dolphin measured 108.2 meters (355 feet), 67.4 meters (221 feet), and 36.6 meters (120 ft). It could operate at a sea depth of 460 meters and had a maximum drilling depth of 6,100 meters (20,000 feet) (1,500 ft).

Byford Dolphin was a drilling rig with cutting-edge gear that first passed tight certification requirements under Norwegian law but was later prohibited from Norwegian seas. Byford Dolphin could travel with its engines (to avoid drift and ocean currents), but it needed specialized tugboats to transport it over vast distances.

Accidents And Incidents:-

Deep Sea Driller accident

The rig capsized on March 1, 1976, as it was transported from a North Sea block to Bergen. Six crew members died after they fell out of their boats, even though the entire crew was evacuated.

Diving Bell Accident

Four divers were in a diving chamber system on the rig’s deck at 4:00 a.m. on Saturday, November 5, 1983, while drilling in the Frigg gas field in the Norwegian part of the North Sea.

A trunk and a small passageway connected the diving bell and the chamber system. The divers were Edwin Arthur Coward, a 35-year-old British man, Roy P. Lucas, a 38-year-old British man, Bjrn Giaever Bergersen, a 29-year-old Norwegian man, and Truls Hellevik (Norwegian, 34). Two dive tenders, Martin Saunders and William Crammond (British, 32), assisted them.

As Hellevik prepared to close the trunk’s entrance to the chamber system, the pressure suddenly dropped from nine atmospheres to one as it decompressed explosively. All four divers, including Crammond, died instantaneously; Saunders, the other tender, suffered severe injuries. At the time of the catastrophe, a view of the decompression chamber was taken from above. Divers D1–D4 and dive tenders T1–T2 make up the group. The portion connecting chamber 1 to the diving bell is the trunk.

Just before the incident, a trunk connected decompression chambers 1 and 2 to a diving bell, along with a third chamber that wasn’t used at the time. Crammond and Saunders, two seasoned divers, used a clamp to keep the connection established by the trunk sealed.

Coward and Lucas were dozing off in chamber 2 with a 9 atm pressure. Bergersen and Hellevik’s diving bell had just been winched up and attached to the trunk following a dive. The two divers put their wet gear in the trunk and entered chamber 1 through the trunk.

The Usual Course of Action Would Have Been:

  • Lock the door to the diving bell, which was previously open to the trunk.
    To tightly shut the bell door, slightly raise the diving bell’s pressure.
    Close the door to chamber 1, which was ajar with the trunk.
  • Depressurize the trunk gradually until it reaches 1 atm.
  • To detach the diving bell from the chamber system, open the clamp.

Before Diver 4 (Hellevik) could shut the entrance to the room, Crammond opened the clamp holding the trunk locked for an unexplained cause. This prevented the first two steps from being finished.

The system’s unsealed chamber decompressed explosively as a result. The bell struck the two tenders as air poured out of the chamber system with such power that it jammed the inside trunk door and pushed it aside. All four divers perished; Crammond, one of the tenders, died; Saunders suffered severe injuries.

Medical findings:-

The four divers’ remains were subjected to medical examinations. The most striking observation was the presence of intravascular fat in organs, particularly the liver, as well as massive levels of fat in heart chambers, major arteries, and veins.  This fat must have precipitated from the blood already present because it was unlikely to be embolic.  According to the autopsy, the lipoprotein complexes were denatured by the blood’s fast bubble formation, rendering the lipids insoluble. The three divers still intact inside the chambers most likely had their blood boil quickly, ending their circulation. The blast forced the fourth diver through the partially obstructed entryway, where he was torn and disfigured by the explosion and would have died instantaneously.

Coward, Lucas, and Bergersen perished in the locations shown in the diagram after being subjected to the consequences of explosive decompression. According to an investigation by forensic pathologists, Hellevik was pushed through the crescent-shaped opening that the jammed interior trunk door had created, which was 60 centimetres (24 in) long and made when Hellevik was moving to secure the inner door while being exposed to the highest pressure gradient.

The escaping air and pressure caused his thoracoabdominal cavity to be divided, which caused his body to be fragmented. All his internal organs from his chest and abdomen—aside from the trachea and a portion of his small intestine—were expelled along with his thoracic spine. One part was discovered 10 meters (30 feet) vertically above the outer pressure door. These were projected a fair distance.


The commission in charge of the accident’s investigation concluded that the diving tender’s opening of the clamp was a mistake. The inside hatch’s rim became stuck on the door opening because the trunk door’s central hinge, which resembled a butterfly valve disc, was spun too far to the left. A crescent-shaped opening was left behind, resembling a manhole cover left ajar but still in place.

The result was a horizontal aperture that measured 24 inches across. It is unclear if the tender who opened the clamp before the trunk was depressurized did so at the supervisor’s request, on his initiative, or as a result of a misunderstanding. At the time, the only means of communication for the tenders outside the chamber system was a bullhorn mounted on the wall; nevertheless, due to the intense noise from the rig and the sea, it was difficult to hear what was being said. The divers regularly worked 16-hour shifts and were worn out from the long, hard work hours. [Reference needed]

Engineering failure was also blamed for this catastrophe. The outdated Byford Dolphin diving system, manufactured in 1975, lacked interlocking mechanisms, fail-safe hatches, and outboard pressure gauges that would have prevented the trunk from opening while the system was under pressure.

Norske Veritas had issued the following certification rule before the accident: “Connecting mechanisms between bell and chambers are to be so arranged that they cannot be operated when the trunk is pressurized,” necessitating the use of fail-safe seals and interlocking mechanisms in such systems. Norske Veritas and the Norwegian oil directorate made the rule final for all bell systems a month after the accident. [Reference needed]

Former Byford Dolphin crew members and NOPEF (a Norwegian oil and petrochemical union) have come forward to accuse the probe of being a cover-up. They asserted that the panel looking into the accident failed to include in its report the negligent lending of crucial equipment to the Norwegian Petroleum Directorate, which was sought by Comex and approved by the diving department and which was a key factor in the accident.

In addition, they claimed that the accident was caused by a lack of appropriate tools, such as interlocking clamping mechanisms (which could not be opened while the chamber system was still under pressure), outboard pressure gauges, and a secure communication system; all of which had been delayed due to exemptions granted by the Norwegian Petroleum Directorate.

What Is The Byford Dolphin Accident?
What Is The Byford Dolphin Accident?

Why Is Decompression Sickness So Bad?

Decompression sickness, one of the most terrifying illnesses for deep-sea divers (more frightening than a chance encounter with a Kraken), occurs when a diver leaves the dark depths too quickly, causing their blood to bubble up as if it were boiling.

It’s one of the most challenging aspects of diving because no expensive or high-tech gear can shield a diver from it. Divers refer to it as “the bends.” Divers fill their compressed air tanks with more oxygen and nitrogen during scuba diving. While most of the nitrogen is absorbed into various tissues, most of the oxygen is used up in your bloodstream.

As divers descend below the surface of the water, the weight of the ocean begins to press down on them. This intense pressure causes even the oxygen and nitrogen molecules in your tissues to be compressed, which accelerates and increases the rate of dissolution of the nitrogen molecules.

Excruciating pain, paralysis, instant bewilderment, and in many cases, even death can result from a diver ascending too quickly because the sudden drop in pressure causes the dissolved nitrogen molecules to bubble up as if they were boiling suddenly. The diver will need to be treated in a recompression chamber where they will once more be placed under extreme pressure and have that pressure reduced very slowly over a lengthy period. If the diver survives the initial shock of the bends.

This is due to the laws of physics, which state that the liquid will typically boil at a lower temperature when the surrounding gas pressure is lower. Even at room temperature, liquids will boil once the vapour pressure reaches the atmospheric pressure. The fast drop in atmospheric pressure causes the nitrogen molecules in our tissue to bubble, which is a severe kind of decompression sickness.

What Is The Byford Dolphin Accident?

On November 5, 1983, while the divers were returning from a standard procedure, the now-famous Byford Dolphin tragedy occurred, which resulted in the explosive decompression fatalities of four divers and one dive tender.

Edwin Coward and Roy Lucas, two divers, were relaxing in chamber 1 of their cramped living quarters when the Byford Dolphin Incident occurred. Divers Bjrn Bergersen and Truls Hellevik were simultaneously plunging into chamber 2 through a trunk attached to the diving bell. The diving tenders William Crammond and Martin Saunders used clamps to attach the bell to Chamber 2 on the trunk.

The pressure inside these chambers, the trunk, and the diving bell must be perfectly balanced in a typical situation. This guarantees secure connection and disconnection of the diving bell from the chambers. This process is under the dive tenders’ control and must adhere to the particular protocol:

The diving bell door needs to be shut and locked first. Second, the diving bell’s pressure is raised to seal its doors. Third, the trunk’s opening to Chamber 1 needs to be sealed. Fourth, the diving bell and chambers’ connecting trunk is depressurized to the pressure of one atmosphere. Finally, the diving bell can be freed from the chambers thanks to the clamp’s release.

Even though everyone on the team had extensive expertise, a tragic and catastrophic explosive decompression catastrophe occurred, killing all 4 divers and 1 tender, leaving Martin Saunders as the lone survivor despite his terrible injuries.

The initial findings of the Norwegian government’s investigation suggested that diving bell tender William Crammond had committed the fatal blunder of releasing the diving bell before it could be inflated and before it could be sealed off from the trunk. The pressure differences between the water, the living chambers, and the trunk resulted in catastrophic decompression, killing every room diver. The trunk itself struck both tenders, resulting in 1 fatality.

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