To conduct offshore oil and gas operations, the construction and maintenance of equipment at extreme depths is required, often beyond 50 meters towards the seafloor. For divers that reach this far into the murky blue, they must descend and ascend extremely carefully, taking time to decompress at each small increment to avoid horrible decompression sickness.
Decompression sickness, also known as the bends, is one of the greatest challenges of diving. As a diver descends through the depths, the pressure around them increases, owing to the weight of the ocean pressing onto their bodies. Gases such as nitrogen are breathed in until the diver’s tissues are saturated, meaning these gases are dissolved within the tissue to the point that they are at the same concentration as the breathing mixture. This changes due to pressure, so the divers must adjust as they move up or down.
Fail to do so correctly, and the consequences are horrible. Decompression sickness occurs when a change of pressure happens too fast, resulting in dissolved nitrogen forming bubbles in their tissues and blood. A potentially life-threatening condition, it can cause excruciating pain, confusion, paralysis, and even death. Once diagnosed, decompression sickness can require long stints in a recompression chamber to readjust, based on severity.
So, for large oil-mining rigs that require almost constant work on equipment on the seafloor, how can companies avoid the long periods of waiting as divers adjust to new pressures? The US Navy found a radical solution in 1957 – simply keep the divers under extreme pressure, 24/7.
This idea, called the Genesis project, marked the beginning of saturation diving, one of the most dangerous and well-paid jobs that exists today.
Saturation diving is a diving technique that involves staying under pressure for so long that all your bodily tissues become in equilibrium with the inert gases in the breathing mixture (either helium or nitrogen), and then staying under that pressure for long periods of time. These divers leave the safety of dry land and enter pressurized living quarters, after which they are transferred down to an underwater habitat via a diving bell. Once they are saturated, they will stay under intense pressure and breathe a mixture of oxygen and helium for weeks, until their tour of duty is over and they can be decompressed.
Life is exhausting, claustrophobic, and intense for these divers. Breathing the specialized mixture causes chills throughout their body due to the helium, and there is an array of medical complications that can arise from long-term exposure to harsh depths, alongside an almost constant risk of death. A number of strict regulations are enforced to minimize the risks of these issues, from mandatory diving times to forced time-off. Grouped together, these risks result in saturation diving becoming one of the most specialized jobs in the world, with just 336 people employed in this role in 2015 in the US.
The Byford Dolphin Explosive Decompression Accident
It was a routine procedure on the Byford Dolphin oil rig on Saturday, November 5, 1983, in which four divers were returning from a dive and exiting the diving bell into their compressed living chambers. The chambers consisted of chamber 1, in which Edwin Coward and Roy Lucas were resting, and chamber 2, where Bjørn Bergersen and Truls Hellevik were entering after their work. Chamber 2 was connected to the diving bell by a trunk, which the bell would attach to and be secured by a clamp operated by two diving tenders, William Crammond and Martin Saunders.
In these situations, the pressure must be carefully balanced to ensure the diving bell can be disconnected from the chamber system. The tenders were in charge of the procedure, which should go as follows:
1. The diving bell door is closed.
2. Pressure is increased in the diving bell to seal the door shut.
3. Chamber 1 is closed off from the trunk.
4. The trunk is depressurized to a standard 1 atmosphere.
5. The clamp is released, freeing the diving bell.
Despite being experienced in this procedure, Crammond supposedly made a fatal error. Between steps 2 and 3, whilst the chamber door was being closed, Crammond unexpectedly released the diving bell clamp. The trunk was now open to the environment and the chamber, which had a huge pressure difference – and the result was an explosive decompression. All four divers were exposed to a pressure gradient far too extreme for the human body to withstand, resulting in their immediate and violent deaths. The air rushing out of the trunk forced the diving bell from its position, striking the tenders, killing one and severely injuring the other.
The deaths of the divers are considered one of the most gruesome deaths in history. Due to the speed of the incident, it is expected that all the divers passed instantly and painlessly – but the scene left behind was horrific.
The pressure differential caused three of the divers’ blood to flash boil, almost instantaneously killing them. The fourth had it even worse – the rushing air forced his body through a gap just 60 centimeters (24 inches) long, launching vital organs and body parts up to 10 meters (30 ft) away. The medical examiners described some of the organs to be so intact, it was "as if dissected out of the body."
Serving as a stark reminder of the dangers of saturation diving, the Byford Dolphin accident resulted in the formation of the North Sea Divers Alliance, created from the relatives of the victims. The following report determined the cause of death to be human error, but the Alliance filed a lawsuit claiming there was insufficient safety equipment onboard. After 26 years of fighting, a report found the chambers contained faulty equipment that led to the accident, suggesting Crammond was absolved of responsibility. The relatives finally received compensation for the loss of their loved ones.
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