Byford Dolphin
| Byford Dolphin Deep Sea Driller (1974-1978) |
|
|---|---|
| General | |
| Owner: | Byford Dolphin Pte. Ltd. ( Fred. Olsen Energy ) |
| Operator: | Dolphin triplet |
| Tenant: | BP |
| Registration: | Singapore Panama (1974-2005) |
| ID: | IMO no. : 8750584 Call Sign: 9VDG7 |
| Dimensions, weights and capacities | |
| Length: | 108.2 m (355 feet ) |
| Width: | 67.4 m (221 feet) |
| Depth: | 36.6 m (120 feet) |
| Crew: | approx. 102 |
The Byford Dolphin is a pillar-supported semi-submersible rig developed by Dolphin Drilling , a subsidiary of Fred. Olsen Energy . It is currently used by BP for drilling in the British North Sea production area. In 1983 the Byford Dolphin suffered a serious decompression sickness in which five people were killed.
description
The Aker H3 drilling rig was built from 1972 to 1974 under construction number 695 at the Norwegian shipyard Aker Verdal A / S. It is measured with 11,792 GT and 3,538 NRZ. The Singapore-registered oil rig is owned by Byford Dolphin Pte. Ltd.
The drilling rig can be used in water up to 458 meters deep. The maximum drilling depth is 6096 meters. The drilling platform can still be used in hurricanes with wind speeds of up to 100 knots (around 50 m / s ) and waves 31 meters high. She can be towed at up to 4.5 knots.
Four diesel generators from Rolls-Royce with an apparent power of 1,910 kVA each and an emergency generator from MTU with an apparent power of 844 kVA are available for the power supply.
There is space for 102 people on board.
Decompression accident from 1983
The accident occurred on November 5, 1983 at 4:00 am when the oil rig was in the Norwegian Frigg natural gas field in the North Sea. At that time, four divers and two assistants were in two decompression chambers , which were connected to a diving bell via a short passage . When a diver tried to close the hatch between the chamber system and the passage, there was an explosive drop in chamber pressure from nine to one atmosphere in a fraction of a second . One assistant and all four divers were killed instantly; another assistant was seriously injured.
the accident
At the time of the accident, the connecting passage between decompression chambers 1 and 2 and the diving bell was closed by a clamping device. This clamping device was operated by two assistants who were both experienced divers themselves. There was a connection to a third decompression chamber, but this played no role in the accident. At the time of the accident, divers T1 (35 years) and T2 (38 years) were resting in chamber 2 at a pressure of 9 atm. The diving bell with divers T3 (29 years old) and T4 (34 years old) had just been raised and connected to the passage. Both divers left their wet diving equipment in the passage and climbed up to Chamber 1.
The normal workflow for exiting the diving bell was as follows:
- Close the hatch to the diving bell
- Slightly increase the pressure of the diving bell to close the hatch tightly
- Close the hatch between passage and chamber 1
- Slowly lower the pressure of the passage to 1 atm
- Open the clamping device to separate the diving bell from the chamber system.
After completing the first two steps and T4 should have proceeded to the next step, one of the assistants opened the clamp for an unknown reason, which resulted in the explosive decompression of the chamber system to 1 atm. A huge pressure wave shot out of the pressure chamber into the passage and pushed the diving bell away.
The assistant who opened the clamp was killed and the other seriously injured. Diver T4, who was exposed to the highest pressure gradient, exploded due to the abrupt expansion of the body's internal gases. All of his limbs and thoracic and abdominal organs, including the thoracic spine, shot out of the body and were hurled through the 60 cm hatch to the pressure chamber. Remains of his body were found scattered on the platform, including near the derrick, which was more than 10 m above the pressure chambers. Divers T1-T3 were also exposed to the rapid drop in pressure and were killed instantly.
Autopsy findings
An autopsy on the four divers found noticeably large accumulations of fat in the large blood vessels and the heart chambers, as well as in the blood vessels of various organs, especially the liver. This fat was probably not embolic, but deposited in situ from the blood when it boiled and the denaturation made the lipoproteins insoluble. The rigor mortis was unusually strong. The accumulations of blood in the internal organs were bright red and there were two cases of profuse bleeding in the liver. Large amounts of gas were found in the blood vessels in all organs, and bleeding was found in the soft tissues. One of the divers had a large blister under the conjunctiva of his eye.
Investigation and trial
An investigative commission came to the conclusion that the accident was due to human error by the assistant who opened the clamping device. Crew members of the Byford Dolphin and the trade union NOPEF (Norwegian oil and petro-chemical union) accused the commission of not sufficiently addressing the causes of technical errors and held exemptions from the Norwegian authority Oljedirektoratet responsible for the accident. The diving facility, which dates back to 1975, was not equipped with fail-safe hatches and other safety features that would have prevented the passage from opening in the event of excess pressure. In response to the accident, the Nordsjødykker Alliansen interest group was founded in the 1990s. The families of the killed divers received compensation from the Norwegian government in 2009.
Web links
Individual evidence
- ↑ Technical data , DNV GL
- ↑ a b c d e Byford Dolphin , Fred. Olsen Energy
- ↑ a b J.C. Giertsen et al.: An explosive decompression accident. American Journal of Forensic Medicine and Pathology 9, 2: 94-101 (June 1988)
- ↑ Norges offentlige utredninger NOU 1984: 11 Dykkerulykken på Byford Dolphin, ISBN 82-00-70889-6
- ↑ http://cdiver.net/blog/2009/10/20/norwegian-government-finally-pays-out-for-1983-byford-dolphin-diver-death/#more-3678