The Byford Dolphin is a semi-submersible Norwegian oil exploration rig converted from a diving rig. It floats in the North Sea to find and drill crude oil deposits. Built on the "Aker H-3" design, the rig is operated by Dolphin Drilling, a Fred Olsen subsidiary. It is able to manoeuvre with its own engines (to counter drift and ocean currents), but for long-distance relocation it must be moved by specialist tugboats. A derrick is a lifting device composed of one mast or pole which is hinged freely at the bottom. ... Pounds-force per square inch (lbf/in²) is a non-SI unit of pressure. ... Natural gas drilling rig A drilling rig or oil rig is a structure housing equipment used to drill for and extract oil or natural gas from underground reservoirs. ... The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ... Jump to: navigation, search Nodding donkey pumping an oil well near Sarnia, Ontario, 2001 Petroleum (from Greek petra – rock and oleum – oil), crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. ... Fred Olsen or Fred. ... An engine is something that produces some effect from a given input. ... Drift may refer to: Drift (linguistics), the variation of speech. ... Jump to: navigation, search This article is about the boat. ...

As a drilling rig, the Byford Dolphin is near the top of its class. It is equipped with advanced drilling equipment and has to meet very high levels of certification under Norwegian law. However, the rig has suffered some serious accidents, most notably an explosive decompression accident in 1983 known as the Byford Dolphin diving bell accident that killed five workers and badly injured one more. An accident is something going wrong unexpectedly. ... Explosive decompression (ED) is a sudden drop in pressure that occurs in 0. ... Jump to: navigation, search 1983 is a common year starting on Saturday of the Gregorian calendar. ...

Diving bell accident

The compression chamber at the moment the accident occurred. D1 - D4 are divers; T1 and T2 are dive tenders.

At 4:00 AM on November 5, 1983, four divers were in a compression chamber system attached to a diving bell on the rig, being assisted by two dive tenders. One diver was about to close the door between the chamber system and the trunk when the chamber was explosively decompressed from a pressure of 9 atm to 1 atm in a fraction of a second. Five of the men were killed; the other was severely injured. Jump to: navigation, search ImageMetadata File history File links Byford_Dolphin_Accident. ... Jump to: navigation, search ImageMetadata File history File links Byford_Dolphin_Accident. ... Jump to: navigation, search November 5 is the 309th day of the year (310th in leap years) in the Gregorian Calendar, with 56 days remaining. ... Jump to: navigation, search 1983 is a common year starting on Saturday of the Gregorian calendar. ... Diving bell A diving bell is a cable suspended watertight chamber, open at the bottom, that is lowered underwater to operate as a base or a means of transport for a small number of divers. ... Explosive decompression (ED) is a sudden drop in pressure that occurs in 0. ... When expressed as a measurement, an atmosphere or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on the Earth. ...

The situation just before this accident occurred was as follows. Compression chambers 1 and 2 were connected via a trunk to a diving bell. This connection was sealed by a clamp operated by two tenders (T1 and T2), who themselves were experienced divers. A third chamber was connected to this system, but was not involved. On this day, divers D1 (35 years old) and D2 (38 years old) were resting in chamber 2 at a pressure of 9 atm. The diving bell with divers D3 (29 years old) and D4 (34 years old) had just been winched up after a dive and joined to the trunk. Leaving their wet gear in the trunk, the divers then climbed through the trunk into chamber 1. A winch is a machine that is used to wind up a rope. ...

The normal procedure would have been to (a) close the bell door, (b) The diving supervisor would then slightly increase the bell pressure to seal this door tightly, (c) close the door between the trunk and chamber 1, (d) depressurize the trunk to 1 atm, and (e) open the clamp to separate the bell from the chamber system.

Operations (a) and (b) had been completed and D4 was about to carry out operation (c) when, for some inexplicable reason, one of the tenders opened the clamp. This resulted in the high pressure within the system being released into the external atmosphere, causing explosive decompression. A tremendous blast shot from the chambers through the trunk, pushing the bell away and hitting the two tenders. The tender who opened the clamp died, and the other was severely injured. Explosive decompression (ED) is a sudden drop in pressure that occurs in 0. ...

Diver D4 was shot out through the small jammed hatch door opening, being ripped apart. Subsequent investigation by forensic pathologists determined that diver D4, being exposed to the highest pressure gradient, exploded with violence due to the rapid and massive expansion of internal gases. All of his thoracic and abdominal organs, and even his thoracic spine, were ejected, as were all his limbs. Simultaneously his remains were expelled with force through the narrow trunk opening left by the jammed chamber door, less than 60 centimetres (24 inches) in diameter. Chunks of his body were found scattered about the rig. One part was even found lying on the rig's derrick, 10 metres directly above the chambers. His death would almost certainly have been painless and instantaneous. Forensic pathology is the legal branch of pathology concerned with: Determining cause of death (including murder, accident or unexpected death) Examination of some wounds and injuries due to crime or negligence Examination of tissue specimens that may be relevant to rape, or other crimes. ... In biology, an organ (Latin: organum, instrument, tool) is a group of tissues, which perform a specific function or group of functions. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... A limb (from the Old English lim) is a jointed appendage of the human or animal body; a large or main branch of a tree; a representative, branch or member of a group or organization. ... For the geometric term, see diameter. ...

Medical findings

Medical investigations were carried out on the four divers' remains. The most conspicuous finding of the autopsy was large amounts of fat in large arteries and veins and in the cardiac chambers, as well as intravascular fat in organs, especially the liver. This fat was unlikely to be embolic, but must have "dropped out" of the blood in situ. It is suggested that the boiling of the blood denatured the lipoprotein complexes, rendering the lipids insoluble. An autopsy (also known as a post-mortem examination, necropsy or obduction) is a medical procedure that consists of a thorough examination performed on a corpse after death, to evaluate disease or injury that may be present and to determine the cause and manner of a persons death. ... Section of an artery An artery or arterial is also a class of highway. ... Jump to: navigation, search In biology, a vein is a blood vessel which returns blood from the microvasculature to the heart. ... The heart and lungs (from an older edition of Grays Anatomy) The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. ... Jump to: navigation, search The liver is an organ in vertebrates, including humans. ... In medicine, an embolism occurs when an object (the embolus, plural emboli) migrates from one part of the body (through the circulation) and cause(s) a blockage (occlusion) of a blood vessel in another part of the body. ... In situ (in place in Latin), a term used in: biology, where it means to examine the phenomenon exactly in place where it occurs (without removing it in some special medium etc. ... A lipoprotein is a biochemical assembly that contains both proteins and lipids and may be structural or catalytic in function. ... Figure 1: Structure of a Lipid. ...

The rigor mortis was unusually strong. The hypostases (accumulations of blood in internal organs) were light red, and in two cases there were numerous hemorrhages in the livers. All the organs showed large amounts of gas in the blood vessels, and scattered hemorrhages were found in soft tissues. One of the divers had a large sub-conjunctival bulla (a blister in the tissue of the eye). Rigor mortis is a recognizable sign of death that is caused by a chemical change in the muscles, causing the limbs of the corpse to become stiff (rigor) and impossible to move or manipulate. ... A hypostasis, from the Greek word ὑπόστασις [1] meaning foundation, base or that which stands behind is a term in linguistics to describe the relationship between a name and a known quantity, as a cultural personification (i. ... Hemorrhage (alternate spelling is Haemorrhage) is the medical term referring to the presence of blood in the interstitial tissues. ... The conjunctiva is a membrane that covers the sclera (white part of the eye) and lines the inside of the eyelids. ... Bulla can refer to: The English anime name of Bra, a Dragon Ball GT character. ...

Investigation

The committee investigating the accident concluded that it was due to human error on the part of the dive tender who opened the clamp. It is not clear whether the tender who opened the clamp before the trunk was depressurized did so by order of his supervisor or on his own initiative, due to miscommunication. At the time the only communication the tenders on the outside of the chamber system had was through a bullhorn attached to the wall surface; with heavy noise from the rig and sea, it was hard to listen in on what was going on. Fatigue from many hard hours of work also took its toll on awareness amongst the divers, who would often work 16 hour shifts. A megaphone is a cone-shaped device designed to amplify sound. ...

This incident was also an engineering failure, in that the system was not equipped with fail-safe hatches. Subsequently a law was passed in Norway requiring such systems to have fail-safe seals that would close automatically. Safety engineering is used to assure that a life-critical system behaves as needed even when pieces fail. ...

Some individuals have alleged that the investigation was a cover-up, and that the accident was due to a lack of proper equipment including clamping mechanisms equipped with interlocking mechanism (which would be impossible to open while the chamber system was still under pressure), outboard pressure gauges and safe communication system, which had been held back due to dispensations done by the Norwegian Petroleum Directorate. When a scandal breaks, the discovery of an attempt to cover up the evidence of wrongdoing is often regarded as even more scandalous than the original deeds. ...

Other incidents

• In late November 2001, the rig was left adrift without control in a storm. Although 17 of the 71 workers were evacuated by helicopter, the company claimed there was no serious danger.
• On April 17, 2002, a 44 year old Norwegian worker on the rig was struck on the head and killed in an industrial accident. The accident resulted in the Byford Dolphin losing a exploration contract with Statoil, who expressed concerns with the rig's operating procedures. The incident cost the company millions of dollars in lost income.

Jump to: navigation, search For other uses, see November (disambiguation). ... Jump to: navigation, search 2001: A Space Odyssey. ... April 17 is the 107th day of the year in the Gregorian calendar (108th in leap years). ... Jump to: navigation, search 2002(MMII) is a common year starting on Tuesday of the Gregorian calendar. ... An Industrial Injury is any disease or bodily damage resulting from working. ... Picture of a Statoil Station in the Republic of Ireland - Statoil has grown to become a major international company A Statoil petrol station sign in Estonia Statoil is a Norwegian petroleum company established in 1972. ...

See also

• Decompression sickness
• Piper Alpha

Decompression sickness, (DCS), divers disease, the bends, dysbarism, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. ... The Piper Alpha was a North Sea oil production platform operated by Occidental Petroleum (Caledonia) Ltd and Texaco, which owned a 22 percent share. ...

References

Giertsen, J.C. et al., "An Explosive Decompression Accident", The American Journal of Forensic Medicine and Pathology, 9(2):91-101, 1988.