Alexander L. Kielland

1980

Ekofisk field, the fatigue crack, one hundred and twenty-three Location: North Sea, Ekofisk oil field · Coordinates: 56.50°N 3.17°E · Casualties: 123 · Survivors: 89 · Depth: 74 m · Cause: structural failure · capsize — A pre-existing fatigue crack in one of five bracing columns propagated during a North Sea storm at 18:30 on 27 March 1980, severing the column. The loss of the column imbalanced the semi-submersible hotel platform; it heeled through 35 degrees and capsized in twenty minutes. The crack was traced to a defective weld at a welded hydrophone flange. · Fate: righted 1983 · scrapped · Type: semi-submersible accommodation rig · Tonnage: 10,105 tons · Crew: 212 · Flag: Norway · Launched: 1976 Norwegian semi-submersible accommodation platform in the Ekofisk oilfield. On the evening of 27 March 1980, a fatigue crack in a weld around a hydrophone flange severed one of her five support columns. She heeled 35 degrees and capsized in twenty minutes. 123 dead of 212 aboard. Norway's worst peacetime maritime disaster and the spur to an overhaul of North Sea platform certification. The Vessel The Alexander L. Kielland was a Norwegian semi-submersible offshore accommodation platform, built at Compagnie Française d'Entreprises Métalliques at Dunkerque, France, and delivered to its owner Stavanger Drilling Company in 1976. She was an unusual combination of offshore industrial equipment: she was designed as a "flotel", a floating accommodation platform supporting up to 386 offshore workers, rather than as a drilling rig. Her platform design was an adaptation of the semi-submersible drilling rig architecture to the specific requirements of accommodation service: five vertical columns supporting a main operating deck on which her housing blocks, mess hall, recreation facilities, and helicopter deck were located. Her hull was 99 metres long and 85 metres wide (at her pontoons); her operating deck was 25 metres above the sea surface. She had been chartered by Phillips Petroleum for the accommodation of workers on the Ekofisk 2/4B production platform in the Ekofisk oil field in the Norwegian North Sea. Her specific mission through the late 1970s was to house the additional operational crew and contractor personnel working on the Ekofisk platforms, operating approximately 200 kilometres offshore from Stavanger. She was moored adjacent to the Ekofisk platforms by anchors and a flexible connecting bridge. The Disaster The subsequent investigation, conducted by the Norwegian Kongelig Kommisjon (Royal Commission) between March 1980 and March 1981, identified the specific cause of the sudden list. One of the platform's five support columns, designated "Column D", had failed structurally at a welded connection at the column's base. The specific weld failure was a fatigue crack that had been propagating for approximately two years, through the normal operational cyclic loading of the platform. The crack had reached critical length on the evening of 27 March 1980 and had propagated completely through the column at approximately 18:29:30. The sudden loss of Column D's structural support produced an immediate 20-degree list as the platform's main deck began to transfer load to the four remaining columns. The four remaining columns could not carry the asymmetric load; Column C collapsed approximately 15 minutes after Column D. The platform rolled onto her port side at approximately 18:47 on 27 March 1980 and capsized completely. The evacuation of the 212 people aboard, at night, in the North Sea storm, was catastrophically inadequate. Only four of the platform's seven lifeboats were launched successfully; the three others were trapped by the capsize or destroyed during the roll. The platform had also been equipped with 20 life rafts; approximately half were launched successfully, though many were damaged by the capsize and could not maintain stability in the heavy seas. 123 of Alexander L. Kielland