NOV's two main predecessors, Oilwell Supply and National Supply, were founded in 1862 and 1893, respectively. These two companies manufactured and distributed pumps and derricks. In 1930, acquired Oilwell Supply. In 1958, merged with National Supply. In 1987, National Supply merged with USS Oilwell to become "National Oilwell". Varco was founded as Abegg and Reinhold Company by Walter Abegg and Baldwin Reinhold i.
[pdf] A wear bushing, or sleeve, is installed in the casing head housing, or indeed in any compact or casing head spool, to protect the hanger landing preparations from damage while the drill string, tools, or other tubulars are run through, or rotated in, the wellhead. .
In some systems, the sleeve is held in place by a set of tie-down bolts contained either in the top flange of the housing or in a separate hold-down flange installed between the housing.
[pdf] Jackup rigs are so named because they are self-elevating with three, four, six and even eight movable legs that can be extended (“jacked”) above or below the hull. Jackups are towed or moved under self propulsion to the site with the hull lowered to the water level, and the legs extended above the hull. The hull is actually a water-tight barge that floats on the water's surface. When the rig reaches the work site, the crew jacks the legs downward through the water and int.
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