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] 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] Kelly Pin drilling tools are essential components used in the oil and gas industry for drilling operations. These tools are designed to securely connect the drilling rig’s Kelly bar to the drill pipe, providing a reliable and efficient transfer of torque and rotational power.
[pdf] 
