| 摘要 |
A mud saver valve comprising a tubular body connectable between a kelly and a drill string. A piston is mounted therein and includes a bore substantially coaxially aligned with the central opening. A plug is removably mounted in the piston and is movable between a first position wherein a spear sealingly engages the valve seat and a second position that allows fluid to flow upward between the spear and the valve seat. The piston is constructed with an elongate intermediate body section having a plurality of O-rings secured therein and disposed beneath angled ports for enhancing lateral stability of the piston within the body. The valve seat is furthermore secured within the body by a spanner ring with the valve seat being formed with a curved mating surface adapted for flushly engaging a curved valve seat surface of a valve seat disposed upon the piston. Both the upper and lower valve seats are removable for field repair while axially actuatable with lateral stability.
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