Mud saver valve

Claim 2

A mud saver valve, which comprises: a tubular body connectable between the kelly and the drill string: an annular seat ring mounted within said body, said seat ring having a central opening; a piston axially movably disposed within said body for engagement with said seat ring, said piston having a bore substantially coaxially aligned with said central opening and a flange extending radially outwardly from said piston to slidingly engage the interior of said body, said piston having a port above said flange communicating the exterior of said piston with said bore; a plug removably mounted in said piston above said port to normally close said bore, said plug including a shear ring removably inserted in said bore with a shear pin shearingly connecting said shear ring with said piston, and a spear axially movably mounted in said shear ring for movement between a first position wherein said spear sealingly engages said shear ring and a second position to allow fluid to flow upwardly between said spear and said shear ring; and means for urging said piston into engagement with said seat ring.

Claim 3

The valve as claimed in claim 1, including means for stabilizing said piston within said body.

Claim 4

The valve as claimed in claim 2, wherein said stabilizing means includes a plurality of longitudinal fins extending radially outwardly from said piston to slidingly engage the interior of said body.

Claim 5

The valve as claimed in claim 1, wherein: said shear ring includes central aperture; and said spear includes a first portion sealingly engageable with said central aperture of said shear ring, a second portion below said first portion forming a flow passage between said spear and said central aperature, and means for limiting the upward travel of said spear with respect to said shear ring.

Claim 6

The valve as claimed in claim 1, wherein: said shear ring includes upper cylindrical aperture and a lower cylindrical aperture having a diameter smaller than the diameter of said upper aperture, said upper and lower apertures being connected by a shoulder; and said spear includes an upper cylindrical portion having a diameter substantially equal to the diameter of said upper portion of said shear ring, and lower cylindrical portion having a diameter substantially equal to the diameter of said lower portion of said shear ring, said upper and lower portions being connected by a shoulder engageable with said shoulder of said shear ring, said lower portion including a plurality of longitudinal grooves and a plurality of feet extending radially outwardly therefrom to limit the upward travel of said spear with respect to said shear ring.

Claim 7

The valve as claimed in claim 1, including an elastomeric seating surface mounted to seat ring and forming a seat with said piston.

Claim 8

The valve as claimed in claim 1, wherein said urging means includes a compression spring disposed between the lower side of said flange and an annular ledge in the interior of said body.

Claim 9

The valve as claimed in claim 1, wherein said spring is adapted to compress fully when mud is flowing downwardly through said valve.

Claim 10

The valve as claimed in claim 1, wherein said seat ring includes a downwardly depending skirt for preventing washing of said body.

Claim 11

A mud saver valve, which comprises: a tubular body connectable between the kelly and the drill string; an annular seat ring mounted within said body, said seat ring having a central opening; a piston axially movably disposed within said body for engagement with said seat ring, said piston having a bore substantially coaxially aligned with said central opening and a flange extending radially outwardly from said piston to slidingly engage the interior of said body, said piston having a port above said flange communicating the exterior of said piston with said bore; a plug removably mounted in said piston above said port to normally close said bore, said plug including a shear ring, removably inserted in said bore and a spear axially movably mounted in said shear ring for movement between a first position wherein said spear sealingly engages said shear ring and a second position to allow fluid to flow upwardly between said spear and said shear ring, said shear ring including a central aperture, and said spear including a first portion sealingly enageable with said central aperture of said shear ring, a second portion below said first portion forming a flow passage between said spear and said central aperture, and means for limiting the upward travel of said spear with respect to said shear ring; and means for urging said piston into engagement with said seat ring.

Claim 12

A mud saver valve, which comprises: a tubular body connectable between the kelly and the drill string; an annular seat ring mounted within said body, said seat ring having a central opening; a piston axially movably disposed within said body for engagement with said seat ring, said piston having a bore substantially coaxially aligned with said central opening and a flange extending radially outwardly from said piston to slidingly engage the interior of said body, said piston having a port above said flange communicating the exterior of said piston with said bore; a plug removably mounted in said piston above said port to normally close said bore, said plug including a shear ring, removably inserted in said bore and a spear axially movably mounted in said shear ring for movement between a first position wherein said spear sealingly engages said shear ring and a second position to allow fluid to flow upwardly between said spear and said shear ring, said shear ring including a central aperture, and said spear including a first portion sealingly enageable with said central aperture of said shear ring, a second portion below said first portion forming a flow passage between said spear and said central aperture, and means for limiting the upward travel of said spear with respect to said shear ring; and means for urging said piston into engagement with said seat ring.