Tubular string control valve
United States Patent 2921601
US Patent References:
Back pressure valve
- - 1814549

Drill stem
- - 1818508

Valve
- - 1916767

Means for flowing wells
- - 2154768

Core barrel operated float valve
- - 2162578


Inventors:
Fisher Jr., Hiram H.
Publication Date:
01/19/1960
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Assignee:
BAKER OIL TOOLS INC
Primary Class:
137/496
Other Classes:
166/321, 251/339, 175/318, 137/515.700, 137/504
International Classes:
E21B21/10; E21B34/08; E21B21/00; E21B34/00
US Patent References:
2676611Fluid pressure trip controlled emergency shutoff valves
2797705Valved piping arrangement