US PATENT SUBCLASS 137 / 515
.~.~ In couplings for coaxial conduits, e.g., drill pipe check valves

Current as of: June, 1999
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137 /   HD   FLUID HANDLING

455  DF  LINE CONDITION CHANGE RESPONSIVE VALVES {11}
511  DF  .~ Direct response valves (i.e., check valve type) {14}
515.~.~ In couplings for coaxial conduits, e.g., drill pipe check valves {3}
515.3  DF  .~.~.~> Valve seat threaded into a coupling element
515.5  DF  .~.~.~> Valve seat formed on or carried by a coupling element
515.7  DF  .~.~.~> Valve seat clamped between coupling elements

DEFINITION

Classification: 137/515

(under subclass 511) Valves in which the valve is associated with or mounted in a housing provided with means for joining it with pipe at both ends, the three elements being longitudinally aligned when connected.

(1) Note. Many of the patents classified in this subclass are for use in a drill string.

SEE OR SEARCH THIS CLASS, SUBCLASS:

155, for gas lift valves for wells.

SEE OR SEARCH CLASS

166, Wells,

86.1+, for a well pipe having an anchor or seal with a valve, subclass 97.1 for a well cap or head with a valve, and subclasses 316+ for valves, closures, or changeable restrictors down in a well 251, Valves and Valve Actuation,

148+, for valves contained in a pipe line or coupling, and see the search notes to subclass 148.