Door system for a mine stopping

Dormant borehole sealing device

Double acting hydraulic mechanism

Double acting shock absorbers for drill strings

Double barrier system for an in situ conversion process

Double collet release mechanism

Double cylinder screen

Double guided mud pulse valve

Double piston in-the-hole hydraulic hammer drill

Double rod cylinder feed system

Double seal with lubricant gap between seals for sealed...

Double seated gas lift valve

Double shearing rams for ram type blowout preventer

Double shoulder oilfield tubular connection

Double slot selective mining system

Double tube jetting tool

Double walled insulated tubing and method of installing same

Double-acting accelerator for use with hydraulic drilling jars

Double-acting jar

Double-acting jar