door - drop
- double-glut butt joint
- double-groove preparation
- double-groove weld
- double-head burner for edge preparation
- double-head weld
- double-headed coil stand
- double-hearth furnace
- double-high mill
- double-humped resonance curve
- double-J groove
- double-j groove weld
- double-J joint
- double-J tee butt weld
- double-looping pit
- double-oblique crystal
- double-pass mill
- double-pipe condenser
- double-piston explosive press
- double-pressed
- double-probe system
- double-probe technique
- double-quadrant valve
- double-quantum transition
- double-reduction unit
- double-resuperheat machine
- double-rod drawbench
- double-roll crusher
- double-roller guide
- double-run pull-off transfer
- double-shrink pattern
- double-sided (hot) bed
- double-sintered
- double-skip charging
- double-skip hoist
- double-spade guide
- double-spiral classifier
- double-stack kiln
- double-stage nitriding
- double-stage regulator
- double-stand rolling mill