Swivel Sub 31/2" FH x 41/2" IF API7-1 SPEC
A sub is a special short length of threaded pipe used to connect drill pipes to drill collars, with a drill pipe connection on one end and a drill collar connection on the other.
There is a wide range of subs available, including:
Swivel Sub
Straight (slick) Crossover Sub
Bottleneck (reduced section) Sub
Crossover Sub with Float Bore
Bit Sub with Float Bore
Bit Sub without Float Bore
Top Drive Saver Sub
Kelly Saver Sub
Kelly Saver Sub with a stretched on rubber protector
Lift Sub (18 deg taper)
Lift Plug
