There are several types of subs used within the industry which may vary by manufacturer, the most common being the following:
• Bit Sub: The bit sub connects BHA components to the bit and is often bored for a float sub.
• Crossover Sub: A short subassembly is used to enable the connection of two components with differing thread types or sizes.
• Float Sub: A float sub has a body which contains a one-way check valve to prevent drilling mud and cuttings flowing back up the drill string.
• Lift Sub: The lift sub is a solid device useful for picking up slick components at the surface.
Drill Collar - Lift
• 2-7/8" Connection and smaller
• 3-1/2" Connection and smaller
• 4-1/2" Connection and smaller
• 6-5/8" Connection and smaller
Pump-In (Through Bore)
• 2" 1502 x 3-1/2" and smaller
• 2" 1502 x 6-5/8" and smaller
Rotary Connections
• 1-1/4" thru 2-3/8"
• 2-7/8" thru 3-1/2"
• 4" thru 6-5/8"
Tubing Connections
• 1" thru 2-1/16" CS Hydril
• 2-3/8" thru 3-1/2" CS Hydril
• 2-3/8" thru 3-1/2" PH-6
• 2-3/8" thru 3-1/2" EUE, 8R
• 4-1/2" EUE, 8R
• 4-1/2" CS Hydril
• 4-1/2" PH-6