Rotary Drill Pipe and Subs
Drill pipe, saver subs, crossover subs and shock subs that connect the rig spindle to the bit. Thread consistency and wall thickness are the specification.
Features
- Saver subs take the thread wear that would otherwise fall on the rig spindle or the pipe, and they are cheap to replace.
- Crossover subs allow a string to be built between two thread standards, which is how existing pipe stocks are used up.
- Shock subs absorb axial vibration, which extends bit bearing life in hard, broken formations.
- Wall thickness and hardbanding determine pipe life where the string rubs the hole wall.
- Thread greasing and correct make-up torque at every joint decides whether pipe lasts a season or a month.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Outside diameter | 114 - 273 | mm | Sets annulus velocity and string stiffness. |
| Sub type | saver / crossover / shock | Each solves a different problem in the string. |