An alternative to couplings is to include the female part of the threaded connection as an integral part of the drill steel.
Like most developments, it has its advantages and disadvantages. Male/Female drill steel pro- vides more rigid connections and is easier to uncouple and handle. The service life also tends to be better than with separate couplings. This is fortunate because the coupling end cannot be re-placed.
The advantages of drilling with M/F steel include: easy handling, quicker uncoupling, tighter con-nections and the potential to drill straighter holes.