Derrick
Derrick and Mast are tall steel structures built to support the loads of the drilling tools which can weigh many tones. The tallest Derricks or Masts are about 200 ft where as the shortest is about 65 ft. The Mast structure is assembled in horizontal position and then raised to vertical as a single unit on a pivot point using the power of drawworks or hydraulic pistons. Whereas Derrick is assembled vertically by bolting one piece at a time.