how many feet of drill pipe can be stacked on a derrick
The derrick supports the crown block and provides a place to stack pipe that is pulled out of the hole. The depth rating of the derrick is related to the size of the rig. The height of the derrick is commonly referred to in multiples of pipe joints (a joint of pipe is approximately 30 ft long). Rigs that can stack double joints of drill pipe are called double derricks, and those that stack three joints are called treble derricks. Part way up the derrick are the monkey board (3) and pipe fingers. The derrickman handles the top end of each stand of pipe from the monkey board during trips.