Cr 32, 42 and 50 are used for core drilling and acaryote drilling. Boreholes are not very deep. They are mainly used in mining industry, for exploration and the hydrogeology.
Diameters 50, 60 and 70 are used for drilling deep boreholes, max. to the 1300 m deep – depending on the composition of rocks. They serve for nuclear geology. The drilling pipes are connected by screwing of the ends of convolutes.