Abstract: A connection between a drill pipe (1) made of carbon- or glass fiber-reinforced plastic and a tubular, preferably metal connector (2) that is partially held in one end (3) of the drill pipe (1) and is cemented to it is characterized in that a thrust element (8) that is positively connected to the connector (2) in the region of the end (3) of the drill pipe (1), in which the connector (2) is held, presses on the outside of the end (3) of the drill pipe (1).

Abstract: A connecting device, for example, a plug (1) for connecting electrical power supply lines (3), includes a connection (4a) for feeding electrical signals representing the operating state of an electrical, mechanical, hydraulic, or optical device into the power supply line (3). The use of such a connecting device in drilling and production facilities is also described.

Abstract: A connection between a drill pipe (1) made of carbon- or glass fiber-reinforced plastic and a tubular, preferably metal connector (2) that is partially held in one end (3) of the drill pipe (1) and is cemented to it is characterized in that a thrust element (8) that is positively connected to the connector (2) in the region of the end (3) of the drill pipe (1), in which the connector (2) is held, presses on the outside of the end (3) of the drill pipe (1).

Abstract: A device for detecting the length of a drilling column that has a plurality of pipes (1) assembled on couplings (2) is characterized in that on the pipes (1), there is at least one electrical line (3, 4) that is galvanically connected to the couplings (2). On one end of the electrical line (3, 4), there is a means (7) for the feed of electrical pulses into the electrical line (3, 4) and for detecting the propagation time of the electrical pulses from the means (7) to a reflection site on the other end (5) of the electrical line (3, 4) and back.