A cylinder tube assembly group, comprising a cylinder tube and a connection piece , wherein the cylinder tube comprises a cylinder basic body and a connection portion (1.3), wherein the connection portion (1.3) has an outer shell calotte , an inner shell calotte , a structural strengthening zone and a connecting borehole , wherein the outer shell calotte is arranged on a cylinder outer shell (1.1) and the inner shell calotte is arranged on a cylinder inner shell (1.2), and wherein the calottes are formed as cold-formed concave embossing-form portions, wherein the structural strengthening zone (1.4) is arranged in a forming region between the calottes , wherein the connecting borehole is designed for a pressure medium passage of a pressure medium and as a punched borehole and passes through the calottes , and wherein the structural strengthening zone encompasses the connecting borehole , wherein the connection piece is arranged at the connection portion (1.3) and comprises a pressure-medium tube and a connection section, wherein the pressure-medium tube is designed for a pressure-medium line of the pressure medium, wherein the connection section has an annular axial boundary contour (7.1), wherein the annular axial boundary contour (7.1) and an annular mating surface (3.1) of the outer shell calotte form an annular contact surface, wherein the cylinder tube and the connection piece are connected in a positive substance manner at the annular contact surface by means of a ring weld seam and the ring weld seam forms a sealing plane, and wherein the pressure medium tube and the connecting borehole form a common pressure medium channel. comprising a cylinder tube and a connection piece , wherein the cylinder tube comprises a cylinder basic body and a connection portion (1.3), wherein the connection portion (1.3) has an outer shell calotte , an inner shell calotte , a structural strengthening zone and a connecting borehole , wherein the outer shell calotte is arranged on a cylinder outer shell (1.1) and the inner shell calotte is arranged on a cylinder inner shell (1.2), and wherein the calottes are formed as cold-formed concave embossing-form portions, wherein the structural strengthening zone (1.4) is arranged in a forming region between the calottes , wherein the connecting borehole is designed for a pressure medium passage of a pressure medium and as a punched borehole and passes through the calottes , and wherein the structural strengthening zone encompasses the connecting borehole , wherein the connection piece is arranged at the connection portion (1.3) and comprises a pressure-medium tube and a connection section, wherein the pressure-medium tube is designed for a pressure-medium line of the pressure medium, wherein the connection section has an annular axial boundary contour (7.1), wherein the annular axial boundary contour (7.1) and an annular mating surface (3.1) of the outer shell calotte form an annular contact surface, wherein the cylinder tube and the connection piece are connected in a positive substance manner at the annular contact surface by means of a ring weld seam and the ring weld seam forms a sealing plane, and wherein the pressure medium tube and the connecting borehole form a common pressure medium channel. <EOS>