Two-layer conveying pipe. The wear-resistant inner pipe is uniformly through-hardened to 63HRC over its entire length. The outer pipe is pressure bearing. The male-female geometry of the weld-end surfaces centers the pipe and seals it tightly. O-rings are used as sealing elements. Particularly suitable for GRP “High performance plastics” due to the tight tolerances and after additional treatments of internal surfaces. With 3/4 inch sleeve for connection of measuring instruments, secondary air lines, etc.