Two-layer conveyor elbows with a wear-resistant inner elbow and a pressure-bearing outer elbow. The inner elbow is uniformly through-hardened over its entire length. The elbow extensions have the same material specification. The wear layer has a hardness of 63 HRC. The ESSER TWIN 700 series has been used for decades in a wide variety of construction projects worldwide. 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.