In selected pipe joints inductive position sensors are installed to supervise the joint gaps. At least three sensors are mounted and calibrated in each measurement joint. As a general rule, two or three measurement joints are aligned one after another. The inductive position sensors project to the interior of the pipe radially about 8 cm and have a length of about 35 cm. An additionally required box with the side lengths of 32 cm x 32 cm projects 20 cm to the interior of the pipe.

The following images show the arrangement of inductive position sensors to measure the joint gaps in reinforced concrete pipes and the arrangement of the sensors in GRP-jacking pipes with additional inductive position sensors to measure the bending of the pipe.