Repair and reconstruction of engineering structures - Assessment and Refurbishment of Steel Structures - page 307

measurements of the whole surface of the pipe. Such plungers consist of several modules,
connected with each other by means of a universal joint. From one to five modules are
used, depending on the diameter and construction of the device (Figure 6.145). Such
modular construction is necessary because of the large number of electronic systems to
be packed inside. Moreover, the device has to travel around bends easily. During the
travel test the pipe wall thickness is measured, and also the distance from the heads to the
wall. When the two results are correlated it is possible to determine whether the corrosion
damage is from inside or outside the pipe (Figure 6.146).
Figure 6.145 Intelligent piston to test
the technical condition of the pipeline