Repair and reconstruction of engineering structures - Assessment and Refurbishment of Steel Structures - page 343

circumference were installed in the test pits so that the initial measurement state and null
reading could be defined.
When another change in the pipeline emplacement occurs, i.e. the pipeline is dug out,
also the dynamic conditions and normal stresses are changed, and these changes are also
recorded. The sensors in the test pits monitored the situation in the original excavation
during the subsequent depressurizing and repair works. While depressurizing the
pipeline, a value of ∆σ=338.0 MPa was measured in the cross sensor, which exceeded the
theoretical value by approximately 50 MPa. A defective weld in the pipeline was repaired
in this case by replacing a section of pipe. The cutting and subsequent insertion of the
new section is shown in Figures 6.182 and 6.183. After cutting and subsequent
stabilization of the pipeline a pressure of 40 MPa was released over the given section.
The pipeline was now behaving elastically and the components of the additional
longitudinal stresses caused by slide were eliminated.
Figure 6.182 The cut pipeline