Repair and reconstruction of engineering structures - Assessment and Refurbishment of Steel Structures - page 338

Figure 6.177 A view of the rigid,
movable binder and lifting presses
During lifting, the stress in the pipeline covering was monitored tensiometrically. The
sensors were placed in the lifting area and where the pipeline entered the ground. At the
same time, deformations in vicinity of the guard ends were also monitored. In all repairs
under operational pressures, the safety rules for working in vicinity of a gas pipeline must
be followed.
6.2.3.6 Lowering flooded pipelines
During floods pipelines are often flooded. At one locality, the pipeline was flooded above
ground for a length of 92.0 m (Figure 6.178) and insufficient soil covering was left over a
section of about 250 m. At the same time the pipeline was offcentred from its horizontal
axis by about 1200 mm and approximately 700 mm above the ground. Tracks showing
that agricultural machinery had ridden over the flooded pipeline were assessed but no
cracking was detected by magnetic tests. Scratch traces were removed by grinding to a
maximum depth of 1.0 mm. The original damaged insulation was removed and the
pipeline was cleaned by sand blasting. The length to be repaired, of approximately 150
m, was loaded with standard reinforced-concrete loading saddles. The density of the
arrangement of loading saddles, as well as the distances between supports of the pipeline
during lowering were determined from static calculations. The pipeline insulation is