Buderus Manual on Trenchless Installation of Ductile Cast ... - Duktus

7. 2 A description of the technique
In the relining technique, ductile cast iron pipes to DIN EN [7.1] or DIN EN 98
[7.2] are pushed or pulled into the existing, old pipeline. They slide on their sockets
when this is done. What is important in this case is for the old pipeline to be properly
prepared. When work of this kind was done in the past, it was found that a coefficient
of friction of µ < 1.0 can always be achieved if the old pipe is properly prepared – if encrustation
is removed (Fig. 7.1), if gaps in the floor of the pipe at the sockets are closed
off, if lubricant is applied to the floor of the pipe, and so on.
Generally speaking, the annular space left between the old pipe and the new pipe is
filled with an alkaline insulating material. If this is done, ductile iron pipes with zinc
coating and cover coating are sufficient (Fig. 7.2). If not, ductile iron pipes with cement
mortar coating have to be used.
Fig. 7.1 High-pressure cleaning of the old
pipeline
7.2.1 Pulling-in
For pulling-in, the positive locking longitudinal
force-fit BLS ® restrained joint (Fig.
7.3) needs to be used.
Fig. 7.3
Cut-away views of the DN 80 to DN 500 and
DN 600 to DN 1000 BLS ® restrained joints
A description of the technique, pulling-in
Fig. 7.2 Insulation of the annular space
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