Vetter Pipe sealing bags and bypass bags FS - Manual (Page 9)

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9 Secure the sealing bag with a securing line in order to avoid
the bag slipping back when deflated.
9 The support structure should be made so that the sealing bag
can be supported over a large area.
9 Leave the shaft and/or pipeline.
9 Make certain that no staff remain in the area of danger.
9 Inflate the sealing bag to the permitted maximum operating
pressure from a safe position
There is a danger of the bag catapulting outwards. The pressure
or water column must be completely reduced within the pipeline
before the support structure is removed. Otherwise the sealing
bag could catapult outwards. After completion of the work, pres-
sure reduction is to be carried out via the inflation hose (ventila-
tion nipple) or the controller (pressure reduction via the knurled
screw of the safety valve). Generally this must be made outside
the pipeline or shaft.
9 If the water has completely flowed out of the shaft/pipeline
then release the compressed air out of the bag.
9 Now remove the support structure and take the bag out of
the shaft/pipeline.
4.2 Support structure
The type of support structure depends on the structural factors in
the pipe, the pipe itself and the counter-pressure to be expected.
The following support possibilities are only drawing diagrams and
are given as examples.
General details of support (presented as a diagram)
1 Bag centre
2 Inflatable bag sleeve
Support suggestion for a ditch
(presented as a diagram)
Support suggestion for a street inlet shaft
(presented as a diagram)