X - HKU Libraries

Because PVC pipework is light,internal pipework can easily "be displaced ordamaged during concreting, when cement grout orconcrete can enter and "block the pipe permanentlyso that it never functions* ibr this reason,particular care should be taken to ensure that PVCpipework to be cast into concrete is firmly andrigidly fixed within the formwork before concretingstarts*4*16.3 Movement^ ^ joints*3 (Cont'd)! 1983)As a general principle f pipework should avoidmovement joints or cress them without physical connection*Hhere pipework crosses a movement joint,provision must be made for the pipe to move in sympathywith the structure*Horizontal or near^horizontal pipework crossinga movement joint may be connected by a sleeved or flexibleconnection across the joint*Vertical | or neaiwertical , pipework crossingfrom a deck to a column may also be connected by meansof a flexible connection. Preferably the pipe should bebroken, with the upper pipe discharging into a hopperhead at the top of the column downpipe big enough toaccommodate both the anticipated discharge and theanticipated movements* Flexible connections areunlikely to last as long as the rest of the structure,and must therefore be accessible and replaceable, ifused. Their short life makes their use undesirable,they should be avoided as far as possible.