Flexible couplings in water piping

[mflam]

We are replacing a 12 inch water main in a city street with cement lined ductile iron pipe. We will be stopping about 30 feet away from a highway overpass where the main is hung below the bridge.

The plan calls for finding the existing main, cutting it and coupling to it with a solid sleeve. Then we'll hang a gate valve and start the replacement pipe.

There was a break at this location several years ago. The repair has served well with no further problems.

Should we put in a flexible coupling near the abutment?

 

[rconner]

I have noticed you have not yet gotten any responses to your inquiry. While I believe that flexibility is good when it comes to underground piping connections in general (as thus all differential settlements, ground, and/or relative ground to structure movements will not immediately result in unnecessary strain or stress in piping barrels, when joining flexibility is available), you might want to post at least a sketch of exactly what you are talking about to get more learned or experienced responses from others. Connections of directly buried pipelines to any much larger structures, that might result (for various reasons) in different basic support conditions, in particular can be locations where significant relative movement can occur. They are thus locations where flexibility may be particularly valuable. [Notice e.g. the guidance with regard to “Seismic Conditions” on page 5 of the publication at

http://www.sitelevel.com/click?url=http://

http://www.dipra.org/pdf/bridgeCrossings.pdf&sid=TpLYIo9x8QzPlod6

.]