Fully restrained water pipeline?
Fully restrained water pipeline?
(OP)
Hi All-
I am looking at a project in southern California and the 24" Ductile Iron Potable water pipeline is shown as having fully all joint restrained. The pipeline has straight section several hundred feet long. I am wondering why the designer would indicate full restraint in the straight sections. I am not yet completely familiar with the design considerations of Southern California; is this due to seismic forces? Is this common here?
Thanks for the help!
I am looking at a project in southern California and the 24" Ductile Iron Potable water pipeline is shown as having fully all joint restrained. The pipeline has straight section several hundred feet long. I am wondering why the designer would indicate full restraint in the straight sections. I am not yet completely familiar with the design considerations of Southern California; is this due to seismic forces? Is this common here?
Thanks for the help!





RE: Fully restrained water pipeline?
Independent events are seldomly independent.
RE: Fully restrained water pipeline?
However, even though modern rubber-gasketed sockets can tolerate quite a bit of deflection and pull-out, there have been at least a few joint "pull-out" separation/leaks of unrestrained pipes in some soil environments in at least a few substantial earthquake events, where that specific soil mass was subject to excessive "lateral spreading" (and local "fissuring"), or substantial localized/relative ground movements or subsidence etc. Modern ductile iron restrained joints have multiple features that can be quite helpful in such cases, including some axial extensibility/extension (space in the joints, to absorb tensile and compressive ground waves without much challenging great compressive strength etc. of barrels), joint flexibility (ability for pipes to digress off the line of each other with movement in the joint, again without challenging great beam strength), as well as great tensile strength restraint capability to quite positively prevent separation (that allows joints that might be near a wide local fissure to mobilize/pull significant lengths of pipe on either side some though the ground, again without leaks or separations). Modern loose polyethylene sleeving or wrap, used now mostly for standard corrosion protection of ductile iron piping in potentially corrosive soil areas, aids further in this load distribution/mobilization process, acting as a sort of pipe-to-ground lubricant to the restrained joint piping.
RE: Fully restrained water pipeline?
If this line is located near potential liquifaction areas, than that could be a valid reason for additional restraint.
Now, given that things might have changed since the Northridge, Landers and Big Bear quakes. Additional resiliency is likely being designed for all underground utilities.
RE: Fully restrained water pipeline?
But I could see the reasoning behind restraining all joints in seismic zones. These articles discusse what they are trying in LA: http://www.kubota-global.net/us/news/2012/20121022...
http://www.dailynews.com/news/ci_22641789/earthqua...
RE: Fully restrained water pipeline?
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RE: Fully restrained water pipeline?
Thanks
RE: Fully restrained water pipeline?
Richard A. Cornelius, P.E.
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