Water line design on steel bridge
Water line design on steel bridge
(OP)
If I want to design a 8" PVC line through a steel bridge, would this line need to be encased? Or would I have to replace the PVC with a different material? What can I use for expansion? Is there a helpful book or website for this type of design? The water line is to go between the 1st and 2nd I-beam, then through the wall and back under the ground at each end. The line will be exposed to the weather and I will have to consider the cold and the heat. Does anyone have any advice?





RE: Water line design on steel bridge
http://www.dipra.org/
www.SlideRuleEra.net
RE: Water line design on steel bridge
RE: Water line design on steel bridge
RE: Water line design on steel bridge
In addition the Poissons ratio is only 0.35. Hence when pressurised the pipe will shrink from its anchors and cause local stresses that may fail. It will also need more pipe supports than for a ferrous product.
RE: Water line design on steel bridge
It seems like there is stigma against plastic. Would plastic be alright if it was inside a carrier pipe, thus it would have room to expand and contract? I for one would really appreciate some more explanations and comments on this thread. The only thing I have to offer is that steel pipe is also an option.
RE: Water line design on steel bridge
Problems with PVC-U include:-
1) thermal expansion/contraction which can result in failure due to "follow on" strains exceeding the material design parameters. Do NOT assume that the thermal strain will occur linearly along the length of pipe on a bridge crossing. One section may be exposed to the sun, its temperature increases, the material weakens and all the strain occurs in a small section.
2) PVC-U has low fracture toughness below 5C. Wind chill on a bridge can easily get the pipe surface below this figure.
3) Wind loading can cause a pipe surface to fret in a bridge crossing
4) Sunlight and UV can be detrimental to PVC-U in the long run.
5) Vibration due to wind or traffic load can cause problems
If you intend using steel make sure it is epoxy coated on the outside and lined internally either with cement or PE, epoxy etc.
You could consider spiral wound stainless steel, its cheaper than coated carbon steel.
I would stay away from GRP.
There is nothing wrong with ductile iron cement lined pipe. Just because its been around for a long time dont discount it.
RE: Water line design on steel bridge
Unless I'm way out of my league here, the first thing you need to do is determine what the utility company will allow you place on the bridge. I have yet to meet with a utility representative that has left this up to the bridge engineer.
Most utilities are run in between girders for slab and girder bridges so that impact damage is prevented. Most utilties require a single roller type hanger with some companies using double roller hangers. Most of these are hung not from the slab but from special diaphragms attached to girders. The rollers are prefered as they help with expansion and installation. Most contractors like to put the pipe together and push it across the bridge rather than piecemeal it. So if it's a long distance to push, and I've seen 300+ feet tried, there are hang-ups with the double rollers binding.
I have never seen a large utilty on a full depth slab bridge that was not encased in a concrete duct bank.
Most other utilties such that would fit in up to 4" conduit are placed inside the barrier curbs.
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Water line design on steel bridge
1. Relatively easy to accommodate pipe movement (both thermal expansion and the deflection / vibration all bridges experience in use).
2. Cement lining has excellent flow characteristics (Hazen & Williams, C = 140) and it maintains a high value over many years.
3. The pipe exterior (iron) is resistant to corrosion.
4. The pipe itself has good structural properties that maximize the spacing of pipe hangers or other supports.
In my previous post I gave a link to DIPRA. Here is specific link (free .pdf download) at the DIPRA website, "Bridge Crossings With Ductile Iron Pipe"
http://www.dipra.org/pdf/bridgeCrossings.pdf
www.SlideRuleEra.net
RE: Water line design on steel bridge
We have done many bridges for various applications and have placed the pipes in different configurations. The advice given by Stanier and SlideRuleEra are on point.
Typically only see pvc for short term applications ... as pointed out by other posts, for the reasonss stated. Good Luck.
RE: Water line design on steel bridge
RE: Water line design on steel bridge
RE: Water line design on steel bridge
It may be best to address your specific questions with regard to the insulated/pre-insulated piping to those folks who specialize in these aspects and support of same (e.g. Thermacor, Urecon, Perma-Pipe(spellings?)) etc. I believe most at least exterior insulated piping I've seen however does have secondary "jackets" that are often probably firmer/mmore impermeable than the insulation itself, the jackets accomplish varied functions, and sometimes also various "shoes" are used between the insulated pipes and/or jackets that perhaps also help to spread loads/wear etc.
RE: Water line design on steel bridge
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RE: Water line design on steel bridge
RE: Water line design on steel bridge
It tends to freeze.
A line can be insulated but is is often more economical and maintenance free to bury it in the stream bed or push it under the river.
Rick Kitson MBA P.Eng
Construction Project Management
From conception to completion
www.kitsonengineering.com
RE: Water line design on steel bridge