Deflection in DIP

[nutbutter]

I was curious what is considered the maximum deflection allowable for construction/design of DIP water mains. I know this will vary by location, but I'm just looking for some general idea. I'm talking about standard AWWA C900 DIP. I've heard from 2-5 degrees. Does that sound about right?
Peace,
Stoddardvilla

 

[LCruiser]

I'm not quite sure how you're measuring deflection in degrees. I think that's usually measured in %. To get deflection in DIP is difficult anyway, I would think...

 

[rconner]

You can go to the the websites dipra.org or acipco.com (and thereafter follow navigation buttons or search dialogue boxes to keywords including "design") for a lot of information on this. ANSI/AWWA, ISO/BSEN, and ASTM etc. consensus standards also publish allowable limits of ring deflection in buried service for ductile iron pipe (as I assume you are talking about, though "C900" is a standard designation for pvc, not DIP water pipe) up to 5%, depending on size and whether the specified pipe for the application is cement or more flexibly lined etc. Please clarify if any of the assumptions herein are incorrect.

 

[nutbutter]

Yes, assumptions are correct. Thanks for the websites. I haven't done much work designing water main extensions so it'll help. DIP will be lined with polyethylene.
Peace,
Stoddardvilla

 

[nutbutter]

Nevermind my previous question, I think I may have asked the wrong one. I'm not curious about "deflection", but moreso about how horizontal/vertical bend angles can be obtained outside of standard bend angles (90, 45, 22.5, 11.25 degrees).
If I need to make a 9 degree bend, is there any way to introduce another 2.25 degrees into the bend to use a standard 11.25 degree bend?
I'm just a little confused. Having never worked on pipe installation in the field, I'm unsure how they go about achieving bends that are outside of the standard bend range. Are there smaller bends? Do they fit the pipes at a slight angle (this is what I meant by "deflection", my bad), if so how large can this angle be? Etc?
Anyway, I asked the wrong question. Hopefully this will clarify what I'm asking. Any help would be much appreciated. Oh yeah, also it's polyethylene-encased (not lined) and lined with standard cement.
Peace,
Stoddardvilla

 

[rconner]

For at least many small diameter ductile iron pipe systems, and with a level of contractor experience, there is often little need at all for small angle bends (and a pile of them is sometimes left over after jobs). As possible e.g. with contemporary allowable joint deflection features at acipco.com, a contractor can generally start "deflecting" joints (we are now talking about in effect axial joint deflection off line, not ring deflection due to earth loading) a little ahead of time when laying toward the small angle devation or inflection point, and the line can be turned (as in a radius) in just a few joints of straight pipe without a fitting.

 

[LCruiser]

The deflection, or "pull" is dependent on the joint dimensions. Therefore, the angle of the bend depends on the diameter of the pipe. The joint details should list the amount of pull, in inches (or cm, whatever). the arctan of the pull over the diameter is the angular displacement.

 

[CarlB]

Generally a deflection of 5 degrees per joint is allowable, for DIP up to 12" diameter.

See publication

http://www.dipra.org/pdf/joints.pdf