HDPE pipe elevation tolerance.
HDPE pipe elevation tolerance.
(OP)
Hi, guys,
I have some deep underground HDPE pipes, DR 9 and DR 11. I am wondering who know elevation(grade) deviation for these kind of pressured pipes.
Many thanks for your kind consideration. Any reply is greatly appreciated.
Best regards,
I have some deep underground HDPE pipes, DR 9 and DR 11. I am wondering who know elevation(grade) deviation for these kind of pressured pipes.
Many thanks for your kind consideration. Any reply is greatly appreciated.
Best regards,





RE: HDPE pipe elevation tolerance.
Without knowing what your concerns are, it is difficult to say what deviations are reasonable.
RE: HDPE pipe elevation tolerance.
These pipes are 8" and 10". As built deviation is around 100 mm. Without any sepecial reason, I think 100 mm deviation is acceptable. Do you have any similar experience?
RE: HDPE pipe elevation tolerance.
RE: HDPE pipe elevation tolerance.
RE: HDPE pipe elevation tolerance.
RE: HDPE pipe elevation tolerance.
Yes, I permitted 50 mm deviation of elevation for contractor. I don't know why they can't install pipe within the tolerance. These pipes are not big or heavy. Gee.
RE: HDPE pipe elevation tolerance.
Where the trench bottom soil can be cut and graded without difficulty, pressure pipe may be installed directly on the prepared trench bottom. For pressure pipe, the trench bottom may undulate, but must support the pipe smoothly and be free of ridges, hollows, and lumps. In other situations, bedding may be prepared from the excavated material if it is rock free and well broken up during excavation. The trench bottom should be relatively smooth and free of rock. When rocks, boulders, or large stones are encountered which may cause point loading on the pipe, they should be removed and the trench bottom padded with 4 to 6 inches of tamped bedding material. Bedding should consist of free-flowing material such as gravel, sand, silty sand, or clayey sand that is free of stones or hard particles larger than one-half inch.
http://www.plasticpipe.org/pdf/chapter07.pdf
The grade deviation should not matter unless you are outside the cold bending radius of the pipe.
One would assume that CVG is referring to the recommendations for location of services. In the UK, there are some recommended depths for water mains. The tolerances at the recommended depths vary from 150-300 mm. The recommended locations will be set by the local utility planning agency.
RE: HDPE pipe elevation tolerance.
cold bending radius is only one parameter that should be evaluated. there are others including the references to air pockets and frost zones which have already been mentioned.
RE: HDPE pipe elevation tolerance.
My assumption is that this is water pipe. He may be talking about sewer pipe, irrigation pipe, force main, or whatever. He has also not said what type of terrain that he working in. He might be working in Times Square or the open plains.
RE: HDPE pipe elevation tolerance.
Thanks!
RE: HDPE pipe elevation tolerance.
Perhaps you can tell what this installation consists of:
New or existing location?
Application of Piping: water main, water sewage, gas, or whatever?
Industrial or municipal?
Installed in city street or in farmland?
RE: HDPE pipe elevation tolerance.
See e.g. the reported issues raised (so to speak) in the second paragraph at http://
With high levels of compaction also required by many specifications (as it appears here) for any sort of long-term, dependable support of plastic pipes (at least those with low long-term stiffness in and of themselves), it doesn't explain exactly how this conundrum is to be avoided!
RE: HDPE pipe elevation tolerance.
The pipe is new installed in industrial area for waste water. Before installation, dewatering had been done to dry trench.
RE: HDPE pipe elevation tolerance.
The minimum depth is usually specified as the frost line, but the maximum depth is not specified.
Having said that, you must also keep the force main the specified distances away from water mains and other buried utilities.
I did find a standard specification online for laying tolerance:
Installation tolerances for the pipe shall not vary more than 50mm (2") horizontally or 25mm (1") vertically from the alignment and elevations shown on the Approved Plans.
h
However, unless you have that specified in the Contract documents, there is no way that you can force the Contractor to maintain that tolerance.
The only reason that one would want a laying tolerance is to assist in the future line tapping
RE: HDPE pipe elevation tolerance.
Richard A. Cornelius, P.E.
WWW.amlinereast.com