I believe the Ductile Iron Pipe Research Association ("DIPRA"), in conjunction
of course with I suspect interested Owners of the specific pipeline systems, has
accomplished hydraulic testing on at least a few installed actual (u)pvc systems
that are referred to on page 9 of 14 of their publication at
<a href="http://www.dipra.org/pdf/DIPvsPVC.pdf">http://www.dipra.org/pdf/DIPvsPVC.pdf</a> . This was as I understand it in the
fashion of a great many more hydraulic tests they have performed with a great
many other interested Owners of actual iron piping systems over many decades.
While I heard no mention in conjunction with their detailed reports of this pvc
flow testing that any internal "ripples" were evident in those specific piping
systems (nor that such phenomena was even known to DIPRA at that time), I
believe the installed pvc piping in all those cases (that I believe had been
installed just a few years) achieved an actual H-W "C" many points below what
the pvc industry claims. I doubt internal waves, ripples, or whatever will help
much, and in my personal opinion hydraulic and other system performance is
dependent on many more factors than perception, an interior smooth to the touch
in localities, or a the visibly smooth external surface everyone sees! I
suspect interested pipeline Owners/consultants could obtain copies of the actual
detailed flow testing technical papers from DIPRA, if they are interested.
Apparently, however some others are aware at least of "wavy" pvc internal
conditions, as I saw this mentioned recently (on page 640 of Appendix C of the
hardcopy), in the table "C-factors for various pipe materials" in the extensive
technical publication from Haestad/Bentley, "Advanced Water Distribution
Modeling and Management". I have also noticed that this publication/data is now
viewable online at
<a href="http://www.haestad.com/library/books/awdm/online/wwhelp/wwhimpl/java/html/wwhelp.htm">http://www.haestad.com/library/books/awdm/online/wwhelp/wwhimpl/java/html/wwhelp\
.htm</a> (I believe the H-W data is under "Tables" "C." there).
While I do not look at much of this pipe, I believe I have incidentally seen
such internal pvc wavy or lumpy conditions on a few occasions myself, the last
being what I happened to see same in a piece of pipe that was sent to our
research laboratory for unrelated mechanical testing of the material a few years
ago (we did/could not test that one piece of pipe for flow properties). I have
a couple photographs of the internal conditions of that particular pipe I
received, if you wish to compare notes off this list.
Randy Conner
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=0-pw32u6xDUWIK5ymq5_tAjBgloOe1DkG1PdVv2YyiS7RezrkbS9ylXufSkeuNxNuHdIvH2Eb9CXE-tR--pfhf84">PipingDesign@yahoogroups.com</a>
[mailto:PipingDesign@yahoogroups.com]On Behalf Of Robin Badcock
Sent: Wednesday, August 03, 2005 6:17 PM
To: <a href="/group/PipingDesign/post?postID=0-pw32u6xDUWIK5ymq5_tAjBgloOe1DkG1PdVv2YyiS7RezrkbS9ylXufSkeuNxNuHdIvH2Eb9CXE-tR--pfhf84">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Pipe friction
Dear group,
We have had new 250 PN 6 UPVC RRJ pipes delivered to site; these pipes have a very ripply finish inside the entire pipe barrel. This is for all pipes (1350m)
Ordinarily, a pipe of this size and construction would attract a Hazen-Williams coefficient of; C-151.(Australian Pump Manufactures Pipe Friction Handbook).
The question has been asked as to what influence the ripply bore may have as to increasing energy losses.The ripples are perhaps more like elongated smooth scales that are overlapping somewhat so as to have a layering effect. They are smooth to touch and are approximately 13mm in length, 10mm in width, and are oval in appearance. The protrusion into the water flow (above what would be considered the normal pipe barrel base line) is in the order of 0 .75-1mm. Hence, from the crest of one scale to the valley of the next adjacent scale is approximately 1mm.
Question: I seek suggestions as to what the new coefficient may be estimated at;
and I seek suggestions as to where information may be gleaned to
reinforce this information/suggestions.
I have been scouring my hydraulics manuals with some success, although there seems to be more information on all the other Friction Loss Equations that have ever been cooked-up. I guess I could work through some of the other formulas and extrapolate the information across so as to get a rough indication as to the new C value, but hey you Dudes are far smarter than I and I am curious as to what may arrive in my mail box.
Cheers for now and thanks.
Robin
[Non-text portions of this message have been removed]
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