Fused PVC and AWWA C-900/905

[drkevans]

Does anyone have any documentation on if fused PVC meets AWWA C900/905 standards? It's my understanding that because of the fused joint there is some confusion on if the AWWA standars apply. I've heard both ways; that it does and it does not meet these standards.

Thanks!

 

[coloeng]

Go to the attached website for additional information about fusible pvc. Just remember that these are the guys selling it.

http://www.undergroundsolutions.com

 

[rconner]

I guess the "other side" of the sort of cat fight you have drawn attention to is at least in part reflected in the letter now posted at

http://plasticpipe.org/pdf/ppi-question-awwa-fusible-pvc.pdf

(and the response of the addressee is also posted on that parent page).

 

[coloeng]

As they say, "Let the Buyer Beware". We currently have 4,500 lf of 8-inch and 2,500 lf of 12-inch fusible PVC and a number of installations of 4-inch thru 12-inch HDPE that were all installed via directional drilling. The PVC has been in the ground for about 1-1/2 years and no problems to date. The HDPE is mainly in lengths no greater than 200 lf and used for crossing under deep washes and we have been using it for about 12 years with no significant issues.

The article at the plasticpipe.org website starts out as if it is a news article, but in my opinion quickly devolves into a plug for HDPE. I am not an advocate for fusible PVC or HDPE, just a user of both. I will base my judgement of the quality of both products based on my experience and the experience of other users that I trust. In order to bring new innovative products into the market place some users have to be the guinea pigs, otherwise we would still be using open aquaducts and wood pipe. Sometimes we pay the price for being the guinea pigs.

 

[rconner]

There is indeed something to be said for a pioneering spirit. As long as there are no disputes among bidders or other parties etc. to a construction project, nor unanticipated problems with the performance of any chosen/supplied elements of a project once built, I guess there is for that matter arguably even little need for “consensus standards” (nor for that matter unquestioned conformance to same). I am however aware that pvc “welded” joint end pipes (i.e. solvent cement welded joints) were once specifically included in the original C900 standard (from the first edition in 1975), but they were removed in the 1989 version of that standard (with the statement in the Foreword to that revision, “Provisions for solvent-welded joints throughout the standard were deleted.”) I believe also that when the first edition/of brand new AWWA C905 standard was released in 1988, for 14” and larger pvc pipes, there was no reference whatsoever in that new large pipe standard to any solvent cement, nor for that matter any other form of pvc welding. That new standard even contained the specific requirement under Sec. 3.6 Joints, “A gasket joint shall be provided with each length of PVC transmission pipe.” However, I believe reference in the C90X series of standards to welding or fusing was again variously revived in later versions of the standards to present, but then it appears specifically only then/at least specifically directed to fabrication of pvc fittings, and then (with QC/QA for same etc.) to be under “factory” conditions, as I believe is noted in the PPI letter.

From a technical perspective pronounced thermal, Bourdon, and Poisson behavior (the latter e.g. as advised by Mr. Robert Hucks [e.g. see thread

http://eng-tips.com/viewthread.cfm?qid=125930

.], in a July 1972 AWWA Journal article as, “Since PVC pipe moves axially as well as circumferentially in response to pressure surges (“Poisson’s ratio effect”), pipe may undergo scratching of the outside when buried and in contact with sharp stones in the backfill. This area requires further study…”) could perhaps result in some different responses in a system with at least some relatively long sections of welded pipes than in a conventional rubber-gasketed joining system. I do not know if these behaviours/this history has necessarily any specific relevance to the current dispute, but it perhaps makes it a little hard to believe given same that all members of the standards committees do not have any opinion as to need for minimum requirements/basic philosophy for/ of basic sealing to pipe ends etc!

[BTW I had occasion to see some fascinating construction just a very few years ago, of course now leading into this 21st Century, of a brand new open-air “aqueduct” to transport water a considerable distance in the Andes mountains of South America. While this new aqueduct employed some modern engineering materials e.g. an underlying impermeable membrane and steel-reinforced concrete sections with expansion joints, I suspected it would function in much the same way (i.e. with general success) as had similar aqueducts built in the area for hundreds of years. The only reason I was there was to help them design and install a quite large pressure pipeline siphon, that would allow the aqueduct to pass under a quite deep canyon (a technology I don’t believe at least quite as readily available to ancient engineers). I wouldn’t even be a bit surprised if there is also still some “wood” out there still functioning pretty well as pressure pipe, and/or as a sort of swelling/reasonably durable lining for metal etc. pipes, in an era when cement mortar lining technology was not well available/understood. I guess it remains to be seen whether many “new” products will provide similar value.]