Large Diameter PVC Solvent Glued Pipe for Sewer Service Lines 2

[DrLewinstein]

I noticed on a set of plans that the engineer is calling for 8" PVC solvent welded pipe for an underground sewer service line for an industry. I confirmed that he meant this on purpose and asked him what the thinking was, since bell and spigot joints seem to be more common for this diameter. A 4" glued PVC service line I could understand, but 8" seemed unusual. I have not heard back. Anyone shed some light on this. Have you run into glue pipe for sewer service connections in larger diameters before? Is the thought that they would "never" leak?

Thanks,

 

[fel3]

I have never used glue joint PVC for sewer, only 4" and larger with rubber gaskets (ASTM D3034 and ASTM F679). If the other engineer has called out Sch 80, it could be a wall-thickness issue, perhaps due to shallow burial in a traffic way. I once had to design an extreme end-of-the-line sewer with about 12" of cover in a truck terminal, but I used ductile iron there instead of PVC for strength reasons. It was much cheaper than using standard burial depth and having to add a lift station and that client was all about cheap.

Here is the comparison for For 8" PVC pipe:
-- SDR 35: t = 0.240"
-- SDR 26: t = 0.323"
-- Sch 40: t = 0.280"
-- Sch 80: t = 0.500"
Thus, Sch 80 provides a much beefier wall than the thickest traditional PVC sewer.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[stanier]

8" is hardly large!24" is used for pressure pipe/\. Solvent cemented is more secure as it prevents root growth. Go to a sewage treatment plant and you will see it in action. It also avoids the need for thrust blocks. Sewage is only another fluid.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[fel3]

Stainer…

We don't use thrust blocks on gravity sewers , which is what I inferred from the OP's description of an industrial sewer service. Of course, if it's a force main, then pressure pipe is in order.

The most common practice for municipal gravity sewers, at least in California, is PVC pipe (SDR 35 and SDR 26) with rubber gasket joints, although some cities still require vitrified clay from some reason. For force mains, we typically use PVC water pipe with rubber gasket joints and place warning tape above it. Since gravity sewers and force mains are typically run along the centerline of a paved roadway, roots are rarely an issue, especially for really deep gravity sewers. Rubber gasket pipe assembles quicker than solvent weld pipe, which is certainly one reason it is used. You will sometimes find 4" glue joint pipe being used for residential sewer service laterals because of the root issue, but not always.

Fred

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[stanier]

The authorities in Australia prefer RRjs as they claim it removes the risk of poor workmanship. That said there is no reason why a solvent cement system cannot be used for a gravity main. There are plenty of solvent cemented pipes in sewage treatment plants whether in ABS or PVC-U. If the contractor wants to do it I do not see any reason to prevent it.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[fel3]

Stainer…

I wouldn't prohibit a contractor from using glue joints, but I have never had one request to use them. Glue joints are slower to put together--especially if they have to clean up a pipe that has been cut to fit--and thus would be more expensive to install, all else being equal. In addition, as your authorities in Oz have claimed, rubber gasket joints are more forgiving of poor workmanship.

I haven't done a lot of treatment plant piping, but on the projects I have worked on I don't remember any glue joints for gravity sewers or larger force mains. The only glue joints I remember is <4".

Fred

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[rconner]

Some history of solvent-cemented joints in USA application was revealed, discussed, and friendly debated to some extent on the thread at

http://eng-tips.com/viewthread.cfm?qid=227506

(and probably others that may be available with advanced search in the archives of these forums). The facts are these joints (and as reflected by many comments) have for various reasons as discussed somewhat fallen out of favor, at least for general municipal, domestic and underground service in water and sewer applications in the USA. IMO that does not necessarily mean such joints would not have some utility in special applications.
As far as potential technical drawbacks, while I don't think really rocket science the assembly of the joints does require the rather specialized knowledge of how and in somewhat cryptic fashion also exactly how much of the solvent to apply, by what manipulative technique, and it also involves a powerful solvent that releases VOC’s near the workers and also into the pipeline as well as environment. Furthermore, properly applied assembly creates a very rigid pvc system that frankly allows absolutely no relief for stresses due to subsequent thermal variations, settlements and other movements of pipes, relative to each other and also relative to fittings, valves, services and more formidable structures such as manholes and buildings for the life of the system. I’m not sure that anyone really knows what the long-term effects of such along with environmental exposures on a material like pvc and its joints will be?
All this being said, I noted in the OP the sewer will serve an "industry" -- while not wanting to second-guess the designer, could it also be that the designer is worried that whatever that specific "industry" is discharging into this line could have some unusual and deleterious effects on standard SBR pvc sewer pipe gaskets (but I think I have also heard some problems with glued joints in special applications that the conveyed material worked on the glue to cause leaks!)

 

[bimr]

Nobody uses solvent welded joints for sewers because it is poor design practice. The earth is constantly moving and that is why unrestrained piping joints are used.

If there was a concern regarding leakage of chemicals, then the sewer should be built above grade. Solvent welded joints is not the answer.

 

[stanier]

Bimr,

You are pedalling a myth. There are thousands of metres of ABS pipe in buried situations with solvent cemented joints. The joint is the strongest part of the pipe as it has double the wall thickness. As for PVC-U this has been used in buried applications for pressure systems as well as gravity systems.

Many houses have their sewer systems to the main in PVC-U that is solvent cemented. It provides a more robust system than rubber ring joints.

If the ground conditions are "constantly moving" there is a great concern of debris getting into the roubber ring joint seal and wearing, causing leaks and allow root ingress.

The only reason is economic as the RRJ system is more quickly installed by less competent operators.

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/