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Application of 4" Solvent Weld Pipe for Sanitary Building Sewer

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  • Application of 4" Solvent Weld Pipe for Sanitary Building Sewer

    Hey friends, I am a civil engineer researching pipe types used for the SBS on the private side. Solvent weld connected DR35 is permitted per OBC and NPCC, but there is very little information about it available in the usual sources (UniBell PVC manual, pretty much the bible). I work in the area of preventing clean water (inflow and infiltration, or I/I) from getting into sanitary sewer systems. These glued pipes are very sensitive to proper installation, PVC pipe requires proper bedding, haunching, embedment and cover to function properly (it gets its structural integrity from the soil around it. None of these are called for in the OBC/NPCC. A long, rigid pipe is very sensitive to snapping with soil settlement, etc. We see a lot of these failing in a short period of time (a whole bunch of failures around Ottawa recently). Gasketed pipe is more flexible, and is required on the public side. I know drain layers, rather than plumbers, tend to install these, but can anyone comment on their experience, and provide any information about testing, etc., for this pipe (I've been through CSA, ASTM, etc. and all the testing listed was done on gasketed pipe). Thank you! See snap of the two pipe types. We frequently see the shattered DR35 white, glued pipe on site, very, rarely shattered DR35 green pipe...

  • #2
    Probably has to do with expansion and contraction especially with extreme temperature changes.

    Gasketed pipe can move while glued pipe can't move. Something has to give.

    Rick.
    phoebe it is

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    • #3
      We use cpvc and c900 both of which require careful handling in cold temperatures. During a project in central California over a winter I learned that you cannot drop cpvc lengths of plastic on concrete without shattering or risking a hairline crack.

      Another time we installed 10" c-900 for a fire service in Carlsbad, CA. during cooler months and it got to maybe 35 overnight. We needed a short 5' section for a lateral to a hydrant. I cut the pipe and I was careless putting it down and instead dropped on asphalt paving which I had done many times but usually in warmer weather and with JM Eagle Blue Brute, pretty tough stuff. This was a listed product though different and cheaper. Anyway it shattered and we all sort of stood there with incredulous looks. I made a new section and we didn't have problems but I learned another lesson about plastic pipe and cold weather.

      Hairline cracks show up readily for us becuase we test both plastics to 200 psi. On waste and vent it may not be as readily apparent during a test. During backfill and compaction these fractures might grow in size due to the added stress from a wheel or plate compactor on a backhoe or even a walk behind power compactor. The compaction process might even be starting a problem and since there is no pressure in the line you would not know it.
      Last edited by Mightyservant; 11-07-2018, 11:00 PM.

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      • Bob D.
        Bob D. commented
        Editing a comment
        Keep the pipe filled with water during backfill. It provides support to the pipe. Put a slight pressure on the pipe (<5 PSIG) with a tell tale gauge (large dial, low pressure like a Ashcroft 4" 0-30 PSI or a digital gauge). If you have a leak it will show up ASAP. On a small peanut bourdon tube gauge you won't see it, but on a 4" dial even 1/4 pound is noticeable. For a digital gauge you'll see tenths or hundredths of a pound on the display depending on the instrument. Dwyer makes some nice digital gauges.

    • #4
      You want to rid of the problem, you have to cure the cheapness disease and lengthen guarantees. maximum profit - Low costs = cheapness disease

      It's the only way to solve it. They'll keep on making it and contractors will keep buying and installing because they only have to provide 1 year guarantee. They say who care if it leaks underground no one is going to see it.

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      • #5
        Thank you brother, we will definately keep those gauges in mind. Most testing is straightforward but we occasionally get a gem that requires our undivided attention.

        Digital gauges are great since you can instantly recognize what is happening. Brilliant idea.

        -Be safe

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