Primer only (no cement) on a 52psi system

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Kevin Aillaud, May 21, 2020 at 9:44 PM.

  1. Kevin Aillaud

    Kevin Aillaud New Member

    Joined:
    Thursday
    Location:
    Valle, Arizona
    Hey guys,

    I am building an off-grid system with my girlfriend and as we were laying the 3/4" PVC intake to the structure, she primed the joint but didn't cement them. We buried the pipe 30 inches (below the frost line) and covered it in rubber insulation, all under the deck and tent structure. Once the project was complete, she told me didn't cement the joints (she used the purple primer only, thinking that was all that was required).

    My question is this: will the primer alone hold up to a moderate pressure system? The water pump we are using is a 52psi pump.

    The reason I am asking is in order to remedy this problem, we would have to tear up the entire structure to access the joint that is not cemented, basically starting us all over from scratch. If I can avoid this, I sure would like to!

    All the other joints are primed and cemented (these I did myself). It's just the one 90 degree elbow joint she did that is directly under the deck, leading vertically into the structure (so it's the last elbow joint underground before the pipe comes up above ground).

    Based on the pressure and the distance from the pump (about 30 feet), will this joint hold up with primer alone?

    Thanks in advance!
     
  2. DIYorBust

    DIYorBust Active Member

    Joined:
    Mar 5, 2019
    Location:
    Long Island, New York
    Cement only I wouldn't worry. Primer only I'd be more concerned about. Is there a way to test it?
     
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  4. plumber69

    plumber69 In the Trades

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    Start digging it back up.
     
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  5. Kevin Aillaud

    Kevin Aillaud New Member

    Joined:
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    Location:
    Valle, Arizona
    Possibly, but I don't know how. The pump isn't attached yet and all the pipe is buried.

    We have the pipe wrapped in insulation and PVC tape, and buried the pipe 30 inches under dirt.....I am hoping this will provide enough weight on the elbow joint to prevent it from popping off? I have conceded that there may be a leak at this joint but if I am going to completely fix this issue (use cement on this joint), I will be ripping up the deck and, essentially, restarting the project.

    Is that worth it for a single elbow joint that has been primed but not cemented?
     
  6. Kevin Aillaud

    Kevin Aillaud New Member

    Joined:
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    Location:
    Valle, Arizona
    Yeah, it's not a matter of digging it back up. The elbow joint is under a 28X28 deck, about at the middle. I would need to rip up the entire deck to reach it, starting the project from scratch. I'd like to avoid this...if possible. If there is a chance the elbow joint will hold with the primer, insulation, PVC tape, and dirt load weight on it...then I don't want to scrap this project and start from the beginning.

    I'm basically taking about 2 months of work and about $15k for a non-cemented elbow joint. My GF made a mistake and we are not building this to code (it's an off-grid system).

    Come on guys...what're my chances here? What's the worst that could happen and is it worth tanking the project to start over?
     
  7. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    You will be forced to dig this up at some point as primer has no adhesive properties.

    If you wait, what damage is likely to occur when the elbow blows off and water continues to flow underground? If no one is around, water could continue to flow over several hours, maybe even days.
     
  8. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    As an alternative, abandon the line and run new poly pipe into the building at an alternate location. Poly pipe will allow a continuous run with no joints to prime and glue.
     
  9. Jeff H Young

    Jeff H Young Active Member

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    Now if its pressurized to 52 psi and it blows apart is that a problem? It could blow today , tomorrow or 3 monthes from now. most applications and circumstances it would be unacceptable. I recomend testing befor burying pipe
     
  10. ShadowAviator

    ShadowAviator Member

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    Location:
    Middle of Nowhere, Kansas
    I would assume in arizona, that water is pretty valuable. I wouldn't want the chance for losing water to a leak.

    While there are some building codes that I may not feel are needed, cementing pvc is pretty important.

    I am no expert but this is my understanding. Primer is mostly for cleaning the pvc in prep for cement. It does soften the pvc some, but not enough to really weld two pieces of pvc together.

    I would add my vote to the "bite the bullet and dig it up" pile. Or as banner suggested, try and maybe run a new line to an easier location if possible.

    I am not really sure what this deck looks like, can you post a picture? Is there any way you just take up a few boards or just remove part of the deck?
     
  11. DIYorBust

    DIYorBust Active Member

    Joined:
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    Location:
    Long Island, New York
    Ok, clearly you want to avoid remaking the joint, so here is what I would say is something you could consider. Make a joint the same way out of the same materials you used, and pressurize it. Evaluate the performance of the test joint, and decide if you want to take your chances. The primer is similar to the cement, so who knows, you might get lucky. It's certainly not a guarantee that it will hold up in the field, but if it seems to work, perhaps you could install some kind of device to shut it down if it starts leaking.

    I think overall the answer is that this is not acceptable practice, and has a high chance of failure. Good luck.
     
  12. fitter30

    fitter30 Active Member

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    Tear it out and do not test with air pressure.
     
  13. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    If it springs a leak, what are the consequences? You are not going to get a $4000 water bill from the city. Maybe you will have to order a new water truck delivery. I would wager it won't fail if she was able to seat the pipe all of the way. Win some, and lose some.

    Are you going to be fretting about it? If so, change it. Its not like the pipe is 40 inches down.

    If the under-deck area is hard to access, maybe you could build an access hatch. It might provide some storage space as a bonus. A Homewerks Worldwide 3/4 in. PVC Slide Repair Coupling might make the repair easier.
     
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Primer has some solvents in it that allow it to clean and etch the joint before adding the cement. The cement also has solvents, but adds in some dissolved plastic that helps to fill in those microscopic irregularities of the pipe and also is strong enough to melt the pipe to allow it to be fully bottomed out in the fitting's hub. It's REALLY hard to fully insert a pipe into a standard socket without slathering both sides with cement.

    So, you have a situation where it isn't fully inserted meaning it's not as strong, and the surface that is left is not smooth any more. It's not worth the chance, IMHO. Then again, I'm not the one that needs to redo all of the work.

    Is the deck a cement slab, or wooden? If it's wooden, you could probably pull up the floor boards to gain access. If you know approximately where that joint is, you shouldn't need to dig out the whole length. Being underneath the deck may make it hard to notice if there's a slow leak. It may not blow apart, but continually keeping the area damp isn't great, either.
     
  15. Mr tee

    Mr tee New Member

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    I think in the future you will be able to make many stupid mistakes and your girlfriend will hold her tongue and not say a thing.
     
  16. Plumbs

    Plumbs In the Trades

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    Oct 16, 2019
    Location:
    Virginia
    I've seen unglued cpvc joints hold near 100 psi with no leaks then blow apart months later. Inside the house this causes a lot of damage.
    Underground the damage probably won't be as bad. But you run the risk of it blowing when nobody is around or it might leak, follow the recently excavated trench, show no signs above ground and cause a $2,000+ water bill before anyone catches it. I've seen that many times as well.
    If it was my house I'd repair it. I don't see why you'd have to dig up the whole line to make one repair. Like someone else said, put an access panel in the deck instead of removing the whole thing. Sure, it may not look as nice but it's better than tearing it all out. Then use a repair coupling. They make compression repair couplings that will save you a lot of time.
     
  17. plumber69

    plumber69 In the Trades

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    Location:
    Prince Rupert, British Columbia
    I highly doubt an unglued joint would hold 100 psi
     
  18. JerryR

    JerryR Member

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    Location:
    Florida
    Unless you dig it up and fix it you will never sleep well again.
     
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  19. Plumbs

    Plumbs In the Trades

    Joined:
    Oct 16, 2019
    Location:
    Virginia
    You can believe it or not but I did the repair myself. This was when I worked doing new construction. We had to test the line by filling the pipe to 100 psi, letting it sit overnight and having it inspected by the county the next day.
    This particular joint was at a tee in the basement and the way it was setup there was a 90 on the end of the tee which held it up to the joist. I'm guessing that's what held it in place so long. The guy who put the joint was constantly dry fitting joints and had his fair share of leaks but none like this.
    These people lived in the house for about 2 months before the line blew apart. They never saw any leaks or stains before it happened. The house pressure was only at 60 psi after the prv.
    It's like cold soldered joints. I did one this week where the homeowners wanted to replace all their copper lines with CPVC because the copper kept getting pinholes. One joint just came apart in my hands as I started to cut. When I looked at it there was no solder in the fitting nor on the pipe. The only part that had solder was on the outside of the joint. Yet somehow it held for over 30 years this way. Now, there was proof it leaked at some point many years back but it wasn't leaking when I arrived.
     
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