PVC pipes keep separating, what is causing this?

[M10507]

I moved into a new home last year with a 44k gallon, inground pool with a SWG. I used TFP to manage it myself and had a few minor problems but it was generally great.

This year I have had PVC pipes rip out / rip apart near the pump at least 6 times since Memorial Day.

I thought it might be that the DE filter was getting too dirty overnight and increasing the pressure, but the last two times the pipes separated I had closed the filters to make sure pressure didn't get too high over night.

Any idea what could be causing the problem? I am not doing anything all that different from last year but am having all sort of problems.


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[Rossterman]

Can you post a few pics of the equipment pad so we can see how it is plumbed?

 

[zea3]

Is this plumbing work that you did yourself? Did you close valves to the filter with the pump still running?

 

[M10507]

Yes. Here you go. And thank you

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[NeedMoreSun]

Where is it bursting? Looks like a lot of flex PVC there. Just a possibility but having used it often for whole room circulation behind a huge in-wall reef tank I know that flex tends to back out of fittings when cemented and needs to be held longer for it to set.

 

[M10507]

Is this plumbing work that you did yourself? Did you close valves to the filter with the pump still running?

The original work was done by the prior owner. A friend and I repaired the pipes.

I never change the valve on the pump with it running (I learned that last summer).

I have closed the ball valves on the return side with the pump running.




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[M10507]

Thanks NeedMoreSun, oddly the flex has never broken. I have had the pipes break once where water enters the pump and multiple times at either the spot where water exits the pump or the threaded joint above where water exits.




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[Rossterman]

Are you saying the white plastic pipe that is screwed into the pump discharge port separates from the treads in the black pump housing?

 

[M10507]

That is what happened this time, but other times the pipes separated between that point and the valves

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[JohnT]

If that threaded adapter came out it probably points to a cracked pump housing from overtightening the fitting.

Also looks like a rigid PVC joint isn't square.

A properly made PVC joint isn't going to come apart without a lot of force. Far more than your pump can apply.

 

[M10507]

Thank you. I will check the pump housing. Will that be obvious upon inspection or could there be micro cracks I won't see?


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[duraleigh]

PVC joints must be made carefully and especially straight - not crooked. A crooked joint means the ends are not mated properly and will often separate.

PVC is pretty easy when you see someone do it properly. If you don't. it is pretty easy to make some mistakes as you are gluing it together and I believe that is what you have done.

I would check the pump for cracks where the water exits and if it's OK, I would redo that entire section.

 

[M10507]

Thank you Duraleigh.

And thank you to everyone else who has responded.

I realized that this was user error on multiple fronts.

The PVC work was subpar but (and incredibly embarrassingly) I also was setting the valves to closed when they should have been on re-circulate.

Yikes. If Darwinism works My bloodline should run out pretty soon.


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[NeedMoreSun]

Just in case, I also see plenty with healthy doses of blue cement. Others I can see purple primer, but PVC cement was also used right?

I hate asking what appears like a dumb question, but even having worked with PVC many times I somehow missed the cement on just one joint and ended up soaking myself after the pump was on

 

[M10507]

I believe so. I am the helper when it comes to this stuff.

I will retry it tonight once water levels come back (and I finish self administering 100 lashes).

I will check for housing cracks, make sure all joints are square and make sure I use primer and cement.

Thanks again and sorry to be so stupid.


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[Rossterman]

The white threaded section is NPT (nat'l pipe taper) threads. You want to make sure the pump doesnt use straight pipe threads as there wont be enough thread engagement to hold it together(normally they use NPT but not always).

If the housing isnt cracked and you used just two wraps of teflon tape when last assembled, my bet is that the threads in the pump housing but are damaged from the pvc fitting separating and pulling out several times. If so, there are two options:

1. Get a NPT tap and cut the threads a little deeper. You will need to ensure that you dont cut them too deep that the pvc fitting bottoms out without tightening up. 1 1/2" taps are probably pretty expensive to buy so maybe you can rent one?

2. If there is some bits thread engagement left, you could glue the pvc fitting into the pump housing and see if it holds. You have a union above the pvc fitting so wouldnt be a problem removing pump for,servicing down the road.

 

[M10507]

Thanks


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[duraleigh]

Put me in the dumb crowd, too. My backwash pipe worked just fine for almost a year and then one day, simply separated at a coupler.

My equipment is in a garage and you can imagine what 90 gpm did to the stuff we had on the floor.

I was dumbfounded until I discovered I had not glued or primed it. Doh!

 

[jmastron]

Do yourself a favor and use a different kind of union at the pump -- this is what I used on a Pentair IntelliFlo; I don't know whether there are similar designated for other brands or why these wouldn't work on any pump with the same thread size:

Pump Unions for IntelliFlo - Threaded 2" w/O-Rings (2 Union Sets)

Note the additional gasket on the part that threads into the pump (in addition to inside the union). That gasket seals against the pump without relying on the threads themselves to seal (no need for tape/dope/overtightening) -- especially when there's a discrepancy between tapered vs straight threading.

 

[tmobileguy]

but even having worked with PVC many times I somehow missed the cement on just one joint and ended up soaking myself after the pump was on

I missed two joints on my pad pumping I redid last month....One was kind to me and just had a small leak and when I looked it, I realized that the joint wasn't even glued. The other one (which was actually the first out of the two), separated with a nice 60 gpm all over my pump room for about 5-10 sec until I could shut it off

Glad to know I'm not the only one...