I just recently installed a 12" siphon pipe in my pond dam. It runs about 15 feet down the water side of the dam. When we put it together it seemed like we got a good connection - but I noticed today that the joint at the 22 1/2 degree elbow has slipped about an inch. This is the joint right under the 4" air intake tube. This means the glue did not bond it properly. The pond is now about half full - meaning the inlet pipe and about 7 feet of pipe is now submerged. I am not sure how this is going to be repaired since I cannot get down to the bottom to push the pipe up and re-glue it. I have a bad feeling that it may slip all the way off eventually - particularly when the siphon did kick in. So I had an idea - what if I used stainless steel screws and sunk them into the coupling and pipe to stop it from slipping off? I can do that right now while there is no water to that connection yet. Even if it was not perfectly airtight at that joint it would all be under water in a big rain and should mean that the siphon would kick on. Am I right or I am I dreaming? Thanks everybody!

Perhaps hose clamp small sections of iron pipe around the pipe, same on the joint, then use a come along to re-fit it? The small pipes would give you a place to put the hooks from the come along. Adding adhesive as its tightened?

Sounds like a reasonable solution to me. I would use the hex head self tapping sheet metal screws.

I would take something with a couple hooks (like a tow strap to tow cars for instance) and hook it onto opposing sides of the pipe and pull some pressure on it to see if I could pull the pipe up any. I would be surprised if you could, but if you can it means the glue totally failed. What I would be more inclined to believe is that the pipe slipped before the glue had totally done its job. PVC glue will sometimes do this if the joint is not held together till the joint sets. On that big of pipe I would imagine the glue used would be fairly slow set to give time to fully slide the joint together. But I am just speculating.

I have used the described screws to hold PCV pipe joints together that I wanted to take back apart (a mechanical joint, not a pressure capable sealed joint).

If you have room to move around, try using a come along attached to straps above and below the joint, reapplying the glue. But the screws might do it. Good luck with that pipe job.

Tracy

I think the screws would work

I would try to jack it back together, then pre-drill some screw holes all around through the outer piece, inject glue into them with a syringe, and apply the screws.

Thanks to everyone for their help! I sunk a bunch of #14 stainless steel screws around the connection after predrilling and filling the holes with marine grade silicone sealant. It is holding quite a bit of weight as 15 feet of 12" pvc is pretty heavy - but I think it will work. If it fails I guess I will have to come up with plan B and more money.