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Best way to join pipe without a fitting?

5K views 33 replies 12 participants last post by  SeniorSitizen 
#1 · (Edited)
I am working on a project and need to put many pieces of 2" pipe through a 4" pipe. Rather than spend $1400 on fittings, I've decided to get a 60mm hole saw and just drill holes in the 4" pipe.

Question is, what is the best way to make the seal leak-tight? I'm thinking PVC cement. The only other thing I can think of is silicone, but I don't think it would hold up as well over time.

Is PVC cement the right choice? Is there another option?
 
#5 ·
I need 96, and there about $15 a pop. They will be under almost no pressure.

I think im going to get the bit i need and do a test run with pvc cement, silicone, maybe even a 2 part epoxy like jb weld. Thought about maybe even using hot glue, no real experiance with it though.
 
#3 ·
What is the application?

Doesn't really matter.....if I think I understand what your proposing.....not going to work.

Yes...you can use primer...and then PVC cement to 'glue' those 2" tubes into your 4" header.....as long as you can insure that they will NOT move, and you don't use too much pressure, you 'should' be ok....but....I really doubt you can keep the tubes from moving...

For PVC to have a strong bond...it needs lots of surface area...you are not going to have lots of surface area...

Additionally, there are numerous issues connecting pipes/tubes to a larger round pipe (header).....if you want an idea of what is involved....look at the costruction of radiators.

Good luck...
 
#4 · (Edited)
What is the application?

Doesn't really matter.....if I think I understand what your proposing.....not going to work.

Yes...you can use primer...and then PVC cement to 'glue' those 2" tubes into your 4" header.....as long as you can insure that they will NOT move, and you don't use too much pressure, you 'should' be ok....but....I really doubt you can keep the tubes from moving...

For PVC to have a strong bond...it needs lots of surface area...you are not going to have lots of surface area...

Additionally, there are numerous issues connecting pipes/tubes to a larger round pipe (header).....if you want an idea of what is involved....look at the costruction of radiators.

Good luck...
Indeed your contact surface is going to be limited to the thickness of the 4" pipe as far as trying to glue it.

I was thinking you could use something like flexible rubber flashing like for roof vents to both stabilize and seal (so long as the 4" will not be under pressure) but I cannot imagine they will be any cheaper than PVC slip fittings?

Does your 2" material have to be the same as the 4"? What about 2" rubber and 4" pvc. If you could compress the rubber feeding it through the openings it would expand to grip the sides of the hole without any cement? Again, so long as you do not have pressure running through the 4".

And again, just to be sure? Does the 2" connect to the 4" or pass unbroken through it? I read your post as though you were passing it through but ddawg read it as you wanting to connect.
 
#9 ·
Well, the point is to join, but technically it will pass through - otherwise you'd need to have a curved end on the 2" pipe.

While it would be a ***** to do, fleece + fiberglass would be cheap and pretty-well guaranteed to work. You could wrap the 2" pipe in a 1" strip of fleece, force it 1/2 through the hole, then let the resin soak in the fleece. That's how I made the corners on my waterproof table - took 5 gallons of fiberglass and about 2 weeks to build, but it is incredibly waterproof.
 
#10 ·
Well, the point is to join, but technically it will pass through - otherwise you'd need to have a curved end on the 2" pipe.

While it would be a ***** to do, fleece + fiberglass would be cheap and pretty-well guaranteed to work. You could wrap the 2" pipe in a 1" strip of fleece, force it 1/2 through the hole, then let the resin soak in the fleece. That's how I made the corners on my waterproof table - took 5 gallons of fiberglass and about 2 weeks to build, but it is incredibly waterproof.
I am confused. It would help to know what you are trying to build?
 
#13 ·
Actually welding it might be your best bet if you can get PVC compatible rods. I should think so. I still worry about how much lateral stress your pass through pipe is going exert. Will it slide around?

Anyhow, I looked and even Harbor Freight has plastic welding kits for like $15. You might look for something with an adjustable heat source and pay a bit more though.

 
#15 ·
Without the full info on what it is your really trying to do your just wasting every ones time here having to guess.
You have the benifit of picking the brains of some clever people that have been there done that for free, shame to not use there time wisely.
 
#29 ·
And sadly, patents are beyond the reach of most commoners unless you have a free patent clinic near you willing to do some of the work.

Beware places like Legal Zoom that suggest they can get you a provisional patent for $300. There is no such thing as a provisional patent. You can file a provisional application for a patent. It starts the clock ticking and if used strategically can extend the life of a patent by a year---once you get it. The provision granted is that you file a real, non-provisional application within one year. If you do not, you could loose the right to patent.

Provisional patent applications are not reviewed on merit. They do allow you to put patent pending on things. They provide no intellectual property protection whatsoever.

Real patents cost thousands but the process, including being matched up with an examiner in the trademark and patent office is complex. A surprisingly small number of products sold actually have patents. And a miniscule number of patent disputes ever go to court. It is just to expensive.
 
#17 ·
Going to be used for an indoor garden:



If you put the plants directly through a hole in the pipe, they tend to overflow when the plants get larger and the roots start to create resistance. By raising the plants out of the water, even by only a few inches, the hope is that the main area runs faster and won't overflow at the brim.
 
#19 ·
Yeah - I've only ever seen it done by drilling a hole, or using a fitting on super-price, small systems. If fittings were so crazy expensive, that would be that way to go, but 4" T's go from $10-15 -- makes sense if your adding a sink and just need one, but it's crazy if you need 96.

Going to do some serious R&D now that I have some options - kind of like the idea of plastic welding. I want to see just how tight the pipe goes in too - if it's snug going in, I might just need some pvc cement.
 
#25 ·
Now that I see what you are trying to do, I would think you could do it by a butt-joint and cement. Buy a hole saw (make sure its the correct size - 4" pipe will be 4.5" od" to get the correct shape on the 2" pipe. You might get a stronger bond with ABS rather than PVC, but both are pretty cheap, just buy some and try it.
 
#28 ·
Why not spend the $ upfront and buy a 2" TAP. Drill your hole and THREAD it and use 2' male threaded adapters with a little bit of teflon tape. If you use schedule 80 for the 4" pipe the wall thickness will be greater and thus more threads for the adapters to grab. Leak proof and would work well with some pressure. Just my .02

SK
 
#34 ·
The most economical way may be to research pipe saddle templet. After that begins to put the nerves on edge take a short piece of your 2 and 4 inch pipe to a reputable welding shop that may already have a templet for that size of pipe. The process would be to cut the end of the 2 inch pieces to saddle the 4 inch using the templet as the pattern and then do the plastic welding.
 
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