Fitting fittings on PVC pipe

[knuckle-dragger]

I'm using the standard schedule 40 PVC piping to construct railings for a platform. No water (or any other fluid) will flow through the pipes but I need to disassemble the railings for storage, hence no gluing (but the same question would apply even if there was). Connection will be secured by drilling a hole through the fitting and pipe and putting in a bolt and nut.

The problem is that the fittings are an interference (or worse) fit on the pipe and short of cutting about 1/64" off the inside of the fitting or the outside of the pipe end I can't get the pipe to bottom out in the fitting. Up to now I've laboriously used a belt sander to grind back the last inch or so of the pipe (just chamfering the end doesn't help) but there must be a better way!

I remember many years earlier having the same problem with 4-inch sewer line (the current pipe is 1 1/4") and there I was running water (and other things) in it. The sewer line didn't leak but I doubt any pipe was bottomed into its fitting.

So what's the secret?

[RicodJour]

The PVC cement acts as a lubricant, so use some lubrication. Silicone spray would work.

R

[dadiOH]

Soapy water

[RogerT]

The secret is that the PVC fittings are slightly tapered, which causes them to only go part way in when dry-fitting them. When gluing the fittings together, the glue acts as a solvent and enables the fittings to then go together and completely bottom out. But, you don't want to glue them since you need to be able to disassemble them for storage.

Using any type of lubricant, such as soapy water or silicone that has already been suggested will not work. I have tried that and every other type of lubricant I could think of, including powder. Your only option, if you need to be able to put them together and take them apart again later on, is to do what you are already doing -- which means sanding the male ends enough so they will go all the way into the female ends of each connection.

I know this because I went through a similar investigation in the past, including posting the question here. In my case, I wanted to be able to dry-fit several fittings together to accomplish a complex set of turns up between some joists and through a floor, and I needed to be able to put them fully together and still be able to turn and adjust each one. I got the ultimate answer here -- which was that it can't be done due to the tapered fittings -- when someone pointed out the taper issue for me.

After sending this, I'll try doing a quick Google search to see if I can find a website that shows how the PVC fittings are tapered etc.

[RogerT]

Here are some links I found that talk about or show how the female PVC fittings are tapered:

[Pete]

I believe that PVC electrical conduit fittings are not tapered, and work with Sched 40 pipe. But they're usually gray, not white; and the choice of fittings and sizes is limited.

[dpb]

Don't know the application of the railing/platform or distance between supports nor what supports are, but Sch 40 1-1/4" isn't terribly strong and not much suited to the purpose it would seem...

--

[RicodJour]

I am not sure I follow you. In your situation you were going to be gluing the PVC as it was a drainage system and had to be water tight, yet you were willing to contaminate the joint with silicone and other extraneous stuff? Just so you could mark the joint? I'm afraid I just don't understand what the issue was. I've had assemblies that would have given Rube Goldberg a headache, and I've always done them the same way. Assemble a few pieces of pipe and fittings into sections to get a close-enough fit, glue the pieces into sections, then glue and assemble the assorted sections. You're just trying to limit the degrees of freedom. Once you get down to the last couple of joints, they can be measured. And you can always use slip couplings or Fernco (or approved equal) banded couplings.

The OP's situation is different as he'll be using bolts and there is no critical reason to have the joint fully bottomed out (it's rarely critical in plumbing as there will always be a discontinuity anyway). The silicone spray won't disappear in a tightly fitting joint, and the silicone will provide enough wiggle room to allow the railing to be disassembled.

I'm not sure what size PVC the OP's planning on using for the railing, how high the platform is, or how wise it is to use PVC for a railing. It may very well be that PVC is a poor choice for the railing in the first place.

R

[knuckle-dragger]

First let me thank the posters for their responses.

I agree that reducing the internal diameter of the fitting would be more appropriate but that would require something like a small version of the hone used to remove the lip on the top of the cylinder in an automotive engine. Mucho dinero I would think. Alternatively putting a taper on the pipe using a lathe would also work. OTOH I'd have to buy the lathe first . I guess I'm going to continue to use the belt sander.

For everything up to about 2 inch I've never had a gluing problem but as I pointed out in my original post 4-inch is problematic. Maybe all plumbers are built like a young Arnold Swartzenegger?

As to the use of the railings, I didn't really ask your opinion on their suitability for their intended purpose nor am I willing to countenance any nannyistic commentary. Keep to the subject!

[RicodJour]

It doesn't work that way, Sparky. It's an open forum - if you're doing something stupid, or if people have questions to determine if you're trying to do something stupid, they'll point out it's stupid or ask if you are trying to do something stupid. Learn to deal with it. Do anything else would be stupid.

R

[Joe]

[Jim Elbrecht]

-snip-

In other words-- "I didn't come here for a conversation. I came to have my hand held with some advice, that, if I choose to follow it, can be blamed for the failure of the project."

ESAD

Jim

[jamesgangnc]

Galvinized electrical conduit would be another choice. I agree with the other posters about the use of pvc, it's not really very strong nor is it uv resistant. Combine that with all the extra work to deal with the tapered fittings.

[trader4]

I understand his issue. I just went through the exact same thing a few months ago. In probably 95% of cases, you can do as you suggested, which is to glue up sections and in such a sequence that you have enough freedom to measure and then fit the last couple of connections. Especially true with new work. But there are close quarters work, where you have to mate up to existing work and you just don't have enough freedom and unless you get several angles/lengths right at the same time, it isn't going to work. It's for those situations that you need to dry fit ahead of time. By dry fitting, you can get the cut lengths exact and also mark the angles between pipe and various elbows, etc, so that when gluing it goes together just right.

And I agree with those that say lubricants don't work. I tried soapy water and it had no effect. I didn't realize at the time that the sockets are actually tapered, but it makes sense. The primer/glue dissolves it a bit so it then goes together.

[trader4]

I had that thought about using it for railings as well. I can picture PVC just shattering from a hard sideways blow when you need it most.

[RogerT]

Hard to explain, but it was a series of 3 or 4 Street 22-1/2' that had to go up through and around a joist and floor in a tight space in a corner to get to the next floor to create the toilet flange. The problem was how to get them all alligned so that the top and bottom were at the right place to meet the sewer stack below and the toilet above and so that both ends were hoorizontal/level on the top and bottom.

[Edward Reid]

Seems like someone missed the smiley due to the fact that it was created multisyllabically instead of with ACSII art.

Edward

[knuckle-dragger]

Sorry, it does work that way because I am in total control of the amount of information I feed you. I repeat: If I wanted commentary on the use of the pipes I would have asked for it.

[knuckle-dragger]

That's correct.

No hand holding requested, just simple straight advice on a limited question. If you don't choose to do that, you're free to not reply.

[knuckle-dragger]

The use is totally inside. It doesn't need to be too strong but it does need to be cheap. Galvanized conduit in any reasonable size would be way too costly, besides I'd have to have the unpleasant experience of talking to an electrical supply house. Same goes for untapered electrical PVC conduit fittings. If I wanted to do anything nearly so elaborate I'd use chain link fencing.

It just occurred to me that the answer is a tool like an oversize pencil sharpener with the appropriate taper. Perhaps even a chuckable pin on the inside so you could put it into an electric drill. Hmmm! After all PVC piping is used in lots of applications other than carrying fluids so easier assembly and disassembly would be valuable. OTOH not many people know about the taper ...