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?
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.
Here are some links I found that talk about or show how the female PVC
fittings are tapered:
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
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
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
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.
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.
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 <g>. I guess I'm going to continue to use the belt
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!
On Nov 9, 10:24 pm, email@example.com wrote:
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.
On Nov 10, 9:23 pm, firstname.lastname@example.org wrote:
You missed the point, Cupcake. It's not about what you do, it's about
you telling us what to do. In general the objective is to prevent
people from doing stupid things, but sometimes, well, people insist on
being stupid. Good luck with your project.
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.
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 ...
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.