In previous projects I really haven't had the need to dry assemble a
bunch of fittings to get the alignment right and make sure it would
all work before gluing. In the case of some recent work with 2" PVC
I had pipes making a tight 180 turn and together with a 3 way valve,
it all has to align just right with the existing piping in a short
distance with no wiggle room.
So, I put the pipes and fittings together dry first, to make sure they
aligned OK. But there were two problems:
1 - It was very hard to get the dry pipe to bottom in the sockets of
2 - It was even harder to then pull them apart.
I tried using some dish washing soap, but it didn't help much. Which
got me to wondering if there are any tricks the pros use?
On Aug 4, 12:58 pm, firstname.lastname@example.org wrote:
Newer PVC seems to have more of the tight fit problem than I can
recall from past projects. Nowadays I routinely use regular machine
shop type sanding strips to get a decent moveable fit. With the
heavily bodied cements (resin containing) being used it should make no
difference at all in mechanical integrity. Haven't had any leakers,
ever, in doing this. Using sanding strips makes it less likely to make
a dumb mistake such as making a groove with a flat file that could
The biggest "trick" I think the pro has is the experience and practice
such that can make stuff fit properly simply by measuring lengths
minimizing the need for nearly as much dry fitting as we diy'ers.
My general approach to a similar situation tends to be to do one joint
at a time so to minimize the accumulated measurements required and then
the last assembly generally isn't bad. Any given situation can lead to
peculiar issues, of course that might make more trials a useful exercise.
$0.02, etc., ...
The problem with one joint at a time is that if an earlier joint has a
freedom of movement that affects the positioning of a fitting that is
coming 3 connections later, if it it gets set at the wrong angle you
then can't make the last connection. Which is why I needed to dry
fit several fittings and short lengths of pipe simultaneously.
On Aug 4, 2:35 pm, email@example.com wrote:
Ain't those situations fun? I've had to create some new swear words -
like Ralphie's dad in A Christmas Story. I use a Sharpie to make some
alignment marks on each joint, and then glue pieces up into assemblies
and then glue up assemblies. I don't know how critical it is to have
the joint bottomed out. Preferable? Sure, but I don't think it
affects things too much. When I've cut into other people's work I've
found substantial gaps where the pipe didn't bottom out in the
fitting, but that didn't seem to create any problems with drainage.
That's why you should carefully measure and *not* attempt to dry-fit. Measure
to the bottom of the seat in each fitting, because that's where the pipe is
going to wind up when the solvent is applied and the joint is made properly.
Trying to dry-fit plastic pipe is an exercise in futility: the pipes *never*
bottom in the fittings, so there's no way that the final assembly (with
solvent, and hence with the pipes bottomed) will be the same size as the
On Aug 4, 10:59 pm, firstname.lastname@example.org (Doug Miller) wrote:
You can easily measure lengths in most cases. But when you have a
complex series of fittings at angles within a small area that has to
then align with 3 existing fixed pipes, it's not just a matter of
simple measurement. You need to know the angles can come together
correctly together with the various pipe lengths involved.
On Aug 6, 7:15 pm, email@example.com wrote:
Umm... yeah... If you have that sort of problem and need to dry fit
because you can't measure the lengths needed and visualize the
angles, you are probably lacking enough skills so that you should
hire someone to do the work for you even though you know how to
glue the pipes together yourself...
Explain exactly how one "visualizes" the angles. Seems everyone else
here understands the issue, because like me they have had cases where
it is necessary to dry fit prior to assembly. In the case in point,
I had a 3 way 2" valve that had to align with 3 different pipes on 3
different levels, all within a tight area. This isn't a case of
running a waste line across a basement, where the angles and lengths
aren't critical, you can make it up as you go and make adjustments
farther along if needed.
On Aug 4, 10:58 am, firstname.lastname@example.org wrote:
PVC pipe / fittings are not meant to completely dry fit to the same
depth as when doing the final glue up.
On the solvent glue cans, the instructions often note that dry fitting
should result in insertions 1/2 to 1/3 less than full depth.
The solvent action of the glue allows the pipe and the fitting to
but back to your original question....
The fittings are not meant to be dry fit completely.
If you need to get things to fit up exactly correctly, sequence your
assembly and measure the socket depths.
Using primer & glue you should be able to get the pipes to completely
Marking pipes & fittings so that desired orientation is maintained can
Uhhh.... no. No. NO!
Please don't attempt to give advice on subjects you know nothing about. The
primer/cleaner makes the pipe sticky, not slippery. No way will it work as a
lubricant. Good grief.
Please don't top-post, either.
Deburr (and maybe even chamfer like a dowel) the hell out of square-cut
ends, is the one plumbers always told me. The 'slip fit' for new pipe
and new couplings is pretty tight anyway. One burr or non-square end cut
can make the dry-fit a case of pounding an oval peg into a round hole,
if the approach angle is slightly off 90 degrees. Even more so when you
are using glue with a very short open time. This is why ground assembly,
and making as absolutely few joints in the air as possible, is the best
approach for DIYs. My BIL did some feeds, drains and vents for his
washing machine move that look like something out of Rube Goldberg, to
get all the runs to line up. Too bad about the stud and plate that used
to be there. He would have been better off cutting the whole mess back
about 15 feet, and starting over. (What can I say- he is a college
professor with a green thumb, and a nice guy, but he is no DIY. But my
SWMBO sister will not be denied.)
Yeah, I kind of thought about that. I guess you could use a Dremel
or similar and grind it out. Would be cool if they sold alignment
ones that were slightly over sized and a different color, like red, so
they wouldn't get used improperly.
The process of dry fitting, PVC pipe(s) and fitting(s) is fraught with prob
lems. This is because the industry standards for both the pipe and the fit
ting socket are designed to provide an interference fit within the bottom 1
/3 of the socket. This is where the solvent in the cement creates a fusion
bond of the pipe and fitting. The socket of the fittings have a slight ta
per, to assist in rounding the pipe and achieve the fusion bond area necess
ary to provide a leak free, joint that can withstand the forces of the sys
Sanding or grinding the diameter of either the pipe or fitting can jeopardi
ze the quality and/or performance of the solvent welded joint.
Pipe fitters that fabricate pipe assemblies use the takeout dimensions prov
ided by ASTM standards for PVC fittings. These dimensions can be found wit
hin ASTM D2467. Another choice for getting the takeout for PVC fittings ca
n be found at: http://www.expert4pvc.com . There are two FREE options that
can provide you the takeout you are seeking. First is the html page at: htt
p://expert4pvc.com/HandyTools.html or the Android app at: http://expert4pvc
On Saturday, March 21, 2015 at 9:06:45 PM UTC-4, email@example.com wrote:
oblems. This is because the industry standards for both the pipe and the f
itting socket are designed to provide an interference fit within the bottom
1/3 of the socket. This is where the solvent in the cement creates a fusi
on bond of the pipe and fitting. The socket of the fittings have a slight
taper, to assist in rounding the pipe and achieve the fusion bond area nece
ssary to provide a leak free, joint that can withstand the forces of the s
dize the quality and/or performance of the solvent welded joint.
The idea was to grind the necessary ones out and keep them for fitting purp
When actually assembling, you use a normal one. They only cost $.50.
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