Measuring PVC assembly before cementing

[pawel]

Hi.

I've done a few PVC assemblies so far. I would normally assemble the whole thing together, check if it fits, and then disassemble, and cement the slip-ons.

What I find challenging is that trying things on is a bit different from the final product, mostly because the fittings are very tight, and it's hard to push a pipe into a fitting all the way through. However, when applying cement, the slip on full and easy. So quite a few times it didn't much help that I checked how everything would fit together in advance.

I thought about using things like WD40, or other lubricants on the fitting and the pipe ends, but I'm not sure if after using that it wouldn't affect the quality of the cementing itself.

Thanks!
Pawel.

 

[phishfood]

A lot of the time, the pipe gets run wild (anotherwords, past the end point) then the excess gets cut off. If it is easy to get center to center measurements, then I deduct the takeoff for the fittings and precut the pipe.

 

[havasu]

Never use any petroleum or lubricant on a PVC pipe unless you want instant failure.

 

[pawel]

Never use any petroleum or lubricant on a PVC pipe unless you want instant failure.

Right, so I was wondering what should I use instead

Thanks,
Pawel.

 

[havasu]

You can always use a slight mist of dish soap out of a spray bottle, provided you rinse it out before gluing up the fittings.

 

[pawel]

A lot of the time, the pipe gets run wild (anotherwords, past the end point) then the excess gets cut off. If it is easy to get center to center measurements, then I deduct the takeoff for the fittings and precut the pipe.

I try to do exactly that, but then it's not that easy to measure how much space a fitting will take (rather how much space there would be left. Like if the simple slip joint is 2", how much of a pipe will actually fit in). My idea is to put it all together dry, and cut little pieces here and there as needed. The problem is that if I'm checking it dry, the pipe will settle deeper when cementing...

Thanks,
Pawel.

 

[phishfood]

Rather easy, actually. Place the opening of the fitting on a flat surface, then measure to the centerline of the other opening. Then measure the depth of the socket that the pipe fits into, and subtract that from your first measurement. The difference is the fitting takeout.

What you mentioned, the pipe slipping further into the socket when you glue it, is one reason a professional rarely will dry fit a fitting. Another and bigger reason is that it is ridiculously easy to forget to pull it back apart and cement it.

I know the takeout of many of the more common drainage fittings off the top of my head. 3" short sweep= 3", 3" long sweep= 4", 3" 1/8 bend= 1 3/4", 2" short sweep= 2 1/8", 2" long sweep= 3 1/4", 2" 1/8 bend= 1 1/4", 1 1/2" short sweep= 1 1/2", 1 1/2" long sweep= 2 3/4", 1 1/2" 1/8 bend= 1".

 

[havasu]

I just got a headache reading that math!

 

[pawel]

@phishfood: thanks!

Gotta say, In my puny defeinse,

a) mostly work with 3/4" pipes, in those fittings every 1/8" counts, and boy everybody is having a party deciding how deep a pipe should slide in the piece (it's typically 1", but it's up to 1/4" around)

b) When I mock things up on a paper, and figure out all the sizes, and measure, and cut, I miss this one crucial piece, and the whole thing goes to trash

c) Unions are harder to measure, since they won't lie flat, and I love unions

I'll work on perfecting my ability to measure, thank you for your help