Troubleshooters.Com and Steve Litt's Pool Resurrection Page Present

My Tricks for Making Pipes Fit

Copyright (C) 2009 by Steve Litt




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These are tricks I use Personally, right now! They very well may be completely wrong, and they're subject to change at any time. Do not base your own pipefitting techniques on this document, but instead do your own experiments and find your own authorities. I post this more as a reminder to myself than as a reminder to others. However, because it just may give others food for thought, I've posted it online as food for thought.



I'm Steve Litt. I created the Universal Troubleshooting Process (UTP). I create and license UTP courseware, as well as teaching the UTP onsite. I've written four books on troubleshooting: Twenty Eight Tales of Troubleshooting, Troubleshooting: Tools, Tips and Techniques, Troubleshooting Techniques of the Successful Technologist, and The Manager's Guide to Technical Troubleshooting. Past professions include software development, electronic repair and corrosion protection.

According to Dictionary.Com, pipefitting means "The act of connecting pipes." Plumbers, pool professionals and people with outstanding three dimensional imagination, find pipefitting easy. People like me, not so much. So I've written this document as several pipefitting tricks serving as a reminder to myself.\

Patterns and Solutions

I see pipefitting similar to a Rubics Cube -- if you find yourself in a certain situation, you can get to the goal with a specific series of actions (in this case, elbows and pipes between them). This document discusses those situations and solutions, which can be combined to run some pretty sophisticated piping.
  • Connecting inline two pipes with a U connection
  • Connecting two perpendicular, intersecting pipes
  • Connecting two perpendicular, not quite intersecting pipes
  • Connecting two parallel pipes
  • Connecting two parallel pipes too close for a U connection
  • Connecting two pipes in parallel planes
  • Connecting two pipes, in parallel planes, not at the closest point
  • Connecting two pipes not in parallel planes
Pipes parallel and in linecoupling
Pipes parallel and in lineelbow->pipe->elbow->pipe->elbow->pipe->elbow
Pipes parallel and not quite in lineelbow->pipe->elbow->pipe->elbow->pipe->elbow
Pipes parallel but not in lineelbow->pipe->elbow
Pipes perpendicular and intersectingelbow
Pipes perpendicular and not quite intersectingelbow->pipe->elbow->pipe->elbow->pipe->elbow
(instead of elbowing straight into the other pipe, elbow on the other pipe's plane perpendicular to the other pipe, then elbow parallel to the other pipe, then elbow toward the other pipe, then elbow into the other pipe. You would have to do this if the pipes miss by an inch or two -- not enough to simply U in a pipe between them.)
Pipes perpendicular but not intersecting (each on a different parallel plane)elbow->pipe->elbow
Pipes not parallel or perpendicular, in separate but parallel planes.elbow->pipe->elbow
(The connecting pipe must be at a point as follows: If you look perpendicular to the parallel planes, it's the apparent intersection of the two points)
Pipes not parallel or perpendicular, in separate non-parallel planes.elbow->pipe->elbow->pipe->elbow
(Very difficult, trial and error)
Pipes not parallel or perpendicular in separate but parallel planes, but no possible connection at the apparent intersection.elbow->pipe->elbow->pipe->elbow->pipe->elbow
(Aim elbow and pipe from end of one pipe in its plane, and aime elbow and pipe from end of other pipe perpendicular to its plane. Since both planes are parallel, the two added pipes will be perpendicular to each other. Install a pipe between the two added pipes, perpendicular to each added pipe, using elbows. In order to do this, each of the added pipes must be cut to proper length)

Dry Fit First

Some pipe routes seem beautiful when imagined, but lead to collisions or other problems. So what I've resolved to do is dry fit strategic parts first, to make sure it works in principle, parts that should be turnable are turnable, and everything seems to fit together reasonably. Pipes that should intersect perpendicularly should actually do so, although of course since they're probably longer and need to be cut, one will pass over the other.

If there will be no chance to turn anything (no unions, patches or threaded pieces), dry fitting yields the last opportunity to get angles right.

Measure Twice, Cut Once

Pipefitting requires precision. With 1.5 inch pipes, I find that if I'm off by more than a centimeter, I'm in big trouble. And for shorter runs or straight runs, I find the tolerances must be even tighter.

Fitting Assumptions

Handy Techniques

Riff: Connecting Threaded Vertical and Horizontal Holes

Filter valves typically have a threaded hole into which a horizontal pipe screws. Pumps typically have an output threaded hole into which a vertical pipe screws. If each pipe goes into an elbow leading to its own horizontal pipe, that means the horizontal pipe from the pump can twirl in a horizontal plane, while the horizontal (more or less) pipe from the filter valve can twirl in the vertical plane.

You can then adjust the pump pipe until it's in the same horizontal direction as the pipe from the filter valve, and adjust the filter valve pipe until it's in the same vertical direction (probably straight horizontal) as the pipe from the pump, thus making the two pipes parallel. To fine tune parallelness, site down the pipes in the plane containing both, and adjust until the gap between them appears parallel.

This technique depends on having the threaded fittings tight but moveable. The way I do this is to put teflon tape on the male adapter part, put silicone sealant on both, then screw it in as tight as I can by hand. Then I glue in the elbow in a direction such that I'll have to tighten the fitting an eighth to a quarter turn to adjust it to the right place. Now I can use the threaded adapter to make fine turning adjustments, although I try not to move it too much, and do all the adjustment as soon as possible so the silicon sealant is still wet when the adjustment is made.

Finally, I trial and error several pipe segments between the parallel pipes to find one that fits at both ends of the pipe. Then I re-adjust the angles, then try the pipe again, etc. When they're properly parallel, I use a square to cut them both to a compatible length, glue an elbow into the pipe segment that fit on both ends, glue that onto one pipe at the proper angle to just touch lips with the other pipe, wait for the glue to dry (a couple minutes with Rain or Shine glue). then I bend things and glue on that last elbow, careful to get the right angle, and careful to use plenty of glue to act as a lubricant so the pipes slide all the way into the elbow. Do one side of the elbow at a time and wait a few minutes for the glue to dry.

Teflon Tape

Here's how I put on teflon tape:
How I wrap teflon tape
By doing it that way, the tape is pulled tight when screwed in.

Pipe Route Learning Laboratory

A pipe route learning laboratory can be had for about twenty five bucks -- well worth the money for anyone thinking about doing pool piping. It's simple enough -- buy twenty feet of pipe, eight elbows and maybe four 45 degree elbows. Cut the pipes in lengths between six inches and two feet, and play with them by connecting in various configurations. The purpose is to study several recognizeable patterns:

Connecting two inline pipes with a coupling

This is obvious in theory but not so easy in practice, with the following requirements:
The basic technique is like this:
  1. Cut the pipes suffiently to
  2. Free up enough of both pipes so each can be bent in the same direction sufficently to accommodate a coupling.
  3. Glue up 1 side of the coupler and the more bendable side of the pipes
  4. Bend the more bendable pipe sufficiently to clear the other pipe
  5. Twist the glued side of the coupling all the way onto the most flexible pipe
  6. Wait a couple minutes
  7. Glue up the other pipe and other side of the coupling. Use lots of glue so as to serve as lubricant. You'll need to bend the more flexible pipe to do this. An assistant makes this much easier.
  8. Quickly bend both pipes in the same direction until the pipe is in position to go into the the coupling, although the angle will be wrong. Then, by pushing the pipes toward their normal orientation, force the pipe all the way into the coupling.
The process is made much easier if one of the pipes can be rotated via a union or threaded adapter plus elbow.

Connecting inline two pipes with a U connection

U connection

Connecting two perpendicular, intersecting pipes

This is a single elbow. It's easy if the pipes can be bent enough to put on and glue the elbow. When putting it on the first pipe, be careful to point it the right way or you'll need to cut and patch. When putting it on the second pipe, use plenty of glue to lubricate, because you won't be able to twist -- only push.

Connecting two perpendicular, not quite intersecting pipes

If the pipes were far enough apart, you could simply cut them at their closest approach and link them with two elbows and a pipe segment. But if they're closer than two elbow sleeves (and even this would be cutting it very close), then you need to do something more creative. You need three elbows and two pipe segments between them.

It's important to use a pipe construction kit to simulate this in order to understand it. One three dimensional picture is worth a thousand words. Assume for example that one pipe is vertical and one is east/west, but is 1 inch north of the vertical pipe. If you're looking at the pipes from the south, the horizontal pipe appears behind the vertical one. Water flow is intended to come from the east and go down toward the ground.

Cut off the horizontal pipe about a foot east of the vertical, and install an elbow straight up. Install an elbow on the straight up segment pointing directly at the vertical pipe. Install a pipe segment into that elbow that just touches the vertical pipe, and cut the vertical pipe so its lip just touches the lip of the horizontal pipe segment. Install an elbow between them, using plenty of glue to act as a lubricant.

Perpendicular, almost interstecting, before   Perpendicular, almost intersecting, after

You could have done a similer thing with  a little more direct piping as shown to the right. This has the obvious advantage of using less pipe and being neater and less of an eyesore. It has the disadvantage of being harder to do because there's less pipe to bend in making that last join.Perpendicular, almost intersecting, more direct

Connecting two parallel pipes

You connect parallel pipes with a U or an S:
Parallel pipes, U connection         Parallel pipes, S connection

Be careful -- they must be very parallel -- otherwise you might not be able to glue the joints, or the finished joints might be brittle and subject to early failure.

Keep in mind also that pipes needn't be completely horizontal or completely vertical to be parallel. They must simply have the same three dimensional slope. If two straight pipes have the same distance between them over their lengths, they are parallel.

Sometimes pipes are parallel by definition. The input and output pipes coming out of a

Connecting two parallel pipes too close for a U connection

Connecting two pipes in parallel planes

Connecting two pipes, in parallel planes, not at the closest point

Connecting two pipes not in parallel planes

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