Black Pipe Measurements

rickster05

Have 3 sections of pipe needed for LP.  Anyone care to confirm my math?

ethicalpaul

It would be a lot easier in centimeters!

EBEBRATT-Ed

The first 2 examples I understand. I come up with slightly different measurements. Rule of thumb on 1/2 & 3/4 pipe is that it will make in the fitting 1/2" which may not be exactly what the book says but your within tolerances with your measurements.

The last example I don't understand what your doing

The other issue is that pipe and nipples will "make in" to different fittings different amounts. They are not supposed to but they do. Threads going into a union will usually make in more than an elbow for instance. There is always some variability in the fitting quality also which is variable.

mattmia2

Remember the pipe will expand and contract in length so you don't want to arrange it so the length has to be exact, you want to give it a little wiggle room at the corners and ends which will also give you a little play in your fitting length.

OldawgBryant

I don't quite follow this, but I am guessing you are trying to figure-out your length of pipe after deducting how much it threads into the fitting (coupling, 90 tee, etc)? I am trying to understand this stuff myself, as I am working with laying-out 1-1/4 black pipe. I am making a mock-up of the supply/return, but I see how the lengths change after cranking everything tight.
What does "TE," & "CF" mean? I have experienced a loss of about 1/2" when tightening 1/2" & 3/4" black pipe to fittings. Do things change for WARD USA parts vs. Home Creepo Vietnam parts?

Mad Dog_2

Yeah.  I'm not sure of his terminology.  In our excellent NYC Local # 2 Apprenticeship,  We learned....

E to E = End to End Measurements.
E to C  = End to Center Measurements
C to C   = Center to Center 
T.B.E.     = Threaded both ends

Basically, all Measurements that involve fittings in a run 🏃‍♂️ or developed length, are to be measured from the fittings center.
The distance from the Center to the end of threaded portion of the female fitting is "the fitting take off" and is deducted from the overall length.  

For the Gold Standard Of Master Plumber Practical Exams, the NYC standards allow no more than two threads showing after full tightening, no wrench marks perfectly sqaure and shall not leak under air pressure test.  

If you take your time with the Measurements, you'll get the hang of it.  1/8ths of an inch accuracy 👌 usually works out but I try for 1/16th.  The better fitting manufacturers like Ward & Anvil (USA 🇺🇸)  tell you the takeoff of each fitting.
Screw pipe is the true test of a plumbers skills.  Mad Dog 🐕 

ChrisJ

ethicalpaul said:

It would be a lot easier in centimeters!

Convert all of the fractions into decimal and then it doesn't matter.

EBEBRATT-Ed

Best way to do an end to center is to make the fitting onto the pipe permanently. Then measure from center to the far end then cut the pipe and thread it. This does not always work with short pieces or nipples, but it eliminates 1/2 of any possible
"Make in" error and makes things more accurate.

rickster05

Thanks all.  The feedback was helpful!  This was an easier task when I had my grandfathers powered cutter/threader/dies.  Was easy to do it piece by piece as you go and make the measurements and adjustments on site…