finding center lines on 45 degree/ecen. reducers

[sjmj1966]

I love this site and hope someone can lend me a hand. I'm an above average pipe welder and an average fitter and want to improve my fitting skills. I would like to know how to accurately find the center line on 45 degree fittings and eccentric reducers. I am not too bad at doing it by eye but some days my eyes don't work the best. I have always been pretty mathematically inclined and figure their has to be a better way using measuring tools. Any suggestions are greatly appreciated. Thanks

[lotechman]

For elbows I just measure the OD then set up some scrap blocks to half the diameter with a sharpened soapstone ( bevel one side only) and then use it like a surface gauge. Set the elbow on a flat surface and scribe the line on both inside and outside of elbow curve.
How you do a reducing elbow?? I am thinking I am fortunate to not have run into that problem.

[sjmj1966]

Thanks for the info. Havent figured out the ecen. reducers yet other than eyeballin it. Gotta figure it out soon cause we fit quiet a few of them.

[duaneb55]

Use lotechman's same method only first set up the eccentric with a block under the small end 1/2 the difference between the large/small diameters with the ends of the reducer perpendicular (square) to the table/fixture. The "centerline" soapstone block would be 1/2 that of the large end diameter.

[SwampWater]

I saw an old man do it with a square and soapstone on a truckbed I'll see if I can't get this awnsered at work

[Fishinsin station]

What size reducers, so what you do is have the flat side faceing you, with the bigger side down, with soap stone make a square box the size of the bigger end, mark the center, on the line facing you, on the sides running away from you draw a line at half the Od of the smaller side, extend the line out so you can hold a square on it, measure from the square to the reducer until it measures 1/2 the difference in size, once its turned right mark the reducer with soap stone at the center line of the big end, extend the line out, whatever end you need to fit up, put a mark on the pipe at center and your done...

[Vince144]

To find the center line on 45 degree fittings you just have to multiply the Diamater of the pipe by 5/8

ex: 2 inch pipe: 2 x 5/8 = 1.25
6 inch pipe: 6 x 5/8 = 3.75

Or you can divise the diamater in half, in half, in half and add the first answer with the last togheter

ex 2 inch pipe : 2__1__1/2__1/4 = 1.25

ex 6 inch pipe : 6__3__1 1/2__3/4 = 3.75

[Fishinsin station]

Vince that the 5/8's formula doesn't work on fittings under 3 inch

[Shiftace]

Originally Posted by Fishinsin station

Vince that the 5/8's formula doesn't work on fittings under 3 inch

And isn't that for pulling your take-offs anyway?

[Vince144]

Originally Posted by Shiftace

And isn't that for pulling your take-offs anyway?

This is the way we do it ,well is the way i learn and it's work great

[Vince144]

Originally Posted by Fishinsin station

Vince that the 5/8's formula doesn't work on fittings under 3 inch

I don't know where do you learn to fit... but for butt weld fitting it's work very well,the 5/8 formula for all 45 degres , and if you want to find any center of any angle you just have to do this.

(half degres of what you are looking for) multiply by TANGENT = x / radius of the pipe

x = center of the angle
For each long radius fitting , the radius is 1 1/2 the diamater of the pipe.

So there is my example again.

Find 45 degres of 2 inch pipe

22.5 (Tan) = x / 3
x = 3 (22.5 Tan)
x = 1.2426

So this formula work to find center of any butt weld long radius angle

Find 45 degres of 6 inch pipe

22.5 (Tan) = x / 9
x = 9(22.5 Tan)
x = 3.7279


And for any angle ex: 60 degres 2 inch pipe

30 (Tan) = x / 3
x = 3 (30 Tan)
x = 1.73

So the center of an 60 degres fittting is approximately 1 3/4 inch


I'm only a pipewelder of the UA local 144 but i know how the pipefitting works

[CamAus]

If you put 2 45s together to make a 90 it makes it a bit easier to get them to sit flat. Sitting flat on a level surface, use a square and level to mark one centre line. I always measure what the circumference actually is and divide by 4 to get the other points.

Eccentric reducers.. Well I don't have any suggestions apart from by eye, but would be keen to find out a better way also!

[woohoo]

on 45's I always used the divide by 2 method for the takeouts and my measurements come out good.

as far as the eccentric reducers go, eyeballing works ok for me on the small ones but the bigger ones are tricky to eyeball for me.

[Fishinsin station]

A two inch bw 45 is 1.375 e-c not 1.25 just saying...

[Vince144]

It's my mistake 1.25 it's the center of sanitary butt-weld fitting and the 5/8 formula work great for all size



and for standard 45 fitting you've got the right answer, it's does not work under 3 inch

[MainePiper]

take a piece of 1/2 all thread and stick in the pipe vice. Then slide your fitting onto the all thread. by rights it will naturally sit on the all thread with bottom of pipe on top if that makes sense. The take a framing square and a level and mark it as if you were marking top/center on a piece of pipe.
http://www.pipefittercalculator.com/...-piece-of-pipe

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