pipe intersection template 1

[CadLady]

I need to do a layout so that we can match two pipes together. I need to give the shop a template for the cuts in the pipe. Does anyone know how to make the cutting template?

The pipes will be at 45 degrees from each other.

 

[MikeHalloran]

I used to be able to do it 'by hand' on paper, but that was a long time ago.

More recently, I haved "Rhinoceros" to do it. With practice, you can set up an arbitrary two-pipe intersection as a 3D model in Rhino and unwrap a template in less than half an hour. It's usually faster to build the geometry in Rhino than to import it.


Hint: Newer versions of Rhino may not have this bug, but as of version 3 or older, you have to add one dimension to the flat pattern in Rhino before exporting it as DXF.
... else the scale comes out wrong.
Actually, it's not really a bug, just a different philosophy about intrinsic units.

I used AutoCAD to annotate the patterns, and to store them as DWG files, because that was the house standard where I was working.

I have also found it extremely wise to include a dimensioned reference line on the image that's plotted as a template, and blank lines for date and initials, so that whoever pulls it out of the plotter can actually measure the reference line to be sure that the intended plot scale was carried through the process, and initial and date that the check was done. Most of my templates would turn a $1000 sheet of stainless into scrap if/when they were wrong.


Photo shows patterns printed at 1/10 in foreground, with actual tube junction in background.





Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

If you are using software, try Pepakura.

 

[dhengr]

CadLady:
Any good mechanical drafting text book should cover this layout problem, if you don’t have software which will do it. Also, sheet metal layout text books will cover it.

 

[dvd]

Look for information on parallel line development. Think about the weld joints when deciding where the pattern needs to be developed. A pattern of the outside pipe intersection will not provide any joint preparation.

Pipefitters know how to use curv-o-mark layout tools (so do I). You might investigate getting one of these for the shop to develop their own layouts.

https://pipefitter.com/store/curv-o-mark

 

[Timelord]

Everybody has CAD nowadays, so just model the joint as sheet metal, flatten it and print it at 1:1.

Timelord

 

[robyengIT]

if it can help send me the data and I will send DXF file

 

[kingnero]

http://www.metalgeek.com/static/cope.pcgi

 

[racookpe1978]

ANY qualified pipe fitter working for longer than 3 months will have a handbook showing him (or her) the layout cuts.

Specify the final weld material, pre- and post-weld heat treat or soak requirements, and the weld spc's .... Let him make the cuts.

 

[MikeHalloran]

In the marine exhaust shop, our fitters did the simpler intersections, e.g. 90 degrees with intersecting axes, in our low priced stock, 316L, by themselves, cutting the holes after rolling.

When the angles got strange, or the intersections got complicated, or the tube axes didn't intersect, or they wanted to cut most of the hole in the flat blank state before rolling, or they were using expensive high-nickel alloys, they would ask for a template.

... as in the example I gave above, one of a pair of 'surge tees' for a yacht with two v-type engines. The branches enter at different angles, their axes don't intersect the 'run' axis, and the branch tubes intersect each other, and the run tube, and the cap at the forward end of the run tube. ... and the parts for port and starboard are never symmetrical.

Having a fitter manually lay out a piece like that consumes a lot of their expensive time. It's cheaper and faster to have a designer or an engineer crank out a template using a CAD program, even if the fitter doesn't make a mistake.


Mike Halloran
Pembroke Pines, FL, USA

 

[berkshire]

CadLady,
By your handle you are using Cad of some sort, If you are using Auto cad It will not unfold patterns, you need an add in program like Littio to unfold your parts.
Using my 3D parametric modeling program I was able to draw , cut, and unfold for your flat pattern in 11 key strokes.

For Calculations and illustrations, find a copy of the Pipefitters and Welders hand book.by Thomas W. Frankland available on Amazon .

By the way which Cad program are you using?

B.E.


You are judged not by what you know, but by what you can do.

 

[JStephen]

I calculate dimensions from the geometry involved in a spreadsheet and plot the points, doesn't take too long.
In a lot of cases, you're going to wrap the pattern around the OD, but the intersection is the ID, etc., so assuming zero thickness is not always a good plan.
If it's just a mitered ell with contact on the outside, the pattern is just a sine wave. Draw one, make a block, and you can easily scale it to any dimensions.