# how to draw elbow of a pipe using fillet.

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i tried to draw elbow of 12" pipe, i am using fillet tool, i am not sure if there is easier way to draw this elbow or turn of this pipe. i used R=10" on fillet 1 (f1) which looks ok but f2 (Inner radius) does n't look right, my question is what is rule or fomular to get the correct radius?

[ATTACH=CONFIG]48892[/ATTACH]

Edited by Sengna

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If you think about it, you will realize that the inside radius needs to be smaller than the outside radius by

the dimension of the pipe. If you have used a 10" radius on the external fillet, what will that make your internal fillet radius?

How could that be?

You could do this by using the OFFSET command, and setting the offset distance to the dimension of the pipe,

once you have determined the correct radius for either one of the fillets.

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Short radius elbow will have a center line radius of 1X pipe diameter.

Long radius elbow will have a center line radius of 1.5X pipe diameter.

So a 12" short radius elbow would have a center line radius of 12, an inner radius of 12-6=6, outer radius of 12+6=18.

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Unfortunately I don't think it is quite that simple even though I know nothing about piping. Pipe elbows it would seem, must have a minimum inside radius.

The elbow or bend is called out as a centerline radius.

I have no idea what the standards are myself, but it will depend on the usage and type of pipe, and whether it physically can be bent, or the elbows have to be welded in place, or threaded on.

I do know for sure that 12" pipe will not bend on a 10" outside radius. Your inside radius would be negative 2".

From what I can see on the interwebs, my best guess is to start with an inside radius equal to the pipe radius, which is 6", then add the diameter of the pipe which is 12", to obtain the outside radius of 18".

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Short radius elbow will have a center line radius of 1X pipe diameter.

Long radius elbow will have a center line radius of 1.5X pipe diameter.

So a 12" short radius elbow would have a center line radius of 12, an inner radius of 12-6=6, outer radius of 12+6=18.

Youj got there using job experience, didn't you. My guess wasn't all that far off.
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Find the radius you require on the list, long or short then draw this with your fillet.

half the pipe o.d then offset this from the ceterline radius.

Steel / Stainless 12" pipe outside diameter = 323.9mm

Edited by gazza_au
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If you are tasked with drawing double lined piping then you may want to look at this freebie gem from ASMI, which automatically draws the fittings based on the radius which you preset: http://www.cadtutor.net/forum/showthread.php?30545-*FREE*-HVAC-or-Piping-program-for-AutoCAD

Hope this helps. -Tannar

Nice tool Tannar thanks.

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Short radius elbow will have a center line radius of 1X pipe diameter.

Long radius elbow will have a center line radius of 1.5X pipe diameter.

So a 12" short radius elbow would have a center line radius of 12, an inner radius of 12-6=6, outer radius of 12+6=18.

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Short radius elbow will have a center line radius of 1X pipe diameter.

Long radius elbow will have a center line radius of 1.5X pipe diameter.

So a 12" short radius elbow would have a center line radius of 12, an inner radius of 12-6=6, outer radius of 12+6=18.

Edited by Sengna
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Find the radius you require on the list, long or short then draw this with your fillet.

half the pipe o.d then offset this from the ceterline radius.

Steel / Stainless 12" pipe outside diameter = 323.9mm

This is what i need thanks you, unfortunately i have to go search for the English Unit

before i do that let me make sure if i know how to read this table:

NPS=12 then A=457mm which Approx. =17.99212598 inch, correct me if i am wrong.

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Sengna 457mm / 25.4 = 17.99" (18") I will attached some more charts of pipe wall thickness and diameter if you need them?

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If you are tasked with drawing double lined piping then you may want to look at this freebie gem from ASMI, which automatically draws the fittings based on the radius which you preset: http://www.cadtutor.net/forum/showthread.php?30545-*FREE*-HVAC-or-Piping-program-for-AutoCAD

Hope this helps. -Tannar

```(defun c:DUCT(/ actDoc ang1 ang2 ang3 ptLst enDist
fPt lEnt lObj lPln oldVars oldWd
plEnd plStart1 plStart2 prDir
segLst Start stDist stLst tAng
vlaPln cFlg *error*)

(defun GetPlineVer(plObj)
(mapcar 'cdr
(vl-remove-if-not
'(lambda(x)(=(car x)10))
(entget plObj)))
); end of GetPLineVer

(defun asmi-PlineSegmentDataList(plObj / cLst outLst)
(setq cLst
(vl-remove-if-not
'(lambda(x)(member(car x) '(10 40 41 42)))```

Edited by SLW210
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Some more data sheets for you.

Thanks gazza_au

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Quickest way is to just drag/drop into AutoCAD, then type DUCT at the command line. To have the program always available, add it to your Startup Suite.
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Sengna - the larger radius of 18 you have correct, the inside radius should be 6 and not 12, 12 is the center line radius so you would subtract 6 from 12 = 6.

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Sengna, please read the Code Posting Guidelines and use Code Tags for Code in the future.

Most designs will use long radius elbows, where there is room, for improved flow.

There is also an extra long radius elbow and it is 3x pipe diameter at center radius, which you may or may not run across.

Be easier to make a set of elbows as blocks on a tool palette than to try to draw them each time.

Here is a chart. http://www.bwfitting.com/elbow-size.html

Another as a PDF http://www.st-pipefittings.com/ANSI-B16.9-elbow.pdf

P.S. I have an excel file from Pipedesigners.com with info for ELLs, Tees, Flanges, Eliptical Heads, etc., but it is too large to post here, even as a Zip file.

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Sengna, please read the Code Posting Guidelines and use Code Tags for Code in the future.

Most designs will use long radius elbows, where there is room, for improved flow.

There is also an extra long radius elbow and it is 3x pipe diameter at center radius, which you may or may not run across.

Be easier to make a set of elbows as blocks on a tool palette than to try to draw them each time.

Here is a chart. http://www.bwfitting.com/elbow-size.html

Another as a PDF http://www.st-pipefittings.com/ANSI-B16.9-elbow.pdf

P.S. I have an excel file from Pipedesigners.com with info for ELLs, Tees, Flanges, Eliptical Heads, etc., but it is too large to post here, even as a Zip file.

Lisp routine already exist here and running and draws them all in each schedules according to standards.

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That's all fine and good if you have the ability to run LISP, there are others that do not have such capabilities or desires.

Plus, it is very important to know what the end result of a LISP needs to be to insure correctness and accuracy.

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