How would I dimension bent pipes on a engineering drawing?

[hlffwft]

Hi i am about to create engineering drawings for a refrigeration unit, and although i won't have any problem creating the design on Solidworks, when i come to dimension it (which i will probably do in AutoCAD), i am unsuare what exactly i would need to dimention.

 

All my exiting dimensioning work has been for machined components from solid bock, where i dimentioned every aspect of them. However for something like bent pipes this wouldn't seem that appropriet, and it's only the overall dimentions that seem important. Woudl it be correct just to dimention what seems importnat?

 

Many thanks

[Ritch7]

dimension it by the angle the pipe is bent? diameter section etc post a sample of what your'e trying to dim.

[Tankman]

I would think you could dimension the appropriate, the fabricator could easily determine and cut to suit the straight tubing (pipe) lengths.

 

I am assuming "bent tubing", or, am I wrong?

[Ryder76]

One thing - always dimension pipe or tubing on the centerline of the pipe/tube.

[Jack_O'neill]

When I worked for a tubing fabricator, we would give an aligned dimension from one end, to the tangent of the bend, then give the angle of the bend, the centerline radius, and then to the next tangent, and so forth till we got to the end of the tube. The O.D. and wall thickness of the tube were listed in the bill of materials.

 

I attached an example. Not saying this is the industry standard, it's just the way we did it.

example.dwg

[Tankman]

Jack:

 

Looks fairly standard to me, I do a lot of pipe, valves, fittings, chemical storage tanks.

 

A nice free piping program is available, again free online, worth having.

 

https://shop.charlottepipe.com/lit/category.aspx?categoryid=26&openid=26

[tgrsx]

how would one draw that centerline going through the bend? thanks in advance

[Jack_O'neill]

tgrsx,

 

sorry, i've been away from the forums for a while, work has kept me insanely busy. I hope you're still watching this topic. There are a number of ways to do that, but I simply drew the straight lines first, then used the "fillet" command to get the radius I wanted. Then to draw the lines representing the outside of the tube, simply offset the centerlines an amount equal to half the diameter of the tube. In other words, if you want a half inch diameter tube, offset by 1/4", change the layer or linetype as desired and there you have it.

[moon47usaco]

What would be the standard to dimension a 3D bend that changes axis. For example on the drawing provided by Jack_O'neill say there was a 90 degree bend at the end of the lower left 2" segment that was going 90 degrees to the right (Towards the screen on this top view).

 

3D-example.dwg

[ReMark]

Wouldn't that depend on whether or not the user is dimensioning the 3D model or 2D views extracted from the 3D model?

[shift1313]

If you use solidworks routing the dimensions are automatically populated in the drawing. If you model thrm manually you are likely drawing a centerline path for a sweet. Dimension that sketch. Not sure why you would exit solidworks to dimension this in acad cause you will lose valuable data.

 

If you are making bent copper tubing, for example, routing will automatically put the entire length in the bom. I like to dimension from arc center of bends. It kind of depends on how it will be bent but that is likely the best for automation. If its a manual process you might have to dimension the straight sections and call out the radii and angle.