Mesuring Chute / Duct Transition. 1

[Mallon]

Im interested in how people would tackle this problem / measure a tricky transition.

I have an outlet to a piece of equipment and the inlet to a piece of equipment downstream that need mating up with some duct / chute work.

The inlet is offset in all directions ie x,y,z.

Both the outlet and inlet have flanged connections which I have the details for I just need to get the correct size transition made to mate to these two flanges.

what is the most accurate way to measure this in order for a piece to get fabricated.

My first thoughts were find the centre of the oulet and the centre of the inlet and run a string between the two to get that dimension then try and find the other dimensions ie height and the two offsets from the outlet.

What are peoples thoughts. There are no existing drawings of the positions so has to be site measured.

thanks shaun

 

[SwinnyGG]

Do you have clear line of sight between flanges?

 

[hendersdc]

Depending on the size and your accuracy needs you may find it is easier to mock up with cardboard and then measure that instead of trying to measure everything directly.

 

[dvd]

If it's big stuff, you could contract with a laser scanning contractor to make a 3-d laser scan and get a point cloud of the entire area. It is accurate and fast. It allows you to design hangers from existing steel, also.

If you want to go the cheap way, get centerline dimensions and use a level to determine where the flanges are located in space.

My recommendation is to have your local sheet metal fabricator/installer come on-site and measure it and then install it - they have a stake in the accurate measurement if they have to fab and install.

 

[pylfrm]

Mallon,

With a suitable combination of six straight line dimensions (perhaps measured with string) between known points on the two flanges, you could in theory reconstruct the geometry, including angular misalignment. Imagine measuring the length of all six actuators of a Stewart Platform.

This will only work well if the flanges are fairly close relative to their size.


pylfrm

 

[Mallon]

When I say flange I mean Jacobs flanges that are connected with clamps so there is a slight/small margin of error.

DVD. My company wont pay to get a laser scanning contractor in or fabricator so looks like im going to have to try my best and get centreline dimensions / levels .


Hi jgKRI yes there is a clear line of sight.

 

[EdStainless]

It is easier if the flanges are one above the other, then gravity helps you out.
The historical techniques for developing a duct transition (such as in HVAC work) is all graphical.
I have watched a guy hang a couple of plumb lines, measure offsets, and begin cutting and folding tin.

If yours have a horizontal separation then physically constructing horizontal projections of the center lines would allow you to determine the true horizontal distance, and the offsets.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[berkshire]

Mallon
If the two flanges are one above the other and parallel then as Ed says a couple of plumbobs are all you need drop a line from one corner then measure the off set to the corresponding corner below. Draw a plan view of the two flanges superimposed one over the other. Measure from the edges where you can get hard dimensions rather than trying to get centerlines. If the duct is horizontal then spirit levels are in order.
B.E.

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

 

[dvd]

Don't forget about using a cheap laser pointer squared to flanges for projections in any orientation.

 

[berkshire]

DVD I second the cheap laser pointer idea.
B.E.

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