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Re: Aluminum Rectangular Tubing

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Make sure your connection details to the building will accommodate movement of the aluminum due to temperature changes.  The coeffIcient of expansion of aluminum versus steel is about twice as much.

Neil Moore, SE, SECB

At 02:14 PM 1/5/2007, Gerard Madden, SE wrote:
It's 10 feet up the building above the windows. I suppose someone could hang on it if they could jump that high. No NBA team in the town, but I'm sure some highschoolers could reach it.

Yeah, I found it strange as well to see the painting note in the drawings, I thought that was usually done to steel that is in contact with aluminum.

I also need to determine the best way to fasten it with lag screws. I was going to use a neoprene washer between the head of the lag and the end plate, but wondering if that's too general a note to place.

I also have one condition where I need to attach the outrigger to a structural tube steel column that's exposed. I was thinking of using threaded studs and then neoprene washer to the nut. But the back of the end plate will be up against the steel and was wondering if I should place washers on both sides of the end plate to keep them not in contact.

Yeah, the welding will hurt, but it's unavoidable. But sounds like the 6061 will work pretty well. The forces are fairly small (wind).


On 1/5/07, Robert Kazanjy <rkazanjy(--nospam--at)> wrote:
I strongly recommend against paint for alumimum

aluminum is meant to be anodized for decorative purposes but then that's the architects job, right?

Painting is just asking for problems downstream.

2' ?   Can someone hang or stand on this feature?  Or set a plank?  for painting or window washing? or something equally dangerous?

Welding to the base plate with reduce your Fy appreciably....

with 6000 series you can re-heat treat to T6 if you need those properties  5000 series no re-heat treat  :(


On 1/5/07, Gerard Madden, SE <gmse4603(--nospam--at)> wrote:
Thanks Everyone. Very helpful.

The aluminum is for small aluminum decorative bands that extend off the side of the building. They pop out  about 2 ft max and are exposed to the weather.

The architectural details call for them to be painted "Metallic Silver".

I'm checking the outriggers (2" square tubes) for the cantilever effect and designing the end plate anchorage to the building wall. There is welding of the tube end to the anchorage end plates.


On 1/5/07, Robert Kazanjy <rkazanjy(--nospam--at) > wrote:

6061 is the alloy number.......the suffix T4,  T6 is the temper designation

Most of the extruded aluminum sections are 6061-T6 or 6063-T6 (at least in SoCal)  the 6000 series alloys are weldable, hove decent strength & corrosion resistant.

At my local supplier "THE MOST COMMON aluminum for 2x2 square tubes."

would be square corners & 6061-T6 (or 6063-T6)

In my experience nearly all aluminum sections are extruded (even the ones that look like rolled steel sections)....aluminum extrusion is cheap & easy

Just to throw you a curve ball......

architectural aluminum is often 5000 series  like 5052....better corrosion resistance than 6000 series

more general flavor info

short answer   6061-T6 is probably fine unless you've got a corrosive environment

I assume the item will be anodized?


On 1/5/07, Gerard Madden, SE <gmse4603(--nospam--at)> wrote:
Couple of quick questions.

What is the alloy number in the 6061 series that is common used for 2" - 4" square and rectangular aluminum tubes? Is it 6061-T1 or -T5 ? Or some other one?

I went to Alcoa's website and they have good info, but they have Rectangular Tubes with Rounded Edges and and Rectangular Tubes with Square Edges. Both are extruded. not sure which one is more common.

Basically, what I'm after is THE MOST COMMON aluminum for 2x2 square tubes. So I'm not sure which alloy that is and which edge type. I take it that all aluminum shapes are extruded, not hot-rolled like steel.

This is for some small decorative attachment mountings for a building.