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Square tubing versus pipe for tower
By Gary D, Section Homebrewed Electricity Posted on Fri Jul 11, 2003 at 07:24:06 AM MST
Square tubing vs. pipe for tower?

After seeing the square tubing mast test jeep test rig article, was wondering which might be best for a jenny tower for a 9 footer? With the square, you have many options of wall thickness, and can slip one size over another without welding and would make drilling any holes much easier without a jig. Just rambling here... any ideas? Any weld shop carries this tubing in different grades. Pro's con's? Thanks Gary D.

Square tubing versus pipe for tower | 4 comments (4 topical)

Re: Square tubing versus pipe for tower (none / 0) (#1)
by electronbaby on Fri Jul 11, 2003 at 07:53:47 AM MST

Gary D,

I used square aluminum tubing (4" x 4") for a 20' tilt up tower two weeks ago during field day. I had a dual rotor 9' prop on top of the tower and it worked quite well. The tower was pulled up with my jeep in 4 wheel low gear. I have pics and I will post them as soon as I get them developed (no digital that day). :( I think square tubing is a lot less prone to bending and things would be a lot stronger if you used steel thick wall tubing. Have fun!!

RoyR
Have Fun!! RoyR KB2UHF

Re: Square tubing versus pipe for tower (none / 0) (#2)
by RobD on Fri Jul 11, 2003 at 09:06:36 AM MST

I think the cost is higher for square tubing. I don't remember the cost of square tubing but 2" .093 wall runs about $2.00 a foot here close the Canadian border where our metal comes from. Square runs standard thicknesses so you can only get 1/16, 1/8, 3/16 or 1/4 etc. Round tubing may run a higher carbon content so it's stronger for weight. Square tubing is plain vanilla 1018 low carbon steel. You should also be able to get round in telescopic sizes (one tube fits into another). When you telescope square you have the internal weld to contend with as opposed to DOM (drawn over metal) which has no seam weld. Of course there's the back yard aspect. That's the tubing that always wins out here RobD

Re: Square tubing versus pipe for tower (none / 0) (#3)
by troy on Fri Jul 11, 2003 at 09:33:00 AM MST

This will sound like a truism, but either will work fine if they're strong enough. Both are available in different wall thicknesses. But if it were a contest, the round pipe would win. It's the same strength in every direction. Square tubing is stronger in the diagonal directions. That means it's relatively weaker on the flat sides.

So if you had a hundred pounds of steel, you could make a slightly taller mast with the round steel tubing than the square tubing, and still have equal resistance to bending (compared to the weak faces of the square tubing). Schedule 40 pipe is quite strong and widely available at most steel suppliers. "Normal" water pipe and fencing material is not that great as a structural material.

The other evidence that a round cross section structural member is a little better, is that commercial guyed towers that use a single structural element are virtually all round.

As far as ease of fabrication, take your choice. I'd use what I find down at the recycling yard for ten cents a pound. Make it strong enough that it can't possibly fail, but always take safety precautions with the idea that it definitely will fail.

Best regards,

troy

Re: Square tubing versus pipe for tower (none / 0) (#4)
by Gary D on Sun Jul 13, 2003 at 07:40:28 AM MST

Thanks for the various views. Pro's and cons are great! Makes for more info and choices! That is why I love this board. Didn't check prices or check the local scrapyards before the original post, so will definatelly see if I can get a deal. Was also thinking of I beams due to being able to get them at scrap price, but thought that they could dam up air more than either square or round. But running the pole for the genny high enough above it could negate that problem. Thanks all Gary D.

Square tubing versus pipe for tower | 4 comments (4 topical)

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