Tower Joint Fabrication

[bvan1941]

Gents,
I can weld well enough to fabricate what I need, but with thoughts of building this new tower for my new 9' Servo WT, I have a few concerns about strength of the joints for this much heavier overall project.

I've located some heavy wall 4" used pipe for sale. Contemplated removing my first 31' (3") tower and replacing it with the 4" pipe, increasing height to 45 feet. Naturally increasing guy wire size as well.
Question:   when joining this 4" pipe, can I get adequate joint strength using the square "flange type" method, or should I fabricate a sleeve type joint?

The top weight of the 9' foot WT assembly, I estimate to be about 100-120lbs. I'm Planning on using this as a "test" tower going forward, experimeting with future units. Hope I've given enough background for answers.
Bill

[brucedownunder]

  Hi Bill ,,  I use the sleeve type joint ..

  A length of close fitting sleeve ,for 4 inch pipe , I'd go for around 18 inches long..

  It's easy to weld while slowly rolling the tube ,remember to very carefully remove ALL  galvanising for around 1/2 inch where the welding is to be done ..  Cold Gal paint the weld immediately with a couple of coats.

 Handy hint here -make the middle of your sleeve an attachment place for your guy cables. Weld on 3/8 steel flanges with a hole drilled in them . Don't go for just re-inforcing rod as we have had an occasion on this forum with these failing.

Faily smooth/firm fitting pipe sizes are availble , but you may have to go heavy pressure pipe wall size .

Have fun

Bruce

[bvan1941]

Bruce,
 Glad you gave the length for the sleeve. Forgot to ask about sleeve length in my post.
Thanks,
Bill

[philb]

I use the sleeve type joint also. I have had 2 tower failures, but never on a sleeved joint.   

What is the pipe thickness? If if is 10 gauge or less, you can either cut a piece off the pipe you are going to use for the tower or find another one about the same thickness.

The sleeved joints are more forgiving for bad welds caused from dirty material or lack of weld penetration. So, prep is as important as welding skills.

I didn't see if you had specified galvanised material or not. I prefer non-galvanized pipe because fumes can be very bad to breathe.

[bvan1941]

Philb,
wall thickness, don't have answer for you as they are about 100 miles east of me and I haven't seen the pipe myself. The guy has taken over the salvage yard from his Dad. He's not sure but says it's bigger than schedule 40. Don't know if it's Galvanized or not. It has been painted so it's anyones guess right now.

I hope I can find some tubing about the same size to use for sleeving, but will split the 4" if I have to. My intent is to drill holes in sleeving and weld both together. I will also tack tops and bottoms around the sleeve pipe joint.  Understand from some other posts, welding all around the joint is recipe for cracking later on.
Any additional advice for sleeve construction is welcome, but as of now intent is to follow the Dan's pattern if no other method is better.
Bill

[Dale S]

I would weld angle iron length wise at the slits in your sleeves, the angle iron should have at least six holes for bolts, this is called a draw band, there is no need to weld to the tower pipe at all. I'd use at least 1/2" grade 8 bolts and constantly tap the draw band as you tighten it up.

[bvan1941]

Dale,
I did weld a piece of angle to my first tower at the top section but I never heard of a "draw band" before.

Trying to "picture" what I think you mean. Must be something like (4) angle iron pieces evenly spaced around the pipe?
(3) bolts each on both sides of the joint?

Bill

[birdhouse]

bill-
i think fab is talking about taking a piece of pipe about 18" long with a slit in it, and welding thick angle to it along both sides of the slit.  then drilling holes in the angle for bolts.  imagine a "clamp sleeve"  via bolts.  then, no welding ect. 

i'd be a little worried about how thick that pipe is.  more for excessive lifting forces than anything.  i went the other route and used slightly thicker than schedule 10 pipe.  WAY thinner than schedule 40 pipe.  the pipe is still thicker than a few manufacturers that make tower kits for 12' turbines. 

i've got the PDF's if you want them. 

adam

[bvan1941]

Gents,
Thanks for explaining to the "MM"---- sure feels stupid on this end for not understanding the OBVIOUS !!!!

Nothing like making a fool of yourself--
Bill

[Dale S]

How can you make a fool of yourself if you didn't know what I was talking about, don't sweat it man, somewhere on the otherpower site in the wind section they show how they make their draw bands.
Check out this page. http://www.otherpower.com/new17page5.shtml

[bvan1941]

Dale S,
Thanks, That was what I was going to do, copying that idea to a "T".
If it held their big pipe securely, mine would be a cinch.
Bill

[dang]

A detail from an example near me - two large holes (3/4") that make a mild hinge point opposite the draw-brackets. Might be leftover as a manufacturers process or somesuch but it looks to make sense on smaller pipe sizes as the hinge to evenly spread the collar apart on and then flatten out when clamping.



Also - if you're using welded pipe then cut at the weld seam & make the effort to clear any weld slag ridge remaining.

[bvan1941]

Dang,
Thanks for the pix. Will clear the slag from the seam before welding the bolt flange on the sleeve as you advised.
Bill