Tower Materials question

[Ronnn]

I got a suggestion from the local scrap yard/steel pipe supplier to use 8 inch sch.40 pipe as the base or first joint for my 60' tiltup tower. He's not an engineer so he says he over builds.  The second joint would be 6 inch sch. 40 followed by a joint of 4 inch sch. 40. They would fit inside eachother with a welded ring at the base of each nesting section that would go a prudent distance [ what would that be? 2'? ] into the section below and at the selected distance there would be a second welded ring to weld to the end of the lower section. Each joint is only welded to the preceeding joint at the exterior ring. This tower would weigh around 1225 lbs. Would this be too heavy to raise with the standard gin pole/pickup in low range method. There will be a 10' homebrew trubine at the top, four guy wires.  Could I begin with a 6" section as the base? or even four inch? If I used all the same diameter pipe they want to weld rings to the adjoining ends of the pipe and bolt them together. Is that sufficient assuming a certified welder knows what he is doing?

This damn math problem says, and I quote: 2 + = and I am supposed to put the correct answer in the box.

2+ is all I know to put. But boy is this a pain in the ass. I posted all this yesterday and it never got posted because I forgot to fill in the fear and loathing answer. I belong to about 10 forums of all kinds. Never have I seen such a lugubrious posting protocol. Please let's find a better way to speak with each other. I very much appreciate the information available here so I will do this but I really don't think all this is necessary for feel safe.

Ron

[DanB]

Hi Ron - could you do us a favor and repost your last two postings as comments to this story, rather than new postings - for the sake of keeping the board reasonably 'clean' and all the comments in one place?  I just set your last two postings 'not to show' in hopes that you could just keep it all here in one place.

thanks.

[DanB]

It's much much stronger than it needs to be for a 10' turbine.  You could build the whole tower out of 2.5 in sched 40 pipe for a machine that size (that would be marginal but it would work).  I don't see much advantage to having thicker stuff at the bottom than at the top.  If you really want it strong you could go to 3 in pipe and feel quite safe.  I prefer to use thinner walled pipe or tubing, and larger diameter if you can find the materials.  

You could certainly raise what you have planned and it could work fine - it's just a lot more work/steel than you need.

[TomW]

This is a family place, Ron so please restrain your use of colorful metaphors!

Thanks.

Tom

[Ronnn]

Sorry Dan, I should have used the reply button to the origional post. I think that is what you mean.  But I think from the answer I got I don't need to ask the one question about the size of the gin pole stock. I can just do it out of the three inch stock. The other was just a correction to some poor communication on my part. Many of the forum formats I've seen have an edit button for after you have hit the send button. I sometimes forget to preview a post or am in too much of a hurry.

Ron

[Ronnn]

Tom feel free to reply to my email addrress if you like but, I have to ask, what colorful metaphors?  Da*n?  Fear and loathing?  You object to these? These are the only words I can picture as colorful. I will certainly comply if this is what you mean.

Ron

[Rover]

He probably meant your reference to your discomfort in your hind quarter lol

[SparWeb]

By making the tower much heavier than necessary, you make all the supporting, lifting, and towing equipment necessary to use it heavier.  For example, your suggested tower weight is about 3x heavier than the 3" sched 40 pipe tower that I have, so you should expect to need 3x the force to raise it.

If you come up with a way to build it and raise it with a crane, then leave it where it is, then you could use it for quite large turbines, such as 14 or 16 foot diameters.  However if you want it to tilt up for you, shaving some weight would be in order.

[scoraigwind]

I agree that it's best to use the same pipe size all the way up a guyed tower.  2 1/2 inch pipe is good enough for a ten footer as Dan says but in a sixty foot length it wold need very careful support.  Long thin pipes are a bit unstable in themselves and tend to buckle very easily during erection if they are not perfectly supported at a large number of guy points.

I don't see any advantage to overlapping pipes in the weld joint.  Welding is very strong and a simple butt weld is going to be strong enough (in theory), but adding a few external lugs that overlap the joint does provide a factor of safety.  Butt joint welds tend (around the circumference) to pull the pipes out of line as they cool.  It's a lot easier to get a straight joint if you weld the pipes onto external lugs first, because those welds will shrink in a different direction and do not pull lengthwise on one side of the pipe.  I like to fit two lugs on the sides of a pair of pipes horizontally and then roll them 90 degrees and do it again.  It's very difficult to see whether they are correctly lined up in a vertical plane, because they will sag between supports.  But you can line them up "as seen from above", and weld lugs along the sides to lock them perfectly in line.