Pipe joining options

[SmoggyTurnip]

As stated in my other diary I am planing on building a 100' tower.

10" OD X .134 wall thickness pipe.

Thinking about the options of joining these pipes together I have:

1. Use sleves like DanB's excelent recent tower.
   
2. Just weld the pipes together.
   
3. Weld 1/2 steel plates to the ends of the pipes (12" X 12") - drill holes in the plates and bolt the sections together.
   
   

DanB's method looks quite simple but I am concerned about the strength.  Am I worring too much?

Welding seems simple - I can't see a downside to it yet.  I think my biggest worry here is that Dan didn't do it this way so there must be a downside that I don't see.

Welding plates is the most expensive way to go but it seems to me it would be strong and it would be eaiser to get the pipes lined up this way (I think) as opposed to just welding the pipes together.

Any thoughts?

[dinges]

Flange mounting (or, 'welding plates on it', as you call it) would be my favoured method of construction.

I think this is what 'the big boys' are using too (though they usually have the bolts on the inside, not the outside). As size of towers increases, we more and more get out of the realm of easy DIY construction and into the area of professional construction. It might be interesting to check how the big towers are constructed. I think they use flanges.

BTW, I wouldn't make my own flanges but try to find original ones and weld them on.

Erecting such a tower would be easier too (if you have access to a crane), one could bolt the sections together. No need for erection by means of a ginpole. Even without a crane, it should be possible to build an aid so the tower can build 'itself', i.e. like cranes can build themself up (but in our tower case, without hydraulic lifting of the upper part). Not sure if I make myself clear, but when building radiotowers, they usually install a temporary pole that is used to hoist the next section of the tower up.

Peter.

[SmoggyTurnip]

Thanks Peter,

If the flanges are bolted together on the inside how do

they access the bolts?

I really want to be able to tilt this tower down so I can

experiment with different blades and stuff like that.

.

[electrondady1]

hi smoggy , i think peter is thinking  of the mega watt units like the ones they have been building around here . the "pipes" are like 10 or 12 feet in dia. with stairs inside.

 the tough thing about butt welding your tower sections or using  flanges on the ends, might be to get them allined perfectly. you wouldn't want any sort of deflection , dog leg  happening .  the way dan has done it with a coller , when you tighten it up the pipe is lined up .

[whatsnext]

There is also no reason not to have the collars slide inside of your pipe sections with a flat plate between each pipe, attatched to the collars, as this gives you a handy place to connect guy wires without having to worry about a weld failing. The other nice thing about this is that your welds won't have to be that good because there is really no load on them. As some of these towers become larger it will make more sense to start climbing them instead of tilting them up and down all the time and that means using a crane to build them srtaight up.

John...

[whatsnext]

Just as an addition to this, that considering the price of steel, fabbing a lattice type tower is looking better every day.

John...

[Murlin]

Welding on extruded fab steel can be tricky sometimes and you can often run into brittleness problems if you don't use the right rod, or if the composition of the steel you are welding on is of low quality.  One thing with cheep fab steel is that you never know exactly what you are getting.

Sometimes you can cause stress points that will crack out over time on applications where it the steel is put under loads.  While 1" of weld will usually hold 10,000 PSI, the area around the weld becomes questionable.

Murlin

[kenputer]

100' tower on PEI,should be almost able to see that from Bell river or Tignish even here in Nova Scotia, I'll be watching for it.

Ken

[Countryboy]

I have to agree with Murlin on this one.  Weld and the steel have different tensile strength.  They flex differently.  Vibrations running down the tower cause the metal to flex in minute amounts.  Over time, I suspect that you will find cracks appearing at the edges of the welds.

Here on the farm, we use air to blow grain thru pipes to fill tall grain bins.  These pipes are connected with sleeves similar to Dan's.

If you would prefer to go with bolt together flanges, I would recommend welding the flange to a short piece of tubing just smaller than the inside diameter of your tower tube.  Slide this tube and flange into the end of the tower tube, and weld in place.  This will help strengthen the area of weld, and keep your tower straight.

I suspect sleeves like Dan's will be your cheapest coupler that is dependable.

[jimjjnn]

I believe Peter is referring to the megawatt unit towers that have stairways and even a rudimentery lift. The maintenace people can go inside the towers and up the stairs(ladders)to service the alternators. The flanges are inside also and are bolted together .

[coldspot]

100' WOW!!!

If plates are used don't forget the hole for the wires to run thru.

$0.02

[skyking01]

Flanges mounting is my preferred choice of joining pipes too.

This is what we have been using for quiet some time now in fabricating communication towers and it is the safest means of joining two sections. We also use this method of connection in our industrial axial flow pumps with 20 in diameter which we used to irrigate fishpond with a head of 30 ft. A big flow of water rushes in with no problem on the joints.

As least you have the options to choose..

skyking01