I may be in the wrong forum for this question, but I don't know where else it might belong. I'm looking to make a flagpole from galvanized pipe. I plan to place the pipe inside another larger I.D. pipe acting as a sleeve, which will be buried 3 feet in the ground. Does anyone have any idea what minimums I might need to be looking at in terms of weight, wall thickness, type of pipe, alloy, or anything else that might be pertinent to such a project? I'm looking at about 20-25 feet above ground.

When I put in mine (not quite as tall) I sunk a PVC pipe into the ground just big enough for the galvanized to fit. (Mine is small enough that I can take it down if I want to so the PVC allows me to put a cap on it to keep water out when not in use.) For 25', I'd use at least 1-1/2 to 2" with PVC sleeve and maybe cement at bottom to help secure it (at least sand).

Out of curiosity, what are you doing for pulley, etc in raising flag?

(BTW... this prob should have been put in Home & Gard/Ext Imp or Other H&G)

I'd be looking at EMT (electric metal tubing) or ridgid conduit in electric department. A lot lighter. Maybe some Schedule 80 PVC, (it can be painted) if it's ridgid enough. Ridgidity depends on size more than wall thickness.

For that height, you want to install no less than 2" aluminum. I think they sell them in 20' lenghts. I would avoid plastic. There will be constant flexing pressure on the mast due to combination of large flag hanging on top and winds blowing into it.

Blackcomb: Yes, you have to pay attention to selection of materials for your project. In my area, pole of such a hight would have to have permits issued and would have to be inspected by Building Inspector. It is safety issue here. Also, you probably will have to pour foundation of certain depth to carry your flag pole. I would call your local Building Department and ask them for advice. They have engineers on hand who will advise you free of charge. Let us know how you did ! Good Luck !

If you stay with a metallic pipe be sure it is electrically grounded. Installing inside of a PVC pipe would actually insulate the pipe and make it into a lightning rod.

ballengerb1 - thanks for adding the note on grounding. I reread my post and saw I'd forgotten that.

Design it so you don't need a crane to raise and lower it! With galv. Pipe the weight is a definite concern. Even with 3 sections it will be very awkward. Of course, for 24 hr/day display you will need lighting.