Steel pipe for flag pole

Do any of the landowners in your community have water wells?

My flagpole is one 21' length of 1" galvanized steel well pipe. Seems to be the standard length, our well has always had 21 foot sections, replaced when they corrode and get pinholes with new 21 foot sections.

The well company we use will either haul the old pipe off, or leave it. I'd give you one of mine, but looks like you might be one time zone too far away.

1 1/2 inch sched 80 pipe or 1 1/4 inch square tube with 1/4 inch wall thickness might fit (with rounded corners it is 1 7/8" across the diaganal) and good luck bending it!!

I appreciate that. I'll check around, that may work.

I like that idea, but that also sounds HEAVY! lol Hopefully I can lift it in place! ;-)

You SAID you wanted something that would not bend in the wind - - - -

4130 Chromolly tube. Pretty sure it comes in standard 20' sections.

I like that idea, but that also sounds HEAVY! lol Hopefully I can lift it in place! ;-) ==========================================

Fence suppliers can get similar tubing in several diameters and wall thicknesses. My 50' TV antenna mast is made of 1-5/16" fence top rail at 1/4 the cost of Radio Shack mast.

Great ideas. I'm going to do some checking around today and see what I can find. I like the option of the Chromolly tube.

Great ideas. I'm going to do some checking around today and see what I can find. I like the option of the Chromolly tube.

=====================

Sold by the inch:

I found a local shop that has the 4130 tube. Kinda pricey stuff, but to keep costs reasonable what wall thickness do you think would do the job? 1.5" with 3/8" wall is about $18/ft. I don't think I would need that much wall thickness but I really have no idea?

I found a local shop that has the 4130 tube. Kinda pricey stuff, but to keep costs reasonable what wall thickness do you think would do the job?

1.5" with 3/8" wall is about $18/ft. I don't think I would need that much wall thickness but I really have no idea?

===============================

I'm not a professional engineer so I can't design for you, and if I was one I wouldn't work for free.

You can search for sites like these:

That is a lot thicker than needed. The 20' one I have is 3" with 1/8" thick aluminum.

Good to know. I priced 1-3/4" .120 wall 4130 and it came to about $325! I think i'm going to go back to 1-1/4" sch 40 inside the aluminum. I think I only had 1" previously after seeing how Sch40 is measured from ID, not OD. I would like 1-1/2", but it's just a tad too big to fit inside the 2" aluminum at the joint. So I think stepping up 1 size, and making it 1 full 20' piece instead of 2 with a joint,,,,,, hopefully it will be enough.

Good to know. I priced 1-3/4" .120 wall 4130 and it came to about $325! I think i'm going to go back to 1-1/4" sch 40 inside the aluminum. I think I only had 1" previously after seeing how Sch40 is measured from ID, not OD. I would like 1-1/2", but it's just a tad too big to fit inside the 2" aluminum at the joint. So I think stepping up 1 size, and making it 1 full

20' piece instead of 2 with a joint,,,,,, hopefully it will be enough.

==============================

Pipe standards originated back when pipe was made from wrought iron which is weaker than steel. The ID of modern steel pipe is approximately the same as the old Extra-Strong standard.

Chain link fence posts have the same OD as pipe, though thinner walls and different size designations in fractions close to the actual OD. Electrical conduit has the same ID as pipe and a smooth interior without the weld seam, thus EMT and fence posts of the same nominal pipe size telescope in some combinations.

I agree the newer steel with a thinner wall is likely stronger, but it's also way more expensive. I priced 1-3/4" 4130 with .120 wall in a 20' stick and it was $325. I priced 1-1/4" Sch 40, which is 1.68" OD and is $32 for the same 20' stick. I originally had 1" black pipe, so i'll be increasing by 1/4" OD and 1 solid piece instead of 2 jointed 10' pieces. The previous bend/break happened at the joint where the threads were cut. Going a size larger should increase strength, and 1 solid instead of 2 should also help a fair bit. If the 4130 was $100 instead of $300, I would go that route, but I just can't justify that much cost.

Not exactly what you asked, but the maximum bending force is at the base. So you could probably get by with a pipe inside the bottom 15 feet.

Dan

That sounds like a pretty good idea. If this sch40 1-1/4 doesn't hold up, i'll likely do something like that with the larger pipe.

I completely agree with this. The break was at the top of the first 10ft section, so since I can get sch40 in 10 or 20ft lengths, I just went with a 20ft section in the 1-1/4 size instead of 1" as well as eliminated any joints. That should fare pretty well for the next several years. If it fails, I may at that point upgrade to a larger diameter pipe and re-do my concrete hole in the ground.

I really like your idea with the two pipes in the ground so you can pivot the main pole down. Mine is a piece of concreted in PVC in the ground and I lift the pole and drop it down in that PVC. It works fine for the weight of the aluminum pole, but is a bit of a challenge with the two pipes.

Just to be clear, my main pole is 2" aluminum and does fine until winds are up around 45-50 with a flag, then it's bending pretty good and will buckle. The 1-1/4" sch40 is now inside the aluminum just to add strength. (1-1/4" sch40 is the ID, so the OD is about 1-3/4 and fits pretty snug inside the 2" aluminum sections) I previously had 1" sch40, with a joint mid way up, so this is 1/4" larger, and now a single piece with no joints. So in theory, it definitely increased strength from what I had but I'm sure it's still not the greatest.

In the meantime, I will be looking for some pipe like you used. If this doesn't hold up, i'll have a piece ready to use to make it stronger. I definitely do like your ideal though.