I'm not a welder but seems like I remember galvy being difficult (read impossible)to weld. Also seems like a 16 foot length would be a little more difficult ot obtain. I think the home improvments stores usually only carry 10 foot lengths.

A steel shop should have some sort of stock that'll work and they prolly could thread the top end for receiving an elbow to eliminate the welding. Wouldn't go with plain steel due to environmental reasons (rust). A good paint might help there though.

Also if this is for sliding, threaded unions for connection would prolly remove chunks of flesh each time down. I'd think you'd want a continuous piece of something sturdy and smooth (welds even when ground smmoth would be rough and this would also be hard to achieve on a round pipe). On that note the galvining process sometimes leaves surface imperfections that could slice flesh too, not so much on OD of pipe but on dipped items I've handled before seems there were little points and protrusions from the dipping process on edges and such.

Most of the fire poles I've seen are brass but I'm not sure how it would weather. I would think it would require care since the copper content would cause a patina.

a steel shop should have all kinds of stock that would work. I'd think you'd want about 1.5" not for strength but for ergonomic reasons. anything smaller might be hard to grab depending on how big your kid's hands are....maybe smaller would be the way to go if it doesn't bow.

Not trying to be crass, but you may want to look into a "stripper pole". They would be smooth, similar length, and obviously the right strength. Could be a cheaper alternative to a custom stainless rod from a welder's supply house.

Thanks for the reply!
If I can get a 20 foot pole and have it cut down, where I put the elbow should be above the smooth slide area.
I am thinking 3 -4 feet in the ground then 16 feet straight up- then a 90 elbow with a 2 foot piece and flange to connect it to the header. I might have to have the pipe cut about a foot.
I looked into a "stripper pole" but they are so expensive and I still would need to get a 90 degree elbow on it to attach it to the tree house.
I think I will go to a steel supply place and see what is available that will not break the bank! LOL
I would love to have a piece of steel or iron either welded or "rolled" for the 90 degree curve I need.
If I use steel or iron instead of galvanized, I thought about having it welded or rolled and then prime and paint it.
I have no clue what it would cost though.

Here is a pic of the shape I need.
{{!gwi}}

Pipe comes in standard lengths of 20' when threaded (TBE) or randoms of 20-21' when plain end or beveled, so your dimensions would enable a 90deg. bend, thus eliminating any welding, which would burn off the protective galvanising.
A muffler shop may be able to do the bend- I presume you would use Sched.40 pipe.
A welded pipe fitting would allow a tighter bend radius if needed, but joints would need proper finish coats.
Plain steel (black pipe)isn't a bad idea; there are some very durable urethane coatings available.
I would not place the pipe in concrete, but use a bolted flange base plate. Condensation corrosion on the inside of the pipe will eventually cause failure at the pipe/cement juncture.

I recently made one out of a single piece of galvanized steel which is very sturdy and cemented into the ground; however, it is a little rough on the hands, pretty easy for the kids to climb up which they love, but I wish it were smoother and slippery. I would use stainless steel