Question about Saarinen Tulip Chair  

I've never dealt with the non-swivel
But I'd be surprised if the connection (from base to shell) were radically different.
Post a photo of the underside, perhaps?

Top and bottom

Hmm.
That IS quite different than the swivel.
Well, it's safe to assume that the threaded rod (which you see the tip of) runs the length of the tulip base, and is screwed to the bottom of the shell (hidden from sight by the tulip base).
To get the tulip base off, you need to remove that circular plate shown in the photo. I can't see a nut-- is there one? Is it possible that the circular plate is threaded, and can be unscrewed?
Looks a bit rusty, apply plenty of WD40 before proceeding.
(Why do you want to disassemble this, anyhow?)

Yes, odd it is a bit different
from the swivel.
And i was about to ask the same question.
Why do you need to remove it?
On ours we wd'd and navel gelly but ended up cutting the stem.
It is a standard threaded rod so we replaced it.
I was a bit obsessed about cleaning it up.
I think ours was exterior for years. I had to de-rust it for interior.
That might be the interest in cleaning it up...?
My floors are 50yr old terrazzo tile, waxed. Rusty feet are a menace.

Thanks
Thanks for the suggestion. There is no nut on the end, just the threaded stud. There is a small gap between the round plate and shell, looks like a rope gasket is in between. I applied WD-40 once and will do so again before trying to twist the plate. I want to separate the shell because there is a small crack on the underside (right where it contacts the base) and am considering repairing it.

Well
It's proving difficult to get a good grip on the circular plate, but the thing is not budging at all. I don't think I will try to force it any more. If someone happens to figure out a way to disassemble this chair, please post it here.
Thanks for the replies!

how about the swivel model
Pardon me for piggy-backing on your thread, but for that matter, does anyone know how to disassemble the swiveling model; the one without the arm rests? I'm looking at the plate under the cushion and i've no idea how to take that off. I'm looking under the base of the stem, and rather than a bolt, I see a completely circular metal post or plate. What would I do if I wanted to separate the two parts of the chair?

Spring clip or retention ring
You need one of these to remove the spring clip simlar to this pic
http://www.leevalley.com/garden/page.aspx?c=2&cat=2,54322&p=57216

Future reference. From the Knoll museum in PA...
The Chair is a fiberglass shell with a cast aluminum painted base. Still is. It's painted with a Rilsan coating w/c is thicker than paint.
The Tulip Table was designed at the same time and started out with a cast iron base. It came with various tops in laminate, marble or wood, could be round or oval, and was available in various sizes. Today, the base is made of cast aluminum same as the chairs.
The bushings allow the chair to swivel. If your chairs are more than 20 years old, you might be able to get replacements on Knoll Parts Hotline -- 800-343-5665, ext 1007. If your chairs are less than 20 years old, the chairs are now made in Italy, and getting parts are a bit trickier. Either way, within the base of the chair, there are all these parts and pieces -- it may be hard to get them back in properly. You might want to call Sol, at Prestige Furniture, Queens, NY 718-721-2200.
If you need to paint the fiberglass you should find an auto body shop good with Corvette's. They should sandblast the table and chair bases to prep them for the powder coating. The paint years ago was not as bright as the white today. But you can get a close match with Sherwin