Help identifying round orange chair  

sorry,
first thought was commode / chair with toilet, without the bowl....

haha.. good guess, but there was definately a seat on it, looks like it may have been a ratan, from the pieces that are still there.  

Magnus Olesen used a lot of ratan, and bentwood designs..

Thank you for that lead, I looked at some of the chairs by them, there are some similar, just can't seem to find the exact one.  

My magnus Olsen chairs do not use screws, but the chair is similar here is a quick photo of one.

yes, it is very similiar, I love the lines on these style chairs