These curved exhaust pipes are too large to go unsupported for this distance, so I felt a framework was in order.
I started with a thick piece of styrene long enough to transverse the two pipes. They are rounded over and represent the concrete base to the supports. Square tubing is placed so the 1/8th" 'H' beams just touch the outside of the pipes.
A nibbling tool makes short work of clearing most of the waste from the bracket that conforms to the diameter of the pipe. A sharp knife and a file complete the clean-up.
To prevent the uprights from racking, this flat stock is added to the 1/16th" horizontal 'H' beam,
then glued between the vertical 'H' beams. Those machinist's squares come in handy again.
The curved brackets are attached, then the inner square tubes, and the uprights can now be glued in place. Finally an 'X' brace of .060 square stock stiffens the uprights.
The final assembly slipped under the pipes. there is a small gap between the pipe and the curved bracket because a sheet of styrene will be laid over the Masonite base.
There are going to be lots of pipes floating around this steel mill complex, so a jig to make more of these is probably in order. I'll be sure to take pictures. Don