Steel greenhouse trusses

when I covered my greenhouse a couple years ago, I used 2" polyurethane pipes as the bows for the plastic sheeting to be stretched on. they were not particularly stable once they became heated from the sun and eventually collapsed.
I decided eventually I will install multiwall corrugated panels for the roof covering but for now once again I will re sheet it with plastic sheeting. But I wanted something stronger for the bows Meaning I wanted trusses made of steel, I used a few of the 8ft diameter hose reels I had cut them in half and semi straightened out the radius to give me the 12 ft long bowed trusses
Attachment 45295
I used foam camper seal to cushion the plastic sheeting from the steel trusses and to add an insulation layer between the steel and the plastic sheet
Attachment 45296