Can Gray EMT Conduit Be Used For Cat IV Furnace Venting?

Opinions are fine, but if absolutes...
..."No it can't"
..."It's against code"
..."Electrical conduit is not intended for furnace venting"
(and white drain pipe ever was?)
..."Yes, it perfectly acceptable!"

aren't accompanied by links to astm codes, furnace mfg's installation instructions, national mech codes and/or fuel gas codes, etc, then they are useless.

I can't find a reason for the exclusive use of white except convention and that its tighter elbow radii are often needed to fit existing space restrictions. The only possible difference in chemical composure of the two is gray's better UV resistance. But I cannot even find confirmation of that.

So why bother asking?

It's dimensionally identical to sched 40 white plumbing pvc and there is no mention in several furnace installation guides I checked, when sched 40 pvc is required, of "white".

As they are commonly stocked at big box stores and regional suppliers, the gray conduit has a few advantages.

It's cleaner looking than sewer plumbing branching out of your furnace.

Elbows, 90 and 45, are MUCH larger radius than plumbing pvc, theoretically providing better flow and looking more streamlined.

10ft lengths are stocked with belled ends which require fewer fittings to complete the job. I've only seen blank ends on white pvc commonly available at home improvement and HVAC suppliers. Otherwise it's special order and even more expensive.

Home Depot, for example.
10ft length of sched 40 conduit is $5.40. Belled end.
10ft length of sched 40 plumbing is $6.60 plus the 97. cent coupling required if joining lengths.

Yes, I realize the only person alll of this matters to in the end, lacking any existing code clarification, is the local inspector. I'd still like to know if a code exists.