Was transite pipe made to also be an oval shape?
I did asbestos abatement for 15 years and never saw oval transite pipe.
I installed transite pipe and never seen oval pipe.
Where did you see it and why do you ask?
Marcel 
I found it in an 70+ year old home that only the water heater was venting into. I could not get into attic space only form hatch. The texture appered to be the same as the transite I have seen before. I have no picture yet, sorry.
Yes have seen a ton in my time used primarily in my area for the old wall type gas heaters. I still see some occasionally abandoned and once in a while still in use. Next time I run across some will take a Pic and post if for all of you young guys:p 
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I’ve seen the “oval” shaped Transite vents as well. The same shape of the Type BW steel vents.