vent pipe in attic

Is any single wall vent piping allowed in the attic space? Example…their is a gas furnace located in the attic space, the vent pipe consists of a 1) single wall 90 degree elbow into a 2’ piece of single wall metal pipe into a verticle b-vent that exits thru the roof.
Is this small portion of single wall pipe ok in attic area???

Heat vents in attics must be B-type. No exceptions.

Brian,

Code in our area allows for a single wall elbow or start collar (less than 4") at the draft diverter collar on the furnace, then double wall (B’vent) thru the roof.

Good Luck