Air sucked into the pipe is gonna be cool air and it will crap up a foot or two of that pipe just off the top of the stove into glaze creosote in a heartbeat. Don't ask how I know. On single wall I seal it at the connector with rope gasket and a hose clamp since that stove is in the basement and looks ain't an issue. Stove gasket is fiberglass and will rock up until around 1,400 degrees.It gets that hot you have more problems on your hands than that at the moment.