I use stainless but some people use PVC and if you knew what that stuff was made of then galv should be ok for exhaust. (IMHO) The heat isn't high enough but for legal reasons I will say do not use galv.
Slappin that bass like some delerious funky preist!!!
UDS, Half Pint (Mini UDS), Weber, ProQ 20, Kegrilla
*250 gallon cooker- 'The Meat Beast!!'*
British BBQ Championships
Grand Champion 2008
British BBQ Society - Southern Championship
Grand Champions 2009