sealing vents through metal roof

[metolent]

I have a standing seam metal roof and plan to do the roof penetrations for the plumbing vents and the chimney shortly.  What type of sealant have you guys used for both the plumbing vents as well as the chimney?  Should I use the high-temp Silicone for the chimney flashing?  Any preferences for types/brands of Silicone?  I don't want to have to go up there very often....

[MountainDon]

I used pure clear silicone standard caulk on both roof penetrations (chimney and bathroom vent). That went under the flexible roof jack and a bead around the boot to pipe. I also put a bead of silicone around the one joint in the chimney that is above the roof.