fred wrote:

Compression joints do not require tape or any other sealant to make a
good joint, this is true for both water and gas.

Agreed - but what I'm wondering is this - when you create a dead-end in
a gas pipe system like this, is there any requirement to purge it (to
get rid of the trapped air) or do you just allow time and the natural
diffusion of gases to do the job.

--
Andy