I am trying to hook up a gas dryer. The gas line has a flare fitting 1/2 in. that goes into a 1/2 in. x 3/8 in. coupling/reducer (in order to fit into a 3/8 in. gas connector, as suggested by help from Home Depot) and then into an excess flow valve, which then goes into a 3/8 in. gas connector (and then the dryer) Should I put Teflon Tape or Sealant on any of these connections?
You will use
Pipe sealant ( pipe dope ) or yellow pipe tape ONLY on the connection going into the female part of the excess flow valve.
Not on flare compression fittings.
video from brasscraft, maker of the excess flow valve.
This video will show all you need to know.
Looks like you have to connect the gas flex directly to the valve and no other other fitting in-between since the valve itself has already the flare male and the hose is flare female, you can't put either of those fittings because they're taperd and not flare the question is only if the valve and hose are the same size if not then you need a flare reducer or another size hose, and no sealant should be applied on treads of a flare connection since the seal is achieved by the flare being tight and not through the treads.