Gas pipe trap nipple relative to flow direction

I know that a natural gas black pipe requires a 3-4" trap nipple below the turn when the flow in the pipe changes direction from vertical to horizontal, in order to catch possible particles coming from the supply.

Is such a trap required in the opposite case, when the pipe turns from horizontal to vertical? Can I just use an elbow going up or do I still need a tee with a short nipple that the flow would not be going into but particles may still get trapped in thanks to gravity?