Seraphim as Angels?

In Numbers 21:6 Yahweh sent הנחשים השרפים (HaNachasim HaSeraphim) "Burning Serpents" among the people.

In Numbers 21:8 God tells Moses to make a שרף (Seraph) and set it on a pole.

In Numbers 21:9 Moses makes a נחש נחשת (Nechash Nechoshet) "a Bronze Serpent" and sets it on a pole.

Thus, it appears that both נחש (Nechash) "Serpent" or שרף (Seraph) "Burning One" can be used as a synecdoche for these "Burning Serpents."

What is the connection between the use of the שרף (Seraph) in Numbers 21 and elsewhere where it means a Burning (and Flying) Serpent and the use in Isaiah 6:2 and 6:6 where it is used of Angels?

Certainly it simply means that these Angels (who I submit are Cherubim) are "Burning" in the sense of the following verses:

Exodus 3:2: The angel of the LORD appeared to him in a blazing fire from the midst of a bush; and he looked, and behold, the bush was burning with fire, yet the bush was not consumed.

Heb 1:7 (which is a quotation from Psalm 104:4): And of the angels He says, "WHO MAKES HIS ANGELS WINDS, AND HIS MINISTERS A FLAME OF FIRE."

Certainly there is no distinct order of Angels called שרפים (Serpaphim)? These are simply כרובים שרפים (Kerubim Serpahim) "Burning Cherubs."

The obvious connection here is Satan. He is a נחש-כרוב-שרף (nechash-kerub-seraph) a "Burning (flying) Serpent-Angel"...