Combined metal / plastic tubing apparatuses and methods of manufacture

A tube assembly, comprising:

• a tube comprising a metal pipe portion and a polymeric pipe portion;
• the metal pipe portion extending from a first end to a first transition end and defining a first radially outer surface and a first radially inner surface, the first transition end comprising a first tooth element and a second tooth element disposed circumferentially adjacent to the first tooth element, the first tooth element comprising a first peak, a first valley, and a first transition portion extending axially and circumferentially from the first valley to the first peak, the first peak spaced apart axially from the first valley, the first transition end including a radial transition having a taper in a radial direction;
• and
• the polymeric pipe portion having a second transition end and defining a second radially outer surface and a second radially inner surface, the second transition end having a complementary shape to the first transition end, the second transition end bonded to the first transition end, wherein:
• the tube is configured to transport a fluid during operation of the tube assembly,
• the fluid contacts the first radially inner surface of the metal pipe portion and the second radially inner surface of the polymeric pipe portion in response to transporting the fluid through the tube, and
• the second transition end bonded to the first transition end by injecting a liquified polymeric material into a mold and allowing the liquified polymeric material to cool, solidify, and form the polymeric pipe portion.