Semiconductor vaporizers are designed for the vaporization of high purity gas applications in the electronics industry. Natural draft vaporizers utilize convection as the heat transfer mechanism. It comprises a number of individual multi-finned aluminum heat transfer extruded elements lined with a cold drawn bright-annealed electro polished stainless steel tube. Extrusions are connected in series. Liners are hydrostatically expanded into the extrusion element to ensure 100% contact and efficient heat transfer.