Patent ID: 7043151

Claim:
A method for manufacturing a pipe heater in a furnace, said pipe heater having a stainless steel pipe, said steel pipe having an outer side, an inside and opposing end portions, said pipe heater further having an electric resistor on said outer side of said stainless steel pipe, wherein said heater is adapted for heating fluid flowing through said inside of said pipe, said method comprising the steps of: forming a vacuum within said pipe by positioning said pipe into said furnace and evacuating said furnace; scaling both end portions of said pipe for interrupting flow through said vacuumed pipe; forming a lower insulating layer on said outer side of said pipe by baking an insulating glass material thereto; forming a heat generating layer on said lower insulating layer by baking said electric resistor on top thereof; forming an upper insulating layer on said heat generating layer by baking an insulating glass material on top thereof; and cutting off said two end portions of said pipe.