A method of producing an umbilical includes providing an elongate flat metal strip, providing an elongate service carrier, encasing the service carrier in an insulation that is strain tolerant and high temperature tolerant, forming the metal strip into a tube shape around the insulated service carrier, and thereafter welding the edges of the metal strip to form a tube surrounding the insulated service carrier. The method may further comprise coiling the umbilical onto a spool. Such an umbilical may be useful for carrying fluids, power, control signals, or the like into a well.