Abstract: Access to the interior of a vessel during fabrication and assembly of the vessel is provided by a channel structure formed around the circumference of the vessel. The channel structure comprises an outer surface that is radially inwardly offset from the exterior surface of the vessel around the circumference of the vessel. The outer surface of the channel structure is bounded by upper and lower circumferential transition areas which join the outer surface of the channel structure to the surface of the vessel. The channel structure is arranged such that when an upper portion of the vessel is separated from a base portion of the vessel by removing the material comprising the upper transition area, the upper portion of the vessel will receive within its inner diameter the outer surface of the channel structure.

Abstract: A method of manufacturing a double walled vessel is herein disclosed. The method involves the steps of forming an outer vessel having at least one reassembly channel formed therearound and forming an inner vessel having at least one element fitting formed integral thereto. At least one control housing is secured to the outer surface of the inner shell in registration with the element fitting. Heating elements and other control apparatus are installed in the element fittings within the control boxes. The outer vessel is sectioned at the reassembly channel, thereby allowing the inner vessel to be inserted into the outer vessel. The outer vessel is reassembled to enclose the inner vessel therein and a curable foam material is injected into the space between the inner and outer vessels to maintain a constant spatial relationship therebetween and to ensure the structural integrity of the outer vessel.