Depending on the manufacturing process, multi-layer high-pressure vessels primarily feature structures such as the wrapped type, plate-wound type, strip-wound type, and shrink-fit type.
In the shrink-fit method, the inner diameter of each outer shell section is slightly smaller than the outer diameter of the inner shell section it is to fit over. The outer section is heated to expand, allowing the inner section to be inserted; this process is repeated sequentially until the design length is reached. Finally, the end flanges and bottom head are welded to the shell assembly to complete the vessel.
The shrink-fit shell structure utilizes assembly prestress to improve the uniformity of internal stress distribution and enhance material utilization. This structure also inhibits crack propagation between layers, thereby ensuring equipment safety to a certain extent. To achieve uniform assembly prestress along the entire length of the shell, precise machining of the mating surfaces and careful control of the assembly process are required.
During the manufacturing of shrink-fit vessel shell sections, ovality and straightness must be strictly controlled to ensure the required interference fit. The shell sections do not undergo machining on their inner or outer surfaces; instead, plate-rolling machines are primarily used to achieve the necessary roundness. These vessels typically feature a two- or three-layer structure. While this type of vessel offers high productivity and material utilization, it requires large-scale heating furnaces and plate-rolling machines.