How are heat exchangers with welded inner holes at both ends manufactured?
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I have seen the drawings of a shell-and-tube heat exchanger; as shown in the attached drawings, the ends of some of the heat exchange tubes are welded with internal holes, and there are no access ports in the heat exchanger shell for entry. If internal welding is used at one end, it is understandable; but what is the sequence for manufacturing and assembly when internal welding is used at both ends, and how is non-destructive testing carried out on the pipe fittings?
Internal hole welding is done using specialized welding machines.
Welding the inner holes at both ends is simply not feasible from a manufacturing perspective.
Awaiting guidance from those more experienced; looking forward to it. . . . . . . .
Welding is carried out on the inner holes at both ends, and the manufacturing process is roughly as follows: First, the left tube sheet is erected and secured, after which each heat exchange tube is welded one by one (note: when welding each heat exchange tube, it is important to ensure that the tube remains perpendicular to the tube sheet; it is advisable to use a special fixture for this purpose – a 20-millimeter-thick circular plate on which holes are drilled to match those in the tube sheet, with the hole sizes corresponding to those of the heat exchange tubes on the tube sheet). Once one end of all heat exchange tubes has been welded, the fixture is removed, and then the other end of the tube sheet is tentatively fitted in place. After inspection to confirm that everything meets the requirements, the right tube sheet is placed in position, and the junction between the shell side cylinder and the left tube sheet is welded together. Finally, the right tube sheet is joined, and specialized equipment for internal hole welding is used to weld the joints of the heat exchange tubes on the right tube sheet. I specialize in pressure vessel manufacturing at my company, and I’m not sure how good the process plan I’ve prepared for this heat exchanger is; I would appreciate it if experts could give me their feedback.
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For the internally welded heat exchanger, the right tube sheet has been welded last, and the cylinder has already been spot-welded. How should the right tube sheet be welded to the heat exchange tubes, and how can it be inspected? I have no experience with internally welding equipment; I would appreciate some guidance. Thank you!