Points to note when expanding tubes into tube plates
Ends of expanded tubes must never be welded to tube plates.
When expanding tubes into plates it is essential to start at the top of the vessel surplus of 5 mm (3/16") must be kept. One must ensure that tube ends remain exposed above the tube plates.
Five-roller expander with safety clutch should preferably be used instead of usual three-finger expander.
Provide a crash stop in order to avoid swelling of the tubes just inside the plate-level.
When replacing tubes in plates, make sure that the surface of the bottom plate is quite clean and smooth. If necessary it must be repaired adequately.
It is necessary to protect tubes near the steam entrance. Baffles should be built in. This will avoid thermal shock and mechanical stresses which might be especially high at this particular part of the vessel.