Tubes shall be inserted such that their ends shall project out 2 to 3 mm beyond the tube plateouter surface. The tube shall then be expanded using an electronic automatic torque control tube expanding unit or pneumatic tube expander so as to get 4% thinning of the tube walls and the elongation of the tube ends shall be 0.40 to 0.60 mm. Tube expansion shall be so controlled that neither over expansion nor under expansion of the tubes takes place. Tube expansion shall be checked with a dial bore gauge indicator. Tube expansion shall be carried out to a length of 70% to 80% of the tube plate thickness. In no case, the expansion shall go beyond the tube plate thickness. The tube insertion shall be such that the excess length of all tubes shall be at the same tube plate and they shall be cut off by a cutting tool followed by expansion. Both ends of tubes after expansion shall be flanged properly. Finally, proper chamfering shall be carried out. Incremental Expansion of condenser tubes shall start from the peripheral holes of the tube plate and shall proceed towards the centre of the tube plate in such a sequence as to avoid any deformation of the tube plate.