on the end portion such as the end portion 116 of fig2 b of a full length tube which may be several feet long in addition the shorter segment simplifies dimensional control and repairs of defective joints it is very important to appreciate that weld defects are easier to repair with this embodiment as members can easily be cut away heat affected zones cut away ends squared and the welding repeated this embodiment therefore represents an excellent general repair method for both the integrally backed joint of fig2 and the double corrosion barrier sleeve and tube extension segment of fig3 it should also be appreciated that the tube of fig3 when assembled is inserted tackrolled welded and expanded in a similar manner to that described above with regard to fig2 f and 2g the embodiment of fig4 is similar to fig3 except that no separate transition segment is used in this embodiment a transition region 140 is formed at the end of the tube 100 but unlike the embodiment of fig2 a g the transition region does not continue into a reduced diameter tube portion 116 for the sleeve 102 to be inserted over rather a sleeve and tube assembly 142 similar to the double corrosion barrier 134 of fig3 is preferably full penetration laser butt welded at joint 144 to provide the double pressure and corrosion barrier radiography may be employed to verify the integrity of the weld within the context of the steam generator dimensions alluded to above the inside diameter of the tube 100 should vary smoothly at the portion 146 of the transition region 140 over a length of.