an apparatus is disclosed for expanding the ends of a sleeve that has previously been installed into a defective section of inaccessibly located soft metal heat exchanger tubing . the sleeve ends are expanded using an apparatus of a plastic bladder connected to a series of connectable sections of sufficient length to reach the ends of the installed sleeve . the expansion is performed by locating the plastic bladder inside the sleeve at one end and hydraulically compressing the plastic bladder and forcing it to expand in diameter as a function of poisson &# 39 ; s ratio to thus expand the sleeve end into the tube .