Abstract: The present invention relates to a convenient process to detect leaks in a partially disassembled floating head-type heat exchanger. The heat exchanger is partially disassembled by removing the floating head end shell cover. A lightweight, flexible membrane having low gas permeability is then attached to the exchanger so as to cover the floating head gap. Gas is then introduced into the shell side of the exchanger.Leaks may be detected by observing the end face of the floating head tube sheet for an indication of the gas using a soap solution and observing the formation of soap bubbles.