In reactor operations such as venting or dumping, some of the HRT flanges are subject to rapid temperature changes. Tests were conducted using 0.5- and 1-in. reactor type ring joint flanges subjected to thermal shocks from 25 to 300 deg C and from 300 to 25 deg C No apparent flange leaks were noted Bolt loadings following the tests were about the same in flanges having standard HRT carbon steel bolt-ferrules and in flanges having A-110AT titanium ferrules as well as in flanges having bolts without any fernules. (auth)