The effects of thermal cycling on residual stresses are studied in thick-walled 316L stainless steel pipe. A relatively small AT of 280°F is considered. The residual stresses are measured by an x-ray diffraction technique. The initial stress state of the pipe wall shows periodic and random variability in stress from -30 to 20 ksi. The pipe was thermal cycled between a furnace and a quenchant bath. The macro residual stresses became 10 ksi more compressive after the first thermal cycle. Thereafter no significant changes are measured in the macro residual stresses, however, the micro residual stresses continue to increase linearly with the number of cycles. / Master of Science