Thermal Shock

Thermal shock is caused by a sudden marked change in temperature either from hot to cold or from cold to hot. The stresses resulting from the sudden unequal expansion or contraction of the different parts may cause distortion only or distortion plus cracking. Thick metals are more susceptible to cracking than are thin ones. The most likely time of temperature shock is during unit start-ups when the process fluid is more likely to reach a dry point within the tubes. Heating or cooling rates should be controlled to avoid thermal shock.