Heat shock failure

Heat shock failure is the mechanical failure of a material due to sudden exposure to high heat. 

Stress cracking as discussed above need not only be due to an active environmental. Often a thermal stress can lead to cracking. Heat shock failure is also seen to relate rather linearly with MFI, as given in Fig. 9.73 taken from Ref. 48. 

Thermal shock failures using water result from the water vapor entering the enamel layer through small, submicroscopic cracks formed at the instant of shock. The water condenses in the cracks and in the bubbles of the enamel traversed by the cracks. On subsequent heating, the vapor from the entrapped water expands to cause spalling of the enamel layer. Other quenchant Hquids, such as toluene, oils, and other organic Hquids, also cause fine, almost invisible cracks, but thermal shock failures do not result with these quenchants on subsequent heating (39). 

Heat shock proteins (HSPs) are synthesized by cells in response to an increase in temperature, as well to various other stressful stimuli. Their main function is to ensure intracellular protein homeostasis, thus preserving the cells viability in the presence of aggression. Current evidence points to a protective role for HSPs in several aspects of critical disease, such as ischemia-reperfusion, ARDS, and multiple organ failure. The increase of a few degrees Celsius above the normal environmental temperature of cells leads to the heat shock response 1) rapid expression of heat shock genes, 2) suppression of normal protein synthesis, and 3) the ability of cells to survive a second and otherwise lethal heat challenge (thermotolerance). 

Fekete A, Treszl A, Toth-Hey P, Vannay A, Tordai A, Tulassay T, Basarhelyi B. Association between heat shock protein 72 gene polymorphism and acute renal failure In premature neonates... 

Lovis C, Mach F, Donati YRA, Bonventure JV, Polla BS. Heat shock proteins and the kidney. Renal Failure 1994 16 179-192. Muller M,GauleyJ, Heikkila Hydrogen peroxide induces heat shock protein and proto-oncogene mRNA accumulation in Xenopus laevis A6 kidney epithelial cells. Can j Physiol Pharmacol 2004 82 523-529. 

Heart failure, targeting 1284 Heat shock proteins... 

Lovis C, Mach F, Donati YRA, Bonventure JV, Polla BS. Heat shock proteins and the kidney. Renal Failure 1994 16 179-192. 

On initial start-up and shut-down the heat exchanger can be subjected to damaging thermal shock, overpressure or hydraulic hammer. This can lead to leaky tube-to-tubesheet joints, damaged expansion joints or packing glands because of excessive axial thermal, expansion of the tubes or shell. Excessive shell side flowrates during the "shake down can cause tube vibrations and catastrophic failure. 

---