14 Start-Up, Shutdown, and Lay-Up
Cyclic operations create stress conditions that can cause environmental and thermal fatigue within the equipment. These operating conditions can also lead to the accumulation of contaminated or high-concentration condensates during cool-downs. Such solutions can promote surface penetration of the materials of construction during periods of flexing and increased stress present during restarts or reheats. As the number of cycles increases, so does the probability of metal failure because fatigue cracks initiate and undergo growth during each successive thermal cycle. These stresses can be minimized by following the OEM site-specific recommendations for cyclic operations.