Restricted Startup and Shutdown
Most pressure vessels in locations with a mild winter climate will not require special materials selection or CV-impact testing to assure adequate resistance to brittle fracture at their operating pressure during startup and shutdown. The minimum design metal temperature for each component can be conveniently established by determining the minimum temperature permitted by the Code for the material of construction and nominal thickness. The maximum temperature determined in this manner would be designated as the minimum design metal temperature for the vessel. The operating pressure during startup and shutdown should not be allowed to exceed 40% of MAWP at lower temperatures (35% of MAWP for vessels built in 1999 and later), but this should not place prohibitive restrictions upon startup and shutdown procedures.
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