Two plates are held together by bolts made of ASTM B98 (UNS C65500) copper–silicon. The bolts are 3 mm in diameter; they have a thermal conductivity of 36 W/m⋅K, a specific heat of 377 J/kg⋅K, and a density of 8.55 g/cm³. The bolts are situated in between the two plates, and they are occasionally exposed to hot steam at 200°C with a convection heat transfer coefficient of 50 W/m²⋅K. The length of each bolt exposed to the steam is 25 mm. According to the ASME Code for Process Piping, the maximum temperature allowed for ASTM B98 bolts is 149°C. If the initial temperature of the bolts is 20°C, how long can the bolts be in the hot steam before the maximum use temperature is reached?

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Calculate the characteristic length of the bolt L D 14L D nDL Here z is the exposed length of bolt ... View the full answer