On the design of high-temperature fixed tube sheet heat exchangers
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According to GB/T151, when calculating fixed-tube-sheet heat exchangers, it is necessary to determine the allowable axial stress of the heat exchange tubes, as specified in 7.3.2.2 of page 56 of the standard. This stress is controlled by the yield strength at the design temperature of the heat exchange tube. For example, the allowable stress value for the S30408 material remains valid up to 700 degrees, whereas current standards only provide yield strength values up to 550 degrees. Above 550 degrees, there is no yield strength value, which results in the absence of an allowable axial stress for the heat exchange tubes; thus, SW6 refuses to perform the calculation. What is the appropriate way to handle this situation?
But the last few columns of values are on the right side of the black line; Q345R has allowable stress values at 475, but obviously, the design temperature cannot reach 475