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When running the calculations, the following values are indicated: for triangular tube routing, the number of tubes is n=418; the material used for the tube sheet is 20MnMo, with an elastic modulus of Ep=178000 MPa. The center distance between the heat exchange tubes is S=25 mm. The area of the partition grooves in the tube sheet (including tie rods and dummy tubes) is Ad=70.7 mm*mm. The corrosion allowance for the tube sheet is c2p=2 mm. The depth of the partition grooves on the shell side of the tube sheet is Hs=43 mm, while the depth on the tube side is Hh=440 mm. The input thickness of the tube sheet is δp=30 mm. The stiffness reduction factor is η=0.4, and the strength reduction factor is μ=0.4. The material of the tubes is S30408; the outer diameter of the tubes is d=19 mm, the wall thickness is δt=2 mm, and the nominal length of the tubes is L=3000 mm. The equivalent length at which the tubes may become unstable is lcr=0 mm. The average temperature of the tubes is θt=250 ℃. The allowable stress at the design temperature is tt=94 MPa, the yield stress is σst=123 MPa, and the elastic modulus at the design temperature is Ett=172000 MPa. The elastic modulus at the average temperature is Et=179000 MPa, and the thermal expansion coefficient at that temperature is αt=1.742e-05 per °C. The difference in thickness between the tube sheet and the tube sheet flange is dt=0 mm. The minimum ratio of the thickness of the tube sheet to that of the tube box flange is xt=0.6 mm. The outer diameter of the flange is Do=745 mm. Some of the input parameters should not be less than or equal to zero; please check the entered data