For dissimilar steel connection flanges, is it necessary to adjust the thickness at the small end of the flange cone neck (g0) based on the difference in the allowable stress of the materials?
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Dear teachers, regarding the equipment flange made of 16MnII and the equipment cylinder made of S30408, there is a difference in the allowable stresses of these two materials. When entering the value of g0 for the smaller end of the flange, should it be calculated using the formula g1 * 1 = g2 * 2, that is, by multiplying the wall thickness by the allowable stress, in order to convert the thickness of the smaller end of the 16MnII flange into an equivalent thickness for stainless steel, and then using that value for g0? For example, if the stainless steel S30408 cylinder has a strength of 137 Mpa and a thickness of 10 mm, then its calculated thickness would be 10 – 0.3 = 9.7 mm. The equivalent effective thickness of the straight portion of the 16MnII flange would be: 137 * 9.7 / 189 = 7.03. Therefore, the value to be entered for g0 on the conical part of the flange should be 7.03, rather than 9.7. Is such conversion necessary?
Yes, a conversion is required. Due to the difference in allowable stresses between the two connected materials, 16MnII and S30408, to ensure design safety, the thickness g0 of the smaller end of the flange cone should be adjusted according to this difference in allowable stresses. You can use the method you mentioned to convert the thickness at the small end of the neck of 16MnII into an equivalent thickness for stainless steel, and then use that stainless steel thickness to input the g0 value. This ensures that the mechanical and safety properties are matched across different materials. .