Leg calculation
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For the calculation of H-shaped steel supports, refer to the examples provided in JB/T4712.2-2007. The current design wall temperature for the cylinder is 250 degrees; what standard should be used to determine the allowable stress for these supports? It’s easy to find the required stress values for structural steel at normal temperatures, but what standard should be used for temperatures of 250 degrees? In the example, the stress required is only 105 MPa; then why is the stress required for bending 235 MPa? At room temperature, the allowable stress for Q235A structural steel is 215 MPa – so why is 235 MPa used in the example?
The allowable stress is an inherent property of the material; there is no need to look up the specific value for structural steel – simply use the value for Q235A material. Moreover, Q235A seems to have been phased out as a material for pressure-bearing components, so it is relatively difficult to find information on it. (I haven’t paid much attention to it.) And what was said upstairs is correct – the design temperature for the supports can be taken as room temperature ； 235MPa should be the yield limit.
For structural members, room-temperature yield strength is chosen as the allowable stress. In my opinion, a safety factor should be taken into account, such as 0.9 times the yield strength
A portion of the leg is directly welded to the cylinder wall, and this weld is the most critical shear weld; the design assumptions are conservative when normal temperature conditions are considered.
I don’t know where I can find the required stress for weld metal at corresponding temperatures
The required stress of the weld metal at the corresponding temperature? Isn’t it generally just the normal allowable stress multiplied by a certain coefficient? The allowable stress for bending being 235 MPa is probably due to the use of 1.5 times the allowable stress; the allowable stress for bending is slightly higher than that for shear