Problems with the flange
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In JB4701, for a nominal diameter of 0.25 MPa up to 2000, why is it 0.6 MPa up to 1200, 1.0 MPa up to 900, and 1.6 MPa up to 650? In the heat exchanger design manual, the minimum design pressure for the tube sheet is 0.6, with a nominal diameter up to 2000. I have one with a pressure of 0.15, and the nominal diameter of the heat exchanger is 1900. How should I choose the tube sheet and flanges? This post was last edited by 0536dai on 2009-3-3 16:16.]
I think choosing 0.25 will work.
If JB4701 is to be used, only 0.25 MPa is permissible; select an appropriate material and consult the pressure-temperature chart to verify whether the maximum allowable operating pressure meets the requirements. If the requirements are not met, then either JB4702 must be used, or a non-standard option has to be employed.
When selecting standard flanges, in addition to considering pressure resistance, temperature and medium conditions should also be taken into account.
"In JB4701, for a nominal diameter of 0.25 MPa up to 2000, why is it 0.6 MPa up to 1200, 1.0 MPa up to 900, and 1.6 MPa up to 650? " It is related to the flange structure; the simpler the structure, the less it can withstand high pressures. For a detailed introduction, refer also to Chapter 9 on flanges in GB150. If you compare the standards such as JB4701-4703 for type A flat welding, type B flat welding, and welded flanges with necks, with the flange dimensions and pressure requirements you have, you will be able to identify the problem.
If the temperature and pressure are within the allowable range, choose the 0.25 MPa grade
You can check whether it meets the requirements specified in Table 6 for container flanges; if so, then 0.25 Mp can be used :)
First, select an appropriate material based on 0.25 MPa as specified in JB4701, and then verify whether the maximum allowable operating pressure at the highest operating temperature meets the requirements. If this requirement cannot be met, it can be increased to 0.6 MPa; the dimensions can only be determined by referring to relevant materials. Check the pressure again.