Flange material issue
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If the flange material is specified as 20 on the drawing, does 20 refer to 20 (GB711) or 20 (JB4726)?
It doesn’t seem quite right to use this notation personally; let’s follow the standards required by flange instead.
When I first came here looking for a job, I chose flanges; they didn’t have to worry about the materials at all for me
If steel plates are used, it should be written as 20 (GB711); if forgings are used, it should also be written as 20 (GB711), with the forging grade added
This situation is often encountered on external drawings; it should be handled in accordance with the regulations of HG20603-97. Just decide which material to use based on what criteria are met. Hehe, those working in the manufacturing field need to pay attention to these.
This post was last edited by Pinocchio on 2009-5-27 at 17:37. If it is a forged part, specifying JB4726-2000 20II (if grade II forged parts meet the design requirements) will make things clearer. If it is a plate flange, 20 (GB711) should not be used for GB150 pressure vessels; it is not listed in Table 4-1 of GB150, and it lacks high-temperature mechanical properties, so the allowable stress at the design temperature cannot be determined.
I agree with what was said above; so far, I haven’t come across plate flanges made of 20-grade steel. It’s likely that the designer made a mistake when preparing the material list – forgings should have been used instead. Indicating something like 20+ along with the appropriate quality grade would make things clearer.
Flanges are generally forged parts, while GB711 is a material standard for steel plates.