The design temperature is 538 degrees; it is highly toxic. How should the flanges for the equipment be selected?
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The design temperature is 538 degrees, the design pressure is 0.7 MPa; the medium in question is highly hazardous. The diameter is DN2400. The equipment flanges are of type A flanges with wound gaskets, and the material used is 12Cr1MoV. Calculations were carried out using SW6. Are the type of flange and the chosen material appropriate? If it’s unreasonable, how should one choose? I hope experts can offer their guidance!
Flat welding flanges of type A also come in several sealing types: flat sealing surfaces and male-female sealing surfaces.
The flange material should be 15CrMoR; if forgings are used, WC6 should be chosen. It’s just because of the high temperature.
Refer to Appendix A of HGT20580 and Table 2 of NBT47020; using type A gaskets together with winding gaskets is not appropriate
There is no explicit requirement to use butt welding and gasketing for the equipment flanges; however, following the standards for pipe flanges, butt welding along with gasketing can be used... It depends on individual judgment
Butt weld flange, male-female or RJ face
If disassembly is not frequent, you can check whether the weld lip seal ring for steel pipe flanges specified in HG 20530-1992 meets your requirements; you can also find it by searching for \"weld lip\" on forums
For type A flanges, the operating temperature range is -20°C to 300°C according to NB/T47021, while for type B flanges, it is -20°C to 350°C according to NB/T47022. If the design temperature for your equipment is 538°C, then the operating temperature will not be too low. It is recommended that you use the NB/T47023 standard long-neck butt-weld flanges. If the strength calculations do not meet the requirements, then it will be necessary to design the flanges according to GB/T150 as non-standard flanges; such non-standard flanges are also based on the long-neck butt-weld flange design.