Flat welding flanges with necks cannot be used for pipes at temperatures above 200 degrees
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According to GB/T20801.1-2025, flat welding flanges with necks cannot be used on pipelines operating at temperatures above 200 degrees. Is it really necessary to do this?
I understand the OP’s question now! In accordance with the provisions of this standard, flanges with a neck for butt welding indeed have a working temperature range of -46°C to 200°C, and they are intended solely for transporting non-flammable and non-explosive media; conditions above 200°C are indeed not suitable for using such flanges. However, for the selection of flanges for such industrial pipelines, it is recommended to carefully check the latest official national standards or consult professional process designers to ensure accuracy and avoid mistakes in the selection~
Item C of 6.3.8.4d is based on calculations or draws upon foreign standards; some domestic codes specify an upper limit for operating temperature that is higher than this standard.
GB/T20801.1-2025 is a standard for pressure pipelines; regarding such pipelines, aside from TS31-2025, it is essentially superior to all flange standards (HG/T20592, SH/T3406, GB/T9124.1). Under this standard, the special inspection authorities do not accept the material/temperature selection criteria specified in those three other standards
How was the material chosen?