Can flat-weld flanges be used for gas pipelines?
Thread Content
This post was last edited by losren on 2015-10-23 at 16:59. Can flat welding flanges be used for gas pipelines? It is said that for highly toxic judu fluid pipelines, flat-welded flanges should not be used, and the flange pressure rating should not be lower than PN2.0MPa. Is gas considered a highly toxic poisonous substance? The actual operating pressure is less than 0.2 MPa.
It depends on what standards you use for your design; metallurgical standards can be applied.
Whether a flat-weld flange can be used is determined not solely by the medium, but mainly by the design pressure. Butt weld flanges are recommended
What kind of gas? If it’s the coke oven gas used in steel mills, then flat-weld flanges work fine; but if it’s the type of gas used for cooking at home, then they definitely won’t work
Yes, but only neck weld flat flanges can be used; plate weld flat flanges are not allowed! For detailed standards, please refer to 7.3.1c in SH3059: Plate flat welding flanges shall not be used for pipelines carrying toxic and flammable media
Gas pipelines are just a general term; it depends on the system they are used in. For example, in power plants, there are components related to high-pressure units, wastewater treatment, condensate treatment, and also fly ash systems. It’s still a broad category, but the specific applications vary – the pressure, the medium, temperature, etc., all differ. Based on what the original poster described, I think it can be used; I also supply butt-weld flanges for gas pipeline systems
Then you need to check which flange standard it is – whether it’s JB/T81-94 or HG20593-97.
This is a case of a misunderstanding; a flat welding flange refers to PL rather than SO. If a gas pipeline operates at a pressure below 1.0 MPa, it is not considered a pressure pipeline, and in such cases PL flanges can still be used