Atmospheric pipelines for transporting extremely and highly hazardous media
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Can plate flat-welded flanges be used for atmospheric-pressure pipelines that transport extremely hazardous or highly dangerous media? For pipelines with larger diameters, can SY/T 5037 be applied as the standard, and can Q235B be used as the pipeline material?
Extremely, highly hazardous? Pipelines of GC-1 grade cannot use the standards you mentioned. Q235B should not be usable! Furthermore, plate-type butt welding cannot be used for flanges; at the very least, necked butt-welded flanges should be used!
A flanged pipe with a neck is required; Q235 pipes cannot be used. . . . . . . . . . . . . . .
Atmospheric pressure pipelines are not considered pressure pipelines, right? According to the definition of pressure pipelines, the maximum operating pressure must be greater than 0.1 MPa; therefore, they certainly cannot be classified as GC1(1).
If the diameter does not exceed DN25, it is not considered a pressure pipeline either! Following your approach, it can be used freely..... but in some relatively hazardous medium conditions, designers usually prefer to connect all pipes and fittings of this grade using welding methods in order to prevent leaks. Rules are rigid, but people are flexible; as long as you feel confident, go ahead and use them. Anyway, you followed the guidelines! ;P
The medium specified for use in the new version of SY/T 5037 states that it cannot be used with flammable media