Differences between JB/T79.2-94 and JB/T82.2-94
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According to the standards, JB/T79.2-94 refers to flanges for integral cast steel pipes with male and female surfaces, while JB/T82.2-94 refers to flanges for welded steel pipes with male and female surfaces. I wonder what the difference is between a fully cast steel flange and a welded steel flange for flanged control valves? Aren’t butt-weld flanges and slip-weld flanges both considered integral flanges? Then why are there two separate standard numbers?
Integral cast steel pipe flanges are cast as a single piece, while butt-welded steel pipe flanges are forged.