GB9118.1-2000 suddenly faced with welded neck ring with a loose set of steel pipe flange

This standard specifies a nominal pressure PN and 42.0MPa for the sudden 2.0,5.0,11.0,15.0,26.0 face welded neck ring with a loose set of steel pipe flange types and sizes.
This standard applies to nominal pressure PN2.0 ~ PN42.0MPa the face of sudden neck loose ring welded steel pipe flange cover。