This standard specifies the type and size of loose sleeve steel pipe flanges with tongue and groove facing welded ring plate with nominal pressure PN of 1.6, 2.5 and 4.0 MPa. This standard is applicable to loose-set steel pipe flanges with tongue-and-groove face-to-face welded ring plate with nominal pressure PN1.6~PN4.0MPa.
2011GB/T 9120-2010 Loose plate steel pipe flanges with weld-neck collar and with weld ring neck
2000GB/T 9120.3-2000 Loose plate steel pipe flanges with welding neck collar with tongue and groove face
GB/T 9120.3-2000 Loose plate steel pipe flanges with welding neck collar with tongue and groove face was changed to GB/T 9120-2010 Loose plate steel pipe flanges with weld-neck collar and with weld ring neck.