1. The carbon steel forgings with the nominal pressure from 0.25Mpa to 1.0Mpa and the austenitic stainless steel forgings should comply with the JB4730 I degree standard.
2. The forge piece with the nominal pressure from 1.6Mpa to 6.3Mpa should comply with the JB4730Ⅱdegree or higher standard.
3. The forge piece belongs to the following conditions should comply with the JB4730 Ⅲ degree standard.
(1) Forge piece for flange (PN≥10.0MPa)
(2) Cr-Mo alloy steel forge piece (PN>4.0MPa)
(3) Ferrite steel forge piece (PN>1.6MPa, working temperature no higher than -20 Celsius degrees)