For a Class 2 pressure vessel made of 304 material, if the manhole is lined, is heat treatment required?
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For a Class 2 pressure vessel made of 304 material, with a design pressure of 2.4 MpaG and a diameter of 1.6 meters, the manhole with DN600 size is lined; the flange is made of 16Mn forgings with a 304 lining, while the flange cover is made of Q345R with a 304 lining. Is heat treatment required?
The conditions you provided are not sufficient to determine whether post-weld heat treatment is required; the design drawings will indicate this.
Given this structure, heat treatment is generally not required; of course, that’s different if there’s a design error. Reason: In terms of the medium, carbon steel used for extremely hazardous media requires heat treatment; however, such extremely hazardous media cannot use lining structures. Therefore, the equipment in question is likely to handle media of moderate hazard level or lower, and thus does not require heat treatment ； From the perspective of the bushing structure, it is not suitable for heat treatment, as there is a risk of weld cracking.
This design style has a bit of a small-scale factory vibe