Skirt barrel transition section material
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The tower vessel standards stipulate that the materials for the skirt are divided into materials for the transition section and materials for the body. The material of the transition section should be consistent with the material of the welded tower shell. If the tower shell material is Q345R and the skirt shell material is Q235B, is it necessary to add a transition section made of Q345R material?
The transition section must be added, mainly due to the strength of the weld. The support standards require that the backing plate must be made of the same material as the main pressure component, and the skirt is no exception.
This post was last edited by jizhanwei22 on 2017-2-10 15:36. Whether it is necessary to set up a transition section, generally the following two requirements need to be met.: 1. The design temperature of the tower is higher than 350℃ or lower than -20℃℃ ； 2. The welding of the skirt shell and the tower body may affect the material properties of the tower body (head) (for example, the tower material is low-temperature steel, chromium-molybdenum steel or stainless steel). Therefore, I judge that the tower mentioned by the poster does not need to be equipped with a transition section, unless the design temperature of the tower exceeds 350°C or is lower than -20°C. For details, please refer to Article 5.4.4 of SH/T3098-2011
Looking at the explanations of the standard definitions, not all transition paragraphs are required, but there is a problem with the description in the standard text.
If the strength and operating temperature meet the requirements, Q345R can be welded with the Q235B skirt without transition.