skirt material
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The steel used in 6.2.2 of JB/T4710 for the skirt shell is selected according to the steel requirements for pressure components. According to this article, it is enough to choose the steel plate for the pressure vessel as long as the steel for the group seat shell is used. But I saw some drawings in which the equipment shell is made of stainless steel, and the group seats are made of steel plates for pressure vessels. However, the group seat shell in the section connected to the equipment shell is made of the same material as the equipment body, which is also stainless steel. I don't know what the benefits of this are, please discuss. Thank you. This post was last edited by brainandrain on 2009-4-16 19:52 ]
This section is called the transition section, which is to prevent the direct welding of the carbon steel skirt and the stainless steel shell from affecting the material properties of the shell. When the shell is made of low-temperature carbon steel or Cr-Mo low alloy steel, a transition section is generally added. This post was last edited by lxzzl on 2009-4-16 10:57 ]
The main considerations for setting up the transition section on the skirt of the stainless steel tower: 1. Avoid contamination of carbon steel materials with ferrous ions on stainless steel materials. The alloy elements of stainless steel materials at the joints will be diluted, resulting in a decrease in corrosion resistance. ； 2. Avoid excessive temperature difference stress. The linear expansion coefficients of stainless steel materials and carbon steel materials are very different. They are directly connected without a transition section. When the tower is working, the temperature difference stress will cause the skirt weld to bear the additional force caused by the different expansion amounts of the two materials, causing safety hazards to the tower. HG20652 has detailed requirements for the skirt transition section
The person above got to the point, let me add one more thing: When the equipment with a skirt requires overall heat treatment, a transition section must also be provided on the skirt.