Should a transition zone be added for 20MnMo and Q345?
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Dear experts, the head material is 20MnMo forgings, while the skirt cylinder is made of Q345. The design temperature is 360° – is it necessary to add a transition section for the skirt? Can it still be welded directly?
I’ve seen that it’s specified in the design drawings for the complex – 20MnMo plates for the transition sections. It seems like a rather unnecessary measure; there might be some deeper reason behind it
Paragraph 1 of clause 5.4.4 a) of SH/T3098-2011 specifies explicitly that when the design temperature of the tower (or its bottom) is above 350°C, a skirt with a transition section shall be used.